1. Cereal Chemistry and Bakery products technology
FST 2263

2. Aim of the course:
To provide the knowledge on physico-chemical properties of cereal flours and their contribution in attaining the specific properties of cereal based products
To provide the knowledge and hands-on experience on processing of different bakery products.

3. Intended Learning Outcomes:-
At the end of the course student will be able to;
Describe the physico-chemical properties of cereal flour and flour constituents
Evaluate the functionality of cereal flour constituents in flour based products
Explain the principles of methods used in determining the physicochemical properties of cereal flours and starches
Compare the techniques of processing of bakery products
Discuss the quality control practices applied in bakery industry
Practice the preparation of basic bakery products

4. At the end of the lesson student will be able to;
Identify structure & composition of cereal grains
Compare the nutrient composition and physico- chemical properties of different cereal flour
Differentiate cereal starch according to structure
Explain the specialty of different cereal starches

5. Structure & composition of cereal grains
Wheat
Barley
Rice
Maize (corn),
Oats

6. Cereals Belongs to gramineae (grass) family
Seed is commonly called as grain/ caryopsis
Main CHO source in many nations diet
Each cereal has unique properties which make it
suitable for a variety of food products
Cereals require different conditions to grow.
Ex: rice - tropical climates, oats – cold temperate

7. 1. Wheat
Wheat (Triticum spp.) is a grass that is cultivated temperate zone.
The most important human food grain and ranks second in total production as a cereal crop behind maize; the third being rice
Wheat grain is a staple food used to make flour for breads; cookies, cakes, pasta, noodles.

8. Common Species of wheat :-
Triticum aestivum – Common wheat
T. monococcum
T. vulgare
T. dicoccum – has certain disease resistance qualities
Triticum compactum – Two types; white & red varieties
T. durum/ Durum wheat/ Macaroni wheat – has a hard, translucent, light colored endosperm which makes it suitable as an ingredient for pasta

9. Common bread wheat can be categorized as:
Hard / Soft varieties
Spring / winter varieties
White / red varieties
Hard Red Spring — Hard, brownish, high protein wheat
used for bread and hard baked goods
- use to make bread Flour and high gluten flours
Hard Red Winter — Hard, brownish, high protein wheat
used for bread, hard baked goods and as an adjunct in other flours to increase protein in pastry flour
- use to prepare some brands of unbleached all-purpose flours

10. Soft Red Winter — Soft, low protein wheat used for cakes, pie
Soft Red Winter — Soft, low protein wheat used for cakes, pie crusts, biscuits.
- use to make cake flour, pastry flour, and some self- rising flours
Hard White — Hard, light colored, opaque, chalky, medium protein wheat planted in dry, temperate areas
- Used for bread and brewing.
Soft White — Soft, light colored, very low protein wheat grown in temperate moist areas
- Used for pie crusts and pastry.
Hard wheats are harder to process and red wheats may need bleaching. So, soft and white wheats usually have higher prices than hard and red wheats on the commodities market.

11. Raw wheat seed - food ingredient called whole wheat
can be powdered into flour, germinated and dried creating malt, crushed and de-branned into cracked wheat, parboiled (or steamed), dried, or processed into semolina, pasta
These processed wheat are a major ingredient in such foods as bread, breakfast cereals, crackers, biscuits, pancakes & cakes

12. Structure of the wheat grain:
Wheat grains - generally oval shaped ( range from spherical to long, narrow and flattened shapes)
5 and 9mm in length, weighs between 35 and 50mg
Wheat grain has a crease down one side where it was originally connected to the wheat flower.

13. Wheat grain, showing different sides and cross section to illustrate the depth of the crease

14. Pericarp Outer pericarp
Inner pericarp
Grain
Seed Seed coat (Testa)
Endosperm
Aleurone layer
Germ

15. Pericarp
outer most cover
outer pericarp consists of 3 layers
epidermis
hypodermis
Inner thin walled cell
Inner pericarp consists of
Intermediate cells
cross cell
Tube cell

16. Seed coat
firmly attached to the tube cells
if these layer carries pigments, kernel is colorful
Aleurone layer
Outer most layer of the endosperm which contains vitamin B

17. Structure of the Wheat grain

19. The three main parts are:
1. Bran
outer layers of the wheat grain; removed during milling
About 14% of the wheat kernel
The outer coating or 'shell' of the wheat kernel is made up of several layers
These layers protect the main part of the kernel
Bran is rich in B vitamins and minerals
Wholemeal flour contains all the naturally occurring bran.

20. 2. Endosperm
main part of the wheat kernel or name given to the interior of a wheat kernel
represents about 80% of the kernel weight
The endosperm, once it has been ground down to a powder, is wheat flour
It is from this part that white flour is milled. The endosperm is rich in energy-yielding carbohydrate and important protein.

21. 3. Germ (Embryo)
part of the grain which would sprout if it was planted as a seed
packed with nutrients and protein with which to nourish a new plant
During milling the germ is usually separated from the rest of the wheat grain ( fat content limits the shelf life of the flour)
The germ lies at one end of the grain and represents only 2% of the kernel
rich source of B vitamins, oil, vitamin E and natural plant fat.

