Grain Structure and End-Use Properties

Practical implications of grain structure relate to every step from grain development and production through market ing to processing, utilization, and consumption . The structure and adherence of the hulls may contribute to protection of grain during germination or malting and protection against insect infestations . Germ retention during threshing and separation during processing depend on the germ structure and location in the kernel. The subaleurone and central endosperm layers differ in cell size, shape, and structure and in composition, especially with regard to protein contents and quality. The main factors in grain hardness are the intrinsic hardness of the main components , the strength of interaction within the cell, and the interaction of individual cells to produce overall grain structure. Endosperm structure and hardness is related to wheat conditioning, to breakage in milltng, and to the structure and composition of the mi l led flour particles. Milling quality is governed by morphological characteristics of t he wheat kernel and its mechano-physical properties and by the methods of grinding and separation . Reducing changes in texture and structure during drying of maize and rice are important in minimizing breakage during handling, storage , and transportation, dust formation, and infestation. Differences in grain structure are expressed in differences in composition, gradients of components in grain tissues, and end-use properties . Those differences have important nutritional implications. New microscopic methods to determine grain structure, composition, and end-use properties have the potential of contributing to improved nutritional quality and utilization of cereals by modifying-restructuring grain morphology through classical plant breeding and genetic engineering