This document discusses reactions of proteins involved in food processing. It describes various enzyme-catalyzed reactions like those involving serine, cysteine, metallo and aspartic endopeptidases. It also discusses chemical and enzymatic modifications of proteins for food processing, including succinylation, reductive methylation, and disulfide bond reduction/reoxidation. The enzymatic plastein reaction is described which joins peptide fragments through peptide bonds. Overall, the document provides an overview of reactions and modifications that can change protein properties for uses in food processing.
This document discusses different types of browning reactions that can occur in food, including enzymatic and non-enzymatic browning. It describes two main types of non-enzymatic browning reactions: caramelization which occurs when sugars are heated and Maillard browning which involves sugars and amino acids. Enzymatic browning is caused by polyphenol oxidase enzymes and phenolic compounds interacting with oxygen. Methods to prevent enzymatic browning discussed include maintaining an acid pH, using sulphur or antioxidants, reducing oxygen contact, and denaturing enzymes through blanching.
Proteins are complex polymers made up of amino acids linked by peptide bonds. They serve essential biological functions including catalyzing biochemical reactions as enzymes, transporting molecules, providing structure, and more. This document provides an introduction to food proteins and enzymes, discussing their importance, classification, sources, and functions. It defines proteins and enzymes, explains their roles in biological systems, and outlines the key amino acids that make up proteins.
This document discusses the chemical and physical properties of oils and fats. It begins by describing the structures of lipids and fatty acids, including saturated and unsaturated varieties. It then covers the chemical and biological synthesis of fatty acids. The physical properties of oils and fats are influenced by their fatty acid compositions. Chemical properties include hydrolysis, saponification, halogenation, and oxidation (rancidity). Preventing rancidity involves controlling exposure to light, oxygen, moisture, and bacteria.
The document discusses the process of making protein isolates and concentrates from various sources such as soy, whey, peanuts, and fish. Protein isolates have a very high protein content (over 90%) and are refined to remove carbohydrates and fiber. Protein concentrates contain some carbohydrates and have a protein content over 80%. Common methods for extracting and purifying proteins include isoelectric precipitation, alkaline extraction, and ultrafiltration. Specific examples of production processes are provided for whey protein isolates, fish protein isolates, peanut protein isolates, and soy protein isolates and concentrates.
Fatty acids are basic building blocks of lipids and are amphipathic molecules containing an even number of carbon atoms. They can be classified as saturated, monounsaturated, or polyunsaturated depending on whether they contain single or multiple carbon-carbon double bonds. Long-chain fatty acids are found in meats and fish while medium-chain fatty acids are found in coconut oil. Fatty acids play important roles in cell membranes and producing hormones and are obtained through the diet as essential fatty acids like omega-3 and omega-6 fatty acids. However, high intakes of trans fats and saturated fats can increase health risks such as cancer, heart disease, and diabetes.
This document summarizes the two main types of browning reactions: non-enzymatic and enzymatic. Non-enzymatic browning includes caramelization of sugars with heat and the Maillard reaction between sugars and amino acids. Enzymatic browning is caused by polyphenol oxidase enzymes acting on phenolic compounds in fruits and vegetables when exposed to oxygen. Methods to prevent enzymatic browning include maintaining an acidic pH, using sulfites or antioxidants, reducing oxygen contact, and denaturing the enzymes through blanching.
This document discusses the physico-chemical properties of proteins under two main sections: physical properties and chemical reactions. The physical properties section describes 5 sub-properties: dissociation, optical activity, solubility/hydration/swelling, foam formation and stabilization, and emulsifying effect. The chemical reactions section lists 7 amino acid residues that proteins can undergo chemical modifications with: arginine, glutamic/aspartic acid, cystine, cysteine, methionine, histidine, and tyrosine. Protein properties and reactions are important for understanding protein structure, function, and applications in food processing.
This document discusses non-enzymatic browning in foods. It describes the main types of non-enzymatic browning reactions, including the Maillard reaction, caramelization, ascorbic acid browning, and metal-polyphenol browning. It also outlines factors that influence the Maillard reaction such as temperature, pH, water activity, and methods for preventing non-enzymatic browning including controlling environmental conditions and using preservatives like sulfur dioxide.
This document discusses different types of browning reactions that can occur in food, including enzymatic and non-enzymatic browning. It describes two main types of non-enzymatic browning reactions: caramelization which occurs when sugars are heated and Maillard browning which involves sugars and amino acids. Enzymatic browning is caused by polyphenol oxidase enzymes and phenolic compounds interacting with oxygen. Methods to prevent enzymatic browning discussed include maintaining an acid pH, using sulphur or antioxidants, reducing oxygen contact, and denaturing enzymes through blanching.
Proteins are complex polymers made up of amino acids linked by peptide bonds. They serve essential biological functions including catalyzing biochemical reactions as enzymes, transporting molecules, providing structure, and more. This document provides an introduction to food proteins and enzymes, discussing their importance, classification, sources, and functions. It defines proteins and enzymes, explains their roles in biological systems, and outlines the key amino acids that make up proteins.
This document discusses the chemical and physical properties of oils and fats. It begins by describing the structures of lipids and fatty acids, including saturated and unsaturated varieties. It then covers the chemical and biological synthesis of fatty acids. The physical properties of oils and fats are influenced by their fatty acid compositions. Chemical properties include hydrolysis, saponification, halogenation, and oxidation (rancidity). Preventing rancidity involves controlling exposure to light, oxygen, moisture, and bacteria.
The document discusses the process of making protein isolates and concentrates from various sources such as soy, whey, peanuts, and fish. Protein isolates have a very high protein content (over 90%) and are refined to remove carbohydrates and fiber. Protein concentrates contain some carbohydrates and have a protein content over 80%. Common methods for extracting and purifying proteins include isoelectric precipitation, alkaline extraction, and ultrafiltration. Specific examples of production processes are provided for whey protein isolates, fish protein isolates, peanut protein isolates, and soy protein isolates and concentrates.
Fatty acids are basic building blocks of lipids and are amphipathic molecules containing an even number of carbon atoms. They can be classified as saturated, monounsaturated, or polyunsaturated depending on whether they contain single or multiple carbon-carbon double bonds. Long-chain fatty acids are found in meats and fish while medium-chain fatty acids are found in coconut oil. Fatty acids play important roles in cell membranes and producing hormones and are obtained through the diet as essential fatty acids like omega-3 and omega-6 fatty acids. However, high intakes of trans fats and saturated fats can increase health risks such as cancer, heart disease, and diabetes.
This document summarizes the two main types of browning reactions: non-enzymatic and enzymatic. Non-enzymatic browning includes caramelization of sugars with heat and the Maillard reaction between sugars and amino acids. Enzymatic browning is caused by polyphenol oxidase enzymes acting on phenolic compounds in fruits and vegetables when exposed to oxygen. Methods to prevent enzymatic browning include maintaining an acidic pH, using sulfites or antioxidants, reducing oxygen contact, and denaturing the enzymes through blanching.
This document discusses the physico-chemical properties of proteins under two main sections: physical properties and chemical reactions. The physical properties section describes 5 sub-properties: dissociation, optical activity, solubility/hydration/swelling, foam formation and stabilization, and emulsifying effect. The chemical reactions section lists 7 amino acid residues that proteins can undergo chemical modifications with: arginine, glutamic/aspartic acid, cystine, cysteine, methionine, histidine, and tyrosine. Protein properties and reactions are important for understanding protein structure, function, and applications in food processing.
This document discusses non-enzymatic browning in foods. It describes the main types of non-enzymatic browning reactions, including the Maillard reaction, caramelization, ascorbic acid browning, and metal-polyphenol browning. It also outlines factors that influence the Maillard reaction such as temperature, pH, water activity, and methods for preventing non-enzymatic browning including controlling environmental conditions and using preservatives like sulfur dioxide.
food and water, Food Chemistry, Constituent of foods i.e water carbohyfrate l...Muhammad Naveed Laskani
food and water, Food Chemistry, Constituent of foods i.e water carbohyfrate lipid protein vitamin inorganic material other substances Physical property of water
This document discusses lipid oxidation, which refers to the process by which fats react with oxygen and produce undesirable products. The mechanism of lipid oxidation involves three phases - initiation, propagation, and termination. Initiation involves the formation of free radicals from lipids reacting with reactive oxygen species. Propagation consists of a series of free radical chain reactions where new free radicals are formed. Termination occurs when free radicals combine or convert to non-radical products. Lipid oxidation can be influenced by factors like fatty acid composition, oxygen levels, prooxidants, antioxidants, and processing/storage conditions. It can produce toxic compounds that damage DNA and proteins, potentially leading to health issues like cancer. Antioxidants help inhibit lipid oxidation and
This document discusses the classification and structure of proteins. It describes the four levels of protein structure: primary, secondary, tertiary, and quaternary. The primary structure is the linear sequence of amino acids. The secondary structure involves local folding patterns stabilized by hydrogen bonds. The tertiary structure is the overall three-dimensional shape of a protein determined by interactions between amino acid side chains. Quaternary structure refers to the arrangement of multiple protein subunits. The document also categorizes proteins based on their biological functions and physical properties.
