Microbial spoilage of fish occurs through the utilization of readily available substances like TMAO, urea, and free amino acids. Microbes then hydrolyze more complex tissue components like proteins and lipids. Key quality indices in frozen fish include protein denaturation, lipid oxidation, color changes, drip loss, freezer burn, and black spot formation. Bacterial contamination, foreign materials, heavy metals, decomposition, and pesticide residues can also impact the quality and safety of frozen fish. Proper handling and cold storage are important to minimize spoilage during freezing and frozen storage.
c) Vitamins: Occurrance, classification and general methods of isolation of vitamins, structure determination, synthesis and biological functions of vit-A, vit-B and vit-C.
Amino acids are produced through various methods including chemical synthesis, isolation from natural materials, fermentation, and chemo-enzyme methods. Fermentation is a widely used method that involves growing amino acid-producing microorganisms. There are different types of fermentation including batch, fed-batch, and continuous. Downstream processing is then required to separate and purify the amino acid produced, using methods like centrifugation, filtration, crystallization, and ion exchange. Monosodium glutamate is a common amino acid product that is produced through a fermentation process involving microorganisms and sugar cane, followed by purification steps to form the crystal product.
Riboflavin, also known as vitamin B2, is a yellow pigment that contains a 6,7-dimethylisoalloxazine ring. It functions as an important cofactor in redox reactions as FMN and FAD. Riboflavin is absorbed in the small intestine and transported to tissues like the liver, where it is converted to its coenzyme forms. Deficiency can cause cheilosis, glossitis and corneal vascularization. Rich dietary sources include milk, meat, eggs and liver.
Vitamin B12, also known as Cobalamin, is a water-soluble vitamin that plays a key role in the functioning of the nervous system and the formation of red blood cells. It is produced by microorganisms through fermentation and cannot be synthesized by animals or plants. The document discusses the industrial production process of vitamin B12 through bacterial fermentation using various microorganisms like Streptomyces and Propionibacterium. The production process involves growing the microorganisms in nutrient media under controlled conditions, followed by downstream processing steps like filtration, extraction, and crystallization to isolate vitamin B12.
This document provides an overview of different types of biopolymers, including their monomeric units, structures, and examples. The main biopolymers discussed are carbohydrates, proteins, lipids, and nucleic acids. Carbohydrates include monosaccharides like glucose, disaccharides, and polysaccharides. Proteins are composed of amino acid monomers linked through peptide bonds. Lipids include fatty acids, triglycerides, phospholipids, and sterols. Nucleic acids DNA and RNA are made of nucleotides and store genetic information.
The document discusses principles and procedures for analyzing vitamins in pharmaceutical preparations and dosage forms. It provides details on several methods for analyzing Vitamin A, D, thiamine, and niacin. For Vitamin A, methods discussed include Carr-Price colorimetric method, UV spectrophotometry, and modification of Carr-Price reaction. For Vitamin D, it covers UV spectrophotometry and colorimetric reactions with glycerol-1,3-dichlorohydrin and organic aldehydes. Thiamine analysis methods include thiochrome fluorimetry, silicotungstic acid gravimetry, and colorimetric reactions with p-aminoacetophenone and 6
Introduction to secondary metabolites:
Definition, classification, properties and test for identification of Alkaloids,
Glycosides, Flavonoids, Tannins, Volatile oil and Resins
c) Vitamins: Occurrance, classification and general methods of isolation of vitamins, structure determination, synthesis and biological functions of vit-A, vit-B and vit-C.
Amino acids are produced through various methods including chemical synthesis, isolation from natural materials, fermentation, and chemo-enzyme methods. Fermentation is a widely used method that involves growing amino acid-producing microorganisms. There are different types of fermentation including batch, fed-batch, and continuous. Downstream processing is then required to separate and purify the amino acid produced, using methods like centrifugation, filtration, crystallization, and ion exchange. Monosodium glutamate is a common amino acid product that is produced through a fermentation process involving microorganisms and sugar cane, followed by purification steps to form the crystal product.
Riboflavin, also known as vitamin B2, is a yellow pigment that contains a 6,7-dimethylisoalloxazine ring. It functions as an important cofactor in redox reactions as FMN and FAD. Riboflavin is absorbed in the small intestine and transported to tissues like the liver, where it is converted to its coenzyme forms. Deficiency can cause cheilosis, glossitis and corneal vascularization. Rich dietary sources include milk, meat, eggs and liver.
Vitamin B12, also known as Cobalamin, is a water-soluble vitamin that plays a key role in the functioning of the nervous system and the formation of red blood cells. It is produced by microorganisms through fermentation and cannot be synthesized by animals or plants. The document discusses the industrial production process of vitamin B12 through bacterial fermentation using various microorganisms like Streptomyces and Propionibacterium. The production process involves growing the microorganisms in nutrient media under controlled conditions, followed by downstream processing steps like filtration, extraction, and crystallization to isolate vitamin B12.
This document provides an overview of different types of biopolymers, including their monomeric units, structures, and examples. The main biopolymers discussed are carbohydrates, proteins, lipids, and nucleic acids. Carbohydrates include monosaccharides like glucose, disaccharides, and polysaccharides. Proteins are composed of amino acid monomers linked through peptide bonds. Lipids include fatty acids, triglycerides, phospholipids, and sterols. Nucleic acids DNA and RNA are made of nucleotides and store genetic information.
The document discusses principles and procedures for analyzing vitamins in pharmaceutical preparations and dosage forms. It provides details on several methods for analyzing Vitamin A, D, thiamine, and niacin. For Vitamin A, methods discussed include Carr-Price colorimetric method, UV spectrophotometry, and modification of Carr-Price reaction. For Vitamin D, it covers UV spectrophotometry and colorimetric reactions with glycerol-1,3-dichlorohydrin and organic aldehydes. Thiamine analysis methods include thiochrome fluorimetry, silicotungstic acid gravimetry, and colorimetric reactions with p-aminoacetophenone and 6
Introduction to secondary metabolites:
Definition, classification, properties and test for identification of Alkaloids,
Glycosides, Flavonoids, Tannins, Volatile oil and Resins
This document provides protocols for analyzing vitamins and toxicants in food. It details procedures for assaying various vitamins including vitamin A, vitamin B1, vitamin B2, and vitamin B6. The protocols describe preparing test and reference solutions, carrying out assays by ultraviolet spectrophotometry, liquid chromatography, or titration. Identification steps are also outlined, such as examining absorption maxima and reaction of solutions. The document aims to establish standardized methods for analyzing important nutrients and assessing quality and safety of food.
#medical #students #doctors #foodandnutrition #nurses #NEET #PCM #doctors #nutritioneducation #mscdfsm #dietician #nationaldieticians #RD #REGISTERED #DIETICIANS
#NUTRITIONIST #INTERNATIONALDIETICIANS
This content is made for all student of medical ,nutrition ,doctors ,zoology ,chemistry ,medical who are still preparing for examination .feel free to give suggestion.
