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Lecture 5 - Carbohydrates 1 (1) introduction.pdf
- 1. LectureV Aqsa Akhtar School ofFood and Agricultural Sciences University of Management andTechnology FST-2101 3(3-0) Food Chemistry 1
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- 3. Session 5: LearningOutcomes Course Learning Objective ▪Differentiate between major and minor food components and their functions and physiochemical properties Session Learning Objective ▪Explain properties and reactions of carbohydrates, lipids, proteins, enzymes during storage and processing of food Session learning Outcomes ❖SLO 5.1: Understand the basics of carbohydrates and classes of carbohydrates ❖SLO 5.2: Describe the physical and chemical characteristics of monosaccharides ❖SLO 5.3: Elaborate the different types of monosaccharides and their role in nutrition
- 4. Carbohydrates ▪Hydrates of carbon,containing C, H and O ▪Widely available, and inexpensive ▪Polyhydroxylated compounds having at least 3 carbon atoms and a potentially active carbonyl group which may be an aldose or a ketose group ▪Simply called saccharides (aka sugars) with molecular formula (CH2O)n ▪Carbohydrates comprise of > 90% of the dry matter of plants
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- 6. Carbohydrates (Cont) ▪Present indifferent molecular structures, sizes, and shapes ▪Exhibit a variety of chemical and physical properties ▪Along with glucose and fructose, they are human energy sources, providing 70 – 80% of the calories in the human diet worldwide
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- 8. Types of Carbohydrates SimpleCarbohydrates ▪ Monosaccharides • Glucose • Fructose • Galactose ▪ Disaccharides • Sucrose • Maltose • Lactose Complex Carbohydrates ▪ Oligosaccharides • Maltodextrins • Raffinose • Stachyose ▪ Polysaccharides • Glycogen (Animals) • Starches (Plants) • Fibers (Plants)
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- 13. Functional Groups ▪Monosaccharides containseveral functional groups. They contain the hydroxyl group represented as –OH. They also contain a carbonyl group, which is an oxygen double bonded to a carbon atom ▪The carbonyl group may be an aldehyde or a ketone A carbonyl group is a functional group composed of a carbon atom double- bonded to an oxygen atom: C=O
- 14. 1. Monosaccharides ▪Monosaccharides cannotbe hydrolyzed and referred to as simple sugars ▪Monomeric units joined together to form larger structures, are called oligosaccharides and polysaccharides, and can be converted into their constituent monosaccharides by hydrolysis ▪Classified on the basis of the nature of carbonyl group ▪Monosaccharides that contain a carbonyl group have the suffix “ose” ▪Polyhydroxy aldehydes are called aldoses (Glucose) Polyhydroxy ketones are called ketoses (Fructose)
- 15. Carbohydrates: Condensation 1. Monosaccharides(Cont) Carbohydrates: Hydrolysis
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- 17. 1. Monosaccharides (Cont) ▪Monosaccharides that contain aldehyde group are referred as aldose ▪ Monosaccharides that contain ketone group are referred as ketose
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- 19. 1. Monosaccharides (Cont) ▪Solidsat room temperature ▪Extremely soluble in water ▪ Carbohydrates are hydrophilic substances which are soluble in water and alcohol ▪ The (OH) groups of carbohydrates are primarily responsible for their solubility in water
- 20. 1. Monosaccharides: SimpleSugars Glucose ▪Found in fruits, vegetables, honey ▪Most abundant monosaccharide found in nature ▪Carbohydrate form used by the body, referred to as “blood sugar” ▪Glucose also known as dextrose and grape sugar ▪Basic sub-unit of other larger carbohydrate molecules ▪Excess in the blood is called hyperglycemia and presence in urine (glucosuria) indicates diabetes mellitus
- 21. 1. Monosaccharides: SimpleSugars Fructose ▪Latin word for fruit — "fructus“ ▪Sweetest of the sugars ▪Occurs naturally in fruits & honey, also called “fruit sugar” or levulose ▪Combines with glucose to form sucrose ▪Released by the hydrolysis of inulin ▪Can be converted to glucose in the liver
- 22. 1. Monosaccharides: SimpleSugars Galactose ▪Greek word for milk-"galact“ ▪Found as a component of lactose in milk ▪Synthesized in the lactating mammary gland ▪Constituent of glycolipids and glycoproteins ▪Can be converted to glucose in the liver ▪Accumulation can lead to galactosemia and cataract (galactitol)
- 23. Key Concepts: Summary ✓Macronutrientsessential to living organisms and energy source for the human body ✓Organic molecules in which carbon (C) bonds with hydrogen and oxygen (H2O) in different ratios depending on the specific carbohydrate ✓Plants harvest energy from the sun and manufacture carbohydrates during photosynthesis ✓In a reverse process, animals break down carbohydrates during metabolism to release energy ✓All carbohydrates are made up of units of sugar
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- 25. Take Home Activity Bringsome examples of aldoses and ketose
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