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首页> 外文期刊>Cereal Chemistry >Study of structural and thermal changes in endosperm of quality protein maize during traditional nixtamalization process.
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Study of structural and thermal changes in endosperm of quality protein maize during traditional nixtamalization process.

机译：研究传统尼克化过程中优质蛋白玉米胚乳的结构和热变化。

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摘要

This work presents the study of the structural changes of the endosperm of Quality Protein Maize (QPM H-368C), modified by alkaline cooking at two different temperatures (72 and 92 degrees C) and steeping time of 0-7 hr. Structural changes in the outermost 10% layers, the subsequent 10%, and the remaining 80% of the endosperm as a function of the steeping time were studied using scanning electron microscopy (SEM), X-ray diffraction, and differential scanning calorimetry (DSC) techniques. SEM images revealed that soft and hard endosperm have different shapes and packing factors. The X-ray diffraction patterns of the hard and soft endosperm from raw corn suggest that the hard endosperm consists mainly of amylopectin and has a bigger relative crystallinity quality than the soft endosperm. Samples cooked at 72 and 92 degrees C with and without the Ca(OH)< sub>2 and steeped for 0, 3, and 7 hr, showed structural changes, X-ray diffraction patterns from the outermost 10% layers and subsequent 10% of the endosperm were completely amorphous. This fact is related to the total or partial gelatinization of the starch. The crystallinity in the internal layers of endosperm (remaining 80%) did not have significant changes after the treatments and exhibited the characteristic patterns of crystalline amylose and amylopectin. DSC measurements in the outermost layers of the endosperm did not exhibit the characteristic endothermic peak of starch (from 64 to 81 degrees C) compared with the raw sample, while the endotherm peak for 80% of the endosperm internal layers appears in all cases (72 and 92 degrees C). According to these results, a new definition of the nixtamalization process can be developed as follows. During the nixtamalization process there is a total gelatinization of the starch granules from the most external layers, and a partial gelatinization of the innermost internal layers of the endosperm.
机译：这项工作提出了对优质蛋白玉米（QPM H-368C）的胚乳结构变化的研究，该结构变化是通过在两种不同温度（72和92摄氏度）和0-7小时的浸泡时间下进行碱性蒸煮来进行的。使用扫描电子显微镜（SEM），X射线衍射和差示扫描量热法（DSC）研究了最外层10％，随后的10％和剩余80％胚乳的结构变化与浸泡时间的关系）技术。 SEM图像显示软质和硬质胚乳具有不同的形状和堆积因子。生玉米硬质和软质胚乳的X射线衍射图表明，硬质胚乳主要由支链淀粉组成，相对结晶度比软质胚乳高。样品在72和92摄氏度下烹饪，有或没有Ca（OH） 2 ，浸泡0、3和7 hr，显示出结构变化，最外层10％的X射线衍射图然后10％的胚乳是完全无定形的。这个事实与淀粉的全部或部分糊化有关。处理后，胚乳内层的结晶度（保留80％）没有明显变化，并表现出结晶直链淀粉和支链淀粉的特征模式。与原始样品相比，在胚乳最外层的DSC测量未显示淀粉的特征吸热峰（从64到81摄氏度），而在所有情况下都出现了80％胚乳内层的吸热峰（72）和92摄氏度）。根据这些结果，可以如下开发新的定义。在尼克松化过程中，淀粉颗粒从最外层完全糊化，而胚乳的最内层部分糊化。

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