Biopolymers are polymers produced by living organisms. Degradation is the process by which large polymers are fragmented into smaller molecules. There are several types of degradation including thermal, photo, mechanical, chemical, and oxidative. Biodegradation is the natural process by which organic chemicals are converted into simpler compounds by organisms like fungi and bacteria. The degradation mechanisms of some common biopolymers like starch, cellulose, poly(caprolactone), and poly(lactic acid) are discussed. Enzymes play an important role in degradation through processes like hydrolysis which breaks the polymer chains into monomers.
Lysine is an essential amino acid that is commonly produced through fermentation using microorganisms like Corynebacterium glutamicum. The fermentation process involves growing the microorganism in a stirred tank bioreactor containing nutrients from sources like molasses, corn steep liquor, and minerals. After fermentation, the broth is processed through ultrafiltration, ion exchange columns, and crystallization to isolate lysine hydrochloride. Lysine finds major applications as a food and feed additive due to its status as an essential amino acid for mammals.
The document summarizes key post-mortem biochemical changes that occur in fish after death. It discusses how rigor mortis develops as ATP is broken down and actin and myosin cross-bridges form. It then describes how autolysis and bacterial spoilage lead to degradation of lipids, proteins, and other tissues. Several chemical indices used to measure spoilage are also outlined, including TVN, TMA, alpha-amino nitrogen, and peroxide value.
The document summarizes the production of the antibiotic streptomycin. It was discovered in 1944 from the soil bacterium Streptomyces griseus and was the first effective treatment for tuberculosis. It is produced through submerged fermentation using mutants of S. griseus over 5-7 days. The fermentation proceeds through growth, idiophase of maximum streptomycin production, and death phases. Streptomycin is then purified from the broth using cation exchange resin columns and further processed to remove impurities, concentrated, and dried. Process details such as optimized media, fermentor corrosion, and recovery using weak acid cation exchange resin are also outlined.
This document summarizes the biosynthesis pathways of several important plant-derived compounds. It discusses the precursor molecules and biosynthesis routes for lysergic acid, tropane alkaloids, emetine, and quinine. For lysergic acid, the precursors are tryptophan and an isoprene unit, and it is formed through a series of reactions involving alkylation, methylation, and ring formations. Tropane alkaloids are derived from ornithine, and include compounds like atropine and cocaine. Emetine biosynthesis involves dopamine and secologanin, undergoing reactions like Pictet-Spengler and methylations. Quinine is derived from tryptophan as
Every component of the eye is vulnerable to damage from ROI, particularly retina. There are several reasons for the vulnerability of the retina, including high concentrations of polyunsaturated fatty acid (PUFA), constant exposure to visible light, high consumption of oxygen, an abundance of photosensitisers in the neurosensory retina and the RPE, the process of phagocytosis by the RPE which is known to generate hydrogen peroxide.
This document discusses alkaloids found in plants. It begins by defining alkaloids and their properties, including that they are basic compounds derived from plants and contain nitrogen. It then covers the history of alkaloid isolation, distribution in different plant families, and classification based on chemical structure. The document focuses on the variety of alkaloids and systems used for their classification. It provides examples of different alkaloid skeletal structures and the plant families that contain them.
Structural elucidation and isolation of glycoside, purine and flavanoidsSana Raza
Unit three of chemistry of natural products, consist of the method of extraction, isolation and structure elucidation of Glycoside(digoxin), Flavanoids( quercetin), Lignans( Podophyllotoxin), Purines (caffeine)
Biopolymers are polymers produced by living organisms and contain monomeric units that are covalently bonded to form larger structures. There are three main types of biopolymers: biorenewable, biodegradable, and biomaterials. Biopolymers include proteins, nucleic acids like DNA and RNA, and lipids. These biopolymers have various applications in areas like drug delivery, tissue engineering, and medical implants. Biodegradable polymers break down into natural byproducts and are used for things like drug delivery systems.
Biopolymers are polymers produced by living organisms and contain monomeric units that are covalently bonded to form larger structures. Examples of biopolymers include starch, cellulose, chitin, DNA and RNA. Starch acts as a natural polymer obtained from plants and is composed of glucose. Cellulose is the most common biopolymer and is composed of glucose, forming plant cellular walls. Proteins are biopolymers formed from bonded amino acid monomers into peptide chains. Nucleic acids like DNA and RNA are biopolymers made from bonded nucleotide monomers. Biodegradable polymers can decompose naturally through microbial action.
Biodegradable polymers are derived from biological sources such as plants and microorganisms. They include natural polymers like starch, cellulose, and proteins as well as synthetic polymers like polylactic acid (PLA) and polyhydroxyalkanoates (PHAs) that are biodegradable. PLA is commonly used for packaging and is produced from corn via fermentation. PHAs can be produced by microorganisms and have applications in drug delivery and tissue engineering. While biodegradable polymers address issues with conventional plastics, their production and properties need further improvement for widespread adoption. Continued research aims to enhance production efficiency and material properties.
Natural chemistry Structure elucidation of EmetineAnam Ilyas
The document discusses the structure elucidation of the alkaloid emetine, which is derived from the dried roots of Ipecacuanha plant. It summarizes that emetine has the molecular formula C29H40N2O4 and contains two 6,7-dimethoxyisoquinoline units joined to a C5H8 fragment. The structure of emetine was proved through its total synthesis. Spectroscopic techniques such as 1H NMR, 13C NMR, and mass spectrometry were used to further characterize the structure of emetine.
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.
biocompatibility of biopolymers and their sterilisation techniques.ShreyaBhatt23
what is biopolymers, types of biopolymers, classification of biopolymers, natural biopolymers, sterilization techniques of polymers like dry heating, autoclaving, radiation , chemical agents
Phytic acid is a yellow liquid used as a food additive in Japan that decomposes with heat. It has an empirical formula of C6H18O24P6 and molecular weight of 660.08. Phytic acid is soluble in water and alcohol. It can chelate iron and other polyvalent cations and forms complexes. It also has antioxidant properties by inhibiting iron-mediated hydroxyl radical formation and preventing lipid oxidation.
Vitamin B2, also known as riboflavin, is an essential component of coenzymes involved in redox reactions in the body. It acts as a precursor to FMN and FAD, which are cofactors for redox enzymes. Deficiency can result from poor intake, malabsorption, drug interactions, and genetic defects affecting flavin metabolism. Symptoms include sore throat, cheilosis, and glossitis. Status is assessed by urinary riboflavin levels, erythrocyte glutathione reductase activity, and direct measurement of flavins in plasma and erythrocytes.
1. Fish spoilage begins immediately after death due to enzymatic and microbial action. Enzymes cause changes like glycolysis producing lactic acid and nucleotide degradation impacting flavor.