This document discusses different types of milk products in India. It begins by defining milk and noting that India is the largest producer of milk globally. It then describes several processed milk products including standardized milk, homogenized milk, sterilized milk, flavored milk, toned milk, and double toned milk. For each product, it provides details on the processing involved, standards required, and flows of production. Formulas and processes like Pearson's square for standardization and homogenization equipment are outlined.
Most of the carbohydrates in nature is present as polysaccharides.
These are high molecular weight substances containing large number of monosaccharide units.
Consist of primary chain, in some; branched chains may exist.
This document discusses rancidity and lipid peroxidation. It defines rancidity as the natural decomposition of fats and oils through hydrolysis and oxidation. This process degrades lipids and leads to unpleasant smells and tastes. There are three main types of rancidity: oxidative, hydrolytic, and microbial. Lipid peroxidation is the main cause of rancidity and occurs in three stages - initiation, propagation, and termination. Rancid food can cause health issues like deficiencies, kidney/heart disease, and cancer. The document also discusses ways to measure, prevent, and reduce rancidity and lipid peroxidation through antioxidants and proper food storage and handling.
This document provides information on the functions, properties, and importance of lipids. It begins by discussing the structure of lipids and classification of fatty acids. It then covers various chemical properties of lipids including hydrolysis, saponification, hydrogenation, and rancidity. Physical properties such as hydrophobicity and melting points are also described. The functions of saturated, unsaturated, and essential lipids are outlined. Finally, the structural, clinical, and disease importance of lipids is summarized, highlighting their roles in cell membranes, energy storage, insulation, and brain injury/lipidosis.
The document discusses the functional properties of proteins in foods. It begins by defining functionality as any non-nutritive property that influences an ingredient's usefulness. It then identifies three main groups of functional properties: hydration properties related to protein-water interactions like solubility and viscosity; properties related to protein-protein interactions like gelation and dough formation; and surface properties involved in emulsification and foaming. Specific examples covered include the role of proteins in viscosity, gelation, emulsions, foams, and dough formation. The document concludes by noting how extrusion and enzymatic hydrolysis can alter soy protein properties.
Changes occur to fats during food processing and cooking. Heating fats can cause randomization of glyceride structure, dimer formation, cis-trans isomerization, and formation of conjugated fatty acids. Specific processes like hydrogenation, interesterification, and deodorization further impact fat composition. Deep frying is high heat cooking that promotes reactions like oxidation, leading to rancidity over time. Thermal properties like smoke point are important considerations for fat selection in cooking.
This document summarizes various reactions of carbohydrates including monosaccharides, disaccharides, and polysaccharides. It describes reactions such as reduction, oxidation, acetylation, methylation, hydrolysis, nitration, and color reactions used to identify different carbohydrate types. Specific monosaccharides discussed include glucose and fructose, and disaccharides discussed include sucrose and lactose. Polysaccharides discussed include starch and cellulose.
This document discusses carbohydrates, including their functions as an energy source, how they are broken down, and types such as starch, fiber, and modified starch. It also provides instructions for a task to design a macaroni and cheese product for children that is high in calcium, has a garnish, increases fiber content, and uses a roux sauce method.
Amino acids have several key properties:
1. They are amphoteric, taking on positive, negative, or neutral charges depending on pH. Their isoelectric point is when the net charge is neutral.
2. They have acidic and basic groups that allow them to undergo various chemical reactions like esterification, acylation, and reactions with carbonyl compounds.
3. When heated to high temperatures during cooking, amino acids can form mutagenic and potentially toxic compounds like acrylamide or heterocyclic amines. The Maillard reaction and Strecker degradation play important roles in these processes.
This document provides an introduction to food analysis. It discusses trends in consumer demand for safe, nutritious foods and the food industry's role in meeting these demands. Reasons for analyzing foods include government regulations, quality control, and characterizing raw materials, finished products, and properties during processing. The document outlines various standards and describes analyzing foods to ensure safety, authenticity, and other quality attributes. It also covers selecting appropriate analytical techniques and methods based on criteria like accuracy, cost, and applicability to different food matrices and properties.
This document discusses different types of browning reactions that can occur in foods, including enzymatic and non-enzymatic browning. Non-enzymatic browning includes caramelization, which occurs when sugars are heated and undergo a series of reactions to turn brown. It also includes Maillard browning, which is the reaction between reducing sugars and amino acids or proteins. Enzymatic browning is caused by phenolase enzymes and can be prevented by maintaining an acid pH, using sulfites or antioxidants, reducing oxygen contact, or blanching to denature the enzymes.
Pigments are responsible for the color of many foods. The main pigments in plants are chlorophylls, carotenoids, anthocyanins, and anthoxanthins. Chlorophyll gives greens their color but breaks down during cooking, turning vegetables olive green. Anthocyanins provide red, blue, and purple colors in fruits and vegetables. They leach out during cooking and their color changes with pH. Anthoxanthins are yellow pigments that may turn foods pink. Tannins contribute to colors and astringency. Cooking and pH affect the colors from many natural pigments in foods.
Starch is present in plant cells and contains two types of polysaccharides: amylose and amylopectin. Amylose is an unbranched molecule made of glucose units linked by alpha-1,4 glycosidic bonds that forms helical structures. Amylopectin is a branched molecule with chains of glucose units linked by alpha-1,4 and alpha-1,6 glycosidic bonds that prevents helix formation. When starch is heated in water, the individual granules absorb water and swell in a process called gelatinization which causes thickening. Upon cooling, the starch undergoes retrogradation where the molecules realign into a crystalline structure which can expel water from the gel in a process called
This slide will help you to understand about chemical reactions of monosaccharides and Disaccharides. The carbohydrate can can undergo several reactions like oxidation, reduction, esterification, dehydration and tautomerization to give various products.
Food Chemistry is the study of chemical processes and interactions of all biological and non- biological components of foods.
It covers the basic composition, structure and properties of foods and the chemistry changes occurring during processing and utilization.
It also covers the chemistry of water, carbohydrates, proteins, lipids, vitamins, minerals and enzymes
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food and water, Food Chemistry, Constituent of foods i.e water carbohyfrate l...Muhammad Naveed Laskani
food and water, Food Chemistry, Constituent of foods i.e water carbohyfrate lipid protein vitamin inorganic material other substances Physical property of water
This document discusses lipid oxidation, which refers to the process by which fats react with oxygen and produce undesirable products. The mechanism of lipid oxidation involves three phases - initiation, propagation, and termination. Initiation involves the formation of free radicals from lipids reacting with reactive oxygen species. Propagation consists of a series of free radical chain reactions where new free radicals are formed. Termination occurs when free radicals combine or convert to non-radical products. Lipid oxidation can be influenced by factors like fatty acid composition, oxygen levels, prooxidants, antioxidants, and processing/storage conditions. It can produce toxic compounds that damage DNA and proteins, potentially leading to health issues like cancer. Antioxidants help inhibit lipid oxidation and
This document discusses the classification and structure of proteins. It describes the four levels of protein structure: primary, secondary, tertiary, and quaternary. The primary structure is the linear sequence of amino acids. The secondary structure involves local folding patterns stabilized by hydrogen bonds. The tertiary structure is the overall three-dimensional shape of a protein determined by interactions between amino acid side chains. Quaternary structure refers to the arrangement of multiple protein subunits. The document also categorizes proteins based on their biological functions and physical properties.
This document discusses different types of milk products in India. It begins by defining milk and noting that India is the largest producer of milk globally. It then describes several processed milk products including standardized milk, homogenized milk, sterilized milk, flavored milk, toned milk, and double toned milk. For each product, it provides details on the processing involved, standards required, and flows of production. Formulas and processes like Pearson's square for standardization and homogenization equipment are outlined.
Most of the carbohydrates in nature is present as polysaccharides.
These are high molecular weight substances containing large number of monosaccharide units.
Consist of primary chain, in some; branched chains may exist.
This document discusses rancidity and lipid peroxidation. It defines rancidity as the natural decomposition of fats and oils through hydrolysis and oxidation. This process degrades lipids and leads to unpleasant smells and tastes. There are three main types of rancidity: oxidative, hydrolytic, and microbial. Lipid peroxidation is the main cause of rancidity and occurs in three stages - initiation, propagation, and termination. Rancid food can cause health issues like deficiencies, kidney/heart disease, and cancer. The document also discusses ways to measure, prevent, and reduce rancidity and lipid peroxidation through antioxidants and proper food storage and handling.
