UNIT 10 CHEMISTRY OF FOOD WITH

SPECIAL REFERENCE TO ,~
.'
CEREALS,· PULSES AND OILSEEDS
\
\

Structure
10.0 Objectives
10.1 Introduction /
10.2 Chemical Composition of Foods with Reference to Cereals, Pulses and
Oilseeds
10.3 Carbohydrates and Lipids
10.4 Chemical Reactions of Carbohydrates
10.5 Fatty Acids and Their Properties
10.6 Proteins
10.7 Proteins from Different Sources
10.8 Protein Structure
10.9· Essential Amino Acid
10.10 Let Us SumUp
10.11 KeyWords
10.12 Some Useful References
10.13 Answers to Check Your Progress

10.0 OBJECTIVES
After reading this unit you should be able to:
• . understand role of cereals, pulses and oilseeds in food.
• explain different constituents of cereals, pulses and oilseeds and their
significance in a food.
• define role of different carbohydrates and lipids in food and its different chemical
and metabolic reactions.
• explain basic properties of protein, structure of protein and different sources
of protein. •
• explain significance and role of essential amino acid in food and its nutritive
properties.
• .define role of fatty acids in food and its properties.
• defme role of different nutrients inhuman body.

10.1 INTRODUCTION
The Cereals, Pulses and Oilseeds received a boost in production from a starving
';'\.

situation of importing food grains to a position to export after a gteen revolution in

India. The grains are main. source of starch in form of energy, proteins, calcium,
iron and vitamins of group B in Indian diet. -Cereals are the consumed in large
quantities and frequently by vast majority of population in the world. Cereals are
used as a staple food in large number of countries in world because their cost of
production is low and cost: benefit ratio is high in terms of quantity and nutrients. 23
Basic Pr inclples-H
Cereals are easy to store because 0 low moisture content, easy to handle and
providing blandness to diet.

Legumes are second to cereals as an important source of proteins. As regards

consumption, there are basically two groups oflegumes. First there is high-protein
high-oil group like soybean, groundnut, lupine, etc which are mainly used for
processing. It contains high protein content (35%) and oil content varies from 15-
45%. The second group comprises the moderate- protein low oil types like
cowpea, gram, pea, lentil etc.

Oilseeds are also generally rich source of protein except coconut and fat. Oilseeds
are major sources of edible oil. Edible oilseed meals obtain from oilseeds are rich
in proteins and have been used for preparation of infants food for feeding infants
and school going children in most of the countries in world.

10.2 CHEMICAl~ CO;;,H)OSITION OF FOODS WITH

REF'ERENCE TO CEREALS, PULSES AND
OILSEEDS

Cereals
Cereals are of plant origin which yield edible grains which are consumed directly
or in modified form as major part of diet and also feed to livestock. Rice and wheat
are most important cereals forming part of human food. The major constituents of
the principal cereals are listed in Table 1. Cereal grains consist about two third
carbohydrates, mainly in form of digestible sugars and starches. These grains are
also an important source of several other nutrients such as protein, calcium, iron
and.vitamin B.

The cost of cultivation and production is low and cost benefits ratio is high in terms
in
of yield and nutrients. Cereals are used as a staple diet most developing as well
as develop countries in world. They can also be stored easily for long periods at
low cost, and their moisture levels remain low. They can be consumed in bulk,
they provide blandness to diet and hence can be incorporated in diet for infants.

Table 1: Composition of different Grains

Grains '--Moisture -Carbohyd~atcs Protein I Fat I Fib" GKJ1o<alor,,, I

j (% 0/0 % '!Ic, i % {per 100 gm.)
(j}- --
vihea;-----r--ll-· ._-- -_._+--- ..- ------
13 213 340 I
--
Rice -1- 11 65

~.
-~
y ~fi0~~
8 2 I 9 310
Corn -----t- 11"1 72

; 12 2 6 320
Oats --r--it 1---5 10 317

Rye 11 71 12 2 2 321
----
Buck wheat 10 64 -.--LI 11 2 11 318

The major cereals grown in India, in orderoftheir total production are Rice, Wheat,
Jowar, Maize, Bajra, Ragi, Barley, etc. .

24
 '. ~
Rice :- In India rice crop is most extensively grown and i.ace unts for about Chemistry of Food with
Special Reference to
22 % of total cropped area and almost 40% ofthe total area un er cereal. Rice Cereals, Pulses and
production is roughly 46% of total cereals produced. Oilseeds

Composition of rice:- The mature grain or paddy is botanically known as caryopsis

and consist of a loose outer husk is enclosing kernel. Husk constitutes about 25 %
ofthe paddy. Kernel is made up ofthree parts, which are the pericarp (seed coat)
with the underlying aleurone layer, the starchy endosperm and the germ. The germ,
the pericarp and the aleurone layer are richer in nutrients as compared to endosperm
and they contain proteins and vitamins. Germ, pericarp, aleurone layer are separated
from the grain during milling along with the husk.

In rice carbohydrates is available in form of starch, which provides energy to body.

Rice provides about 350 caloriesll00 gm, while protein content is only 7 % because
it is consumed in large quantity so that total amount of protein which is ingested
through rice is significant. The table 2 shows that rice is poor source of minerals,
especially calcium, iron and carotene but good source of vitamin B.

Table 2: Chemical Composition of Different kinds of Rice

Raw rice Parboiled rice

I Husked Home- Under Milled Home- Milled
pounded milled pounded
\1oisture % 9.7 9.6 9.5 9.7 12.6 13.3

Protein % 7.7 7.3 7.2 6.9 8.5 6.4

Fat % 1.8 1.2 0.95 0.54 0.6 0.4

Carbohydrates % 78.1 80.1 80.95 82.06 77.4 79.1

Crude fiber % 1.1 0.7 0.5 0.2 - -

Mineral matter % 1.6 . 1.1 0.9 0.6 0.9 0.8
Calcium, mg.!100g.>15.9 13 13 10 10 10 10
Phosphorous mg.!100 g. 368 182 146 87 280 150
Iron mg.!100 g. 4.0 2.8 2.5 2.2 2.8 2.2

Thiamine, micro g /100 g. 360 210 190 '103 270 210

Nicotinic acid mg. /100 g. 3.5 2.5 2.2 1.0 4.0 3.8

Wheat :- Wheat in India is cultivated throughout the major part ofthe country.
There are 18 wheat species out of which only 3 species are very common. Different
varieties, forms and hybrids of wheat form the bulk of the crop, and are grown
mainly in Punjab, Haryana, northern Rajasthan, Uttar Pradesh and Bihar. In India
wheat crop is grown most extensively. Wheat flour is.used for making chapattis,
and a variety of other preparations.

It is genus of annual and biennial grasses, yielding various types of wheat, native
to southwest Asia and the Mediterranean region. Triticum durum, Triticum aestivum,
Triticum compactum are most common wheat vane.. ~s and cultivated thought a
world. Wheat grains, botanically, are the fruits (caryopsis) of the wheat plant. Wheat
is the mos: '.'lidely cultivated of all cereals and in most parts of world, it is the
principal staple food of mankind.

Starch is the principal carbohydrate of wheat; glucose and fructose are present in
small amounts . otarch occurs in the' wheat kernel, as granules of varying sizes.
25
Basic Prtnctptes-I! ,Mature wheat grain or kernel is roughly egg shaped' and 4-10 mm in length. The
weightoflOOO kernels varies from33 to 54 g. anti the hectoliter weight fr rn
n.5 - 83.8 kg. (values on 10.5 % moisture basis). The Kettle! consists of three
main parts, namely the bran, the endosperm and th 'germ or embryo. Tn wel1-
filled kernels, the bran. forms 13-14 per cent, the end: »enn 84-85 per cent id
the germ, 2-3 per cent. The bran is tough because of its fiber content; the
endosperm is starchy and friable, and the genu is ncl: in oil.