2. Microbes proliferate in dead fish and produce undesirable compounds like histamine, indoles, ammonia, and TMA that lead to spoilage. Both saprophytic and pathogenic bacteria can grow.
3. Oxidation of lipids in fatty fish causes rancidity and discoloration, a major form of chemical spoilage.
Lecture 8. fish ocmponents and preservationMandeep Kaur
This document summarizes the major and minor constituents of fish, including proteins, fats, vitamins, minerals, and carbohydrates. It then discusses post-mortem changes in fish such as rigor mortis and spoilage through chemical changes like rancidity and autolysis, as well as microbial attacks. Finally, it outlines various fish preservation methods including icing, freezing, drying, salting, smoking, canning, and pickling to inhibit spoilage and microbial growth.
This document provides protocols for analyzing vitamins and toxicants in food. It details procedures for assaying various vitamins including vitamin A, vitamin B1, vitamin B2, and vitamin B6. The protocols describe preparing test and reference solutions, carrying out assays by ultraviolet spectrophotometry, liquid chromatography, or titration. Identification steps are also outlined, such as examining absorption maxima and reaction of solutions. The document aims to establish standardized methods for analyzing important nutrients and assessing quality and safety of food.
#medical #students #doctors #foodandnutrition #nurses #NEET #PCM #doctors #nutritioneducation #mscdfsm #dietician #nationaldieticians #RD #REGISTERED #DIETICIANS
#NUTRITIONIST #INTERNATIONALDIETICIANS
This content is made for all student of medical ,nutrition ,doctors ,zoology ,chemistry ,medical who are still preparing for examination .feel free to give suggestion.
Biopolymers are polymers produced by living organisms. Degradation is the process by which large polymers are fragmented into smaller molecules. There are several types of degradation including thermal, photo, mechanical, chemical, and oxidative. Biodegradation is the natural process by which organic chemicals are converted into simpler compounds by organisms like fungi and bacteria. The degradation mechanisms of some common biopolymers like starch, cellulose, poly(caprolactone), and poly(lactic acid) are discussed. Enzymes play an important role in degradation through processes like hydrolysis which breaks the polymer chains into monomers.
Lysine is an essential amino acid that is commonly produced through fermentation using microorganisms like Corynebacterium glutamicum. The fermentation process involves growing the microorganism in a stirred tank bioreactor containing nutrients from sources like molasses, corn steep liquor, and minerals. After fermentation, the broth is processed through ultrafiltration, ion exchange columns, and crystallization to isolate lysine hydrochloride. Lysine finds major applications as a food and feed additive due to its status as an essential amino acid for mammals.
The document summarizes key post-mortem biochemical changes that occur in fish after death. It discusses how rigor mortis develops as ATP is broken down and actin and myosin cross-bridges form. It then describes how autolysis and bacterial spoilage lead to degradation of lipids, proteins, and other tissues. Several chemical indices used to measure spoilage are also outlined, including TVN, TMA, alpha-amino nitrogen, and peroxide value.
The document summarizes the production of the antibiotic streptomycin. It was discovered in 1944 from the soil bacterium Streptomyces griseus and was the first effective treatment for tuberculosis. It is produced through submerged fermentation using mutants of S. griseus over 5-7 days. The fermentation proceeds through growth, idiophase of maximum streptomycin production, and death phases. Streptomycin is then purified from the broth using cation exchange resin columns and further processed to remove impurities, concentrated, and dried. Process details such as optimized media, fermentor corrosion, and recovery using weak acid cation exchange resin are also outlined.
This document summarizes the biosynthesis pathways of several important plant-derived compounds. It discusses the precursor molecules and biosynthesis routes for lysergic acid, tropane alkaloids, emetine, and quinine. For lysergic acid, the precursors are tryptophan and an isoprene unit, and it is formed through a series of reactions involving alkylation, methylation, and ring formations. Tropane alkaloids are derived from ornithine, and include compounds like atropine and cocaine. Emetine biosynthesis involves dopamine and secologanin, undergoing reactions like Pictet-Spengler and methylations. Quinine is derived from tryptophan as
Every component of the eye is vulnerable to damage from ROI, particularly retina. There are several reasons for the vulnerability of the retina, including high concentrations of polyunsaturated fatty acid (PUFA), constant exposure to visible light, high consumption of oxygen, an abundance of photosensitisers in the neurosensory retina and the RPE, the process of phagocytosis by the RPE which is known to generate hydrogen peroxide.
This document discusses alkaloids found in plants. It begins by defining alkaloids and their properties, including that they are basic compounds derived from plants and contain nitrogen. It then covers the history of alkaloid isolation, distribution in different plant families, and classification based on chemical structure. The document focuses on the variety of alkaloids and systems used for their classification. It provides examples of different alkaloid skeletal structures and the plant families that contain them.
Structural elucidation and isolation of glycoside, purine and flavanoidsSana Raza
Unit three of chemistry of natural products, consist of the method of extraction, isolation and structure elucidation of Glycoside(digoxin), Flavanoids( quercetin), Lignans( Podophyllotoxin), Purines (caffeine)
Biopolymers are polymers produced by living organisms and contain monomeric units that are covalently bonded to form larger structures. There are three main types of biopolymers: biorenewable, biodegradable, and biomaterials. Biopolymers include proteins, nucleic acids like DNA and RNA, and lipids. These biopolymers have various applications in areas like drug delivery, tissue engineering, and medical implants. Biodegradable polymers break down into natural byproducts and are used for things like drug delivery systems.
Biopolymers are polymers produced by living organisms and contain monomeric units that are covalently bonded to form larger structures. Examples of biopolymers include starch, cellulose, chitin, DNA and RNA. Starch acts as a natural polymer obtained from plants and is composed of glucose. Cellulose is the most common biopolymer and is composed of glucose, forming plant cellular walls. Proteins are biopolymers formed from bonded amino acid monomers into peptide chains. Nucleic acids like DNA and RNA are biopolymers made from bonded nucleotide monomers. Biodegradable polymers can decompose naturally through microbial action.
Biodegradable polymers are derived from biological sources such as plants and microorganisms. They include natural polymers like starch, cellulose, and proteins as well as synthetic polymers like polylactic acid (PLA) and polyhydroxyalkanoates (PHAs) that are biodegradable. PLA is commonly used for packaging and is produced from corn via fermentation. PHAs can be produced by microorganisms and have applications in drug delivery and tissue engineering. While biodegradable polymers address issues with conventional plastics, their production and properties need further improvement for widespread adoption. Continued research aims to enhance production efficiency and material properties.