This document provides information on the functions, properties, and importance of lipids. It begins by discussing the structure of lipids and classification of fatty acids. It then covers various chemical properties of lipids including hydrolysis, saponification, hydrogenation, and rancidity. Physical properties such as hydrophobicity and melting points are also described. The functions of saturated, unsaturated, and essential lipids are outlined. Finally, the structural, clinical, and disease importance of lipids is summarized, highlighting their roles in cell membranes, energy storage, insulation, and brain injury/lipidosis.
The document discusses the functional properties of proteins in foods. It begins by defining functionality as any non-nutritive property that influences an ingredient's usefulness. It then identifies three main groups of functional properties: hydration properties related to protein-water interactions like solubility and viscosity; properties related to protein-protein interactions like gelation and dough formation; and surface properties involved in emulsification and foaming. Specific examples covered include the role of proteins in viscosity, gelation, emulsions, foams, and dough formation. The document concludes by noting how extrusion and enzymatic hydrolysis can alter soy protein properties.
Changes occur to fats during food processing and cooking. Heating fats can cause randomization of glyceride structure, dimer formation, cis-trans isomerization, and formation of conjugated fatty acids. Specific processes like hydrogenation, interesterification, and deodorization further impact fat composition. Deep frying is high heat cooking that promotes reactions like oxidation, leading to rancidity over time. Thermal properties like smoke point are important considerations for fat selection in cooking.
This document summarizes various reactions of carbohydrates including monosaccharides, disaccharides, and polysaccharides. It describes reactions such as reduction, oxidation, acetylation, methylation, hydrolysis, nitration, and color reactions used to identify different carbohydrate types. Specific monosaccharides discussed include glucose and fructose, and disaccharides discussed include sucrose and lactose. Polysaccharides discussed include starch and cellulose.
This document discusses carbohydrates, including their functions as an energy source, how they are broken down, and types such as starch, fiber, and modified starch. It also provides instructions for a task to design a macaroni and cheese product for children that is high in calcium, has a garnish, increases fiber content, and uses a roux sauce method.
Amino acids have several key properties:
1. They are amphoteric, taking on positive, negative, or neutral charges depending on pH. Their isoelectric point is when the net charge is neutral.
2. They have acidic and basic groups that allow them to undergo various chemical reactions like esterification, acylation, and reactions with carbonyl compounds.
3. When heated to high temperatures during cooking, amino acids can form mutagenic and potentially toxic compounds like acrylamide or heterocyclic amines. The Maillard reaction and Strecker degradation play important roles in these processes.
This document provides an introduction to food analysis. It discusses trends in consumer demand for safe, nutritious foods and the food industry's role in meeting these demands. Reasons for analyzing foods include government regulations, quality control, and characterizing raw materials, finished products, and properties during processing. The document outlines various standards and describes analyzing foods to ensure safety, authenticity, and other quality attributes. It also covers selecting appropriate analytical techniques and methods based on criteria like accuracy, cost, and applicability to different food matrices and properties.
This document discusses different types of browning reactions that can occur in foods, including enzymatic and non-enzymatic browning. Non-enzymatic browning includes caramelization, which occurs when sugars are heated and undergo a series of reactions to turn brown. It also includes Maillard browning, which is the reaction between reducing sugars and amino acids or proteins. Enzymatic browning is caused by phenolase enzymes and can be prevented by maintaining an acid pH, using sulfites or antioxidants, reducing oxygen contact, or blanching to denature the enzymes.
Pigments are responsible for the color of many foods. The main pigments in plants are chlorophylls, carotenoids, anthocyanins, and anthoxanthins. Chlorophyll gives greens their color but breaks down during cooking, turning vegetables olive green. Anthocyanins provide red, blue, and purple colors in fruits and vegetables. They leach out during cooking and their color changes with pH. Anthoxanthins are yellow pigments that may turn foods pink. Tannins contribute to colors and astringency. Cooking and pH affect the colors from many natural pigments in foods.
Starch is present in plant cells and contains two types of polysaccharides: amylose and amylopectin. Amylose is an unbranched molecule made of glucose units linked by alpha-1,4 glycosidic bonds that forms helical structures. Amylopectin is a branched molecule with chains of glucose units linked by alpha-1,4 and alpha-1,6 glycosidic bonds that prevents helix formation. When starch is heated in water, the individual granules absorb water and swell in a process called gelatinization which causes thickening. Upon cooling, the starch undergoes retrogradation where the molecules realign into a crystalline structure which can expel water from the gel in a process called
This slide will help you to understand about chemical reactions of monosaccharides and Disaccharides. The carbohydrate can can undergo several reactions like oxidation, reduction, esterification, dehydration and tautomerization to give various products.
Food Chemistry is the study of chemical processes and interactions of all biological and non- biological components of foods.
It covers the basic composition, structure and properties of foods and the chemistry changes occurring during processing and utilization.
It also covers the chemistry of water, carbohydrates, proteins, lipids, vitamins, minerals and enzymes
fb.com/careeratfoodscience
This document discusses the classification and properties of proteins. It describes four levels of protein structure: primary, secondary, tertiary, and quaternary. Proteins can also be classified by their biological function, which includes enzymes, transport proteins, storage proteins, contractile/motile proteins, structural proteins, defense proteins, regulatory proteins, and other functional proteins. Classification by shape and solubility includes fibrous, globular, and membrane proteins. Classification by composition distinguishes between simple and conjugated proteins. Nutritionally, proteins are either complete or incomplete. The document concludes by discussing properties like denaturation and its causes like heat, alcohol, acids, bases, and heavy metal salts.
You will know up to date of protein discovery within the shortest form as possible. It is made for an assignment, but I tried to make it aesthetic as possible!
Protein Detection Methods and Applicationangelsalaman
The document discusses various protein analysis methods including gel electrophoresis, SDS-PAGE, and native gel electrophoresis. Gel electrophoresis separates proteins, DNA, and RNA using an electric current applied to a gel matrix. SDS-PAGE separates denatured proteins by size, coating them with negative charges. Native gel electrophoresis separates intact proteins by their intrinsic charge and hydrodynamic size, allowing analysis of conformation, aggregation, and binding events.
Proteins are composed of amino acids and play many essential roles in the body. They have four levels of structure: primary, secondary, tertiary, and quaternary. The primary structure is the amino acid sequence, secondary involves hydrogen bonding into shapes like alpha helices and beta sheets, tertiary is the 3D folding of these structures, and quaternary involves the assembly of multiple protein subunits. Proteins serve as enzymes, hormones, antibodies, and structures. They undergo synthesis from amino acids and breakdown through catabolism. Disorders can occur if amino acid metabolism is disrupted.
This document discusses the different levels of protein structure: primary, secondary, tertiary, and quaternary. The primary structure refers to the amino acid sequence. Secondary structure includes alpha helices, beta sheets, and beta turns formed by hydrogen bonding between amino acids. Tertiary structure is the 3D conformation determined by interactions between side chains. Quaternary structure refers to the arrangement of multiple polypeptide subunits in multimeric proteins. The structures are determined through techniques like X-ray crystallography and NMR.
The document discusses the levels of protein structure from primary to quaternary structure. It defines the primary structure as the amino acid sequence. Secondary structure forms from hydrogen bonding between amino acids and includes alpha helices and beta pleated sheets. Tertiary structure results from folding influenced by interactions between amino acid side chains. Quaternary structure occurs when multiple polypeptide chains interact to form a protein complex. Examples including hemoglobin and glyceraldehyde-3-phosphate dehydrogenase are provided to illustrate the different levels of structure.
The document discusses the structure and formation of proteins. It explains that amino acids join through condensation reactions to form peptide bonds, releasing a water molecule. Multiple peptide bonds form polypeptide chains of varying lengths that fold into unique 3D shapes to serve as functional proteins, such as structural, storage, transport, hormonal, receptor, contractile, defensive, and enzymatic proteins. Common food sources of protein are also mentioned.
The document discusses various methods of food preservation, including drying, commercial drying methods like freeze-drying and osmotic drying, curing using salt and drying, fermentation, pickling using vinegar, using edible coatings, canning which involves heating sealed containers, refrigeration, freezing, and pasteurization which heats liquids to kill microorganisms. It also covers types of food spoilage from biological, chemical and physical changes and how different preservation methods address these changes.
The document provides information about amino acids and their classification. It discusses that amino acids are the monomer units that make up protein polymers. They can be classified based on their structure, side chains, nutritional requirements, and metabolic fate. The 20 standard amino acids are discussed in detail, including their physical and chemical properties. Key reactions of amino acids involving their amino, carboxyl, and side chain groups are also summarized.
This document discusses amino acids and protein analysis. It defines amino acids as aminated carboxylic acids and classifies them in several ways, such as by the location of their amino group or polarity of their R group. Proteins are defined as polymers of 20 amino acids with molecular weights ranging from 5000 to 1000,000 daltons. The document provides protein content percentages for various foods like cereals, legumes, fruits/vegetables, dairy products and meats. It also discusses the Kjeldahl method for determining protein content, which involves digesting samples, distilling released ammonia into boric acid and titrating with acid.
