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Anganwadi Supervisor Paper-2: Food Science and Nutrition · Chapter 1

Food Groups and Nutritive Value

What to remember

  • Foods are grouped by the main nutrient they give: energy-giving (cereals, fats, sugars), body-building (pulses, milk, eggs, flesh foods) and protective (fruits, vegetables, milk).
  • Energy values: carbohydrate 4 kcal/g, protein 4 kcal/g, fat 9 kcal/g, alcohol 7 kcal/g. No single food is complete except mother's milk for a young infant.
  • A balanced diet needs foods from every group in the right amounts; mixing cereals with pulses improves protein quality (mutual supplementation).

Food, nutrient and nutritive value

Food is any substance that supplies nutrients, gives energy and helps growth and repair. A nutrient is a chemical part of food that the body needs. The six classes of nutrients are carbohydrates, proteins, fats, vitamins, minerals and water. Dietary fibre is also needed, though it is not digested.

The nutritive value of a food means how much of each nutrient is present in 100 g of the edible part. The edible portion is the part left after peeling, removing seeds or bones. Food composition is always given per 100 g of edible portion.

The functions of food are:

  • Physiological: energy, growth, repair, and regulation of body processes (protective role).
  • Psychological: satisfaction, pleasure and a feeling of security.
  • Social: food is part of festivals, hospitality and customs.

Nutrition is the science of how the body uses food. A balanced diet gives all nutrients in the right proportion to meet the needs of the body with a small reserve. Malnutrition means either too little (undernutrition) or too much (overnutrition) of nutrients.

Ways of grouping foods

By function

GroupMain nutrientsExamples
Energy-givingCarbohydrate, fatRice, wheat, millets, oil, ghee, sugar, jaggery
Body-buildingProteinPulses, milk, egg, fish, meat, nuts
Protective (regulating)Vitamins, mineralsGreen leafy vegetables, fruits, milk

Food group systems. Indian dietary guidance (by ICMR-NIN) groups foods so that a family can plan meals easily. The older "basic" groups are cereals, millets and pulses; milk and flesh foods; fruits and vegetables; and fats and sugars. A pyramid or plate picture shows that cereals and vegetables should form the biggest part of the diet and fats, sugar and salt the smallest. The guidelines advise variety, enough milk or milk products, plenty of vegetables and fruits, limited oil, salt and sugar, and clean, safe food.

Cereals and millets

Cereals (rice, wheat, maize) and millets (ragi, jowar, bajra) are the staple foods and the cheapest source of energy. They give about 70-80% carbohydrate (mainly starch) and 6-12% protein.

  • Protein: low in the amino acid lysine (the limiting amino acid). Wheat has more protein than rice (rice about 7%, wheat about 11-12%).
  • Vitamins: good source of B vitamins (thiamine, niacin) in the outer layers (bran and germ). They have no vitamin C and no vitamin A (except yellow maize, which has a little carotene).
  • Minerals: poor in calcium, but ragi (finger millet) is the richest cereal source of calcium. Bajra is rich in iron.
  • Milling and polishing remove the bran and germ, so highly polished rice loses thiamine, niacin and fibre. Parboiling pushes B vitamins into the grain and reduces loss.
  • Rice protein is of better quality than wheat protein, while jowar has a lot of leucine (linked to pellagra).

Pulses, legumes, nuts and oilseeds

Pulses (dals) give 20-25% protein, which is about twice that of cereals. Soybean has about 40% protein and is the richest vegetable source. Pulses are rich in lysine but low in the sulphur-containing amino acid methionine.

  • They give B vitamins and iron. Whole pulses have more fibre and vitamins than dehulled dals.
  • Raw pulses have anti-nutritional factors (trypsin inhibitor, phytates). Cooking, soaking, germination and fermentation reduce them.
  • Sprouting raises vitamin C and B vitamins and makes minerals easier to absorb.
  • Nuts and oilseeds (groundnut, sesame, coconut) give protein (about 20-25% in groundnut) and a lot of fat and energy.

Mutual supplementation: cereal proteins are low in lysine and rich in methionine. Pulse proteins are rich in lysine and low in methionine. When eaten together (rice and dal, idli, dosa, khichdi), the mixture gives a better quality protein than either alone. A cereal to pulse ratio of about 3:1 to 4:1 by weight is used for good protein quality.