Natural chemistry Structure elucidation of EmetineAnam Ilyas
The document discusses the structure elucidation of the alkaloid emetine, which is derived from the dried roots of Ipecacuanha plant. It summarizes that emetine has the molecular formula C29H40N2O4 and contains two 6,7-dimethoxyisoquinoline units joined to a C5H8 fragment. The structure of emetine was proved through its total synthesis. Spectroscopic techniques such as 1H NMR, 13C NMR, and mass spectrometry were used to further characterize the structure of emetine.
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.
biocompatibility of biopolymers and their sterilisation techniques.ShreyaBhatt23
what is biopolymers, types of biopolymers, classification of biopolymers, natural biopolymers, sterilization techniques of polymers like dry heating, autoclaving, radiation , chemical agents
Phytic acid is a yellow liquid used as a food additive in Japan that decomposes with heat. It has an empirical formula of C6H18O24P6 and molecular weight of 660.08. Phytic acid is soluble in water and alcohol. It can chelate iron and other polyvalent cations and forms complexes. It also has antioxidant properties by inhibiting iron-mediated hydroxyl radical formation and preventing lipid oxidation.
Vitamin B2, also known as riboflavin, is an essential component of coenzymes involved in redox reactions in the body. It acts as a precursor to FMN and FAD, which are cofactors for redox enzymes. Deficiency can result from poor intake, malabsorption, drug interactions, and genetic defects affecting flavin metabolism. Symptoms include sore throat, cheilosis, and glossitis. Status is assessed by urinary riboflavin levels, erythrocyte glutathione reductase activity, and direct measurement of flavins in plasma and erythrocytes.
1. Fish spoilage begins immediately after death due to enzymatic and microbial action. Enzymes cause changes like glycolysis producing lactic acid and nucleotide degradation impacting flavor.
2. Microbes proliferate in dead fish and produce undesirable compounds like histamine, indoles, ammonia, and TMA that lead to spoilage. Both saprophytic and pathogenic bacteria can grow.
3. Oxidation of lipids in fatty fish causes rancidity and discoloration, a major form of chemical spoilage.
Lecture 8. fish ocmponents and preservationMandeep Kaur
This document summarizes the major and minor constituents of fish, including proteins, fats, vitamins, minerals, and carbohydrates. It then discusses post-mortem changes in fish such as rigor mortis and spoilage through chemical changes like rancidity and autolysis, as well as microbial attacks. Finally, it outlines various fish preservation methods including icing, freezing, drying, salting, smoking, canning, and pickling to inhibit spoilage and microbial growth.
Changes in fish after death include rigor mortis and autolysis. During rigor mortis, ATP breaks down and actin and myosin bind tightly, making the muscle rigid. Autolysis involves the breakdown of proteins, fats, and carbohydrates by the fish's own enzymes. As ATP depletes, pH decreases due to lactic acid formation. Bacteria then invade the fish, leading to microbial spoilage through the production of biogenic amines, organic acids, and off-flavors. Spoilage is influenced by factors like temperature, oxygen content, and acidity. Both autolysis and microbial actions break down the fish muscle and render it unfit for consumption.
This document summarizes key aspects of fish processing and preservation. It discusses the decomposition processes that can occur in fish including enzymatic, oxidative, and bacterial spoilage. It then outlines various preservation processes used to prevent spoilage including temperature control, controlling water activity through methods like drying and salting, physical controls like heating, and chemical controls like reducing pH or adding preservatives. The document also briefly discusses turning low-value fish into fishmeal and fish oil as well as emphasizing that chilling fish immediately after harvest is important for preservation.
Spoilage of fish is a process of deterioration in the quality of fish, which changes its appearance, odour and taste. The breakdown of biomolecules like proteins, amino acids and fats in the fish are the factors responsible for fish spoilage. Thus, a fish can be spoiled by either chemical or biological degradation.
Chemical treatment prior to freezing: antioxidants, cryoprotectants and other...WBUAFS
The document discusses antioxidants and their role in preventing oxidation reactions in cells. It explains that antioxidants terminate chain reactions by removing free radical intermediates, thereby protecting cells from damage or death. Common natural antioxidants found in fish oils include tocopherols, while frequently used artificial antioxidants are BHA, BHT, and propyl gallate. The document also covers cryopreservation techniques and the use of cryoprotectants like glycerol and DMSO to protect cells from freezing damage by reducing ice formation and cell shrinkage.
Chemical factors such as enzymatic activity, oxidation, and microbial growth can cause food spoilage by impacting texture, color, odor, and flavor. Key chemical spoilage processes discussed include rancidity, proteolysis, pectin hydrolysis, enzymatic browning, Maillard reaction, and putrefaction. Rancidity occurs when oils and fats oxidize, producing unpleasant smells. Proteolysis and pectin hydrolysis involve enzymatic breakdown of proteins and pectin that can change food textures and produce bitter compounds. Enzymatic browning and the Maillard reaction cause discoloration. Putrefaction is the anaerobic breakdown of proteins by microbes, releasing foul odors
Vitamins play an important role in the body and must be obtained through diet as they cannot be synthesized. This document discusses the composition of vitamins in different parts of small fish, farmed fish, and marine fish. It describes the characteristics and metabolism of fat-soluble and water-soluble vitamins. The content of various vitamins like A, D, E, B1, B2, B3, B6, B9, B12, C, and K are discussed for different fish types. Finally, the effects of processing and storage methods like drying, cooking, canning, freezing, irradiation, curing, and storage on vitamin retention are summarized.
Fish quality is determined by several factors including its compliance with predetermined standards, total characteristics that satisfy needs, and freshness parameters like appearance, flexibility, eyes, and gills. The freshness of fish can be assessed through sensory analysis by sight and touch, as well as through microbiological tests, chemical analysis of pH, hypoxanthine content, and breakdown of proteins, fats, and nucleotides. Maintaining the quality and freshness of fish involves proper handling from catch to processing to storage and distribution.
Glutamic acid, a key amino acid with diverse industrial applications, is primarily produced via microbial fermentation, particularly using strains of *Corynebacterium glutamicum* and *Bacillus subtilis*. These microorganisms are adept at synthesizing glutamic acid through various metabolic pathways, with glucose or other carbon sources serving as substrates. The fermentation process involves optimizing growth conditions such as pH, temperature, and nutrient availability to maximize yield. Glutamic acid production can be further enhanced through genetic engineering to improve strain productivity and tolerance to environmental stresses. The versatile nature of glutamic acid makes it a valuable component in food additives, pharmaceuticals, and biodegradable polymers, emphasizing the importance of efficient and sustainable production methods.
This document discusses different types of browning reactions that can occur in foods, including enzymatic browning, non-enzymatic browning (Maillard reaction and caramelization), and browning reactions that occur in meat. Enzymatic browning is caused by the enzyme polyphenoloxidase and can be prevented by lowering the pH or destroying the enzyme through heating. The Maillard reaction occurs between amino acids and reducing sugars when foods are heated and produces flavors. Caramelization involves the heating of carbohydrates alone.