The aleurone; which' forms the outer periphery of the en osper n and the innermost
layer ofthe bran, accounts for 3-4 per centofthe weight of 'he kernel; it is usually
removed with the bran during milling. The vitam ins re iorted to be present in a'
, sample of wheat are (per 100 g); carotene 64 micro gram; thiamine 0.45; riboflavin
0.17; nicotinic acid 5.5 and choline 206.0 mg. Whole wheat is a good source of
thiamine and nicotinic acid, but is relatively poor 111 riboflavin. Other members of
the Bscomplex present in wheat include pantothenic acid, p-aminobenzoic acid,
biotin, choline, folicacid and inositol. Distribution of Carbohydrates in Commercial
Wheat Fractions{%) , '

Composition of wheat:- The chemical composition of the wheat kernel varies

widely being influenced by environment, soil and variety.

Composition of Typical Indian Commercial Wheat (%):

-
Starch Protein Fiber Fat Ash
Bran 0 20 9 30 67 ,
Endosperm
....•.
100 72 8 50 23
Germ 0 8 2 20 10

Bran is rich in fib er, protein and ash. It gives dark colour to flour and is normally
used for cattle feed and manufacture for brown bread. Endosperm consists of
essential starch, which is embedded in protein matrix. Germ consist of enzyme
mainly lipase and lipoxigenase, which breaks fat into fatty acids.

Minerals - Mineral constituents in Indian wheat on average are as follows:

Minerals Ca' P Na Mg Fe K Cu S a
, Mg/100 g 41.0 306.0 17.1 138.0 ' 4.9 284.0 0.49 ' 128.0 47,0
r

Maize :- Maize or corn is utilized in more diversified ways than any other cereals.
It is extensively cultivated in India in plains as well as in thehills, especially in the
areas with hot summer. The states ofUttar Pradesh, Bihar, Rajasthan, Madhya
Pradesh and Punjab account for majority of production. It consists of high
percentage of carbohydrates, lipids and protein and quite nutritious for human
consumption. For use as food, maize is ground to flour or whole meal atta and
baked into roti or chapatti; it is in this form that maize is consumed in most parts
of northern and western India .. The ready to eat breakfast cereal cornflakes is a
maize product and also be used in manufacture of starch, dextrin syrup. It is also
eaten roasted or boiled on the cob .
.
Composition of maize:- Maize kernel consists of three main parts, namely hull
or bran coat with high fib er content, embryo or germ rich in oil, and starchy
,endosperm. The proportions of the three kernel parts are approximately as follows'
26
(% of whole kernel); bran, 4.4-6.2 (av. 5.3); germ and scutellum, 10.~-14.1 (av. Chemistry of Food with
Special Reference to
11.9); and endosperm, 79.7 - 83.5 (av. 81.9); the tip-cap which is usually removed Cereals, Pulses and
with the hull in milling, forms 0.8 - 1.1 pere ent (av, 0.83%). I Oil seeds

Proximate composition of Kernel Factions ill maize is:

~ Kernel Faction ~rotein _~ Oil «';10) St3 rch (%) Sugars (%) A~h (%)
1---- I-- --
L Endosperm 9.4 0.8 86.4- 0.64 0.~1
----
34.5 8.2 10.81 10.10
--
f Genn __ 18.8
-- 1----_._-
Bran 3.7 , 1.0 i 7.2, 0.34 0.84
-
Tipcap 9.1 3.8 B 1.61 1159
-
Whole kernel 10.3 4.8 71.5 1.97 1,kt4
I '-----

Sorghum» Sorghum has its origin in Afirica. A large variety of sorghums are
cultivated in tropical and sub tropical region ofthe world and knof to be an
important staple food in many African and Asian countries. In India, sorghum
constitutes an important article of food, after rice and wheat. A grain iF ground to
floor or cooked like rice. In advanced
.
country sorghum is used as an, animal
I
feed.
.
Sorghum plants are widely used as fodder, either green or as hay and silage. Sugar
content of sweet sorghum is very high and these are used for produding syrups.
Sorghum grains is rich source of starch and it is used in fermentation ~dustry for
producing industrial a1cohols and solvents. .
I
I
Composition of sorghum:- A chemical composition of sorghum is similar to maize.
It consists more protein, lower fat arid same amount of carbohydrates as compare
to maize. The quantities of riboflavin and pyridoxine are same but pantothenic acid,
nicotinic acid and biotin is more as compare to maize. Starch is major~arbOhydrate
in sorghum and simple sugar, cellulose and hemicelluloses are also present.
~--
0/0 Moisture Protein Fat Carbohydrates Fiber I 'Minerals
Sorghum 11.9 10.4 1.9 72.6 1.9 11.6
Amount of Protein present in Sorghum

Protein albumin globulin prolamine glutelin

% 5.0 6.3 46.4
.
, 30.4

Pulses
Pulses are second to cereals as an important source of human food. APproximately
100 species of pulses are considered to be edible from among the/over 13,000
pulse species found 41 world. 39 species of edible pulses information is available
on area and methods of cultivation, chemical composition and utilidtion.
. I .
The nutrient composition of edible pulses depends upon species. Protein content
in pulses is higher and is commonly more than twice that of cereal grains. The
nutritional value of pulses is not just confined to their usefulness as a source of
vegetable protein. They are also rich in carbohydrates and are also SOurceof other
nutritionally important materials such as vitamins and minerals. I

Protein :- Protein content in pulses are usually about 20 % of the dry weight of
seeds. Importance of protein not only depends on quantity of protein but also on
27
Basic PrindpJes-I1 its quality which in turn depends on the amino acid composition. All pulses have
sufficient amoynt of leucine and phenylalanine.

Carbohydrates .:-Carbohydrate content in pulses are about 55,,-~0% that includes

starch,! soluble sugar, fiber and unavailable carbohydrates. The unavailable
carbohydrates in pulses include substantial levels of oligosaccharides of the raffinose
family ff sugars, which are notoriously known for the flatulence production in man
andanrals.

Lipidsl:- it consist about 1.5 % of dry matter in pulses mainly polyunsaturated

acids arld these undergo oxidative rancidity during storage in a number of undesirable
changek, such as loss of protein, off-flavour development, and loss in nutritive
quality.
I
Minerals :- Pulses are important source of minerals mainly calcium, magnesium,
. Iron,
ZInC, . I potassium,
. an d p hosp horous.
I·

A chemical composition of some important pulses per 100 gm edible portion is

. given bJlow.
1) Scientific identification:- Cajanus cajan
Lodal name & other common names:- Tuver, Red gram dhal (English)

Nutri1ent Nutrient Composition/lOOg (edible portion)

Pods, Itender Seeds, dry, raw
Energr, Kcal 116 335
Protein, g 9.8 22.3
Fat, gl I 1.7
Carbohydrate, g 16.9 57.6
Fiber, ~ 6.2 1.5
I .
Minerals, g 1 1.7
Beta-carotene, ug - -
Total
\
carotene, ug
. I .
469 132
Folic acid, ug - lO3
Vitamin C, mg 25 -
Zinc, mg 3.1 0.9
Iron, mg 1.1 2.7
I

Calcium, mg 57 73
Phosphorus, mg 164 304
MOistute, g 65.1 13.4

28

/
2) Scientific identification:- Dolichos biflours
.. .'
I
I
I Chemistry of Food with
Special Reference to
Local name & other common names:- Kulad, Horse gram (English) Cereals, Pulses and
Oilseed's,

Nutrient Nutrient Composition/lOOg (edible portion) .

