Basic Food Science And Nutrition: Carbohydrate PDF

STKM 1012 BASIC FOOD SCIENCE AND NUTRITION FOOD COMPOSITION: CARBOHYDRATE Noorul Syuhada 1  INTRODUCTION General classification of nutrient: ✓Source of energy (carbohydrate and fat) ✓Growth and repair (protein, mineral, water) ✓Control of bo...

STKM 1012 BASIC FOOD SCIENCE AND NUTRITION FOOD COMPOSITION: CARBOHYDRATE Noorul Syuhada 1  INTRODUCTION General classification of nutrient: ✓Source of energy (carbohydrate and fat) ✓Growth and repair (protein, mineral, water) ✓Control of body processes (protein, vitamin, mineral, water) 2 3  CARBOHYDRATE Source of energy Contain elements C, H dan O Produced in plants by photosynthesis 4  GENERAL FUNCTIONS OF CARBOHYDRATE IN FOODS 1. Provide energy 17 kilojoules (kJ) per gram 4 calories (kcal) per gram 2. Affect food taste and flavour (e.g. palatable) 3. Affect food texture - Viscosity - Leavened products such as breads and puffed products 4. Effect on food colour - Non enzymatic browning 5  Energy supply to whole body (esp brain and nervous system) Need to be in glucose form Recommended 50 - 60%* of total calorie came from CHO Preferably: - complex CHO (starch) - natural sugar (unprocessed) *Source: WHO Study Group on Diet, Nutrition and Prevention on Noncommunicabale Diseases (1991) 6  FUNCTIONS OF CHO 1. Energy storage in glycogen form Polysaccharide of glucose serve as form of energy storage in human, animal, fungi and bacteria Main storage form of glucose in the body (liver and muscles) Interchange for energy 7  Protect the cells from depressed metabolic functions Preserve normal sugar level in blood (during fasting, dehydration and sleeping) Immediate fuel to muscles 8 2. Protein-Sparing Action Helps to control protein metabolism Adequate CHO prevent conversion of protein into energy Protein is left for the specific function 9 3. Antiketogenic effect Ketogenesis is the biochemical process by which organisms produce a group of substances known as ketone bodies by the breakdown of fatty acids and ketogenic amino acids. Aceto-acetate and beta-hydroxy butyrate are the ketone bodies which are toxic compounds for the body. 10  Prevent formation of ketone bodies. In starvation, diabetes, and other conditions, production of ketones is increased, but they accumulate in the blood because cells do not use them as rapidly as they would use carbohydrates. Accumulation of ketone can cause ketoacidosis (hi conc of ketone due to breakdown of fatty acids) 11 4. Energy for cardiac muscle Glycogen in cardiac muscles is the main source for emergency regarding heart problem. Low level of CHO and storage of glycogen can cause cardiac arrest/ failure and severe pain in chest 12 5. Central Nervous System (CNS) CNS: the complex of nerve tissues that controls the activities of the body. No storage of glucose in CNS (brain) Depends on glucose from blood circulation 13 14  CLASSIFICATION OF CHO Divided according to the size of the molecules - saccharide (basic unit) → CnH2nOn carbohydrate monosaccharides disaccharides oligosaccharides polysaccharides C6H12O6 C12H22O11 3 – 10 mono > 10 mono Starch Cellulose Glucose Sucrose Raffinose Pectins Fructose Lactose Stachyose galactose maltose verbascose Glycogen Fibre 15  MONOSACCHARIDE Simplest group of sugar Divide into 2 Pentoses (C5H10O5) L-arabinose D-xylose Hexoses (C6H12O6) Glucose Fructose Galactose 16 Structures of simple sugar - glucose, fructose, and galactose 17  GLUCOSE Most common monosaccharides Moderate sweetness Also known as DEXTROSE Found in grapes, berries, oranges etc glucose - circulate in blood vessel for energy 18  FRUCTOSE The sweetest monosaccharides Fructose is also known as “fruit sugar” because it primarily occurs naturally in many fruits. In human metabolism, it is transformed into glucose for energy 19  GALACTOSE Bound monosaccharides in food Lactose digestion in human, produce galactose Transform to glucose for energy 20  DISACCHARIDES Disaccharides (di– = “two”) form when two monosaccharides undergo a dehydration reaction (also known as dehydration synthesis). During this process, the hydroxyl group of one monosaccharide combines with the hydrogen of another monosaccharide, releasing a molecule of water and forming a covalent bond. A covalent bond formed between a carbohydrate molecule and another molecule (in this case, between two monosaccharides) is known as a glycosidic bond Glycosidic bonds (also called glycosidic linkages) can be of the