Essay On Wheat Bread

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The seed constituents i.e., proteins, starch, non- starch carbohydrates, lipids and other small molecules determines the processing quality of wheat. The protein content and types determine the end product quality like bread, biscuit, cake, chapatti and noodles etc. Wheat grains can generally be classified as having either a soft or hard endosperm texture. Soft grains are usually used for making biscuits whereas hard grains are used for pan-breads and pasta (Moss, 1973).
2.1 For biscuit making
Biscuit making requires soft wheat with low protein content, the starch granule-associated proteins, Pin, is the primary molecular determinant of grain texture, which is an important property as it determines the end use quality. Puroindoline form the molecular basis of wheat grain hardness. These are low molecular weight, highly basic, highly surface active, quantitative relatively proteins minor non-gluten protein of the wheat caryopsis. They occur in two forms, Pina and Pinb of 13 KDa protein. Morris (2002) the two Puroindoline genes and grain softness protein-1 (GSP-1) (Jolly et al. 1993) is associated with the hardness (Ha) locus is on the short arm of chromosome 5D in common wheat. However, the homologous loci on 5A and 5B lack both Pin genes these have been deleted during the evolution of durum and thus common wheat. The absence of softness conferring Pin genes is considered responsible for the very hard texture of durum, soft texture being restored in common wheat. The Pin genes are contributed by Ae.taudchii (Lagudah et al. 1991), during evolution. Soft texture is encoded by both Pina and Pinb in functional state, encoded by wild allels, designated by Pina-D1a and Pinb-D1a, and diverse mutation in either or both of these genes have...

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...assettes. Co-transformation with the silencing cassettes for both genes resulted in 91% reduction of Pina and Pinb transcripts in some segregating F1 progeny of Kontesa. The silencing was transmitted to the F4 kernel generation of the F3 lines. So lack of both puroindoline proteins in the silenced lines correlated with an essential increase in grain hardness.
Chen et al. (2013) investigated molecular characterization of the Puroindoline-D1 allele in bread wheat cultivars from five geographic regions, resulting in the discovery of two new alleles - Pina-D1s with a 4,422-bp deletion and Pina-D1u with a 6,460-bp deletion in the Ha (Hardness) locus. Molecular markers were developed for both alleles. They analyzed the association of the Puroindoline-D1 alleles with grain texture showed that cultivars with PinA-null allele possessed relatively high SKCS hardness index.

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