Seeds, raw I
Energy, Kcal 321
Protein, g 22 I
Fat, g 0.5 - I
Carbohydrate, g 57.2
Fiber, g 5.3 I
Minerals, g 3.2
Beta-carotene, ug - I
Total carotene, ug - 71
Folic acid, ug -
Vitamin C, mg 1 I
Zinc, mg . 2.8
Iron, mg 6.8
Calcium, mg 287
Phosphorus, mg 311'
Moisture, g 11.8

3) Scientific identification:- Dolichos lablab I

Local name & other common names:- Val ppa di,Field bean (rE nglish )

Nutrient Nutrient Composition/lOOg (edible pprtion)

Seeds, raw
, Energy, Kcal 347 I ..
Protein, g 24.9
. 0.8
I
Fat, g I
I

Carbohydrate, g 60.1
Fiber, g 1.4 I

Minerals, g 3.2 I
Beta-carotene, ug 0 I
Total carotene, ug - I
Folic acid, ug -
Vitamin C, mg 0 I
Zinc, mg -
. ,
I
Iron, mg 2.7 I
Calcium, mg . 60
Phosphorus, mg
-
433 I
Moisture, g 9.6
I

29
 Basic Principles-Il
4) Scientific identificationr-Z, tns esculenta
Local name & other comm on names» Masoor, Lentils (English)

Nutnient Nuitrient Composition/WOg (edible portion)

.Seeds,. raw
Ener~,· Kcal 343
p rotem,
I·
g 25.1
Fat, g 0.7
Carbohydrate, g 59

. Fiber, g 0.7
Minerals, g . 2.1
Beta-carotene, !ig

Tota~ carotene, !ig 270

I -
Foliclacid, ug 36,
Vitamin C, mg o
-
Zinc.mg 2.8
Iron.img 7.58

Calcium, m& 69
Phosphorus, mg 293
Moi~tuJ~\ g 12.4
I' .

5) Scientific identification:- Phaseolu: i aureus Roxb

I .
Loeal name & other common name s:- Moong, Green gram (English)

Nutrient Nutrient Co mposition/l OOg (edible. portion)

-
Seeds, who ,le, raw Seeds, split, raw
- -
En~rw> K'..cal 334 348
Protean, g 24 24.5
. -
Fat, g ".
1.3 1.2
_.
Carboh ydrate, g 56.7 59.9

Fiber, g 4.1 0.8

t- -- ----------------i
Minerals; g 3.5 I 3.5
Beta .-carotene, ug -
Tot; 11 carotene, ug 49 94
-
Fol.ic acid.jig . - 140
Vi tamin C, mg -
Zi.nc, mg 3 2.8
Ir 'on, mg 4.4 3.9
( '::alcium, mg 124 75
. Phosphorus, mg 326 405
Moisture, g 10.4 10.1
,I

30
6) Scientific identiftcation.- Phaseolus mungo _- Chemistry of FOQd with
Special Reference to

·-1
Local name & other common names.- Udad, Black gram (English) Cereals,- Pulses and
Oil seeds

I Nutrient _- __~ utrient Composition/lOOg (edible portion)

I Seeds, raw "_ - I

-~- - 346f """

~Energy, KC~t~"

i Protein, g 24
-------~------------------------~l~------~
Fat, g 1.4
--- -- - ---~--------------------------~----~--~
Carbohydrate IT 59_6
-- ""-----j---------------------------!.-----------:.j

f--F_I_b_er_,_g -r • _+- 0_._9 :, ~

Minerals, g 3.2
---
--"------+-------------------~----~..!---~--~-l
Beta-carotene, ug - I
.------------~--------------------------~--------~
Totalcarotene, ug 38
r--- -
Folic acid, ug 132
-I -
Vitamin C, mg i

Zinc",mg 3.3
Iron, mg 3.8
Calcium, mg 154 '
Phosphorus, mg 385
Moisture, g 10.9

7) Scientific identification:- Pisum sativum -'

_Local name & other common names:- Vatana, PeasIfinglish)

Nutrient Nutrient Composition/I ?Og( edible portion)

Peas, green, tender Seeds, dry - .
Energy, Kcal 93 315_ 1

Protein, g 7.2 -,-

- 19.7
I
Fat, g 0.1 - -,
-,
_L1
Carbohydrate, g 15.~ -.56.5 I

Fiber, g 4 4.5 1

Minerals, g 0.8 2.2

- . r
Beta-carotene; ug - - -
--- - -I
Total carotene, ug 83
-.
39 l
Folic acid, ug - -:.5 I

Vitamin C, mg 9 ~ ~-
Zinc,mg - 2.3
"

1
- Iron, mg 1.5 7,05 i
Calcium, mg 20 75 I
I

Phosphorus, mg 139 298 I

Moisture, g 72.9 16 j

31
Basic Principles-II 8) Scientific ~dentification:- Vigna catjang .
Local ra1e & other common names:- Chowli, Cow peas/pods"

Nutrient Nutrient Composition/lOOg (edible portion)

Pods, te~der Seeds, dry .
J.
Energy, Kcal 48 323
Protem,
. gI 3.5 24.1
,
Fat, g I 0.2 " 1
Carbohydrate, g 8.1 54.5 -, q

Fiber, g I 2 3.8
. Minerals, g 0.9 3.2
,
Beta-carbtene, ug - -
I
Total carotene, ug 564 12
.-
Folic aci~'.llg -- 133
VitaminC, mg 4 -
Z.mc.jng I
- 4.6
Iron, mg' 2.5 8.6
,
Calcium) mg _.
72 77
I

Phosphorus, mg 59 414
-
Moisture, g 85.3 .13.4
-

Oilseeds
Oilseeds hkv~ been uned by for extraction of oil and for purposes of preparation
of food fo~many centuries. These are important source of energy requirement,
consists 2.f5 times m ore energy than protein and carbohydrates and helps reduce
the bulk of food we take. It also an excellent source of fat soluble vitamins A, E
and K and~lay impo rtant role in biosynthesis of several long chain a1cohols.

Palm:- Palm oil is native from West Africa, where wild palm is still harvested and .
the oil is o~tained ~)fClUghsimple methods in the villages. The oleaginous palm,
probably; dame to Brazil together with the slaves coming from Africa, The palm
trees ori8illf1tedfrom the seeds brought by the slaves, after bearing fruit and having
its seeds dispersed by man or animals formed a wide band along the Brazilian
coast The ~and between 10 ON and lOOS oflatitude is particularly propitious to
palm plantation. TIle oleaginous palm produces fruit bunches. Each bunch holds
about 1500 fruits.
I

Composition of palmi- Palm oil is composed by 44 % of palmitic acid, which is

a saturatedfatty acid C16 and less hyper-cholesterolemic than saturated fatty acid
between C 12 to C ][4.. It contains the same amount of saturated and unsaturated
fatty acid. The satuirated fatty acid proportion in palm oil is: 43 % of palmitic acid
and 4.5 % bf stearic~add. The mono saturated proportion in palni oil is composed
by oleic acid being 41 % of its composition. 10 % of palm oil is composed by
linoleum acid (poly unsaturated fatty acid), which is also an essential fatty acid. The
stability offue palrm oiiloccurs due to the following factors: (a) presence of a natural
antioxidant substance; (b) low percentage « 0.5 %) oflinoleum acid.whichis
very sensible to oxi dation; (c) moderate percentage oflinoleum acid (approximately
32 10 %); (d) the exis tence of a protection effect to the structure of the unsaturated
 components. Moreover, palm oil is much less saturated that other oils, such as Chemistry of Food with
Special Reference to
'coconut oil and palm kernel oil. Palm oil can be considered a balanced fat for Cereal's, Pulses and
containing equal quantities of saturated and unsaturated fatty acid. ' Oilseeds

Palm oil is'widely used in the food and other industries. The main application of
. palm oil in foods is: flying; biscuits, ices cream, snacks, foods for babies, cereals,
margarine, milky products, improvers ofbread and chemical preparations for cakes,
chewing candies, among others. Palm oil and its fractions are also important raw
material for soap and oil chemical industries.

