He Yuezhen, Lin Yu-Lian, Chen Chen, Tsai Min-Hui, Lin Amy Hui-Mei
Bi-State School of Food Science, Univ. of Idaho, Moscow, ID, 83844-2312, U.S.A.
Compr Rev Food Sci Food Saf. 2019 May;18(3):641-654. doi: 10.1111/1541-4337.12430. Epub 2019 Mar 28.
Wheat with a low falling number (FN) has been particularly prevalent in recent years and has resulted in a loss of more than $140 million in a single year in the wheat industry in the Pacific Northwest of the United States. FN measurement is a standard method for the evaluation of grain α-amylase activity, and a low FN indicates a reduction in hot wholemeal paste viscosity due to sprouting damage. Recent studies show that a low FN may result from a developmental change of starch and adverse effects of non-α-amylase macromolecules on wheat. In this review, we describe the principles of FN measurement and the relationship between FN and α-amylase. We also discuss the isozymes, locations, and inhibitors of wheat α-amylase. The effects of various aspects of starch, which is the substrate of α-amylase, on wheat FN are also discussed, including starch structural characteristics (for example, starch granule architecture), starch susceptibility to α-amylase, and the interaction between starch and nonstarch macromolecules (for example, lipids). Studies on the effects of planting environments (for example, temperature) and agronomic practices (for example, irrigation and fertilization) on both starch paste viscosity and FN are also reviewed. This paper highlights the importance of considering the impacts of starch and the interactions of starch and other macromolecules, including wheat α-amylase, on wheat FN, which is important for developing strategies to solve the low FN problem.
降落数值（FN）较低的小麦近年来尤为普遍，仅在美国太平洋西北部的小麦产业中，一年就造成了超过1.4亿美元的损失。FN测定是评估谷物α-淀粉酶活性的标准方法，低FN表明由于发芽损伤导致热全麦糊粘度降低。最近的研究表明，低FN可能是由于淀粉的发育变化以及非α-淀粉酶大分子对小麦的不利影响所致。在这篇综述中，我们描述了FN测定的原理以及FN与α-淀粉酶之间的关系。我们还讨论了小麦α-淀粉酶的同工酶、位置和抑制剂。作为α-淀粉酶底物的淀粉的各个方面对小麦FN的影响也进行了讨论，包括淀粉结构特征（例如，淀粉颗粒结构）、淀粉对α-淀粉酶的敏感性以及淀粉与非淀粉大分子（例如，脂质）之间的相互作用。还综述了种植环境（例如，温度）和农艺措施（例如，灌溉和施肥）对淀粉糊粘度和FN的影响。本文强调了考虑淀粉以及淀粉与其他大分子（包括小麦α-淀粉酶）的相互作用对小麦FN的影响的重要性，这对于制定解决低FN问题的策略很重要。