alpha or the beta type. α form– can be digested by human gut enzymes Further reading: https://courses.lumenlearning.com/ivytech-bio1-1/chapter/reading-types-of-carbohydrates/ 21 In sucrose, a glycosidic linkage is formed between carbon 1 in glucose and carbon 2 in fructose 22 Structures of simple sugar disaccharides: sucrose, lactose, and maltose 23  SUCROSE Table sugar, brown sugar, sugar cane, sugar beet mollases (thick dark brown syrup) The sweetness of sucrose is taken as 100 (used as standard for relative sweetness) The linkage between the glucose and fructose (involves aldehyde and ketone groups) is responsible for inability of sucrose to act as a reducing sugar. Non-reducing sugar – cannot donate electrons to other molecules 24  LACTOSE Found in mammalian milk= glucose + galactose Important component of dairy products 4.4 – 5.2 % cow milk 6.8 -8.8 % human milk **** lactose intolerence – cause diarrhea Substrate for growth by the milk-fermenting microflora 1/6 of sucrose sweetness 25  MALTOSE Form during starch degradation and in malted cereal Glucose-glucose 26  OLIGOSACCHARIDES Consists of 3 – 10 monosaccharides Present in small amount, are not digested in stomach & small intestine In large intestine Oligo mono CO2 + H2 enzyme bacteria 27  Present in significant amounts in food are: Raffinose (3 mono {gal+glu+fru}) Stachyose (4 mono) Verbascose (5 mono) Source: Beans, chickpeas, soybeans, lentils 28  POLYSACCHARIDES More than 10 monosaccharide, can reach up to 10,000 mono or more starch, dextrin, dietary fiber – cellulose and other non cellulose polysaccharides 29  STARCH Major polysaccharides in Commodity Starch content (%) most diets Cassava 30 Maize 22 In most staple food – rice, Rice 87 wheat, maize etc Potato 20 Soybean 12 Sweet potato 25 Wheat 64 30 Amylose and amylopectin 31  Composed of 2 types of polymers Amylose – 50-500 glucose unit in straight chain α 1-4 glycosidic Amylopectin – up to 100,000 glucose unit in branched chain Glycosidic between C-1 and C-4 Glycosidic between C-1 and C-6 for branched molecule 32 33  DEXTRIN Dextrin is a generic term applied to a variety of products obtained by heating a starch in the presence of small amounts of moisture and an acid. Intermediate product of starch degradation, between sugar and starch Occur during digestion process Eg: maltodextrin, cyclodextrin 34  CELLULOSE Main component of plant cells walls (20-25%) 2 - 14 thousand of glucose units Not digestible in human – no specific enzyme Effect on stool bulking Due partly to the retention of water by fibre in faecal matter and partly to increase excretion of solids Main source of crude fibre Sources: vege, cereals, bran 35 36  HEMICELLULOSE Heterogenous group of polysaccharides Polymers of hexose and pentose – result branched structure Arabinoxylan (cereals) Glucuronoxylan (fruits) Xyloglucan (fruits, vege, cereals and seeds) Less rigid molecules and > soluble than cellulose 37 Types Main chain Side group source Arabinoxylan Xylose Arabinose Cereal Glucuronoxylan xylose Glucoronic acid Fruits Glucurono – xylose Arabinose + Cereals arabinoxylan glucoronic acid Xyloglucan Β-glucose xylose Fruits, vege, cereals & seeds 38  PECTIC Polymers = D-galacturonic acid + L-arabinose + D-glucose Most soluble plant cell wall component Capable of forming gels Extracted from apple or citrus – jam manufacturing 39 The basic structure of pectic substances 40  LIGNIN Smaller quantities in plant tissues Significantly found in overmature or woody vege, seed-containing fruits like some berries Lignin is a polymer of modified phenylpropane 41  DIETARY FIBRE Chemically complex Def: the indigestible portion of diet – resistant to hydrolysis by human enzymes Found in the walls of plant cells Component of dietary fibre Plant polysaccharides Cellulose Hemicellulose Pectic substances Lignin 42  FUNCTIONS OF DIETARY FIBRE 1. Effects on stool bulking Cereal fibre has the greatest effect on stool bulking The bulking is due partly to the retention of water by fibre in faecal matter and partly increased excretion of solids Increased excretion of solids – protective against a number of diseases 43 44 2. Effects on blood lipids Dietary fibre bound to cholesterol and bile to lower lipid level in blood Study: oats, beans and lentils lower serum cholesterol levels 3. Effects on CHO digestion and absorption Study showed that giving large doses of gums (guar gum) is advantage to diabetics Improvement in sugar metabolism 45