Soybean :- Soybeans occur in various sizes, and in several hull or seed coat colors,
including black, brown, blue, yellow, and mottled. The hull ofthe mature bean is
hard, water resistant, and protects the cotyledon and hypocotyl (or "germ") froja .
damage. If the seed coat is "cracked" the seed will not germinate. The scar, visible
.on the seed coat, is called the hilum (coIors include black, brown, buff, gray and
yellow) and at one end of the hilum is the micropyle, or small operiing in the seed
coat, which can allow the absorption of water. ,

% Protein Oil Carbohydrates Ash

Soybean 40 20 . 35 5

Composition of soybean :- It is a remarkable fact that seeds such as soybeans,

containing very high levels of soy protein, can undergo desiccation yet survive and
revive after water ~sorption. A. The oil and protein content together account for
about 60 % of dry soybeans by weight; protein at 40 % and oil at 20 %. The
remainder consists 9,f 35 ~ carbohydrate and about 5 % ash. The m~jority of soy
protein is a relatively heat-stable storage protein that enables soy food products
requiring high temperature cooking, such ,astofu, soyrnilk and textured vegetable
protein (soy flour) to be made.

The principal soluble carbohydrates, saccharides, ofmature soybeans are the

disaccharide sucrose (range 2.5-8.2 %), the trisaccharide raffinos~ (0.1-1.0 %)
composed of one sucrose molecule connected to one molecule of galactose, and
the,tetrasaccharide stachyose (1.4 to 4:1 %) composed of one sucrose connected
to two molecules of galactose. While the oligosaccharides raffinose and stachyose
protect the viability of the soybean seed from desiccation, they are not digestable
sugars 'and therefore contribute to flatulence and abdominal discomfort in humans
and other monogastric animals. The insoluble carbohydrates in soybeans consist
of the complex polysaccharides cellulose, hemicelluloses, and pectin. The majority
of soybean carbohydrates can be classed as belonging to dietary fiber. Since soluble
soy carbohydrates are.found mainly in the whey and are broken down during
fermentation. On the other hand, there may be some beneficial effects to ingesting
oligosaccharides such as raffinose and stachyose, namely, encouraging indigenous
bifidobacteria in the colon against putrefactive bacteria.

Sunflower :- Sunflower was considered as an ornamental flower until 19th century

after that it was cultivated as an oil seed plant in Russia. The sunflower is a member
of the compositae family. The commercial varieties cultivated for seed purposes
are grv:.:;,ed under Helianthus annuus variety macrocarpus. The cultivated
sunflower contains 34 somatic chromosomes (2n=34). '

Sunflower is mainly used for the extraction of oil. Defatted meal is the main
,byproduct of Sunflower oil extraction and it is rich in protein and certain minerals.
33

.~ •.. -
Basic Princi"ples-Il Defatted meal is mostly fed to animals and birds. The large seeded non-oil seed
varieties normally provide feed for birds and also used as whole roasted seeds
similar to peanuts. After de hulling, the kernels are sold as confectionery nuts.

% I Protein Lipids Carbohydrates Ash

Sunflorer 20.8 54.8 18.4 3.9

Composition of sunflower :- Sunflower oil has high level of linoleic acid. Linoleic
acid is required for the cell membrane structure, cholesterol transportation in the
blood and for prolonged blood clotting. Sunflower oil helps to reduce the serum
_ .cholesterpllevels. The presence of trypsin inhibitor has been observed in sunflower
seeds. However, the activity of the inhibitor is extremely low. The inhibitor is heat-
labile and inactivated easily.
. I
Check Your Progress 1
Note: aI) Use the ;paces given below for your answers.
b) Check your answers with those given at the end of the unit.
1. Why Cereals are more consumed in developing countries in a world?

....... ·1···········································································································
.......................... ~ '.' .
2. Wha~ are basic constituents of pulses, why pulses are an important source of
human food?
1

3. Nam9d important oilseeds, why oils are used as basic component of food?

10.3 CARBOHYDRATES AND LIPIDS

Carbohydrates are energy producing food substances made up of carbon, hydrogen
and oxygen that make up about half of our food intake. Carbohydrates are organic
compounds having plants are the main source add provide the major part of the
energy in our diets and assist in the utilization of fats. Carbohydrates are the most
abundant class of organic compounds found in living organisms. They originate as
products of photosynthesis, an endothermic reductive condensation of carbon
dioxide requiring light energy and the pigment chlorophyll.

As noted ihere, the formulas of many carbohydrates can be written as carbon

34 hydrates, Cn (H20)n, hence their name. The carbohydrates are (l major source of
 metabolic energy, both/for plants and for animals that depend on plants for food. Chemistry of Food with
Special Reference to
Aside from the sugars and starches that meet this vital nutritional role, ccyb0hydrates Cereals, Pulses and
also serve as a structural material (cellulose), a component of the energy transport Oilseeds

compound ATP, recognition sites on cell surfaces, and one of thr e essential
components of DNA and RNA.

Lipids are one of the largest groups of organic compounds, which~e of great
importance in the food, we eat because they are readily digested and utilized in
body and are widely distributed and almost every natural food. Lipids consist of
numerous fat like chemical compounds that are insoluble in water but soluble in
organic solvents. Lipid compounds include monoglycerides, diglycerides,
triglycerides, phosphatides, cerebrosides, sterols, terpenes.fatty alcohols, and fatty
acids. Dietary fats supply energy, carry fat-soluble vitamins (A, D, E, K), and are
'a source of antioxidants and bioactive compounds. Fats are also incorporated as
structural components of the brain and cell membranes.

Most of Fruits and Vegetables contains

. between 0.1 and 1 percent totallipids,'
.

Whole grain cereals have from 1percent for whole barley on the dry basis to 7.4
percent for dry oatmeal, while nuts are very rich in lipids. I
Foods supply carbohydrates in three forms: starch, sugar, and cellulose (fiber).
Starch and sugar are major and essential sources of energy for humans. A lack of
carbohydrates in the diet would probably result in an insufficient number of calories
in the diet. Cellulose furnishes bulk in the diet.
I'

.Since the tissues of the body need glucose at all times, the diet bust contain
substances such as carbohydrates or substances, which will yield glucose by
digestion or metabolism. For the majority ofthe people in the world, more than
. half oft~e diet consists of carbohydrates from rice, w?eat, bread'IPotatoes, and
macarom. .
I
10.4 CHEMICAL REACTIONS OF CARBOHYDRATES
Carbohydrates serv1 as th,eprimary source of energy in th~ cell, and carbohydrate
metabolism is central to all metabolic processes
 ,
Basic Principles-II Carbohydrates have been given non-systematic names, although the suffix ose is
generally used. The most common carbohydrate is glucose (C6HI20J Applying
the terms defined above, glucose is a monosaccharide, an aldohexose (note that
the function and size classifications are combined in one word) and a reducing sugar.
The general structure of glucose and many other aldohexoses was established by
simple ohemical reactions. The Fig. 2 illustrates the kind of evidence considered,
although some of the reagents shown here are different from those used by the
original scientists.
I

sorbitol
C6H1.406

j excess
(- C 'j
,t...H3.-II)'20
[OJ ;
pvnditil~ (dil HNO] )
h ~~t·
,1t::!<;;J

a hexaacetate
C18H26012
1 glucaric acid
. C6H1oOe
hexane
Fig. 2

Hot hyctdodic acid (HI) was often used to reductively remove oxygen functional
groups from a molecule, and in the case of glucose this treatment gave hexane (in
low yield). From this it was concluded that the six carbons are in an un branched
chain. The presence of an aldehyde carbonyl group was deduced from cyanohydrin
formatiorf its reduction to the hexa-alcohol sorbitol, also called glucitol, and mild
oxidation to the mono-carboxylic acid, glucuronic acid. Somewhat stronger
oxidation by dilute nitric acid gave the diacid, glucaric acid, supporting the proposal
of a six-carbon chain. The five oxygen's remaining in glucose after the aldehyde
was accounted for were thought to be in hydroxyl groups, since a penta-acetate
derivative could be made. These hydroxyl groups were assigned, one each, to the
last ~ve c~bon atoms, because geminal hydroxy group are normally unstable
relative to the carbonyl compound formed by loss of water. '.

