Quality requirements for different wheat products are given in Table 2.6:
In India, wheat is primarily consumed in the form of chapati. It is also used for making bread and bakery products. About 80 per cent of the wheat produced in the country is consumed in the form of chapati. All programmes relating to wheat improvement gives priority to chapati making qualities.
1. Chapati Making Quality:
Austin and Ram (1971) have suggested the following standards for different characteristics of good chapati making quality:
Alveographic characteristics:
In addition, the variety should have low contents of crude fibre and phytic acid as higher crude fibre content affects carbohydrate and protein digestibility while higher phytic acid interferes with calcium, iron and magnesium absorption.
Chapaties produced from tall Indian varieties have silky appearance, sweet, palatable and have good puffing characteristics whereas from that prepared with Mexican wheats are brownish in colour, leathery in texture and tend to become brittle on keeping. Chapti quality of dwarf wheats has been considerably improved to meet the domestic requirements.
Protein Content:
Protein content of tall traditional wheats is relatively low ranging from 9 to 15 per cent. However, on an average it is around 10 per cent. More recent dwarf wheats under cultivation in the country have, on an average, around 12 per cent protein. Janak, UP 262, HON 37, Shera and Meghadhoot contain relatively higher grain protein content.
Sedimentation Value:
Wheat grain proteins provide glutein, which gives structural framework for spongy and cellular texture of bread and other backed products. The flour should have high quality protein with strong glutein properties.
Sedimentation and pelshenke tests are used to measure the quality of flour.
Austin and Tikoo (1972) reported a variability of 20-59 ml and classified the varieties as indicated below:
Weak flours have low elasticity, low baking strength and low stability. Breads from weak flours become flowy and crusts make it unattractive. Strong flours absorb greater quantities of water and provide strong dough. They are most suited for mechanised bread making industry. Cultivars Raj 832, K 64, K 65, NP 862, HD 2176 produce strong flour used for blending with soft flour.
Pelshenke Value:
Pelshenke value indicates the quality of protein. Its value ranges from 56-235 minutes. Based on the values, wheat varieties are grouped into four groups.
Most of the dwarf wheats belong to medium strong group. Medium strong flour absorb comparatively greater amount of water and forms dough of moderately sticky consistency. It is often stretchable, elastic and non-sticky. Indian chapties puff well with medium strong dough.
Water Absorption:
Water absorption capacity of flour depends primarily on protein and damaged starch content of the flour. Flour should have high water absorption for bread making. It also determines the softness of chapaties. Flour with low water absorption tends to cook into stiff chapaties.
Damaged starch content of flour depends on grain hardness and severity of grinding. High water absorption capacity of Indian flour is due to high damaged starch content (5-10%).
Alveographic Characteristics:
Alveograph uses air pressure to blow a bubble from a disc of dough. The height of alveograph measures initial resistance of dough to extension and is known as stability (P). Length of curve is an index of dough extensibility (L) and gas retention. The area under curve is a measure of baking strength of the dough.
The ratio of extensibility (L) and stability (P) should be about 1:2 for dough of well-balanced glutein characteristics. The L: P is very high for weak and extensible dough and for a short dough, the ratio is less than one.
Neither too strong nor too weak flour is suitable for bakery because in the former case the flour offers too much resistance to extension, which reduces the amount of dough rise during baking, and consequently the loaf volume is not optimum. A weak flour on the other hand retains the gas produced during fermentation and collapses resulting into poor loaf volume. However, such flour is ideal for biscuit making.
Total Sugars and Diastatic Activity:
Sugar content and diastatic activity of flour add to the sweetness of the flour and chapatis. Diastatic enzymes also produce maltose from flour during relaxation period, which improves the sweetness of chapaties. Hence, certain amount of diastatic activity in the flour is essential. A range from 145 to 385 mg 10-1 g flour for sugars and 114 to 488 mg maltose 10-1 g flour diastatic activity appears to be ideal.
2. Bread Making Quality:
Bread making quality depends on milling characters, flour and dough characters and baking quality. Majority of traditional wheat varieties are reputed not only good for chapaties but also for good bread baking qualities.
A variety which gives a flour recovery of 70 per cent or more (with normal ash content) is considered most suitable from milling point of view. Other important criteria are flour and dough characteristics and backing quality. Flour characteristics and part of dough characteristics have been discussed under chapati making properties.
Mixograph is useful in characterising certain important properties of wheat flour. The mixing time is highly correlated with the baking time. Mixing time also measures the rate of dough development and the rate and extent of increase in mobility of dough as a result of mechanical action. Heera, Moti, UP 310, UP 310, Deccan queen, Hybrid 69 etc., are Indian wheat accessions with better bread making quality.
3. Milling Quality:
Cleaned grains are dried to hasten the milling process. Grains are first cracked or crushed gradually through a series of chilled iron break-rolls. The middlings obtained are granular fractions of the endosperm. Purified middlings are then passed through reduction rolls, where finer and whiter fractions are combined into commercial flour. Flour yields from milling are approximately 70-74 per cent.
Milling quality of wheat is assessed by yield of flour separated from germ and bran, free milling resulting in high yield of flour, low ash content which is a measure of bran content and high test weight and plumpness of grain. Varieties such as UP 360, UP 1109 and CPAN 1670 posses greater flour recovery.