Milk and milk products

Milk is called the "nearly perfect food" because it gives protein, fat, calcium, vitamin A and riboflavin. It is poor in iron and vitamin C, and has little vitamin D unless fortified.

  • Milk protein: casein (about 80%) and whey proteins (lactalbumin, lactoglobulin). Casein is the main protein that curdles with acid.
  • Milk sugar is lactose. Milk fat is rich in short-chain fatty acids.
  • Typical composition (per 100 mL): cow's milk protein about 3.2 g, fat about 4 g, lactose about 4.5-5 g. Buffalo milk has more fat and protein than cow's milk. Human milk has less protein (about 1.1 g) but more lactose (about 7 g) than cow's milk.
  • Curd, buttermilk, paneer, khoa and cheese are milk products. Curd has lactic acid bacteria and extra B vitamins; fermentation also helps people who cannot digest lactose.

Egg, fish, meat and poultry

  • Egg: a whole egg has high-quality protein, so egg protein is used as the reference protein (its biological value is among the highest). The yolk gives fat, vitamin A, vitamin D, iron and choline. The white has protein and a substance called avidin, which binds biotin if the egg is eaten raw. Egg has no vitamin C.
  • Fish: good protein, and fatty fish give omega-3 fatty acids (EPA and DHA). Marine fish are a source of iodine.
  • Meat and poultry: protein of high quality, and haem iron, which is absorbed well. Liver is rich in vitamin A, iron, folate and vitamin B12.
  • Vitamin B12 is found only in foods of animal origin.

Vegetables and fruits

Green leafy vegetables (spinach, amaranth, fenugreek, drumstick leaves, coriander) are rich in beta-carotene (provitamin A), folate, riboflavin, vitamin C, calcium and iron. The iron in them is poorly absorbed because of oxalates and phytates. Other vegetables (brinjal, ladies finger, gourds) give fibre, minerals and some vitamins. Roots and tubers (potato, sweet potato, tapioca, yam) give starch and energy; yellow or orange sweet potato and carrot give carotene.

Fruits:

  • Amla (Indian gooseberry) is the richest natural source of vitamin C. Guava and citrus fruits (lemon, orange) are also good sources.
  • Ripe mango, papaya and orange-coloured fruits are rich in carotene.
  • Banana gives energy and potassium.
  • Fruits give fibre, and vegetable fibre helps in bowel regularity.

Fats, oils and sugars

  • Fats and oils give 9 kcal/g. Groundnut, mustard, sesame, sunflower and coconut oils are the common cooking oils. Vegetable oils have no cholesterol and contain essential fatty acids; ghee and butter have cholesterol and saturated fat. Fats help absorb vitamins A, D, E and K.
  • Visible fats (oil, ghee) are those seen and measured. Invisible fats are in cereals, milk, nuts and meat.
  • Sugar and jaggery give energy. Jaggery has a little iron and minerals; sugar gives only energy ("empty calories").
  • Spices and condiments are used in small amounts; some add iron, vitamin C or flavour.
  • Water is a vital nutrient needed for all body processes.

Energy value and simple calculations

Physiological fuel value: carbohydrate 4, protein 4, fat 9 kcal per gram. The energy of a food = (4 × g carbohydrate) + (4 × g protein) + (9 × g fat).

Worked example: 100 g of a food has 60 g carbohydrate, 10 g protein and 5 g fat. Energy = 240 + 40 + 45 = 325 kcal.

The percentage of energy from fat in that food = 45 / 325 × 100 = 13.8%. For a healthy adult diet, about 55-60% energy should come from carbohydrate, 10-15% from protein and 20-30% from fat (broad guide).

Comparison table: nutritive value at a glance

FoodStrong inWeak in
CerealsEnergy, thiamine, niacinLysine, calcium, vitamin C
PulsesProtein (lysine), iron, B vitaminsMethionine, vitamin C
MilkProtein, calcium, riboflavinIron, vitamin C
EggProtein quality, vitamin A, ironVitamin C
Green leafy vegetablesCarotene, folate, vitamin CProtein, energy
Fruits (citrus, amla)Vitamin CProtein, fat

Exam traps

  • Ragi is the richest cereal source of calcium, but bajra is the millet known for iron.
  • Milk is rich in calcium but poor in iron and vitamin C.
  • Cereals lack lysine; pulses lack methionine. Do not swap them.
  • Soybean is the richest vegetable protein; groundnut is not.
  • Amla is the richest source of vitamin C; orange or lemon is not.
  • Carbohydrate and protein both give 4 kcal/g; fat gives 9, alcohol 7.
  • Raw egg white contains avidin (binds biotin); egg yolk, not white, has vitamin A.
  • Vitamin B12 is absent from plant foods; liver is a rich source.