Glucose ~d other saccharides are extensively cleaved by periodic acid, because

of abund~ce of vi cina 1diol moieties in their. structure. This oxidative cleavage,
known as the Malaprade reaction is particularly useful for the analysis of selective
O~substitu~ed derivatives of saccharides, since ether functions do not react. The
stoichiom~try of aldohexose cleavage is shown in the following equation.

HOCH2(cHOH)4CHO + 5 HI04 ~ HtC""O 4' 5 HCOlH + 5 HIO)

Glucose is betabolized by a stepwise oxidative process according to the balanced

equat~on ..this process c.an beacccn:plis~ed either anaerobica~ly or a~robical1y,
resulting lA the synthesis of adenosine tnphosphate (ATP). An overview of the
process of klucose oxidation appears in the figure below.

Glycolysis Reaction :~ The pathway of glycolysis can be seen as consisting of2

separate pHases. The first is the chemical priming phase requiring energy in the
form of ATP, and the second is considered the energy-yielding phase. In the first
phase, 2 equivalents of ATP are used to convert glucose to fructose 1,6·
bisphosphate (FI, 6BP). In the second phase 1'1, 6SP is degraded to pyruvate,
36 with the production of 4 equivalents of ATP and 2 equivalents ofNADH.
 GLUCOSE Chemistry of Food witll
Special Reference t.
Cereals, Pulses •• d

~
1
Glucose-I-phosphate •••
~t---~- Glucose-6-phosphate
Oilseeds

Pentose
Phosphate
Shunt
Gluconeogenesis
Glycolysis
Glycogen
Anaerobic (cytosol)

Aerobic (mitochondria)

Fatty Acids 4·~--

1
ACETYL CoA

Krebs
Cycle RedUCirEquivalents

AminoACidS/
Fig. 3 Oxidative Phosphorylation

C6H1P6 + 2 NAD+ + 2 ADP + 2 P --> 2 pyruvic acid, (CH/C=Q) COOH +

2 ATP + 2 NADH + 2 H+

At this time, concentrate on the fact that glucose with six carbons is converted
into two pyruvic acid molecules with three carbons each. Only a net "visible" 2
ATP are produced from glycolysis. The 2 NADH will be considered separately
later.

Glucose
ATP

ADP

GIUCose-6 -PhosPhate .
, phosphohexose
1 isomerase

Fr~~~ose-6!-phosphate
phospho-
ADP) fructoknase-t

Fructose-t, 6·bisphosphate

Glyceraldehyde.3.phosphate .• ..Dihydroxyacetone
\ triosephosphate phosphate
isomerase 37
Basic Principles-I1
Glyceraldehy;de-3-phosphate

NAD' + PI=1glyceraldehYde-3_PhOSPhate
dehydrogenase
NADH+ K

1:~~i~:C::::::~:t:ate
~ ---'1 kinase'

3~PhOSP1oglYCerate
phosphoglycerate
mutase

!enolase-,
2-phosphoglycerate

~T~=l:~~;;.v~e
copyright 1996 MW.King Pyru vate
Fig,4

The major steps of glycolysis are outlined in the graphic. There are a variety of '
starting poinfs for glycolysis; although, the most usual ones start with glucose or
, glycogen to produce glucose-6-phosphate. The starting points for other
monosaccha des, galactose and fructose, are also shown.
I •
,

Once glucose is phosphorylated to G-6-P, a six carbon phosphosugar, it can enter

the pentose phosphate shunt, or be converted to glycogen (a storage form of
glucose). G-6-P can also be oxidized to the three carbon intermediate p~v~te.
Pyruvate can be reversibly converted to lactate, which is the final step in the
I ,
anaerobic oxidation of glucose. Everything described so far is anaerobic and occurs
in the cytosJl. The process of anaerobic glucose metabolism results in the net
I -
formation of ATP.

1
Pyruvate is important junction point in glucose metabolism. It can be converted
to lactate, asldescribed above, in the cytosol (an anaerobic process).Altematively,
pyruvate cari be converted to the two carbon metabolite acetyl CoA, which enters
I ,
into an aerobic process known as the Krebs cycle (A.K.A. the tricarboxylic acid
cycle). Sinc~ acetyl Co A can be converted into fatty acids, or into amino acids
via the KreUs cycle, it serves as a third major branch point in metabolism. The
Krebs cycle!produces the reducing equivalents NADH and FADH2, which are
oxidized in the electron transport chain to produce three ATP's per molecule in a
process kn0l~ as oxidative phosphorylation. All of the steps of aerobic glucose
metabolism occur in the mitochondria. ' ,

One molecule of glucose passing through glycolysis, the Krebs cycle and the
process of electron transport/oxidative phosphorylation will produce 38 molecules
ofATP.
38
-I
 I
- •• - •••••.• ~. J .•.•••.•.•.•.•.•..•• , ••. u

10.5 FATTY ACIDS AND THEIR PROPERTIES Special Reference to

Cereals, Pulses and
Fats are c~ncentrated sources of e~ergy beca~se the~ give twice. e1ergy as Oilseeds

compare with carbohydrates or protein on a weight basis. The functlOnr' of fats

are to: make up part of the structure of cells, form a protective cushion and heat
insulation around vital organs, carry fat soluble vitamins, and provide reserve
storage for energy. • . I
J

Natural fats are mixture of mixed glycerides in which the three fatty acids esterifying
glycerol differ from each other. Three unsaturated fatty acids, which are ssential
include: linoleic, linolinic, and arachidonic and have 2, 3, and 4 dou~le bonds
resp~ctively. ~aturated ~ats, along wit~ cholester~l, have been i~p~icated in
arteriosclerosis, "hardenmg of the artenes". For this reason, the dietshould be
decreased in saturated fats (animal) and increased in unsaturated fat (vfgetable).
Th e ch ermca
. 1 names an d d escnptions
.. 0 f some common' fattv ziven im
acidss are given
atty aci
table 3.
.
Table 3
Chemical Names and Descriptions of Some Common Fatty Acids I

Common Name Carbon Double Scientific Name SOUr( es

Atoms Bonds
Butyric acid 4 0 butanoic acid butterfat
Caproic Acid 6 0 hexanoic acid butte fat
Caprylic Acid 8 0 octanoic acid I
cocoput 01'I

Capric Acid 10 0 decanoic acid coco~ut oil

Lauric Acid 12 0 dodecanoic acid . I
coconut 01'I

Myristic Acid 14 0 tetradecanoic acid pa~ kernel oil

Palmitic Acid 16 0 hexadecanoic acid palm oil
Palmitoleic Acid 16 1 9-hexadecenoic acid anitpal fats
Stearic Acid 18 0 octadecanoic acid ani~al fats
Oleic Acid 18 1 9-octadecenoic acid olive oil.
I
Vaccenic Acid 18 1 1I-octadecenoic acid butterfat
Linoleic ACid 18 2 9, 12-octadecadienoic acid gr~pe seed oil
I
Alpha- Linolenic 18 3 9,I2,I5-octadecatrienoic flaxseed
Acid (ALA) acid (lipseed) oil
Gamma-Linolenic 18 3 6,9, 12-octadecatrienoic brage oil
Acid (GLA) acid
Arachidic Acid oil 20 0 eicosanoic acid pt;anut oil, fish
Gadoleic Acid 20 1 . 9-eicosenoic acid fi~h oil
Arachidonic Acid 20 4 5,8,11,14-eicosatetraenoic liver fats
(AA) acid
I
EPA 20 5 5,8,11,14,17- fish oil
eicosapentaenoic acid
Behenic acid 22 0 docosanoic acid /
¥peseed oil
Erucic acid 22 1 13-docosenoic acid ~apeseed oil
I
DHA 22 6 4,7,10,13,16,19- pshoil
\ docosahexaenoic acid
Lignoceric acid 24 0 tetracosanoic acid ~mallamb~ts in
. most fats
39
Basic Principles-I1 Apart from flavour fats are used as shortening, tenderizing, lubricants, fiying media,
whipping agents and for other purpose. Fats are important source of our energy
requirement, they furnish 2.25 times more energy than proteins and carbohydrate.
They are good source of fat soluble vitamins like A, D, E and K and play a part
in biosynthesis of several long chain alcohols.
I
Essential fatty acids are the component member ofliving cell and used by the body
to make prostaglandin's involved in a large variety of vital physiological functions
and these acids play a very important role in immunity. Decreased availability of
these acids leads to impaired growth and diminished mental and physical capacities.