Fish silage is produced by preserving fish or fish waste through the addition of acids or lactic acid bacteria. There are two main types: acid silage produced through the addition of inorganic or organic acids like sulfuric acid or formic acid; and biological silage produced through lactic acid fermentation by bacteria like Lactobacillus plantarum. The fish material is minced and acids or bacteria added, then stored to produce the silage. The acids or lactic acid lower the pH and inhibit spoilage during storage. Fish silage can be stored for over a year and used as animal feed.
Effect of processing and storage on nutrientsPoojaParab12
This presentation describes the effect of processing and storage conditions on nutrients in food namely carbohydrates, proteins, lipids, vitamins and minerals.
This document discusses contamination, preservation, and spoilage of fish. It notes that fish can become contaminated from various sources like water, handling equipment, storage, and transport. Several bacteria are identified as common contaminants. Preservation methods discussed include chilling, freezing, drying, salting, canning, use of preservatives, antioxidants, and smoking. Proper preservation helps extend the shelf life of fish by slowing bacterial growth and enzymatic activity.
1) The document discusses the importance of carotenoids in the diets of ornamental fish for enhancing their natural colors in captivity.
2) Carotenoids are pigments that ornamental fish obtain through their diets as they cannot synthesize them endogenously. Common carotenoids include astaxanthin, lutein, and carotene which impart colors like red, yellow-green, and orange.
3) The document reviews the absorption, transport and metabolism of carotenoids in fish and different sources of carotenoids used in fish diets including synthetic, microalgal, animal and plant-based sources.
The document discusses fatty acid oxidation, including the pathways of beta oxidation and alpha oxidation. Beta oxidation occurs in the mitochondria and involves activating fatty acids with CoA, transport into the mitochondrial matrix via carnitine shuttle, and breaking the fatty acid down into two-carbon units through four reactions: oxidation, hydration, oxidation, and thiolytic cleavage. The products are acetyl-CoA which enter the TCA cycle. Alpha oxidation occurs with branched fatty acids like phytanic acid in peroxisomes or ER and removes methyl branches to allow beta oxidation. Defects can cause diseases like Refsum's disease.
This document discusses fish spoilage, including the key signs of spoilage to look for, factors that contribute to spoilage, and the three main stages of spoilage: rigor mortis, autolysis, and bacterial invasion/putrefaction. It also outlines the main causes of spoilage: enzymatic, mechanical, and bacterial action as well as chemical decomposition like oxidation. Methods for assessing and limiting spoilage are also summarized.
1. Oil spills pollute the environment and harm living things by releasing toxic chemicals. Microorganisms like bacteria and fungi can biodegrade oil through metabolic processes.
2. The biodegradation process involves microbes initially adding oxygen to break down the hydrocarbon molecules in oil into simpler compounds. Nutrients like nitrogen and phosphorus often limit biodegradation and must be supplemented.
3. Different types of hydrocarbons in oil degrade at different rates, with straight-chain alkanes degrading most easily and aromatic rings most resistant to breakdown. Both augmenting indigenous microbes and stimulating their growth through nutrient addition can help remediate oil spills biologically.
This document summarizes the microbes involved in the spoilage of fish and other seafood. It discusses that spoilage is caused by the microbial content of the water the seafood lives in, with common genera including Pseudomonas, Acinetobacter, and Vibrio. The number of microorganisms varies based on the type of seafood and location on the seafood. Factors like temperature, contamination level, and fish condition impact the spoilage rate. Signs of spoilage include fading color, increased slime, sinking eyes, and odor changes. Different bacteria cause spoilage at chilling versus higher temperatures. Specific bacteria are associated with spoilage of different seafood types.
Similar to Mechanism of Microbial Spoilage.pptx (20)
The increase in population and the challenge of feeding them nutritious food is the main issue facing the world. One of the sectors that produces food that is nutrient-rich is the aquaculture industry. This business is entirely reliant on manual labour, which makes for laborious, time-consuming work that consequently raises the cost of production for farmers and results in them receiving a minimal profit today. The effective approach to manage all situation and enhance production while lowering production costs is through automation. water quality monitoring by the sensor-based and controlled areal unnamed vehicles to spray Using biosensors to monitor water quality and remotely piloted aerial vehicles to spray fertiliser or chemicals. The intelligent aeration system regulates the level of dissolved oxygen. The automatic biomass estimation and feeding management are the second things. In order to reduce feed loss and lower the FCR, robotics and automatic feeders are used in ponds and cages. These devices rely on the water's quality and the behaviour of the organisms. A farmer receives information on biomass estimation when the crop is harvested to ensure maximum output. The most essential aspect is the automatic monitoring of the organism's health and welfare management to detect any adverse conditions or early signs of abnormalities. A camera-based visual system known as an underwater surveillance system collects data on water quality, organism activity, feeding, cage biofouling, and net cleaning. The future of the aquaculture sector is automation.
Current Status; Problems and Prospects for Seed Production of Commercially Im...Rajesh Chudasama
India commercial seed production of shellfish is well developed only one shellfish shrimp and prawn this industry monitoring by Costal Aquaculture Authority (CAA). Carb hatcherys are available in India southern states but it is not running like shrimp industry. Other hand lobster and molluscs hatcherys are running in laboratory stages of some institute. In problems of shellfish seed production is not available of good quality of broodstock and biological complexity of life cycle of Sartain species. In future aquaculture production is increasing but it is total dependence on availability of good quality seed.
Soil and water interaction__Physical and Chemical Properties of Soil and Wate...Rajesh Chudasama
In terms of successful and sustainable development of aquaculture two prospects are most important soil and water quality parameters management and its interaction process understanding.
Selection of the site for pond construction soil plays a key role. Soil type, water holding capacity, organic matter, available nutrients and chemical composition of soil these parameters are optimum level is required for aquaculture suitable site.
After water filling of the pond water parameters like pH, dissolved oxygen, total alkalinity, total hardness and total ammoniacal nitrogen interact with soil composition. That things are also dependent on climatic conditions and weather patterns.
Aquaculture is the most reliable sector to the providing world nutrias food. It is all depended on the cultivable species. Asian seabass is one of the candidate species for aquaculture because of the wide range of water quality tolerance, growth performance, and consumer preference. The Indian and Western Pacific Oceans are where Asian seabass is found in its natural habitat. It can be cultured in the earthen pond, floating or stationer cages, and recirculating system. Seed resources are available in rivers and lakes of fresh water, but aquaculture is the depending on the hatchery that produces seed because of the superior growth production. In the nursery phase, cannibalism is predominant in Asian seabass cultivation, which will improve via the grading of a shooter. Feeding is one of the important management for good growth performance and reducing cannibalism to give the optimum feed requirements. The growth rate of the Asian seabass is 400-600 g in 4 to 6 months. Asian seabass farmers are suffering from some infectious and non-infection diseases, it will improve via the good management practices of the culture promises. In this review paper, some key points of Asian seabass farming are covered for better understanding.
