Background

Wheat is the major food grain consumed in temperate countries. Most wheat is consumed after milling to produce white flour, which corresponds to the endosperm storage tissue of the grain. Because the starchy endosperm accounts for about 80% of the grain dry weight, the miller aims to achieve flour yields approaching this value.

Scope and approach

Bioimaging can be combined with biochemical analysis of fractions produced by sequential pearling of whole grains to determine the distributions of components within the endosperm tissue.

Key findings and conclusions

This reveals that endosperm is not homogeneous, but exhibits gradients in composition from the outer to the inner part. These include gradients in both amount and composition. For example, the content of gluten proteins decreases but the proportion of glutenin polymers increases from the outside to the centre of the tissue. However, the content of starch increases with changes in the granule size distribution, the proportions of amylose and amylopectin, and their thermal properties. Hence these parts of the endosperm differ in the functional properties for food processing. Gradients also exist in minor components which may affect health and processing, such as dietary fibre and lipids. The gradients in grain composition are reflected in differences in the compositions of the mill streams which are combined to give white flour (which may number over 20). These differences could therefore be exploited by millers and food processors to develop flours with compositions and properties for specific end uses.

中文翻译：

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小麦淀粉胚乳成分的梯度对制粉和加工有影响

背景

小麦是温带国家消费的主要粮食。大多数小麦在碾磨后被消耗以生产白面粉，这对应于谷物的胚乳储存组织。由于淀粉质胚乳约占谷物干重的 80%，磨坊主的目标是使面粉产量接近这个值。

范围和方法

生物成像可以与全谷物连续珍珠化产生的级分的生化分析相结合，以确定胚乳组织内成分的分布。

主要发现和结论

这表明胚乳不是均质的，而是表现出从外部到内部的组成梯度。这些包括数量和组成的梯度。例如，面筋蛋白的含量减少，但面筋聚合物的比例从组织的外部向中心增加。然而，淀粉的含量随着颗粒尺寸分布、直链淀粉和支链淀粉的比例以及它们的热性能的变化而增加。因此，胚乳的这些部分在食品加工的功能特性上有所不同。梯度也存在于可能影响健康和加工的次要成分中，例如膳食纤维和脂质。谷物成分的梯度反映在磨粉流成分的差异上，磨粉流组合成白面粉（可能超过 20 个）。因此，磨坊主和食品加工商可以利用这些差异来开发具有特定最终用途的成分和特性的面粉。