Fats ~elays the pangs of hunger because they are slow in leaving the stomach and
hence retard the digestion. They are utilized up to 95-98%, the difference in
digestibility/utilizationis depends on melting point. Those who have a melting point
below 43 QCare completely digested, whereas those melting point above 43 QC
are slowly digested and less completely absorbed.

The consumption of fats and oils in India is very low, as per estimate our per capita
consumption is 4-5 kg/annum compared with 40-50 kg/annum in advanced
countries. So, due to low intake of fats, it causes malnutrition mainly in children.
FAO/WHO expert groups has recommended that 30-50 % of our total calories
requirement must be met by oils and fats and ratio of saturated to polyunsaturated
fatty acids should be 1:1. _-

Check Your Progress 2

Note: a) Use the spaces given below for your answers.
I b) Check your answers with those given at the end of the unit.

1. Write a importance of carbohydrates and lipids?

·····1················································ .
...................................................................................................... .~ .
..... \ .

2. Define Glycolysis cycle.

...................................................................................... , .

...... \ .

3. Why fats are good source of energy? Name three essential fatty acids.

10.6 IPROTEINS
Proteins are polymers of amino acids joined together by peptide bonds. There
areW different amino acids that make up essentially all proteins on earth. Each of
these amipo acids has a fundamental design composed of a central carbon (also
40 called the alpha carbon) bonded to:
 Chemistry of Food with
• a hydrogen Special Reference to
• a carboxyl group Cereals, Pulses and
Ot lse e d s
• an ammo group
• a unique side chain or R-group
"
Thus, the characteristic that distinguishes oneamino acid from another is its unique
side chain, and it is the side chain that dictates an amino acids chemical properties.
All life requires protein since it is the -:;11icfti:~,-!ehuilder and part of every cell in
the body. These are polymers of amino acids covalently linked through peptide
bonds into a chain. Amino acids are made up principally of carbon, hydrogen,
oxygen, and nitrogen. Proteins are essential to all life .. Proteins are principal
constituents of the protoplasm of all cells. Twenty different amino acids are
commonly found in proteins and each protein has a unique, genetically defined
amino acid sequence that determines its specific shape and function. Protein is one
of the basic components of food and makes all life possible. Among other functions;
proteins help to: make hemoglobin in the blood that carries oxygen to the cells;
form anti-bodies that fight infection; supply nitrogen for DNA and RNA genetic
material; and supply energy.

They provide for the transport of nutrients, oxygen and waste throughout the body.
They helps to form protective and supporting to'all animals like cartilage, skin, nails,
hair and muscles. They are major constituents of enzymes, antibodies, hormones
and blood. Within and outside of cells,.proteins serve a myriad of functions, including
structural roles (cytoskeleton), as catalysts (enzymes), transporter to ferry ions and
molecules across membranes. Proteins are necessary for muscular growth and
cellular repair and are also functional component of enzymes, hormones, etc. it'
use for energy only when carbohydrates and fats are not available. They provide
the structure and contracting capability of muscles. They also provide collagen to
connective tissues of the body and to the tissues of the skin, hair and nails. Proteins
are essential for growth and repair. They play a crucial role in virtually all biological
processes in the body. All enzymes are proteins and are vital for the body's
metabolism. Muscle contraction, immune protectionand the transmission of nerve
impulses are all dependent on proteins. Proteins in skin and bone provide structural
support. Many hormones are proteins. Protein can also provide a source of energy.
Generally the body uses carbohydrate and fat for energy but when there is excess
dietary protein or inadequate dietary fat and carbohydrate, protein is used. Excess
protein may also be converted to fat and stored. Foods with the best quality protein
are listed in diminishing quality order: whole eggs, milk, soybeans, meets, vegetables,
and grains. ., I

Many of proteins present in plant are deficient in one or more of the essential amino
acids like zein, one ofthe protein of corn, lacking in lysine and tryptophan, while
gliadin one of the protein of wheat is low in lysine. However, both wheat and
corn contains other proteins that possess these amino acids. So, wheat and corn
is supplemented with protein that are relative rich in lysine.

10.7 PROTEIN FROM DIFFERENT SOURC:ttS

Most foods contain at least SOmeprotein. Good sources of protein f~r vegetarians '
" include nuts and seeds, pulses, Soya products (tofu, Soya milk and textured Soya
protein such as Soya mince),' cereals (wheat, oats, and rice), free.r~ge eggs and
Some dairy products (milk, cheese and yogurt). Proteins are large compounds that
41
 Basic Principles-I1
are formed when amino acids combine. They contain carbon, hydrogen, and
oxygen like carbohydrates and lipids, but they also contain nitrogen. Some proteins
may also contain sulfur, phosphorus and iron. Proteins are the building blocks or
cells, tissues, and organs. Plants are the source for protein. However, not all
compounds in the plant that contain nitrogen are proteins. Most foods contain at
least so~b protein. Good sources of protein for vegetarians include nuts and seeds,
pulses, Soya pro.ducts (tofu" Soya milk and textured Soya protein such as Soya
mince), cereals (wheat, oats, and rice), free-range eggs and some dairy products
(milk, cheese and yogurt).

Protein quality is usually defined according to the amino acid pattern of egg protein,
whichis regarded asthe ideal. As such, it is not surprising that animal proteins,
such as meat, milk and cheese tend to be of a higher protein quality than plant
proteins. This is why plant proteins are sometimes referred to as low quality
proteins. Many plant proteins are low in one of the essential amino acids. For
instancejgrains tend to be short of lysine whilst pulses are short of methionine.
This doe not mean that vegetarians or vegans go short on essential amino acids.
Combining plant proteins, such as a grain with a pulse, leads to a high quality protein,
which is dust as good, and in some cases better, than protein from animal foods.
Soya is a high quality protein ~mits own which can be regarded as equal to meat
protein.

The limilg amino acid tends to o{different indifferent proteins. This means when
two different foods are combined, the amino acids in one protein can compensate
for the ode lacking in the other.This is known as protein complementing. Vegetarians
eating a rell-balanced diet based on grains, pulses, seeds, nuts and vegetables
will be consuming a mixture of proteins that complement one another naturally
without requiring any planning. Beans on toast, cheese or peanut butter sandwich
arid rice ith peas or beans are all'common examples of protein complementing.
Wj

'<,
.
Sources of protein (single servings)
Good sources Fair Sources Poor sources
Chick pbas 16.0g Brown rice 4.4g 1 Carrot O.4g
(200g o~ 70z) (200g or 70z)
Baked beans 11.5g Broccoli 3.1g 1 Apple O.3g
(225g 80z) ot (lOOg or 3'lioz)
I
Tofu (110g or 50z) lO.3g Potatoes 2.8g Cream, double 'O.3g
\ (200g or 70z) (20g or 2/30z)
Cow's milk 9.2g Porridge [water] 2.4g Butter/margarine None
('li pint) (160g or 60z)
Lentils ' 9.1g - - Vegetable oil None
(120g o~ 4% oz)
Soya milk ('li pint) 8.2g - - Sugar or syrup None
Muesli I 7.7g - - - -
,(60g or 2%oz)
Egg, boiled 7.5g - - - -
Peanuts 7.3g - - - -
(30g or 110z)

Bread, ~2,slices~ 7.0g - ~ ( .J'\

- I <.! , , ~ .i!f, ' ,
: ,,-(of ;. J;
,I,t. '-,

. :.... ..
~
"