General Reactions involved in amino acid metabolismDhiraj Trivedi
1. The document discusses various reactions involved in amino acid metabolism including deamination, desulfuration, transamination, and transmethylation.
2. Deamination is the removal of the amino group from an amino acid, which can occur oxidatively or non-oxidatively. Oxidative deamination uses amino acid oxidases and releases ammonia and hydrogen peroxide.
3. Transamination is the reversible transfer of the amino group between amino acids and alpha-keto acids, producing new amino acids and keto acids. It requires pyridoxal phosphate and does not release free ammonia.
Ninhydrin is a chemical that detects free amines by producing a purple color when reacted with proteins or amino acids. The document describes an experiment where albumin, gelatin, and pepton were each reacted with ninhydrin solution and heated, producing a purple color in all three trials, indicating the presence of free amino acids. The conclusion is that the ninhydrin test resulted in a positive reaction for albumin, gelatin, and pepton, showing there are free amino acids present.
Lipids are a heterogeneous group of organic compounds that are insoluble in water but soluble in organic solvents. They serve many important functions in the body including as structural components of cell membranes, storage of metabolic energy, transport of fat-soluble vitamins and hormones, and protection and insulation. Lipids are classified based on the presence or absence of glycerol and other components. Major classes of lipids include fatty acids, triglycerides, phospholipids, sphingolipids, sterols such as cholesterol and vitamin D, and other compounds like prostaglandins.
This document discusses protein denaturation, which is defined as any change that alters a protein's unique 3D structure without breaking peptide bonds. Denaturation can be caused by heat, acids, bases, detergents, or other physical and chemical factors. It disrupts secondary, tertiary, and quaternary protein structures but not the primary amino acid sequence. Denatured proteins lose biological activity and may aggregate. In some cases denaturation can be reversed but often it is permanent.
This document discusses the chemistry of proteins and amino acids. It begins by explaining that proteins are abundant organic molecules that make up 50% of cellular mass and are essential for structure and function. The document then goes into detail about the classification, structure, properties and roles of the 20 standard amino acids that make up proteins. It describes how amino acids combine through peptide bonds to form polypeptide chains and proteins. The document provides a comprehensive overview of the biochemistry of proteins and amino acids.
The document summarizes the mechanism of protein folding in 3 sentences:
Protein folding is the physical process by which a polypeptide folds into its characteristic three-dimensional structure, driven by hydrophobic amino acids forming a core shielded from water and polar residues interacting with surrounding water. Key factors that stabilize the folded state include intramolecular hydrogen bonds and hydrophobic interactions. Molecular chaperones assist in protein folding in the crowded intracellular environment to prevent misfolding and aggregation.
The document discusses protein folding and the Ramachandran plot. It describes how proteins fold into unique 3D structures determined by their amino acid sequence. This folding occurs very quickly, within milliseconds. The Ramachandran plot, developed by G.N. Ramachandran, maps allowed phi and psi torsion angles for protein backbone conformation. It has been fundamental to understanding protein structure. The document also outlines protein structure levels from primary to quaternary, common secondary structures like alpha helices and beta sheets, and models of the protein folding process.
This document discusses protein reactions that occur during food processing. It covers both enzyme-catalyzed and chemical reactions that proteins undergo, including proteolytic enzymes like serine and cysteine endopeptidases. Specific modifications are described, such as the Maillard reaction and changes induced by heat, pH, oxidation. Controlling these reactions through processing conditions and enzymes is important for food properties and safety.
Peptides are short chains of amino acids linked by peptide bonds. They are distinguished from proteins by typically containing fewer than 50 amino acid units. Peptides are formed through condensation reactions between carboxyl and amino groups of separate amino acids, releasing a water molecule. Peptide bonds are rigid and planar, contributing to protein structure stability. Peptides serve many important biological functions and can be classified based on their production method, including through ribosomal translation, nonribosomal synthesis, and enzymatic digestion of proteins in foods. Bioactive peptides derived from food proteins can have beneficial effects like lowering blood pressure, cholesterol, and antimicrobial properties.
This document provides an overview of peptides. It defines peptides as short chains of amino acids linked by peptide bonds. Peptides are distinguished from proteins based on their smaller size, typically containing fewer than 50 amino acid units. The document discusses peptide bond formation, characteristics of peptide bonds, classes of peptides, physical properties, examples of individual peptides, food-derived peptides with biological activity, and applications of peptides in molecular biology.
Food-Enzyme.present in food and classificationJuttSab15
This document provides information about enzymes and their properties and uses in food chemistry. It defines enzymes as biological catalysts that are usually proteins and contain an active site. It describes different types of enzymes including hydrolases, oxidoreductases, transferases, lyases, isomerases and ligases. Specific enzymes are discussed like amylases, lipases, proteases, and oxidoreductases. The uses of these enzymes in food applications such as bread making, cheese production, fruit juice clarification are outlined. The document also covers enzyme classification systems and factors that influence enzyme reaction rates.
This document discusses amino acids and proteins. It defines amino acids as molecules containing an amino group and a carboxyl group. Amino acids are the building blocks of proteins. Most proteins are made of L-α amino acids joined by peptide bonds. The document classifies amino acids, discusses their structures and functions, and explains how they are joined together to form proteins through different levels of protein structure.
Enzymes are biological catalysts produced by living organisms that speed up chemical reactions without being consumed. They are proteins that contain an active site that binds to specific substrates to catalyze reactions. Enzymes can be classified based on the type of reaction they catalyze or their site of action. Common digestive enzymes include pepsin in the stomach, trypsin in the small intestine, and enzymes from papaya and pineapple such as papain and bromelain which are used to tenderize meat and reduce inflammation.
This document discusses amino acids, peptides, and proteins. It begins by defining them as monomers (amino acids), polymers of a few monomers (peptides), and polymers of many monomers (proteins). It then covers the structures and properties of amino acids, including the 20 that are found in proteins. Peptide bond formation is explained as linking amino acids together. Various proteins are classified and examples given, including simple proteins like albumins and globulins, and structural proteins like keratins, collagens, and elastins. The roles and importance of proteins in the body are also summarized.
Proteins are macromolecules made of amino acid polymers known as polypeptide chains. The sequence of amino acids in a protein is determined by the gene coding for that protein. Proteins perform essential functions in living cells such as catalyzing biochemical reactions as enzymes, regulating processes as hormones, transporting molecules, providing structure, and more. After synthesis, proteins are often modified with additional functional groups which can confer new abilities like recognizing other molecules or integrating into membranes.
This document outlines the syllabus for a course on enzymology taught at TOBB University of Economics and Technology. The course covers topics such as how enzymes work, enzyme kinetics, inhibition and clinical applications over 12 weeks. Students will present on various metabolic pathways and enzyme-related subjects. The course aims to explain why enzymes are important and their roles in various industries like food engineering. Evaluation will be based on midterm and final exams, as well as a presentation homework assignment.
The document classifies and describes the 20 standard amino acids. It divides them into categories based on their R-groups: non-polar aliphatic, polar uncharged, aromatic, positively charged, and negatively charged. Within each category it provides examples and describes key properties of amino acids like glycine, alanine, valine, leucine, isoleucine, methionine, phenylalanine, tyrosine, tryptophan, lysine, arginine, histidine, aspartic acid, and glutamic acid. It also lists the essential and nonessential amino acids for human nutrition.
This document summarizes the digestion and absorption of proteins in the human body. It discusses that proteins are obtained endogenously from digestive enzymes and cells, as well as exogenously from dietary intake. The stomach contains hydrochloric acid and pepsin to denature and break down proteins. The pancreas secretes trypsinogen, chymotrypsinogen, and other zymogens which are activated and further digest proteins into peptides and amino acids in the small intestine. Aminopeptidases and dipeptidases on intestinal cells complete the digestion. Amino acids are then absorbed via active transport systems involving sodium and ATP. Deficiencies or defects in these digestive processes can impair protein digestion.
The document discusses finding new drug targets for the enzyme alpha amylase. It describes alpha amylase's role in breaking down starch and how both plants and animals produce inhibitors to regulate its activity. Some inhibitors directly block the active site of the enzyme. The document then analyzes research on extracts and compounds from plants that have shown alpha amylase inhibitory effects. Key inhibitors discussed include the drug Acarbose, flavonoids, tannins, and terpenoids. The mechanisms of several of these inhibitors are also examined.
Proteins are the most abundant organic molecules of the living system.
They occur in every part of the cell and constitute about 50% of the cellular dry weight.
Proteins form the fundamental basis of structure and function of life.
