Gelatinized Starch Investigation_Bài gởi qua mail admin của HUONGKIM

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Gelatinized Starch Investigation_Bài gởi qua mail admin của HUONGKIM

Bài gửi  chilinhkgcc on Wed Apr 07, 2010 9:04 pm

1 Introduction
This experiment explores the effects of heat and water on starches. A starch is a polysaccharide—a long chain of sugar molecules [1]. It is made up of both amylose and amylopectin, and each type of starch contains a different percentage of each [2]. As a starchis heated to a particular temperature (between 62◦C and 75◦C for most types of starch), it begins to undergo gelatinization [5]. According to J.M.V. Blanshard of the University of Nottingham, “Gelatinization refers loosely both to the loss of order (...) and also to the swelling of the granule” [2]. The loss of order mentioned here is the breaking down of the starch chain that allows for water absorption and disruption of the crystalline structure of the starch [5]. Gelatinization is important because it changes the taste and texture of a starch granule and makes it easier to digest [4]. We will study the process of gelatinization, how it happens, and under what conditions it occurs. Below are some pictures taken with a digital microscope of potato starch before and after cooking. Figure 1 shows a raw slice of potato with an evident crystalline structure. Figure 2 shows what the starch granules look like after they have absorbed some water and expanded. (Note: Taking some time to use the microscope offers a very helpful visual component for the experiment.)

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