'J .6'.S~ ,
'
j~;", ;. ; .' ; r.
, ,Ita~d.~~e~s~ -
i >:\
"'.
- ",'r" '
-
I i; jL~'i .JJ}d; I,

,
-(30g 'at floij ! I' • il
I'. 'I. ,~ ;

d42
.,.. 'i-,II
\ ' .. " ... " , ' . . ,
I
..
 List of high protein foods from natural sources Chemistry of Food with
Special Reference to
Cereals,Pulses and
High Protein Food Protein , Carbs Oil seeds

, Eggs (1 medium size) 6 grams Og

Milk (1 pint or 568ml) 19 grams, 24 g
Milk (1 glass) 6.3 grams 8g
Soya Milk Plain (200 ml) 6 grams 1.6 g
>

Tofu (100 g) 8 gra1ll:s 0.8 g

Low-fat Yoghurt (plain) 150g . 8 grams 10 g
Low-fat Yoghurt (fruit) i50g 6 grams 27 g
Fish (cod fillets lOOg or 3.5 ounces) 21 grams Og
Cheese cheddar lOOg (3.5 ounces) 25 grams , 0.1 g
Roast Beef (lOOg or 3,5 ounces) 28 grams I Og
Roast Chicken lOOg (3.5 ounces) 25 grams /
Og
Other Meats Average (lOOg or 3.5 ounces) . 25 grams
I
I
og
Different foods contain different proteins, each with their own unique amino acid
composition, The proportions of essential amino acids in foods may differ from
the proportions needed by the body to make proteins. The proportion of each of
the essential amino acids in foods containing protein determines the quality of that
protein. Dietary proteins with all the' essential amino acids in the proportions required
by the body are said to be a high quality protein. If the protein is low in one or
more ofthe essentialamino acids the protein is of a lower quality.1jhe amino acid
that is ill shortest supply is called the limiting amino acid.

I·
10.8 PROTEIN STRUCTURE f
, ,

Proteins are highly complex molecules comprised oflinked amino acids. Amino
acids are simple compounds containing carbon, hydrogen, oxygen, nitrogen and
occasionally sulphur, There are about 20 different amino acids co+only found in
plant and animal proteins. Amino acids link together to form chains palled peptides.
A typical protein may contain 500 or more amino acids. Each protein has it's own
unique number and 'sequence of amino acids which determines it's particular
structure and function. Proteins are broken down into their constituent amino acids
during digestion, which are then absorbed and used to make new proteins in the
body. However, the, essential amino acids cannot be made and so they must be
supplied in the diet. The eight essential amino acids required by humans are: leucine,
isoleucine, valine, threonine, methionine, phenylalanine, tryptophan, and lysine.For
children, histidine is also considered to be an essential amino acid.

Proteins are large polypeptides of defined amino acid sequence. The sequence of
amino acids in each protein are determined by the gene that encodes it. The gene
is transcribed into a messenger RNA (mRNA) and 'the mRNA is translated into a
protein by the ribosome. Structural features of proteins are usually described at
. four levels of complexity:
1) Primary structure: the linear arrangement of amino acids in protein and th~
location of covalent linkages such as disulfide bonds betwebn amino acids.
Primary structure is sometimes called the "covalent structure" of proteins
because, with the exception of disulfide bonds, all of the covalent bonding within
43
Basic Prmclp les-H proteins defmes the primary structure. In contrast, the higher orders of proteins
structure involve mainly non covalent interactions.
2) Secondary structure: areas of folding or coiling within a protein; examples.
inclu~e alpha helices and pleated sheets, which are stabilized by hydrogen
bondi~g. Secondary structure is "local" ordered structure brought about via
hydrogen bonding mainly within the peptide backbone. The most common
secondary structure elements in proteins are the alpha (a) helix and the beta
(b) sheet (sometime called pleated sheet).
3) Tertiary structure: the final three-dimensional structure of a protein, which results
from a large number of non-covalent interactions between amino acids. Tertiary
structure is the "global" folding of a single polypeptide chain. A major driving
.force in determining the tertiary structure of globular proteins is the hydrophobic
effect. The polypeptide chain folds such that the side chains of the no polar
amino acids are "hidden" within the structure and the side chains of the polar
residu9s are exposed on the outer surface. Hydrogen bonding involvinggroups
from both the peptide backbone and the side chains are important in stabilizing
tertiary structure. The tertiary structure of some proteins are stabilized by
disulfide bonds between cysteine residues.
I

4) Quaternary structure: non-covalent interactions that bind multiple polypeptides

into a single, larger protein. All types of non covalent interactions: hydrogen
bonding, van der Walls interactions and ionic bonding, are involved in the
interactions between subunits. Hemoglobin has quaternary structure due to
association
I.
of two alpha globin and two beta globin polyproteins. Quaternary .
structure involves the association of two or more polypeptide chains into a'
multi-subunit structure. Quaternary structure is the stable association of multiple
polypeptide chains resulting in an active unit. Not all proteins exhibit quaternary
structure. Usually, each polypeptide within a multi sub unit protein folds more-
or-less independently into a stable tertiary structure and the folded subunits
then associate with each other to form the final structure. I

10.9 ESSENTIAL AMINO ACIDS

These are nitrogen-containing compounds that are the building blocks 'of proteins.
There are 2F different amino acids from which every protein in the body is made
up of. There are 10 so-called essential amino acids that are not manufactured by
the body and must come from the diet. Humans can produce 12 of the 22 amino
acids. The ~thets must be supplied in the food. Failure to obtain enough of even
1 of the 10 essential amino acids, those that we cannot make, results in degradation
of the body's proteins-muscle and so forth-to obtain the one amino acid that is
needed. Unlike fat and starch, the human body does not store excess amino acids
for later use-the amino acids must be in the food every day.
. . I
Eight amino acids are generally regarded as essential for humans: tryptophan, lysine,
methionine, phenylalanine, threonine, valine, leucine, isoleucine. Two others, histidine
and arginine are essential only in children. These amino acids are required in the
diet. Planls'lof course, must be able to make ~ll the amino, acids. H~ans, on the
. other hand, do not have all the enzymes required for the biosynthesis of all of the
amino acids. '
Arginine:- A bitter tasting amino acid found in proteins and necessary for nutrition;
its absence Fom the diet leads to a reduced production of spermatozoa

Histidine:- An essential amino acid found in proteins that is important for the
44 growth and repair of tissue
 Isoleucine:- An essential amino acid found in proteins; isomeric with leucine Chemistry of Food with
. Special Reference to
Cereals, Pulses and
Leucine:- A white crystalline amino acid occurring in proteins that is essential for Oilseeds
nutrition; obtained by the hydrolysis of most dietary proteins
Lysine:- An essential amino acid found in proteins; occurs especially in gelatin and
casem
Methioninez- A crystalline amino acid containing suifur; found in most proteins
and essential for nutrition
Phenylalanine:- An essential amino acid found in proteins and needed for growth
of children and for protein metabolism in children and'adults; abundant in milk and
eggs; it is normally converted to tyrosine in the humanbody
Threonine:- A colorless crystalline amino acid found in protein; occurs in the
hydrolysis's of certain proteins; an essential component of human nutrition
Tryptophan:- An amino acid that occurs in proteins; is essential fon growth and
normal metabolism; a precursor of niacin
. Valine:- An essential amino acid found in proteins; important for growth in children
and nitrogen balance in adults
Amino acids play central roles both as building blocks of proteins and as
intermediates in metabolism. The 22 amino acids that are found within proteins
convey a vast array of chemical versatility. The precise amino acid content, and
the sequence of those amino acids,of a specific protein, is determined by the
sequence of the,bases in the gene that encodes that protein. The chemical properties
of the amino acids of proteins determine the biological activity' of the protein.
Proteins not only catalyze all (or most) of the reactions in living cells, they control
virtually all cellular process: In addition to the tissues, your digestive and regulatory
enzymes, hormones, blood sugar, blood proteins and brain chemicals are also
composed of amino acids. So, depending on the specific formula you choose, either
to support muscle growth,' fat regulation, brain stimulation, or dietary fortification,
your expectations can be realized.
,
In addition to being the building blocks of structure, amino acids in effect turn on
and off the "chemical switches" that control our metabolism and body function.
1) Amino acids are necessary for growth and cellular replication throughout the
body.
2) Amino acids are a major constituent for muscle, blood, skin, and internal organs.
3) Amino acids control the pathway that allows hormones and enzymes to be
released.