Amino acids are the monomers that make up proteins
B.Sc. Biochem II Biomolecule I U 3.2 Classification of Protein & DenaturationRai University
This document discusses the classification and denaturation of proteins. It describes how proteins can be classified based on their structure, biological function, shape and solubility, composition, and nutritional basis. The main types of proteins classified by function include enzymes, transport proteins, storage proteins, contractile/motile proteins, structural proteins, and regulatory proteins. The document also discusses how proteins can be denatured, or lose their tertiary structure, through the application of heat, acids, bases, alcohols, heavy metal salts, and other stresses. Denaturation disrupts the bonding interactions that give proteins their shape.
Proteins are the major components of the body and are composed of amino acids. There are over 50,000 different proteins in the human body, each with a unique structure and function. Proteins serve many essential roles such as structure, movement, transport, regulation, and protection. They exhibit properties like solubility, ionization, hydration, and buffering capacity that allow them to perform their diverse functions. Proteins can be globular or fibrous in shape, and their molecular masses range from 5,500 to over 2 million Daltons depending on the number of amino acids.
INTRODUCTION TO BIOTRANSFORMATION OF DRUG (METABOLISM OF PHENYTOIN AND CODEINE)ADAM S
1. Biotransformation refers to the chemical alteration of drugs in the body by enzymatic processes, primarily in the liver. This renders drugs more water-soluble and aids in their elimination.
2. Metabolism occurs in two phases - phase I involves oxidation, reduction, and hydrolysis reactions. Phase II involves conjugation reactions like glucuronidation that make drugs more polar and excretable.
3. Key enzymes involved in biotransformation include cytochrome P450 enzymes and UDP-glucuronosyl transferases. Metabolism can inactivate drugs, produce active metabolites, or sometimes toxic metabolites.
Salicylic acid is a plant hormone that is synthesized from phenylalanine and is involved in plant pathogen resistance. It is found throughout the plant kingdom and is also produced by bacteria. Salicylic acid induces systemic acquired resistance (SAR) in plants and the accumulation of defense compounds, helping plants resist subsequent pathogen attacks. Jasmonates are another class of plant hormones that are synthesized from linolenic acid and induced during wounding and pathogen attacks. They regulate various physiological processes in plants and induce the production of proteinase inhibitors, which act as a defense mechanism. Systemin is an 18-amino acid polypeptide that is produced in tomato plants in response to damage and triggers the production of defensive compounds.
Biosynthetic pathways of secondary metabolites MugdhaJoshi21
This document discusses metabolic pathways in higher plants and their determination. It outlines several key pathways including the shikimic acid pathway, acetate mevalonate pathway, acetate malonate pathway, and amino acid pathways that are involved in the biosynthesis of primary and secondary metabolites in plants. Techniques used to study these biogenetic pathways include using isolated organs/tissues, grafting, mutant strains, and tracer techniques with radioactive isotopes.
Enzymes have many applications in food processing. Examples include:
1. Glucose oxidase and catalase are used to remove oxygen and glucose from foods to prevent browning and extend shelf life.
2. Amylases are used in brewing and baking to break down starches.
3. Proteinases or peptidases are used in cheese production, meat tenderizing, and improving dough properties.
4. Immobilized enzymes can be reused, making them more economical for continuous processes.
1. Many factors affect the rate of enzyme-catalyzed reactions including substrate concentration, inhibitors, pH, temperature, pressure, and water content.
2. Enzyme activity is highest at its optimal pH and temperature, and decreases significantly above and below these values. It is also affected by the concentrations of inhibitors and activators.
3. Environmental factors like temperature, pressure, and water content can irreversibly denature enzymes and decrease their activity. Careful control of these factors allows for inhibition of undesirable enzyme reactions in food processing and storage.
This document discusses the physico-chemical properties of proteins, including their physical and chemical properties. It describes proteins' ability to dissociate depending on pH, their optical activity, solubility which depends on factors like pH and salt concentration, and their ability to form foams and stabilize foams through adsorption at gas-liquid interfaces. It also discusses proteins' hydration, swelling power in water, and ability to form gels through polymeric networks or aggregate dispersions.
The document discusses the structure of proteins at different levels:
- Primary structure refers to the amino acid sequence in the polypeptide chain. Secondary structure involves hydrogen bonding that forms alpha helices or beta pleated sheets. Tertiary structure describes the overall 3D shape of the folded polypeptide chain. Quaternary structure involves the interactions between multiple polypeptide subunits. The document outlines the forces that stabilize protein structures such as disulfide bonds, hydrogen bonding, and hydrophobic interactions. Proteins are classified based on their composition, which can include modifications like glycoproteins, lipoproteins, or metal-binding groups.
This document discusses the properties and characteristics of amino acids. It covers their ionic properties, isoelectric points, optical activity, solubility, UV absorption, and various chemical reactions including esterification, acylation, alkylation, reactions with carbonyl compounds, and reactions involving functional groups like cysteine and methionine. It notes that amino acids are important in developing flavors and aromas in foods during high-temperature cooking methods like frying and baking.
1) The document discusses food proteins and enzymes, their importance in biological systems, and their various functions and sources.
2) Proteins are made up of amino acids and play many critical roles including as enzymes, hormones, antibodies, and structural components.
3) The document covers the classification of amino acids, sources of food proteins like meat and dairy, and the roles of enzymes in catalyzing biochemical reactions.
Mahua, Madhuca longifolia (Koenig) (Synonyms, Madhuca indica Gmelin; Family, Sapotaceae), is a large, shady, deciduous tree dotting much of the central Indian landscape, both wild and cultivated. The tree is valued for its flowers, fruits, seeds and timber. The buttercup fruit-seeds, generally ellipsoidally shaped (Figure 1). Madhuca longifolia fruit is valued for its seed which yield high quantity of fat (ca. 50%), commercially known as mahua butter or mowrah butter, and it has many edible and medicinal applications. The butter is of significant commercial importance in India and is used for both edible and cosmetic applications. Mowrah Butter is a yellowish-white butter with a mild odor. The butter is solid at room temperature, but melts readily on contact with the skin. Besides its edible and medicinal uses, Madhuca longifolia fats can also be utilized in the manufacture of laundry soaps and lubricants. Data about mowrah butter are very few and there are not reports in literature about detailed composition of mowrah fat. Recently, in our lab mowrah butter was subjected to detailed and comprehensive analyses to obtain informative profile about the chemical nature of mowrah butter (1). The antiradical action of mowrah butter with also compared extra virgin olive oil. The results will be important as an indication of the potentially nutraceutical and economical utility of mowrah butter as a new source of edible fats.
Oil Recovery from Enzymatically-treated Goldenberry (Physalis peruviana L...Mohamed Hassanien
Fruit processing industry produce a large amount of agro-waste products which are a rich source of dietary fibre, protein and oil. Goldenberry (Physalis peruviana L.) is one of the most promising fruits and many interesting functional products anticipated to be developed from it [1, 2]. The pomace (seeds and skins) represent a large portion of the waste generated during juice processing (ca. 27.4% of fruit weight). To date, there has been no report on the by-products of goldenberry as well as the aqueous extraction of these by-products. This work was done to study the effects of several processing factors on enzyme-aided aqueous extraction of oil from goldenberry pomace and to verify the applicability of this innovative technology to goldenberry by-products. The main variables affecting the hydrolytic process should be enzyme concentration, hydrolysis time, particle size and moisture. The effect of these variables on the oil extractability from goldenberry agro-waste after juice processing was studied. The results provide important information for the industrial application of goldenberry. As a first step toward developing goldenberry as a commercial crop, the data obtained will be useful as an indication of the potentially economical utility of goldenberry as a source of edible oil.
This document discusses various enzymatic analytical methods used for food analysis, including substrate determination, enzyme activity determination, enzyme immunoassay, and polymerase chain reaction. Specifically, it covers:
1) Substrate determination methods like end-point assays that use coupled enzyme reactions to measure food constituents.
2) Determining enzyme activity in food to evaluate quality and optimize processes by measuring reaction rates under controlled conditions.
3) Enzyme immunoassays like ELISA that use antibody-antigen reactions and enzyme-labeled antigens to detect food compounds.
4) Polymerase chain reaction (PCR) which amplifies DNA for sensitive species identification and detecting genetically modified foods. PCR allows analysis of heat-treated foods where proteins
The document discusses factors that affect enzyme-catalyzed reactions, including substrate concentration, inhibitors, pH, temperature, and pressure. It explains how the reaction rate depends on substrate and enzyme concentrations and can be influenced by activators and inhibitors. It also describes how each enzyme has an optimal pH range and temperature, and discusses how temperature affects reaction rates, microbial growth rates, and thermal inactivation of enzymes.
The document discusses the structure of proteins at multiple levels, from primary to quaternary structure. It describes the primary structure as the amino acid sequence linked by peptide bonds. The secondary structure refers to local spatial arrangements, such as alpha helices and beta sheets, formed through hydrogen bonding between peptide bonds. Tertiary structure describes the overall 3D shape of the folded polypeptide chain. Quaternary structure applies to proteins made of multiple polypeptide subunits that assemble into an ordered structure. The document outlines various methods for determining protein structure, including amino acid sequencing and X-ray crystallography.