This document discusses the antibiotic chloramphenicol, including its chemical and physical properties, mechanism of action, therapeutic uses, and side effects. Chloramphenicol is produced by Streptomyces venezuelae and inhibits bacterial protein synthesis. It has broad-spectrum antibacterial properties and is used to treat various bacterial infections in aquaculture like dropsy, furunculosis, and columnaris. The recommended dosages vary depending on the disease and species. While it can boost growth as an immunostimulant when combined with garlic, chloramphenicol also carries risks of hematopoietic toxicity at higher doses.
This document provides information about Ukai Dam located on the Tapti River in Gujarat, India. Some key details include:
- Ukai Dam is the largest reservoir in Gujarat, located 94 km from Surat. It was constructed in 1972 at a cost of 1389.6 million.
- The dam is 80.772 meters high and 4927 meters long, with a catchment area of 62,225 square kilometers.
- Water quality parameters like temperature, pH, dissolved oxygen, nutrients are provided. The bottom is rich in nutrients and favors growth of benthic organisms.
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This document discusses factors modifying drug action, adverse drug effects, drug interactions, and bioassay of drugs. It covers physiological factors like age and sex that can impact drug action. It also discusses pathological, genetic, and environmental factors. It defines different types of adverse drug reactions including dose-dependent and unpredictable reactions. It explains how drug interactions can result from one drug altering the effects of another drug administered before or at the same time. Finally, it provides an overview of bioassay methods used to determine drug potency through measuring biological effects on living tissues or animals.
Marine fish production in Gujarat reached an all-time high of 786,495 tonnes in 2017. Pelagic resources such as ribbonfish and Bombay duck made up 36% of the catch. Demersal resources, including croakers, bull's-eye fish, and catfish, accounted for 30% of the catch. Maximum catch occurred during the post-monsoon and winter seasons. Among districts, Gir Somnath produced the highest volume of fish landings at 3.87 lakh tonnes. Multiday trawlers were the most productive mechanized fishing method.
Present Scenario and Problems of Aquaculture in India.pptxRajesh Chudasama
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The document summarizes techniques for pearl oyster hatchery operations, including broodstock development, induced spawning, larval rearing, and algal culture units. Broodstock are reared using raft, rack, or onshore tank cultures. Ripe oysters are induced to spawn through thermal or chemical stimulation. Larval development proceeds through trochophore, veliger, pediveliger, plantigrade, and spat stages over 3 months. Isochrysis galbana and mixed algae are cultured to feed the larvae and spat. Proper environmental conditions and feeding practices are required to grow pearl oysters from fertilization to spat.
This document discusses indicators for monitoring the sustainability of fishery resources. It begins by defining sustainability indicators as tools that reveal conditions and trends in the fishery sector. It then outlines several types of indicators including: yield-related indicators like catch levels; capacity-related indicators like fishing effort; economic indicators like investment levels; technological indicators like gear regulations; social indicators like employment rates; institutional indicators like research budgets; ecosystem indicators like species biomass; biodiversity indicators like protected areas; and water quality indicators like pollution levels. Finally, it discusses organizing indicators into three categories: pressures on resources, the state of resources, and responses like management actions.
Marine fish production in India was highest in Gujarat at 7,86,495 tonnes in 2017. Pelagic finfish made up 36% of landings in Gujarat, led by ribbonfish and Bombay duck. Gir-Somnath district accounted for the most landings in Gujarat. Maharashtra saw marine fish landings increase 30% to 3.81 lakh tonnes in 2017, with Indian mackerel and croakers as major contributors. Karnataka and Goa also saw increased landings in 2017 dominated by mackerel and oil sardine respectively. The largest producers after Gujarat and Maharashtra were Kerala, Tamil Nadu, and Andhra Pradesh.
Rajesh V. Chudasama submitted a document to Dr. Ritesh V. Borichangar about sediment. Sediment is defined as the matter that settles to the bottom of a liquid and may accumulate in an unconsolidated form. It can be chemically precipitated, secreted by organisms, or transported from land by various means and deposited. Marine sediment specifically refers to deposits of insoluble materials transported from land to oceans, along with remains of marine organisms and other sources, that accumulate on the seafloor.
This document summarizes the biology of several commercially important crab species. It discusses the taxonomy, distribution, feeding habits, and life cycles of mud crabs (Scylla serrata, S. olivacea, S. tranquebarica), swimming crabs (Portunus pelagicus, P. sanguinolentus), and the ridged swimming crab (Charybdis natator). For each species, it provides details on their classification, habitat, diet, reproductive biology involving larval development and spawning, and notes on their commercial fisheries. References are provided at the end from published literature and online sources.
This document describes 10 traditional fishing crafts found in Gujarat, India. It provides details on the size, design features, and purpose of each craft. The crafts described are the Halar Machhwa, Porbandar Machhwa, Cambay Machhwa, Navalaki Hodi, Malia Boat, Dugout Canoe, Lodhia, Madhwad type wahan, Gujarat wahan, and Katch Machhwa. Key details provided include length, beam, decking, planking, sails, and use for gillnet or trawl fishing.
Pasteurellosis is a bacterial disease of marine and brackish water fish caused by Photobacterium damselae subsp. piscicida. It is characterized by white granulomatous lesions in the internal organs. The disease was first reported in white perch in the U.S. in 1963. It takes either an acute or chronic form. In the acute form, there are few clinical signs but the internal organs show necrosis. In the chronic form, the spleen and kidney have small white lesions. Susceptible species include yellowtail, red sea bream, and sea bass. Treatment involves antibiotics administered via food.
This document discusses fish liver oil and its extraction process. It notes that fish liver oil is a good source of vitamins A and D. It classifies fish livers into three groups based on their oil and vitamin A content. The document outlines methods for preserving fish liver, including storing in ice, freezing, chopping and mixing with salt, or grinding and mixing with preservatives. It also describes the industrial process for extracting cod liver oil, including sourcing the fish from various species, and processing the liver to produce an oil that matches the EPA/DHA ratio of raw cod liver oil.
Indian Deep Sea Fishing Vessels in Indian EEZ__RAJESH CHUDASAMA.pptxRajesh Chudasama
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Indian Deep Sea Fishing Vessels in Indian EEZ__RAJESH CHUDASAMA.pptx
Mechanism of Microbial Spoilage.pptx
1. Presented By : Rajesh V. Chudasama
Mechanism of Microbial Spoilage &
Spoilage and Quality Indices in Frozen Fish
Subject
Quality Assurance of Fish and Fishery Products (FPT - 306)
2. • Microbes decompose and spoil fish in ways as given below:
1. Utilisation of readily utilisable simple substances such as non-protein
nitrogenous (NPN) substances
2. Hydrolysis of complex tissue components (eg. proteins) into simpler
substances (eg amino acids) and their subsequent utilization
3. Breakdown of nucleotides.
Mechanism of Microbial Spoilage
3. I. Trimethylamine Oxide (TMAO) Degradation
• TMAO is an osmoregulatory substance present in the tissue of marine finfish
and shellfish. Negligible quantities of TMAO are present in freshwater fishes.