Check Your Progress 3

Note: a) Use the spaces given below for your answers.
b) Check your answers with those given at the end ofthe unit.
1. Write a short note on proteins. Mention at least five good source of proteins
for vegetarians .
...... ~ ,: .
.....................................................................................................................
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45
Ba si c Principles-If 2. Role of amino acids to control our metabolism and body function .
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10.IQ LET US SUM UP.

Food Science consists of basic sciences 'and engineering to studythe fundamental
. physical, chemical, biological, bioch~mical and behavioral science to nature offood,
principlesof food processing and marketing of food.

A basi9 aim of food science is to provide a food, which consists not only processing
of foo~ to maintain its nutritiv'e value but also consider to increases shelflife of a
food. It also consists of different evaluation of food product to maintain a better
.qualityJand reduce spoilage of food and its wastage. Basic aim is also to develop
new techniques of preservation and keeping quality of food and to develop new
products having good nutritive value and quality with help of different branches of
science) and engineering. '. .,' . . . .

.1

10.1t' KEY WORDS

Legumes Legumes are important source of human food,
. 'I world wide distributed and every area has its
local 'pea' or 'bean'.
Essential Amino Acids Amino acids which are not manufactured by
the body, essential for 0 growth of body, must
I

come from the diet.

. ~
Essenttal Fatty Acids The three fatty acids which esterifying glycerol
differ from each other are called essential fatty .
-acids these are linoleic, linolinic, and
arachidonic ..
Proteins . . They are polymers of amino acids joined
together by peptide bonds. .
I
10.12 SOME USEFUL REFERENCES

1~ LillianHoagland Meyer, Food Chemistry, CBS Publication & Distributors:

2. No~an N. Potter, Joseph H. Hotchkiss, Food Science, CBS Publication &
Distributors.
3. S Ranga, Hand book of Analysis and Quality control for fruits and Vegetables,
46 Tata, Mac
. Graw Hill Publication.
.
 lu rms t ry o f Fno d with
. 4. Govindrajan US, Ginger- chemistry, technology and quality evaluation: Part ~,
Sl .dal Reference to
Food Sci : Nutrition 1~82:17(1):1-96. Ce re a!s, Pulses and
Oilseeds
5. Vijaya Khader, Text book of food science and technology, lndian Council of
Agriculture Research.
6. Drewnowski, ''Taste PreferanceAnd Food Intake" Annual Review Of Nutrition,
vo1.17:237-253(volume publication date July 1997)
7. Harry H. Sister, Calvin A. Vonder Werf, Food Chemistry, Van Reinhold
Company.

10.13 ANSWERS TO CHECK YOUR PROG¥ESS

Check Your Progress 1
r

1. Cereals grains consist about two third carbohydrates,mainly in form of digestible

sugars and starches and are also important source of several other nutrierits
such as protein, calcium, iron and vitamin B. Cereals consumed as feed to
livestock are converted into meat, milk, egg etc. Rice and wheat form most
important human food in world followed by other grains.
· The cost of cultivation and production of cereals are low and cost: benefits
ratio is high in terms of yield andnutrients, cereals are used as a staple diet in
most developing as well as developed countries in world. They can also stored
easily for long periods at low cost, and their moisture level remains low."
2. Protein contentin pulses is usually about 20% cfthe dry weight of seeds. All
pulses have sufficient amount of good value protein like leucine and
· phenylalanine. Carbohydrate content in pulses is about 55-60% that includes
~ubstantial levels of oligosaccharides. Lipids consist about 1.5% of dry matter
in pulses mainly polyunsaturated acidsPulses are also important source of
minerals mainly calcium, magnesium.zinciron, pbtas~ium, bd phosphorous ..
Protein content in pulses are commonlymore than twice that of cereal grains.
Pulses are useful source of vegetable protein. Pulses contain carbohydrates of
·the raffinose family of sugars; which are notoriously known for the flatulence
production in man and animals. They 'are also rich in carbohydrates and are
also source of other nutritionally important materials SlIck as vitamins and
minerals,
3.. The important oil seeds are Palm, Soybean, Sunflower, Coconut, Mustered
etc. These are important source of energy requirement, consists 2.25 times
more energy than protein and carbohydrates and helps reduqe the bulk of food
we take. It also consists ofand is excellent source offat solu91evitamins A,D,E
and K and play important role in biosynthesis of several10~g chain alcohols.

Check Your Progress i

1.. The carbohydrates are a major source of metabolic energy, both for plants
and for animals that depend on plants for food. Aside from the sugars and
starches that meet this vital nutritional role, carbohydrates-also serve as a
structural material (cellulose)" a component of the energy transport compound
ATP, recogriition sites on cell.surfaces; and one ofthree essential components
of DNA and RNA. .
Lipids have great importance in the food because they are readily digested
and utilized in body. Lipids consist of numerous fat like chemical compounds
. that are insoluble in water but soluble in organic solvents. Lipids supply energy, .
carry fat-soluble vitamins CA,D, E, K), and are a source of antioxidants and
47
Basic Principles-II bioactive compounds. Fats are also incorporated as structural components of.
the brain and cell membranes.
2. First phase of glycolysis reaction is requires energy in the form of ATP,and in
second phase is called as a energy-yielding phase. In the first phase, 2
equivalents of ATP are used to convert glucose to fructose l,6-bisphosphate
(Fl, 6BP). In the second phase Fl, 6BP is degraded to pyruvate, with the
production of 4 equivalents of ATP and 2 equivalents ofNADH.
I '. .
. C6H1206 + 2 NAD+ + 2ADP+ 2 P--> 2 pyruvic acid, (CH3(C=O}COOH
+ 2 ATP + 2 NADH + 2 H+
At thistime, concentrate on the fact that glucose with six carbons is converted
into .two pyruvic acid molecules with three carbons each. Only a net "visible"
2 ATP are produced from glycolysis. The 2 NADH will be considered
separately l~ter.
3. F~ts ar9 sources ofenergy~cause they.provide.twic,e the ~ergy ~ compared
WIth carbohydrates of protem on a weight basis, The baSICfunctions of fats
are to ~ake up part ofthe structure of cells, forfn a protective cushion and
heat in~ulation around vital organs, carry fat soluble vitamins; and provide a
reserve storage for energy.
The three essential fatty acids are linoleic, linolinic, and arachidonic. These are
unsaturated fatty acids.

Check Your Progress 3

1. All life ~equir~sprotein since it is the chief tissue builder and part of every cell
in the b:ody. These are polymers of amino acids covalently linked through
peptide bonds into a chain. '.
Good sources of protein for vegetarians includes nuts and seeds, pulses, Soya
products (tofu, Soya milk and textured Soya protein such as Soya mince),
cerealsIwheat, oats, and rice), free-range eggs and some dairy products (milk,
cheese and yogurt).
2. A basic role of amino acids is to control our metabolism and body function as
under: .
1) Amino acids are necessary for growth and cellular replication throughout
the body.
2) Amino acids are a major constituent for muscle, blood, skin, and internal
organs.
3) Amino acids control the pathway that allows hormones and enzymes to
be released.
3. There are Eight amino acids which are generally regarded as essential amino
acids forI.humans: tryptophan, lysine, methionine, phenylalanine, threonine,
.
valine, leucine, isoleucine. Two others, histidine and arginine are essential only
in children,

48