Implementation of International Educational ProgramMohamed Hassanien
This document discusses key elements for developing an international educational program, including a vision, mission, goals, values, student learning outcomes, and examples. It provides guidance on writing statements for each element and examples. The vision describes what the ideal future program would look like. The mission states the program's purpose and stakeholders. Goals are broad targets for the program. Values describe the program's principles. Student learning outcomes are specific statements of the knowledge and skills students will obtain.
Fast Antiradical Test for Monitoring Deep Fried OilsMohamed Hassanien
This document presents research on developing a fast antiradical test for monitoring deep fried oils. Deep frying is commonly used worldwide but causes physical and chemical changes to oils through oxidation. The researchers aimed to compare physicochemical parameters and antiradical performance of oils during frying. Oils were analyzed after frying at different time points. Strong correlations were found between total polar compounds, absorptivity at 232nm/270nm, and antiradical scavenging activity against DPPH radicals. This suggests antiradical testing could rapidly monitor oil quality changes during frying. The method is accurate, inexpensive, and independent of oil type.
Lipid Classes, Sterols and Tocopherols of Black cumin (Nigella sativa L.), Co...Mohamed Hassanien
The document analyzes and compares the lipid classes, fatty acid profiles, and triacylglycerol compositions of black cumin, coriander, and niger seed oils. Specifically:
- The neutral lipid fraction constitutes over 90% of the total lipids in each seed oil. Black cumin has the highest ratio of saturated to polyunsaturated fatty acids in its neutral lipid fraction.
- Coriander seed oil has the highest levels of the monounsaturated fatty acid petroselinic acid and contains more triolein and tripetroselinin than the other seed oils.
- Niger seed oil stands out for its high content of saturated fatty acids like palmitic acid and trip
Investigation on Lipid Composition of Exotic OilseedsMohamed Hassanien
This document summarizes the results of a study investigating the lipid composition and bioactive compounds of black cumin, coriander, and niger seed oils. High levels of oils were recovered from the seeds, making them suitable for vegetable oil production. The seed oils contained high amounts of essential fatty acids and antioxidants like tocopherols. Black cumin and coriander seed oils in particular could be produced and marketed as crude oils. The polar lipid fractions of the seeds oils showed antioxidant effects and could potentially be used as natural additives, lecithins, or in cosmetics. Further research is needed to understand how the seed oil compositions relate to biological effects and how processing may impact their structures and antioxidative
The document discusses preparing and testing novel phenolic-enriched lecithin formulations called phenolipids. It proposes that phenolipids could overcome oxidation issues with lecithin by binding phenolic compounds to phospholipids. The objectives are to prepare phenolipids using commercial lecithin and phenolics like quercetin, study their antioxidant properties in triolein models, and evaluate biological activities. Results show phenolipids have higher radical scavenging effects than individual compounds and protect triolein better against oxidation than lecithin or phenolics alone.
NVBDCP.pptx Nation vector borne disease control programSapna Thakur
NVBDCP was launched in 2003-2004 . Vector-Borne Disease: Disease that results from an infection transmitted to humans and other animals by blood-feeding arthropods, such as mosquitoes, ticks, and fleas. Examples of vector-borne diseases include Dengue fever, West Nile Virus, Lyme disease, and malaria.
Osteoporosis - Definition , Evaluation and Management .pdfJim Jacob Roy
Osteoporosis is an increasing cause of morbidity among the elderly.
In this document , a brief outline of osteoporosis is given , including the risk factors of osteoporosis fractures , the indications for testing bone mineral density and the management of osteoporosis
Adhd Medication Shortage Uk - trinexpharmacy.comreignlana06
The UK is currently facing a Adhd Medication Shortage Uk, which has left many patients and their families grappling with uncertainty and frustration. ADHD, or Attention Deficit Hyperactivity Disorder, is a chronic condition that requires consistent medication to manage effectively. This shortage has highlighted the critical role these medications play in the daily lives of those affected by ADHD. Contact : +1 (747) 209 – 3649 E-mail : sales@trinexpharmacy.com
Cell Therapy Expansion and Challenges in Autoimmune DiseaseHealth Advances
There is increasing confidence that cell therapies will soon play a role in the treatment of autoimmune disorders, but the extent of this impact remains to be seen. Early readouts on autologous CAR-Ts in lupus are encouraging, but manufacturing and cost limitations are likely to restrict access to highly refractory patients. Allogeneic CAR-Ts have the potential to broaden access to earlier lines of treatment due to their inherent cost benefits, however they will need to demonstrate comparable or improved efficacy to established modalities.
In addition to infrastructure and capacity constraints, CAR-Ts face a very different risk-benefit dynamic in autoimmune compared to oncology, highlighting the need for tolerable therapies with low adverse event risk. CAR-NK and Treg-based therapies are also being developed in certain autoimmune disorders and may demonstrate favorable safety profiles. Several novel non-cell therapies such as bispecific antibodies, nanobodies, and RNAi drugs, may also offer future alternative competitive solutions with variable value propositions.
Widespread adoption of cell therapies will not only require strong efficacy and safety data, but also adapted pricing and access strategies. At oncology-based price points, CAR-Ts are unlikely to achieve broad market access in autoimmune disorders, with eligible patient populations that are potentially orders of magnitude greater than the number of currently addressable cancer patients. Developers have made strides towards reducing cell therapy COGS while improving manufacturing efficiency, but payors will inevitably restrict access until more sustainable pricing is achieved.
Despite these headwinds, industry leaders and investors remain confident that cell therapies are poised to address significant unmet need in patients suffering from autoimmune disorders. However, the extent of this impact on the treatment landscape remains to be seen, as the industry rapidly approaches an inflection point.
- Video recording of this lecture in English language: https://youtu.be/kqbnxVAZs-0
- Video recording of this lecture in Arabic language: https://youtu.be/SINlygW1Mpc
- Link to download the book free: https://nephrotube.blogspot.com/p/nephrotube-nephrology-books.html
- Link to NephroTube website: www.NephroTube.com
- Link to NephroTube social media accounts: https://nephrotube.blogspot.com/p/join-nephrotube-on-social-media.html
2. -Reactions of Protein Involved in Food Processing
-Enzyme-Catalyzed Reactions (Proteolytic Enzymes)
1-Serine Endopeptidases
2- Cysteine Endopeptidases
3- Metalo Peptidases
4- Aspartic Endopeptidases
-Chemical and Enzymatic Reactions (Modifications) of
Interest to Food Processing
1- Chemical Modification
2- Enzymatic Modification
-Texturized Proteins
3. -The nature of the chemical changes induced in proteins by food
processing depend on a number of parameters, for example,
composition of the food and processing conditions, such as
temperature, pH or the presence of oxygen.
-As a consequence of these reactions, the biological value of
proteins may be decreased:
•Destruction of essential amino acids
•Conversion of essential amino acids into derivatives which are not
metabolizable
•Decrease in the digestibility of protein as a result of intra- or
interchain cross-linking.
•Formation of toxic degradation products is also possible.
-The nutritional/physiological and toxicological assessment of
changes induced by processing of food is a subject of some
controversy and opposing opinions.
4. -The Maillard reaction of the amino group of lysine prevails in the
presence of reducing sugars (for example, lactose or glucose) which
yield protein-bound N-deoxylactulosyl-1-lysine or N-deoxyfructosyl1-lysine.
-Lysine is not biologically available in these forms.
-Acidic hydrolysis of such primary reaction yields lysine as well as
the degradation products furosine and pyridosine in a constant
ratio
5. -A non-reducing sugar (e.g. sucrose) can also
cause a loss of lysine when conditions for sugar
hydrolysis are favorable.
-Losses of available lysine, cystine, serine,
threonine and arginine occur at higher pH values.
-Hydrolysates of alkali-treated proteins often
contain some unusual compounds, such as Damino acids.
6. -In the case of cystine, the eliminated thiolcysteine can form a
second dehydroalanine residue
-Alternatively, cleavage of the cystine disulfide bond can occur by
nucleophilic attack on sulfur, yielding a dehydroalanine residue via
thiol and sulfinate intermediates:
7. -Intra- and interchain cross-linking of proteins can occur in
dehydroalanine reactions involving additions of amines and thiols.
-Ammonia may also react via an addition reaction
8. -Acidic hydrolysis of such a Formation of unusual amino acids
cross-linked protein yields
by alkali treatment of protein
the unusual amino acids as
shown in the Table.
-Ornithine is formed during
cleavage of arginine.
9. -D-amino acids formed through abstraction of proton via C2carbanion.
-The reaction with L-isoleucine is of analytical interest.