One-liners

  • 1. Edible portion is what remains after removing the inedible part of a food.
  • 2. Fat gives the highest energy: 9 kcal per gram.
  • 3. Cereals give 70-80% carbohydrate.
  • 4. Limiting amino acid of cereals is lysine.
  • 5. Limiting amino acid of pulses is methionine.
  • 6. Ragi is rich in calcium; bajra is rich in iron.
  • 7. Soybean has about 40% protein.
  • 8. Casein is the main milk protein.
  • 9. Lactose is the sugar of milk.
  • 10. Egg is the reference protein for quality comparison.
  • 11. Fatty fish are a source of omega-3 fatty acids.
  • 12. Parboiling reduces loss of B vitamins during milling.

Practice questions

  1. Which nutrient gives the highest energy per gram?

    1. Protein (4 kcal)
    2. Dietary fibre (2 kcal)
    3. Fat (9 kcal)
    4. Carbohydrate (4 kcal)
    Answer

    C. Fat (9 kcal)

    Fat gives 9 kcal/g; protein and carbohydrate give 4 kcal/g.

  2. The limiting amino acid in cereal proteins is

    1. Valine
    2. Leucine
    3. Methionine
    4. Lysine
    Answer

    D. Lysine

    Cereals are low in lysine; pulses are low in methionine.

  3. Which cereal or millet is the richest source of calcium?

    1. Rice
    2. Ragi
    3. Maize
    4. Wheat
    Answer

    B. Ragi

    Ragi (finger millet) is rich in calcium.

  4. The richest vegetable source of protein is

    1. Soybean
    2. Bengal gram
    3. Rice
    4. Groundnut
    Answer

    A. Soybean

    Soybean has about 40% protein.

  5. The richest natural source of vitamin C among these is

    1. Orange
    2. Amla
    3. Apple
    4. Grapes
    Answer

    B. Amla

    Amla (Indian gooseberry) is the richest natural source of vitamin C.

  6. The chief protein of milk is

    1. Casein
    2. Keratin
    3. Zein
    4. Gelatin
    Answer

    A. Casein

    Casein is about 80% of milk protein.

  7. Milk sugar is

    1. Maltose
    2. Sucrose
    3. Fructose
    4. Lactose
    Answer

    D. Lactose

    Lactose is the carbohydrate of milk.

  8. Milk is a poor source of

    1. Riboflavin
    2. Calcium
    3. Iron
    4. Protein
    Answer

    C. Iron

    Milk is poor in iron and vitamin C.

  9. Raw egg white contains avidin, which binds

    1. Folic acid
    2. Niacin
    3. Biotin
    4. Thiamine
    Answer

    C. Biotin

    Avidin binds biotin and stops its absorption.

  10. Vitamin B12 is found only in

    1. Fruits
    2. Foods of animal origin
    3. Green leafy vegetables
    4. Cereals
    Answer

    B. Foods of animal origin

    B12 is absent from plant foods.

  11. Which of these cereals is especially known for its iron content?

    1. Sago
    2. Maize
    3. Polished rice
    4. Bajra
    Answer

    D. Bajra

    Bajra is rich in iron.

  12. The protein used as a reference for comparing protein quality is

    1. Egg protein
    2. Wheat protein
    3. Gelatin
    4. Maize protein
    Answer

    A. Egg protein

    Egg protein has a very high biological value and is the reference protein.

  13. Fatty fish are a good source of

    1. Starch
    2. Vitamin C
    3. Omega-3 fatty acids
    4. Dietary fibre
    Answer

    C. Omega-3 fatty acids

    Fatty fish supply EPA and DHA (omega-3).

  14. In functional grouping, cereals are mainly

    1. Energy-giving foods
    2. Regulating foods
    3. Body-building foods
    4. Protective foods
    Answer

    A. Energy-giving foods

    Cereals give mainly carbohydrate (energy).

  15. Compared with cow's milk, human milk has more

    1. Calcium
    2. Casein
    3. Protein
    4. Lactose
    Answer

    D. Lactose

    Human milk has about 7 g lactose per 100 mL, more than cow milk.

