Cereal Chemistry and Dough Properties of Indian Wheat

1. Cereal Chemistry

The grain protein content varies considerably, depending on whether the harvest is from well irrigated highly fertilized fields or from rain fed, low yielding fields to which less fertilizer has been applied. The warm wheat growing areas generally have a higher grain protein content than the cool NHZ. The hill wheat with low protein and a high spread factor is suitable for the biscuit industry. PZ wheat is good for crackers and cookies, as it has a high protein content and strong gluten. High molecular weight (HMW) gluten in Indian wheat varies with the variety. A frequency of 2+12 for Glu-D is usual in > 70 of the Indian varieties and the rest have a 5+10 band. Similarly, the most common Glu-A is band 2* in > 60% of the genotypes and the rest have either band 1 or N (nil). Glu-B is very diverse, and an almost equal number of varieties have either 7+9 or 7+8 or 17+18. The presence of band 7 or only band 20 is found in a few odd wheat varieties. In the CIMMYT material, In the CIMMYT material, Pena (1995) observed that a maximum number of lines contain 2* as Glu-A, 7+9 for Glu-B and 5+10 for Glu-D. The distribution pattern of the CIMMYT material of 1994 is at variance with the Indian material sampled during 2002 despite the fact that the Indian national wheat improvement programme uses the CIMMYT lines extensively in its breeding programme. This mixture of the HMW gluten combinations present in Indian varieties is used for making various value-added end products.

2. Dough Properties of Indian Wheat

The contribution of gliadin and glutenins to gluten strength and extensibility can be inferred from protein content, sedimentation value, dough strength and dough extensibility, the crumb and the loaf volume of the bread. The dough properties or rheological information are of importance in value addition and product development. If the Alveograph ratio of dough tenacity or P (maximum height of the curve) to extensibility or L (length of the curve) is around 0.8 and the total work force (W) needed to cause rupture of the dough is above 200 (erg/g, or 10-4 J) then the bread volume tends to be high and the quality of the product is good. If the flour is stored at a high temperature (40 °C) the dough becomes inextensible (Censkowski et al., 2000), and in many parts of India such high ambient temperatures prevail for several days during summer and contribute to the quality variations in bread during different seasons of the year. The milling and baking industries, located primarily in the southern states, are short of wheat grain suitable for bread and biscuit manufacture. Wheat sample data from different zones show (Tab. 44) that the PZ produces the best wheat available for bread, as the loaf volume and bread rating are high, but the quality is still below what is achieved elsewhere in the world. The NHZ produce meets biscuit quality needs, as the spread factor is the best. In both NHZ and PZ wheat production is lower and there is hardly any marketable surplus. Also these places are far away from the location of the biscuit industry, which makes surface transport of the grain expensive and difficult. The CZ grain meets the demand of the whole grain flour market for the flat, non-fermented Indian bread or chapatti and that of NWPZ and NEPZ is rated next only to the CZ. Growing urbanization and the increasing employment of women has changed kitchen needs, and the branded whole grain flour or atta has created a new market.

Tab. 44: Quality attributes of bread wheat samples of 2002, from different zonesa

India has approximately 1.5 mio ha under durum wheat. It is mostly confined to PZ and CZ, but there are very small areas in Punjab and NWPZ too. The Indian durum has very hard grain and good (approximately 7 ppm) beta carotene. The protein content is approximately 15% in Khapli wheat, the grain is long and deep-golden, with shrivelled cheeks. These tetraploids are used to manufacture semolina, bulgur and several extruded products of high quality.

3. Grain Classification

Wheat grain classification is essential for trade and quality control as the buyer is able to understand the utilities of the supply and negotiate a price. The approach rests on two parameters, namely the physical purity or "Grade" and the other grouping called "Class" which is based on the grain quality traits. Tab. 45 shows the different grades recommended for adoption in India (Gupta, 2002).

The following section describes the five major Indian wheat classes.

Tab. 45: Suggested grading standards for Indian wheat.

 4. Classes of Indian Wheat

Indian Medium Hard Bread Wheat

This is the standard mill quality wheat. Medium grain size and appearance, medium hard, dry gluten 9%, protein > 10%, > HLW 76, seed moisture 11%, total defects 6%, extraction efficiency < 69% sedimentation value < 40. The flour is suitable for non-fermented flat Indian bread chapatti and a number of other ethnic food preparations such as naan, tandori, rumali, roti, puri, bhatore etc. All these ethnic foods are made out of the whole grain flour of this class. This is the largest wheat surplus India produces. It is consumed domestically in various forms. The wheat varieties PBW 343, HD 2786, Raj 3077, Lok 1, GW 273 etc., fall into this class.

Indian Hard Bread Wheat (Premium Wheat)

Bold and lustrous grain, dry gluten 9%, protein > 12%, HLW approx. 80, seed moisture 11%; extraction efficiency is approx. 70%. It is suitable for a variety of fermented and non-fermented breads. The bread quality and rating is high, and a variety of flours can be made from the grain. The varieties C 306, Sujatha, HW 2004, HD 2189, DWR 162, GW 496, Lok 1 (some samples from PZ) and HD 2733 fall into this class. The "cream" of wheat, maida12 and extruded products made from this class have a market chiefly in South Indian states.

Indian Soft Bread Wheat (Biscuit Wheat)

Yellowish / white grain, grain hardness < 5.3, soft textured, dry gluten 7%, protein < 9.5%, HLW 75, seed moisture 12%, extraction efficiency approx. 68%, biscuit spread factor > 7.5. It is suitable for eastern food habits, biscuit- making etc. Local land races of the NHZ and Pissi, a local land race of CZ, fall into this cluster and meet the requirements of the biscuit industry.

Indian Durum Wheat

Large and hard kernel, vitreous grain, betacarotene > 5 ppm, protein > 12%, HLW > 78. Seed moisture is approx. 11%. The durum varieties PDW 233, WH 896, HI 8498, Raj 1555, MACS 2846 etc., fall into this class. It is extensively used for extruded products, semolina and pasta, and for pizza bases, bulgur etc.

Indian Dicoccum Wheat

Hard kernel, longish grain, not plump, betacarotene > 5 ppm, HLW > 78, protein > 13% and seed moisture 10%. It is suitable for breakfast cereal, semolina, for porridge, extruded products and for high-protein foods. Local Khapli land races, NP 200, DDK 1009 etc., fall into this class.

Current Indian Wheat Grading System

Indian wheat is currently divided into different grades based on physical purity, admixtures, broken kernels, shrivelled kernels etc. The suggested grades (Nagarajan, 2004) have not been put into practice as there is no declared difference in price, although in the grain market there is a variation in price on the basis of arbitrary assessment made by the grain merchant. The Indian grain grading system is therefore comparable with the practices followed in other parts of the world and aimed at promoting proper auctioning and pricing of the produce. These developments should be viewed in the context of our need to have harmonized and well accepted grain quality standards and of India's preparedness to become a partner in the global grain trade.