Carbohydrates are the most abundant and diverse class of organic compounds. They consist of carbon, hydrogen, and oxygen and serve important functions in the body such as an energy source. Carbohydrates are classified as monosaccharides, oligosaccharides, or polysaccharides depending on the number of sugar units. Excess consumption of carbohydrates can lead to health issues like obesity, diabetes, and heart disease while deficiency can cause problems like acidosis, ketosis, and hypoglycemia. Carbohydrates undergo several reactions during cooking and processing that influence flavor and color development in foods.

1. CARBOHYDRATES
Presented to:
Dr. Shivesh Sharma
Presented By:
Shradha Suyal
2015BT01

2. CARBOHYDRATES
• consist of C, H and O atoms.
•are polyhydroxy aldehydes or polyhydroxy ketones, also called hydrates of Carbon.
• most abundant & diverse class of organic compounds.
• one of the three major macronutrients found in food.
•critical role in proper functioning of the immune system, fertilization, blood clotting
& human development.
• found in a number of foods like fruits, starchy vegetables ( pea, potatoes), grains,
milk, desserts, yoghurt etc .

3. They serve as
• energy source, fuels and metabolic intermediates (starch, fructans, glycogen).
• part of the structural framework of RNA and DNA.
• structural elements in the cell walls of bacteria and plants, and in the exoskeleton of
arthropods (cellulose, chitin, xylans).
• cell recognition moities(glycolipids & glycoproteins) as important components of cell
membranes, serving as probes through which the cell interacts with its environment.
• Protective substances
-some plant cell wall polysaccharides are elicitors of plant antibiotics (phtoalexins)
E.g In soybean, fragments of pectic polysaccharide (α-4-linked dodecagalacturonide)
induces synthesis of a protein that inhibits insect & microbial proteinases.
- Arabinoxylans have been postulated to inhibit ice formation, thus ensuring winter
survival of cereals.

4. CLASSIFICATION OF CARBOHYDRATES
• Monosaccharides:
simple carbohydrates, cannot be hydrolyzed further into polyhydroxy aldehyde or ketone unit.
Example- glucose, fructose, galactose.
• Oligosaccharides:
polymers made up of 2 to 10 monosaccharide units joined together by glycosidic linkages.
Example- sucrose, lactose, raffinose.
• Polysaccharides:
polymers with hundreds or thousands of monosaccharide units. They are not sweet in taste ;
therefore called non sugars. Are insoluble in water. Can be homopolysaccharides or
heteropolysaccharides.
Example- cellulose, glycogen, starch.

5. TYPES OF CARBOHYDRATES IN FOOD
Three main types :
• starch (complex carbohydrates)
• sugar
• fiber
On nutritional level “total carbohydrate” includes all three types, which is
useful in carbohydrate counting.
Counting can be done by either adding up grams of total carbohydrate or
adding “ carbohydrate units” .
1 carbohydrate unit = 15 g of carbohydrate
 is a meal planning tool used in diabetes management to help optimize
blood sugar level.

6. STARCH
• foods rich in starch include peas, potatoes, corn, dried beans, kidney beans,
grains like oats, barley, rice.
• majority of grain products are made from wheat flour like pasta, bread,
chapattis.
• Grain group includes
-whole grain
-refined grain
• Grain has three parts:
1. Bran- outer hard shell of the grain, part that provides most fiber & most of
the B vitamins & minerals.
2. Germ- next layer, packed with nutrients & fatty acids along with vitamin E.
3. Endosperm- soft part in the center of the grain which contains the starch.
• Refined grain contains only endosperm.

8. SUGAR
• simple, fast acting carbohydrates.
• soluble in water.
• sweet in taste.
• monosaccharide and disaccharides.
• can be reducing or non-reducing.
• two types:
- naturally occurring (those in milk & fruits)
Example- fructose in fruits, lactose in milk.
-added sugars ( those added during processing of food)
Example- saccharin, aspartame.

9. FIBER
• common in plant foods; absent in animal products like milk, eggs, meat,
poultry etc.
• it is the indigestible part of plant foods ( fruits, vegetables, whole grains, nuts
& legumes)
• Dietary fiber when consumed, mostly passes the intestines & is not digested.
• for good health, 25-30 gm of fiber intake per day is required in adults.
• sources include :
-fruits & vegetables (apples, corn, berries)
-whole grains, cereals, oats, bread.
-nuts (peanuts, walnuts, almonds)

10. FLAVOUR & COLOUR PRODUCTION BY CARBOHYDRATES
Flavor & color reactions of carbohydrate constituents of foods may be
classified into:
Enzymatic browning reactions
Caramelization
Maillard reaction
Strecker degradation

11. 1.ENZYMATIC BROWNING REACTIONS
•Part of natural process of decay
•When food substances are deprived of the protection of water, they get oxidized or
chemically dehydrated to reactive intermediates, which polymerize to dull, brown,
humic substances.
•Two types:
Oxidative Browning:
Oxidases are active & convert functional groups to reactive carbonyl compounds
which undergo further non-enzymatic oxidative browning reactions.
Non-oxidative Browning:
Glycosyl hydrolases initiate non-oxidative browning in natural products by the release
of reducing sugars. It is important in color & flavor development in dates, honey, maple
syrup, chocolate & vanilla processing. Reducing sugars undergo a series of reactions
even in the absence of oxygen or other oxidants to yield reactive carbonyl compounds.

