Starch granules chemical structure

Jane, J. L., Shen, J. J. (1993). Internal structure of the potato starch granule revealed by chemical gelatinization. Carbohydr. Res., 247,279-290. 

Sahai, D., Jackson, D. S. (1996). Structural and chemical properties of native corn starch granules. Starch, 48, 249-255. 

Amylopectin molecules are large flattened disks consisting of (1 —4)-linked a-glucan chains joined by frequent 6)-branch points. Many models of amylopectin structure have been proposed. The most satisfactory models are those proposed by Robin et al.,18 Manners and Matheson,19 and Hizukuri 20 all are known as cluster models. Reviews by Morrison and Karkalis21 and Hizukuri22 discuss in detail the chemical and physical aspects of the starch granule and its components, amylose and amylopectin. 

Characterization of the state, nature and structure of the starch granule surface has been somewhat limited. Over the past few years, however, substantial progress in starch surface chemical analysis and surface imaging has been made. The following two sections detail recent developments in these two new areas of starch research. 

The porous internal structures of A-type starch granules agree with known features for example, A-type starches exhibit faster chemical penetration and derivatization reactions,325 have weak points, are more susceptible to enzyme-catalyzed hydrolysis,38... 

This review has shown that most studies on barley starches have been focused on understanding the fine structures, particle size distribution, chemical composition, gelatinization properties and susceptibility towards enzyme hydrolysis. However, there is a dearth of information on the rheological and retrogradation characteristics of barley starches from different cultivars. Furthermore, the response of small and large barley starch granules towards physical and chemical modification needs investigation. Research in the above areas is underway in our laboratories. It is hoped that this study may improve the utilization of different types of barley starches for specific products within the food and paper industry. 

Taylor contended that optimum fractionation could only be realized after complete dissolution of granule structure to give a physically homogeneous starch sol. On this basis, there are two separate phases to the problem of fractionation first, a satisfactory method for dispersing the starch without chemical degradation and, second, the isolation of one or the other of the starch components from this homogeneous sol. 

Structural changes of starch and hydrogen starch granules on heating have been discussed. These changes facilitate the next stage of dextrinization, which is chemical in character. 

Although the general structure of the starch components is now well established, little is known of the fine structure of the starch granule, and investigations by physical, chemical, and biological methods have, in some instances, 3delded conflicting results. ... 

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