  16. Which vitamin is absent in cereals?

    1. Riboflavin
    2. Vitamin C
    3. Niacin
    4. Thiamine
    Answer

    B. Vitamin C

    Cereals have B vitamins but no vitamin C.

  17. Sprouting of grains and pulses mainly increases

    1. Cholesterol
    2. Fat
    3. Sodium
    4. Vitamin C
    Answer

    D. Vitamin C

    Germination raises vitamin C and B vitamins.

  18. Raw pulses contain the anti-nutritional factor

    1. Casein
    2. Lactase
    3. Trypsin inhibitor
    4. Avidin
    Answer

    C. Trypsin inhibitor

    Trypsin inhibitor is destroyed by cooking and germination.

  19. The edible portion of a food is

    1. The whole food as bought
    2. The cooked weight only
    3. The part left after removing waste like peel and seed
    4. The part rich in fibre only
    Answer

    C. The part left after removing waste like peel and seed

    Food composition is given per 100 g edible portion.

  20. Which food is a good source of haem iron?

    1. Liver
    2. Dates
    3. Spinach
    4. Jaggery
    Answer

    A. Liver

    Meat and liver give haem iron, which is absorbed well.

  21. Rice and dal eaten together give a better protein because

    1. Dal has no amino acids of its own
    2. Lysine of dal makes up for lack in rice
    3. Rice has more fat than dal
    4. Rice contains vitamin B12
    Answer

    B. Lysine of dal makes up for lack in rice

    Mutual supplementation: cereal lacks lysine, pulse lacks methionine.

  22. Polishing of rice mainly reduces

    1. Calcium
    2. Vitamin D
    3. Cholesterol
    4. Thiamine
    Answer

    D. Thiamine

    Bran and germ, rich in B vitamins, are removed.

  23. Which of these contains cholesterol?

    1. Ghee
    2. Groundnut oil
    3. Sesame oil
    4. Sunflower oil
    Answer

    A. Ghee

    Only animal fats contain cholesterol.

  24. Which of these is a visible fat?

    1. Fat in egg yolk
    2. Ghee
    3. Fat in groundnut kernel
    4. Fat in milk
    Answer

    B. Ghee

    Visible fats are those added to food, such as oil and ghee.

  25. Iron of green leafy vegetables is poorly absorbed mainly because of

    1. Vitamin C
    2. Oxalates and phytates
    3. Lactose
    4. Casein
    Answer

    B. Oxalates and phytates

    Oxalates and phytates bind iron.

  26. Sugar is called a source of 'empty calories' because it gives

    1. Protein but no energy
    2. Vitamins but no energy
    3. Fat and minerals
    4. Energy but almost no other nutrients
    Answer

    D. Energy but almost no other nutrients

    Sugar gives only energy.

  27. A food has 50 g carbohydrate, 20 g protein and 10 g fat per 100 g. Its energy value is

    1. 370 kcal
    2. 330 kcal
    3. 410 kcal
    4. 480 kcal
    Answer

    A. 370 kcal

    4×50 + 4×20 + 9×10 = 200 + 80 + 90 = 370 kcal.

  28. A food has 70 g carbohydrate, 8 g protein and 2 g fat per 100 g. Its energy value is

    1. 300 kcal
    2. 360 kcal
    3. 330 kcal
    4. 390 kcal
    Answer

    C. 330 kcal

    280 + 32 + 18 = 330 kcal.

  29. A diet of 2000 kcal has 50 g fat. The percentage of energy from fat is

    1. 25%
    2. 15%
    3. 22.5%
    4. 30%
    Answer

    C. 22.5%

    50×9 = 450 kcal; 450/2000 × 100 = 22.5%.

  30. A 1800 kcal diet gives 12% of energy as protein. Protein in grams is

    1. 45 g
    2. 54 g
    3. 60 g
    4. 72 g
    Answer

    B. 54 g

    12% of 1800 = 216 kcal; 216/4 = 54 g.

  31. In a 2000 kcal diet, 60% energy comes from carbohydrate. Carbohydrate in grams is

    1. 360 g
    2. 240 g
    3. 200 g
    4. 300 g
    Answer

    D. 300 g

    60% of 2000 = 1200 kcal; 1200/4 = 300 g.