• The muscle of sharks contains 750-1480 mg per cent TMAO.
• The TMAO reduction is mainly associated with the genera of bacteria such as
Alteromonas, Photobacterium, Vibrio, Shewanella putrefacians, Aeromonas and
intestinal bacteria of Enterobacteriaceae.
• TMA is responsible for the typical fishy odour of the marine teleosts. The level
of TMA found in fresh fish rejected by sensory panels varies between fish
species, and is around 10-15 mg N/100g.
Utilisation of Readily Utilisable Simple Substances
4. ii. Urea Degradation
• Urea is an osmo-regulatory substance present in the tissue of cartilaginous
fishes like sharks, skates and rays.
• It is decomposed to carbon dioxide and ammonia by the microbial enzyme,
urease. This process benefits the bacteria as they use the ammonia for
respiration.
• The production of ammonia also raises the pH of the substrate which
promotes the growth of many urea degrading bacteria inhibiting
competition by many other species.
5. iii. Free Amino Acid Degradation
• The free amino acids are present in the fish tissue in small quantities. After
the death of fish, due to autolysis, free amino acids are formed from tissue
proteins resulting in nutrient rich medium for microbial activity.
• They are also formed from hydrolysis of tissue proteins by proteolytic
enzymes secreted by microbes such as Pseudomonas, Sarcina when the
available free amino acids are scanty or exhausted.
• The metabolic end products come out of the microbial cell. Degradation of
free amino acids takes place in three ways:
6. A. Deamination
• Deamination is the process of the removal of amino group from the amino acids and the
amino group is then reduced to ammonia. The microorganisms associated are
Pseudomonas, Enterobacteriaceae and Lactic acid bacteria. Deamination occurs in four
ways.
Oxidative Deamination
• It takes place in the presence of oxygen with production of keto acid and ammonia. The
keto acid eventually turns into aldehydes, lower fatty acids and carbon dioxide.
Reductive Deamination
• It occurs in the presence of hydrogen producing a saturated fatty acid and ammonia.
7. Hydrolytic Deamination
• In this process, free amino acids are hydrolysed in the presence of water
with the production of hydroxyl acid and ammonia.
• The hydroxyl acid is decarboxylated with the liberation of carbon dioxide
and production of alcohols.
• The alcohol is oxidised further to aldehydes, ketones and lower fatty
acids.
8. Desaturative Deamination
• The amino acid is converted to unsaturated fatty acid with the formation of
ammonia.
Formation of Biogenic Amine from Amino Acids
Amino Acid Precursor Amino Acid Decarboxylase Biogenic Amines
Histidine Histidine Decarboxylase Histamine
Tyrosine Tyrosine Decarboxylase Tyramine
Tryptophan Tryptophan Decarboxylase Tryptamine
Lysine Lysine Decarboxylase Cadaverine
Phenylalanine Phenylalanine Decarboxylase Phenylethylamine
Arginine Arginine Decarboxylase Agmatine
Ornithine Ornithine Decarboxylase Putrescine, Spermidine, Spermine
9. B. Decarboxylation
• Decarboxylation is the removal of the carboxylic group (-COOH) from the amino
acids with the production of carbon dioxide and amines.
• These amines are called biogenic amines and include histamine, cadaverine,
putrescine, agmatine etc.
C. Deamination and Decarboxylation
• Here, both the amino group (-NH) and carboxylic group (-COOH) are
removed from the amino acids. It occurs in three ways viz.
(i) Oxidative deamination and decarboxylation,
(ii) Reductive deamination and decarboxylation and
(iii) Hydrolytic deamination and decarboxylation.
10. • Volatile sulphur compounds are typical components of spoiling fish and
most bacteria identified as specific spoilage bacteria produces one or
other volatile sulphides.
Formation of Volatile Sulphur Compounds
Typical Spoilage Compounds Formed during Spoilage of Fresh Fish
(Stored aerobically or packed in ice or at ambient temperature)
Specific Spoilage Organism Typical Spoilage Compounds
Shewanella putrefaciens TMA, H2S, CH3SH, (CH3)2S, Hx
Photobacterium phosphoreum TMA, Hx
Pseudomonas spp. Ketones, aldehydes, esters, non-H2S sulphides
Vibrionaceae TMA, H2S
Anaerobic spoilers N3H, acetic, butyric and propionic acid
11. • When the simple substances such as TMAO, urea and free amino acids are
completely exhausted, the microbes are start to hydrolysing complex tissue
components such as proteins and lipids to produce simpler substances.
• For utilising protein, proteolytic group of bacteria secrete proteolytic enzymes
from their cells to the surroundings. These enzymes hydrolyse protein into
amino acids.
• These amino acids enters the microbial cell and are metabolised and the end
products are liberated out of cell Alcaligenes, Acinetobacter, Aeromonas,
Bacillus, Corynebacterium, Flavobacterium, Lactococcus, Lactobacillus,
Pseudomonas and S. putrefaciens, Sarcina are associated with proteolysis in
fish.
Hydrolysis of Complex Tissue Components into
Simpler Substances and their Utilisation
12. Breakdown of Nucleotides
• Hypoxanthine which cause bitter off flavour in fish is formed by autolytic
or microbial activity.
Substrate and off Odour / Off Flavour Compounds Produced by
Bacteria during Spoilage of Fish
Substrate Degradation Products
TMAO TMA
Cysteine H2S
Methionine CH3SH, (CH3)2S
Carbohydrates and lactate Acetate, CO2, H2O
Inosine, IMP Hypoxanthine
Amino-acids (glycine, serine, leucine) Esters, ketones, aldehydes
Amino-acid, urea NH3
13. Spoilages and Quality Indices in Frozen Fish
State of Rigor at the Time of Freezing
• The degree of biochemical changes during freezing is affected by the
condition of the fish at the time of capture and the state of rigor at the
time of freezing.
• Drip loss of fillets and blocks prepared from pre-rigor fish is much higher
than in those prepared from post-rigor fish.
• Thus it is advantageous to extend the rigor mortis stage to just before
freezing to enhance the freshness and keeping quality.
14. • Protein denaturation in frozen fish muscle is the cause of a spatial
arrangement of protein molecules, due to the formation of ice crystals
within the muscle fibrils.
• Denaturation brings about definite changes in the chemical and physical
properties of native proteins such as solubility, hydration, optical
properties, digestibility etc.