-L-Isoleucine is isomerized to D-alloisoleucine which, unlike other
D-amino acids, is a diastereoisomer and so has a retention time
different from L-isoleucine, making its determination possible
directly from an amino acid chromatogram.
10. -Heating proteins in dry state at neutral pH results in the
formation of isopeptide bonds between the amino groups of lysine
residues and the carboxamide groups of asparagine and glutamine
residues
11. -These isopeptide bonds are cleaved during acidic hydrolysis of
protein and, therefore, do not contribute to the occurrence of
unusual amino acids.
-A more intensive heat treatment of proteins in the presence of
water leads to a more extensive degradation.
-Oxidative changes in proteins primarily involve methionine,
which relatively forms methionine sulfoxide
-The formation of methionine sulfoxide was observed in
connection with lipid peroxidation, phenol oxidation and light
exposure in the presence of oxygen.
12. -After in vivo reduction to methionine,
protein-bound methionine sulfoxide is
biologically available.
-Serine, threonine, arginine and isoleucine
concentrations are markedly decreased
with increasing concentrations of NaOH.
-New amino acids (ornithine
alloisoleucine) are formed.
and
-Initially, lysine concentration decreases,
but increases at higher concentrations of
alkali.
-The extent of formation of D-amino acids
as a result of alkaline treatment of proteins
is shown in the table.
Formation of D-amino acids by
alkali treatment of proteins
(1% solution in 0.1 N NaOH, pH
12.5, temperature 65 ◦C)
14. -A great number and variety of enzyme-catalyzed
reactions are known with protein as a substrate.
-These include
-Hydrolytic reactions (cleavage of peptide bonds or
other linkages, e.g., the ester linkage in a
phosphoprotein),
-Transfer reactions (phosphorylation, incorporation of
acyl residues, sugar residues and methyl groups)
-Redox reactions (thiol oxidation, disulfide reduction,
amino group oxidation or incorporation of hydroxyl
groups).
16. Proteolytic Enzymes
-Processes involving proteolysis play importanct role in the
production of many foods.
-Proteolysis can occur as a result of
proteinases in the food itself, e.g., autolytic reactions in meat,
or due to microbial proteinases, e.g., the addition of pure cultures
of selected microorganisms during the production of cheese.
-This large group of enzymes is divided up as shown in the Table.
-The main subgroups formed are:
A-Peptidases (exopeptidases) that cleave amino acids or dipeptides
stepwise from the terminal ends of proteins
B-Proteinases (endopeptidases) that hydrolyze the linkages within
the peptide chain and not attacking the terminal peptide bonds.
18. 1-Serine Endopeptidases
-Enzymes of this group, in which activity is relatedto the pH range
of 7−11, are denoted as alkaline proteinases.
-Typical representatives from animal sources are trypsin,
chymotrypsin, elastase and thrombin.
-Serine proteinases are produced by great number of bacteria and
fungi, e. g. B. subtilis and Aspergillus flavus.
-These enzymes have in common the presence of serine and
histidine residue in their active sites.
-Inactivation of these enzymes is possible with reagents such as
diisopropylfluorophosphate (DIFP)
or phenylmethanesulfonylfluoride (PMSF).
19. -Irreversible inhibition can occur in the presence of halogenated
methyl ketones which alkylate the active histidine residue,
or as a result of the action of proteinase inhibitors, which are also
proteins, by interaction with enzyme to form inactive complexes.
-These natural inhibitors are found in the organs of animals and
plants (e.g. pancreas, egg white, potato tuber).
-The specificity of serine endopeptidases varies greatly.
-Trypsin exclusively cleaves linkages of amino acid residues with a
basic side chain (lysyl or arginyl bonds)
-Chymotrypsin cleaves bonds of amino acid residues which have
aromatic side chains (phenylalanyl or tyrosyl bonds).
-Enzymes of microbial origin often are less specific.
20. 2- Cysteine Endopeptidases
-Typical representatives of this group of enzymes are:
papain (from the sap of tropical, melon-like fruit tree, Carica papaya),
bromelain (from the sap and stem of pineapples, Ananas comosus),
ficin (from Ficus latex and other Ficus spp.)
And Streptococcus proteinase.
-The range of activity of these enzymes is very wide and, depending on the
substrate, is pH 4.5–10, with a maximum at pH 6–7.5.
-The mechanism of enzyme activity appears to be similar to that of serine
endopeptidases.
-A cysteine residue is present in the active site.
-The enzymes are highly sensitive to oxidizing agents. Therefore, as a rule they
are used in the presence of a reducing agent (e.g., cysteine) and a chelating
agent (e.g., EDTA).
-Inactivation of the enzymes is possible with oxidative agents, metal ions or
alkylating reagents. In general these enzymes are not very specific.
21. 3- Metalo Peptidases
-This group includes exopeptidases, carboxypeptidases A
and B, aminopeptidases, dipeptidases and prolinase,
and endopeptidases from bacteria and fungi, such as B.
subtilits, and Aspergillus oryzae.
-Most of these enzymes contain one mole of Zn2+ per
mole of protein, but prolidase and prolinase contain one
mole of Mn2+ .
-The metal ion establish contact with the carbonyl group
of the peptide bond which is to be cleaved.
22. 3- Metalo Peptidases
-The arrangement of other
participating residues in the
active site of Carboxypeptidase A,
as revealed by X-ray structural
analysis of the enzyme-substrate
complex is shown.
-The enzymes are active in the pH
6–9 range; their specificity is
generally low.
-Inhibition of these enzymes is
achieved with chelating agents
(e.g. EDTA) or sodium dodecyl
sulfate (SDS).
Carboxypeptidase A active
site
23. 4- Aspartic Endopeptidases
-Typical representatives of this group are enzymes of animal
origin, such as pepsin and rennin (called Lab-enzyme in Europe),
active in the pH range of 2–4.
-At pH 6–7 rennin cleaves a bond of casein causing curdling of
milk.
-Aspartic proteinases of microbial origin can be classified as
pepsin-like or rennin-like enzymes. The latter are able to
coagulate milk.
-The pepsin-like enzymes are produced by e.g. Aspergillus niger.
-The rennin-like enzymes are produced by e.g. Aspergillus usamii.
-There are two carboxyl groups in the active site of aspartic
proteinases.
25. -Standardization of food properties to meet nutritional/physiological and
toxicological demands and requirements of food processing operations is
of importance.
-Food production is similar to a standard industrial fabrication process:
on the one hand is the food commodity with all its required
properties,
on the other hand are the components of the product, each of which
supplies a distinct part of the required properties.
-Such considerations have prompted investigations into the relationships
in food between physical and chemical properties and the structure and
reactions at the molecular level.
-Reliable understanding of such relationships is a fundamental
prerequisite for the design and operation of process, either to optimize
the process or to modify the food components to meet the desired
properties.
26. -Modification of proteins is still a long way from being a common
method in food processing, but it is increasingly being recognized
as essential, for two main reasons:
-Firstly, proteins fulfill multipurpose functions in food. Some of
these functions can be served better by modified than by native
proteins.
-Secondly, persistent nutritional problems the world over
necessiate the utilization of new raw materials.
-Modifying reactions can ensure that such new raw materials (e.g.,
proteins of plant or microbial origin) meet stringent standards of
food safety, palatability and acceptable biological value.
27. -Some protein properties which are of interest to food
processing are presented in the following table.
-These properties are related to the amino acid composition and
sequence and the conformation of proteins.
Properties of protein in food
28. -Modification of the protein properties is possible by changing
the amino acid composition or the size of the molecule, or by
removing or inserting hetero constituents.
-Such changes can be accomplished by chemical and/or
enzymatic reactions.
-From a food processing point of view, the aims of
modification of proteins are:
•Blocking the reactions involved in deterioration of food (e.g.,
the Maillard reaction)
•Improving some physical properties of proteins (e.g., texture,
foam stability, solubility)
•Improving the nutritional value (increasing the extent of
digestibility, inactivation of toxic or other undesirable
constituents, introducing essential ingredients such as some
amino acids).
29. 1- Chemical Modification
-This table presents a selection of chemical reactions of proteins
that are of current importance in food processing.
Chemical reactions of proteins significant in food
30. A- Acylation
-Treatment with succinic anhydride
generally improves the solubility of
protein.
-For example, succinylated
gluten is quite soluble at pH 5.
wheat
-This effect is related to disaggregation
of high molecular weight gluten
fractions.
-In the case of succinylated casein it is
obvious that the modification shifts the
isoelectric point of the protein (and
thereby the solubility minimum) to a
lower pH.
Solubility of succinylated wheat
protein as a function of pH
(0.5% solution in water).
31. -Succinylation of proteins improves the
solubility, the flavor and emulsifying
properties.
-Succinylated yeast protein has not only
an increased solubility in the pH range of
4–6, but is also more heat stable above
pH 5.