  32. Energy given by 10 g of alcohol (7 kcal/g) is

    1. 70 kcal
    2. 90 kcal
    3. 28 kcal
    4. 40 kcal
    Answer

    A. 70 kcal

    10 × 7 = 70 kcal.

  33. Energy in 25 g of pure fat is

    1. 175 kcal
    2. 225 kcal
    3. 100 kcal
    4. 250 kcal
    Answer

    B. 225 kcal

    25 × 9 = 225 kcal.

  34. Which of the following statements is/are correct? 1. Pulses are rich in lysine but poor in methionine. 2. Cereals are rich in lysine but poor in methionine.

    1. 1 only
    2. 2 only
    3. Both 1 and 2
    4. Neither 1 nor 2
    Answer

    A. 1 only

    Pulses lack methionine; cereals lack lysine.

  35. Which of the following statements is/are correct? 1. Raw cereals have 20-25% protein, more than pulses. 2. Soybean has about 40% protein.

    1. 1 only
    2. 2 only
    3. Both 1 and 2
    4. Neither 1 nor 2
    Answer

    B. 2 only

    Pulses and soybean exceed cereals; cereals have only 6-12%.

  36. Which of the following statements is/are correct? 1. Milk is rich in calcium and riboflavin. 2. Milk is a rich source of iron and vitamin C.

    1. 1 only
    2. 2 only
    3. Both 1 and 2
    4. Neither 1 nor 2
    Answer

    A. 1 only

    Milk is poor in iron and vitamin C.

  37. Which of the following statements is/are correct? 1. Highly polished rice has more thiamine than brown rice. 2. Parboiling retains more B vitamins in rice.

    1. 1 only
    2. 2 only
    3. Both 1 and 2
    4. Neither 1 nor 2
    Answer

    B. 2 only

    Polishing removes bran and germ with thiamine.

  38. Which of the following statements is/are correct? 1. Egg yolk gives vitamin A and iron. 2. Raw egg white is a rich source of biotin.

    1. 1 only
    2. 2 only
    3. Both 1 and 2
    4. Neither 1 nor 2
    Answer

    A. 1 only

    Raw egg white has avidin, which blocks biotin.

  39. Which of the following statements is/are correct? 1. Green leafy vegetables are good sources of vitamin B12. 2. Green leafy vegetables are good sources of carotene.

    1. 1 only
    2. 2 only
    3. Both 1 and 2
    4. Neither 1 nor 2
    Answer

    B. 2 only

    B12 is only in animal foods.

  40. Which of the following statements is/are correct? 1. Vegetable oils contain no cholesterol. 2. Ghee contains cholesterol.

    1. 1 only
    2. 2 only
    3. Both 1 and 2
    4. Neither 1 nor 2
    Answer

    C. Both 1 and 2

    Cholesterol occurs only in animal fats.

  41. Which of the following statements is/are correct? 1. Fat gives 4 kcal/g. 2. Carbohydrate and protein give 4 kcal/g each.

    1. 1 only
    2. 2 only
    3. Both 1 and 2
    4. Neither 1 nor 2
    Answer

    B. 2 only

    Fat gives 9 kcal/g.

  42. Which of the following statements is/are correct? 1. Human milk has less protein than cow's milk. 2. Buffalo milk has less fat than cow's milk.

    1. 1 only
    2. 2 only
    3. Both 1 and 2
    4. Neither 1 nor 2
    Answer

    A. 1 only

    Buffalo milk has more fat than cow milk.

  43. Which of the following statements is/are correct? 1. Vitamin C is found in plenty in cereals. 2. Amla is the richest natural source of vitamin C.

    1. 1 only
    2. 2 only
    3. Both 1 and 2
    4. Neither 1 nor 2
    Answer

    B. 2 only

    Cereals have no vitamin C.

  44. Which of the following statements is/are correct? 1. Ragi is rich in calcium. 2. Bajra is rich in iron.

    1. 1 only
    2. 2 only
    3. Both 1 and 2
    4. Neither 1 nor 2
    Answer

    C. Both 1 and 2

    Both are correct.

  45. Which of the following statements is/are correct? 1. Fatty fish provide omega-3 fatty acids. 2. Marine fish are a source of iodine.

    1. 1 only
    2. 2 only
    3. Both 1 and 2
    4. Neither 1 nor 2
    Answer

    C. Both 1 and 2

    Both are correct.

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