22. Chemistry of wheat grain (Per 100 g)

23. Rice (Oryza sativa)
most important cereal crop in developing world
staple food of over half the world's population
production is only slightly below that of wheat
90% is grown in southern & eastern Asian
Grain structure
consists of an outer protective covering, the hull, and the rice caryopsis or fruit
Brown rice consists of the outer layers of pericarp, seed-coat and nucellus; the germ or embryo; and the endosperm

25. Endosperm consists of the subaleurone layer and starchy endosperm.
The aleurone layer encloses the embryo
The hull constitutes about 20 % of the rough rice weight.
The distribution of brown rice weight:
Pericarp %
Aleurone, nucellus, seed-coat %
Germ %
Scutellum %
Endosperm %

26. The endosperm cells : thin-walled and packed with starch granules
The two outermost cell layers are rich in proteins and lipids
have smaller amyloplasts & starch granules than the inner endosperm.
starch granules are polyhedral and mainly µm in size
Protein occurs mainly in the form of spherical protein bodies

27. Chemical composition of rice grain
Hulled rice
Water 10 – 12%
Protein 5 – 9%
Fat 0.6 – 2.6%
CHO 73 – 90%
Fiber 0.2 – 1%
Ash %
Rice bran
Water – 12.5%
Protein – 14.8%
Fat – 22.4%
Fiber 9.6 – 11.1%
Ash – 15%

28. A. Oats (Avena sativa);. B. Barley (Hordeum vulgare); C
A. Oats (Avena sativa); B. Barley (Hordeum vulgare); C. Bread Wheat (Triticum aestivum);
D. Rye (Secale cereale).

29. Rye Chemical & physical characteristics The rye kernel is a caryopsis.
Caryopsis is a small dry, indehiscent, one seeded fruit.
6 – 8 mm in length & 2 – 3 mm in width.
The color is normally grayish yellow
The seed consists of an embryo attach through a scutellum to the endosperm & Aleurone layer

30. The pericarp or fruit coat surrounds the whole seed & adhere closely to it.
A crease or furrow extends the full length of the grain on the ventral side
The nutritional quality of rye protein - superior to that of other cereals because of its better balance of EAA.
Its protein efficiency ratio seems to be higher due to; - the greater amount of lysine present in the water soluble proteins & the higher proportion of globulin & albumin

31. Rye lipids differ from those of most other cereals by having a slightly greater proportion of the highly unsaturated linolenic acid.
Therefore susceptible to oxidation. cause rancidity
Starch granules have a mean particle diameter greater than those of other cereals
shape lenticular shape
spherical shape

32. 8% pentosans in rye (in wheat is 3%)
rye bread has large pores & moisture than wheat bread
Rye has few micronutrients;
Thiamine
Nicotinic acid
Riboflavin
Pyridoxin
Pantothenic acid
Tocopherol

33. Oats (Avenea sativa) grown in cooler & moisture regions of the
temperate zones
varieties
red oats – heat tolerant
southern US, South America, Australia
Winter oats – planted in the late fall, latitude of
Spring oats – planted when the threat of frost is minimum

34. - used to prepare cakes, biscuits, & breakfast cereals
- The physical structure of the oat grain is similar to that of kernel of wheat & barley
- The 3 major divisions
- Bran - Endosperm - Germ
- The oat germ is larger & narrower than the germ of wheat
- Compared to other cereals oat grains are characterized by low CHO contents & higher protein & fat content

35. Barley
Genus: Hardeum
Most of the cultivated barley classified in to two groups
H. vulgare – six rowed barley
H. distictum – two rowed barley
Structure of Barley kernel
The caryopsis is composed of
Pericarp
Integuments
Starchy endosperm
Germ

36. The outer layer of endosperm is made out of aleurone cells
In blue barley, blue color is due to color given by the anthocynin pigments in alkaline aleurone cells
Composition of barley
Protein 12%
CHO 70%
Mineral 2%

37. Low in EAA esp lysine & Methionine
Have more lysine than corn
Contains larger amount of vitamin compared to corn
Barley granules Large granules(A)
Small granules(B)
Large granules(A) - contain high amylopectin
have lower gelatinization tem
small granules(B) -contain low amylopectin
have higher gelatinization tem

38. Uses There are two major groups of protein Glutelins & Prolamins
Albumins & globulins
Uses
source of malt in manufacture of alcohols, wisky, beer
use as a flavoring agent in breakfast cereals, malted milk, infant foods, medicinal syrups

39. Sorghum (Sorghum vulgare )
Staple food in drier part of tropical Africa, china, India
Native home is Africa
The grains are differently colored – Yellow, Red, or Brown
Composition
Fat 3%
CHO 70%
Fiber 12%

40. Millets
Common term used to large number of cultivated grasses with very small seeds
Used as forage & as a food for both man & domestic animals
More important in the East than West
Generally known as poor man’s cereal

41. 1. Fortail millets ( Setaria italica)
- Grown in Japan, China, India – grains are boiled eaten
- In North America - mainly used as a forage crop
2. Proso millet (Panicum miliaceum) – Contains 10 % proteins, 4 % Fat
- A palatable bread can be made from these
3.Finger millet (Eleusine coracana)
- Grown mainly in the tropics
- Most important cereal crop in chena in Sri Lanka

42. Maize (Zea mays)
Originated in low land of tropical South America
Leading producers : USA, China, Russia, India, Italy
Kind of maize:
Cultivars are divided in to groups, according to structure of grains
Pod corn — Zea mays var. tunicata
Most primitive form
not grown commercially

43. 2. Popcorn — Zea mays var. everta
-Grains small with a little soft starch at the center
-When heating cause the grains to pop
3. Flint corn — Zea mays var. indurate
-Grains with hard endosperm
-A little, soft starch in the center
-Well adopted to poultry feed
4. Dent corn — Zea mays var. indentata
-Principle maize of US & North mexico
-White starch shrinks on drying to produce a characteristic dent

44. 5. Sweetcorn — Zea mays var. saccharata
- Grain consist a glossy sweetish endosperm
- Cobs are picked immature for boiling as corn on the cobs
- Also use as a vegetable by canning or freezing
6. Flour corn — Zea mays var. amylacea
- Endosperm consists with soft starch
7. Waxy corn — Zea mays var. ceratina
- Starch is waxy & composed of entirely of amylopectin