12. 2.CARAMELIZATION
•Involves a complex group of reactions that are the result of direct heating
of carbohydrates.
•Heat hastens the inversion of sucrose to yield reducing sugars which
condense to higher oligosaccharide & dextrins.
•When amino acids do not participate in the heat induced reactions, the
complex color & flavor forming reactions of carbohydrates are called
caramelization reactions.
•Brown pigments that characterize caramel & other foods are due to HMF
& its precursors.
•Three commercial types of caramel colors:
i. Acid fast caramel used in cola drinks, made using ammonium
bisulphite catalyst.
ii. Brewer’s color found in beer, made form sucrose in the presence of
ammonium ions.
iii. Baker’s color in baked goods, results from direct pyrolysis of sucrose
to give burnt sugar color.

13. 3.MAILLARD REACTION
•In the presence of amino compounds, the browning of sugars occurs more rapidly,
particularly in neutral or alkaline conditions in a sequence of reactions called Maillard
reaction.
•Browning & aroma formation during cooking, frying, baking or roasting are caused by
this reaction.
•Lysine is the most reactive amino acid followed by met, arg, trp & his.
•Chemical Mechanism:
-Carbonyl group of sugar reacts with amino group of the amino acid producing N-
substituted glycosylamine & water.
-Unstable glycosylamine undergoes Amadori rearrangement, forming ketosamines.
-Several ways for ketosamines to react further:
(produce water & reductones)
(diacetyl, aspirin, pyruvaldehyde & other short-chain hydrolytic fission products)
(produce brown nitrogenous polymers & melanoidins)

14. 4.STRECKER DEGRADATION
•Involves transamination & decarboxylation reactions.
•It is the interaction of α-dicarbonyl compounds with α-amino acids at
elevated temperature.
•The reaction yields aldehydes, aminoketones & CO2.
•These aldehydes contribute to fruity, ester-like, malty green or honey like
aromas in foods.
•Aminoketones formed undergoes further reactions to yield pyrazine
derivatives. These compounds together with products obtained from
dimerization of sugar residues make a major contribution to the characteristic
aroma of baking.

15. CARBOHYDRATE METABOLISM
Metabolic pathways involved:
•Glycolysis the oxidation metabolism of glucose molecules to obtain ATP and pyruvate.
Pyruvate from glycolysis enters the Krebs cycle, in aerobic organisms after moving
through pyruvate dehydrogenase complex.
•The pentose phosphate pathway, which acts in the conversion of hexoses into pentoses
and in NADPH regeneration. NADPH is an essential antioxidant in cells which prevents
oxidative damage and acts as precursor for production of many biomolecules.
•Glycogenesis the conversion of excess glucose into glycogen as a cellular storage
mechanism; this prevents excessive osmotic pressure build up inside the cell.
•Glycogenolysis the breakdown of glycogen into glucose, which provides a glucose
supply for glucose dependent tissues.
•Gluconeogenesis de novo synthesis of glucose molecules from simple organic
compounds. An example in humans is the conversion of a few amino acids in cellular
protein to glucose.

16. HARMS OF EXCESS CARBOHYDRATES
Excess consumption of carbohydrates
causes pancreas to continue secreting
insulin & body is constantly in fat
storage mode. This leads to many health
problems.
• Obesity – excess fat storage.
• Insulin Resistance(Hyperinsulinemia)
– precursor to Type II Diabetes.
• High Blood Pressure - Excess insulin
forces kidneys to retain Na ions, hence
fluid retention increases. Blood retains
more fluid hence Blood Pressure rises.
• High cholesterol – Excess insulin
causes LDL levels to rise.
• Heart disease – When LDL particles
migrate into the walls of coronary artery.
• Prostrate and Breast Cancer.

17. CARBOHYDRATE DEFICIENCY
Caused by not taking a balanced diet.
• Acidosis – shift from glycolysis to lipolysis & ketogenesis for energy needs.
Acidity in blood & tissues rises & causes irreversible cell damage.
• Ketosis – Prolonged fasting or starvation; Acetyl CoA in liver is used to produce
ketone bodies which leads to ketosis.
• Hypoglycemia – Non availability of glucose ; occurs when blood glucose levels
drop under 70 mg/ml. Symptoms include giddiness, fatigue, distress.
•Constipation – Dietary fiber is an essential component of carbohydrate food. It
helps digestion & prevents recto-colon cancer.
•Mood swing - Dietary carbohydrate exclusion causes the brain to stop regulating
serotonin hormone. Low serotonin supply causes mood swing and depression.

18. REFERENCES
•Food Processing and Preservation by B. Sivasankar
•Food Science and Technology edited by Geoffrey Campbell-Platt
•http://allnutriments.blogspot.in/2013/03/carbohydrate-deficiency-
diseases.html
•http://www.diabetes.org/food-and-fitness/food/what-can-i-
eat/understanding-carbohydrates/types-of-carbohydrates.html
•http://www.humfeldchiropractic.com/the-dangers-of-excess-carbs/
•http://www.nadyapeche.com/refined-grains-health-risks/
•https://en.wikipedia.org/wiki/Carbohydrate_counting
•https://en.wikipedia.org/wiki/Maillard_reaction
•https://en.wikipedia.org/wiki/Carbohydrate_metabolism