-Introduction of aminoacyl groups into
protein can be achieved by reactions
involving amino acid and carbodiimides.
-Feeding tests with casein with attached
methionine have demonstrated a
satisfactory availability of methionine.
-Such covalent attachment of essential
amino acids to a protein may avoid the
problems
associated
with
food
supplementation with free amino acids:
losses in processing, development of
undesired aroma …. etc.
Properties of modified wheat
gluten
32. B- Alkylation
-Modification of protein by reductive methylation of amino groups
with formaldehyde/NaBH4 retards Maillard reactions.
-The resultant methyl derivative, depending on the degree of
substitution, is less accessible to proteolysis.
-Hence, its value from a nutritional/physiological point of view is
under investigation.
33. C-Redox Reactions Involving Cysteine and
Cystine
-Disulfide bonds have a strong influence on properties of proteins.
-Wheat gluten can be modified by reduction of its disulfide bonds
to sulfhydryl groups and subsequent re-oxidation of these groups
under various conditions.
34. -Re-oxidation of a diluted
suspension in the presence
of urea results in a weak,
soluble, adhesive product
(gluten A),
-whereas re-oxidation of a
concentrated suspension
in the presence of a higher
concentration of urea
yields an insoluble, stiff,
cohesive product (gluten
C).
35. 2- Enzymatic Modification
-Of the great number of enzymatic
reactions with protein as a substrate,
only a small number have so far been
found to be suitable for use in food
processing.
A- De-phosphorylation
-β-casein is an example to show that
the solubility of a phosphoprotein in
the presence of calcium ions is greatly
improved by partial enzymatic
dephosphorylation.
Solubility of β-casein,
partially dephosphorylated
by phosphoprotein
phosphatase
36. B-Plastein Reaction
-The plastein reaction enables peptide fragments of a
hydrolysate to join enzymatically through peptide
bonds, forming a larger polypeptide of about 3 kdal.
37. B-Plastein Reaction
-The reaction rate is affected by the
nature of the amino acid residues.
-Hydrophobic amino acid residues are
preferably linked together.
-Insertion of amino acid esters into
protein is affected by the alkyl chain
length of the ester.
-Short-chain alkyl esters have a low
rate of incorporation, while the longchain alkyl esters have a higher rate of
incorporation.
-This is important for the incorporation
of amino acids with a short side chain,
such as alanine.
Plastein reaction with papain:
incorporation rates of amino acid
esters as function of side chain
hydrophobicity
38. -The plastein reaction can help to improve the biological value of a protein.
-This figure shows the plastein enrichment of zein with tryptophan, threonine
and lysine (ethyl ester).
Zein enrichment with Trp, Thr, and Lys by a plastein reaction
a 1% substrate, pH 1.6 at 37 ◦C for 72 h
b 50% substrate, at 37 ◦C for 48 h
c 0.1 mol/L in 50% ethanol at 25 ◦C for 5 h
39. -The
amino
acid
composition of such a
zein-plastein product is
given in the table.
-Enrichment of a protein
with selected amino
acids can be achieved
with the corresponding
amino acid esters or by
using suitable partial
hydrolysates of another
protein.
Amino acid composition of
various plasteins (weight%)
40. -Soya protein could be enriched with sulfur-containing amino acids
through “adulteration” with the partial hydrolysate of keratin.
Protein enrichment with sulfur amino acids
applying plastein reaction
41. -The production of plastein with an amino acid profile very close to that
recommended by FAO/WHO can be achieved from very diverse proteins.
Amino acid patterns of some proteins and their corresponding
plasteins
42. -The plastein reaction also makes it possible to improve the
solubility of protein, for example, by increasing the content of
glutamic acid.
-A soya protein with 25% glutamic acid yields a plastein with 42%
glutamic acid.
Soy globulin enrichment with glutamic acid by a plastein reaction
a pH 1.6
b Partial hydrolyzate/Glu-α-γ-(OEt)2 = 2:1, substrate concentration: 52.5%, E/S =
1/50, pH 5.5 at 37 ◦ C for 24 h; sample contains 20% acetone
c 0.2 mol/L at 25 ◦ C for 2 h
43. -Soya protein has a solubility minimum in the pH range of 3–6.
-The glutamic acid-enriched soya plastein has a good solubility over the
whole pH range.
-The glutamic acid-enriched is also resistant to thermal coagulation.
Effect of pH on solubility of soy protein
and modified products.
1 Soy protein, 24.1% Glu;
2 Plastein 24.8% Glu;
3 Glu-plastein with 41.9% Glu
Solubility of soy protein and modified
products as a function of heating time at
100 ◦ C.
1 Soy protein 24.1% Glu;
2 Plastein 24.8% Glu;
3 Glu-plastein, 41.9% Glu.
44. -Proteins with high content of glutamic acid show an
interesting sensory effect: partial hydrolysis of
modified plastein does not result in a bitter taste,
rather it generates a “meat broth” flavor.
-Bitter-tasting peptides, such as Leu-Phe react
preferentially in the subsequent plastein reaction and
are incorporated into higher molecular weight
peptides with a neutral taste.
45. -The versatility of the plastein reaction is also demonstrated by
examples wherein undesired amino acids are removed from
protein.
-The use of a phenylalanine-free higher molecular weight peptide
is advantageous with respect to sensory and osmotic properties.
Such peptides can be prepared from protein by the plastein
reaction.
-First, the protein is partially hydrolyzed with pepsin. Treatment
with pronase then releases amino acids with long hydrophobic
side chains.
-The remaining peptides are separated by gel chromatography
and then subjected to the plastein reaction in the presence of
added tyrosine and tryptophan.
47. -This yields a plastein that is phenylalanine-free and has a ratio of
other amino acids, including tyrosine.
Amino acid composition (weight-%) of plasteins with high
tyrosine and low phenylalanine contents from fish protein
concentrate (FPC) and soya protein isolate (SPI)
48. -The plastein reaction can also be carried out as a one-step process,
thus putting these reactions to economic, industrial-scale use.
An outline for two- and single-step plastein reactions
49. C- Cross-Linking
-Cross-linking between protein molecules is achieved with
transglutaminase and with peroxidase.
-The cross-linking occurs between tyrosine residues when a
protein is incubated with peroxidase/H2O2.
50. -Incubation of protein with peroxidase/H2O2/catechol also
results in cross-linking.
-The reactions in this case are the oxidative deamination of
lysine residues, followed by aldol and aldimine condensations, i.
e. reactions analogous to those catalyzed by lysyl oxidase in
connective tissue
51. -This table presents some of the proteins modified by
peroxidase/H2O2 treatment and includes their ditryrosine
contents.
Content of dityrosine in some proteins after their oxidation
with peroxidase/H2O2
(pH 9.5, 37 ◦C, 24 h. Substrate/enzyme = 20:1)
53. -The protein produced for nutrition is currently about 20% from animal sources
and 80% from plant sources.
-The plant proteins are primarily from cereals (57%) and oilseed meal (16%).
-Some non-conventional sources of protein (single cell proteins, leaves) have also
acquired some importance.
-Proteins are responsible for the physical structure of foods,
e. g. the fibrous structure of muscle tissue (meat and fish),
the porous structure of bread
and the gel structure of some dairy and soya products.
-Many plant proteins have a globular structure and, although available in
large amounts, are used to only a limited extent in food processing.
-In an attempt to broaden the use of such proteins, a number of processes were
developed in the mid-1950’s which confer a fiber-like structure to globular
proteins.
-Suitable processes give products with cooking strength and a meat-like
structure. They are marketed as meat extenders and can be used whenever a
lumpy structure is desired.
54. Starting Material of Texturized Proteins
-The following protein sources are suitable for the production of texturized
products: soya; casein; wheat gluten; oilseed meals such, groundnut, sesame,
sunflower, safflower or rapeseed; zein (corn protein); yeast; whey; blood
plasma.
-The required protein content of the starting material varies and depends on
the process used for texturization. The starting material is often a mixture such
as soya with lactalbumin, or protein plus acidic polysaccharide (pectin).
-The suitability of proteins for texturization varies, but the molecular weight
should be in the range of 10–50 kdal.
-Proteins of less than 10 kdal are weak fiber builders, while those higher than
50 kdal are disadvantageous due to their high viscosity and tendency to gel in
the alkaline pH range.
-The proportion of amino acid residues with polar side chains should be high in
order to enhance inter-molecular binding of chains. Bulky side chains obstruct
such interactions, so that the amounts of amino acids with these structures
should be low.
55. Texturization
-The globular protein is unfolded during texturization by breaking
the intramolecular binding forces.
-The resultant extended protein chains are stabilized through
interaction with neighboring chains.
In practice, texturization is achieved in one of two ways
A-The starting protein is solubilized and the viscous solution is
extruded through a spinning nozzle (spin process).
B-The starting protein is moistened and then, at high temperature
and pressure, is extruded with shear force (extrusion process).