• During freezing denaturation no chemical breakdown are known to take
place and the functional groups of the amino acids are not disrupted.
• This can be manifested later in the quality characteristics of the
resulting frozen fish like color, flavor and texture.
i. Protein Denaturation in Freezing and Frozen Storage
15. • Oxidation of lipids is a major cause of off-flavors and textural changes of
frozen seafood. The oxidation of unsaturated fatty acids involves the
formation of free radicals and hydro peroxides.
• The study of lipid oxidation in fishery products emphasize the non-
enzymatic or auto oxidative processes.
ii. Oxidation of Lipids in Frozen Fish
iii. Colour Changes
• Characteristic colour in seafood is an important factor for consumer
acceptance. Loss of the pink color in crustacean shellfish results from
the changes in the carotenoid pigments:
• Beta carotene (red) → astaxanthin (pink) → astacene (orange-yellow)
• Yellow discoloration of lipid rich regions in frozen fish also results from
lipid oxidation.
16. A. Blue/Black and Brown Discolouration In Frozen Lobster Tails
• As in prawns, black spot development occurs in lobster tails also.
• Proper glazing wrapping and low temperature storage are remedial
measures.
B. Discolouration in Squid and Cuttle Fish
• The important problem in frozen squid and cuttle fish is the yellow
discolouration of the tubes and fillets, Bleeding immediately after catch
and removal of appendages, inksac and gut contents followed by
washing prevent yellowing.
• The semi-dressed material has to be stored in ice and water.
• Treatment with a solution of salt and citric acid is found to improve
colour and texture of the squid and cuttle fish.
17. • The degree of protein denaturation is reflected in the amount of thaw drip
exuded from the cells on defrosting the fish.
• Excessive drip can be related to (a) slow freezing. (b) undue temperature
fluctuation during storage and (C) prolonged freezer storage.
• Drip loss results in a dry texture with loss of compounds contributing to flavor
like amino acids, nucleotides, sugars etc.
iv. Thaw Drip
v. Freezer Burn/Dehydration
• Low humidity in the freezer along with fluctuation in temperature during long
storage periods are causes for freezer burn.
• Weight loss by dehydration is proportional to the surface area and proper
glazing and packaging can reduce this problem. Weight loss by dehydration
should not be more than 50g/m2/24hrs.
18. • Black spot formation or "melanosis" is a major problem in prawn
freezing industry. This is an enzymatic reaction and requires access to
oxygen in addition to the presence of heavy metals like copper and iron.
• Melanin pigments are produced by an oxidative reaction by tyrosinase
on' tyrosine.
• One method of prevention of melanosis is cutting off access to oxygen.
This can be done by keeping the Material in ice and water with a layer
of water above the material.
• Treatment with potassium metabisulphite (0.2 - 0.5 per cent for 1 to 2
minutes) is beneficial to reduce black spot formation. But higher levels
of sulphite cause bleaching of the shell colour.
vi. Black Spots in Shell - on Shrimp
19. • By treatment, the level of sulphite as SO, should not exceed 100 ppm
in raw meat and 30 ppm in cooked meat.
• The maximum black spot permitted is 10 per cent by count in shell -
on types and 5 per cent by count in peeled type.
vii. Weight Loss during Thawing
• On thawing, frozen seafoods lose some weight as thaw drip consisting
of water containing soluble nutrients and flavour bearing components.
• The weight loss due to drip is 5 per cent in headless, 10-15 per cent in
peeled and deveined and 7 to 10 per cent in cooked shrimp.
• It increases with pre-freezing ice storage period. Drip loss is prevented
by treatment with polyphosphate. The maximum residual phosphate
permitted is 5gm/kg as P.
20. • In addition to good organoleptic characteristics, frozen prawns/fish
have to be free from excessive numbers of bacteria.
• Some types of bacteria, for e.g. coliforms, E.coli, Staphylococcus etc
shall be present only in very limited numbers and some types for eg.
Salmonella, V. cholerae, Listeria etc. shall be totally absent.
Precautionary sanitary practices like chlorination of water supplies both
for use in processing and ice manufacture, application of regular
cleaning schedules,
• strict enforcement of workers' hygiene etc. They are very important to
keep down bacterial contamination.
viii. Bacterial Contamination
21. • Materials like flies, cockroaches (whole or body parts), hairs, fibre
pieces, bits of paper and excessive sand can often be encountered in
frozen shrimp depending upon hygienic conditions.
• In the processing premises will solve the problem of filth to a large
extent. The avoidance of peeling on floor and use of potable water for
washing and proper washing of whole prawns with good quality water
can reduce sand content.
ix. Foreign Materials (filth)
x. Contamination with Heavy Metals
• Heavy metals have been recognised as serious pollutants of the aquatic
environment. They include metals like chromium, mercury, cadmium, cobalt, nickel,
copper, zinc, lead and tin and metalloids like arsenic and selenium.
22. • Studies have shown that cadmium is mainly concentrated in the liver
part and this problem can be avoided by careful removal of liver.
xi. Decomposition and Indole in Shrimp
• Decomposition is another serious problem in seafoods. Seafood spoils
very quickly if proper care is not taken during its processing, storage and
transportation.
• Some of the importing countries have fixed tolerance levels for indole.
The maximum permitted limit of indole in shrimp is 25 microgram/
100gm.
23. • In scombroid fishes like tuna, mackerel etc., histamine is formed during spoilage.
Histamine is formed by bacterial action on the amino acid, histidine present in
scombroid fishes.
• Above certain levels, histamine causes food poisoning. The maximum permitted
level of histamine in fish is 20mg/100gm.
xii. Histamine in Fish
xiii. Pesticide Residues
• Aquaculture is carried out either in paddy fields or adjacent areas, the problem of
pesticide accumulation in these cultured fishes cannot be ruled out.
• Some of the most important groups of chemicals widely used as insecticides are
DDT and its derivatives (DDE, DDD, or TDE), aldrin, dieldrin, benzene hexa chloride
(BHC) and polychlorinated biphenyl (PCB).
24. • The packaging material used for packing processed ses foods shall be able to
with stand stress the strain of transportation and storage under cold
conditions.
• Most of the countries which import seafoods have specified the
maximum permissible limits of certain pesticides in the seafoods.
• The limits prescribed by USFDA are 0.3 ppm for Dieldrin and Endrin, 5.0
ppm for DDT, DDE and TDE and 0.3 ppm for Heptachlor. In recent years,
aquaculture is given greater importance in our country.
xiv. Poor Quality Packaging Materials
25. • Mr. F Parthiban, Dr. S Balasundari, Dr. B Ahilan, & Dr. S Felix (2018),
Daya Publishing House, New Delhi, Aquatic Food Safety and Quality
Management, Mechanism of Microbial Spoilage, Spoilage and Quality
Indices in Frozen Fish, pp. 10-26.
Reference