萌动小麦生化指标及Mixolab糊化特性的变化

分析了萌动小麦游离氨基酸、蛋白质、水溶性糖类和破损淀粉含量及Mixolab面团糊化特性的变化。小麦萌动后游离氨基酸总量显著增加,蛋白质含量(干基)也增加,Mixolab仪测定的C2稠度谷值、C3淀粉糊化黏度峰值、C4淀粉糊化黏度谷值、C5淀粉回生终点值均减小。小麦萌动前后,水溶性总糖含量、Bacillus amyloliquefaciens蛋白酶(含内切和外切酶)降解产生的游离氨基酸含量对试验的6个品种差异不显著;除1个品种外,试验的其他5个品种水溶性还原糖含量及Aspergillus melleus蛋白酶(仅含内切酶)酶解产生的游离氨基酸含量显著增加。不同品种小麦萌动前后破损淀粉含量增减不一致。结论为小麦发芽后游离氨基酸总量增加、Mixolab面团蛋白质网络弱化程度加大、淀粉糊化峰值和谷值均降低,可以作为芽麦检测的参考依据。

Changes in Some Biochemical Parameters and Mixolab Pasting Properties of Sprouting-treated Wheat Kernels

This paper deals with the changes in some biochemical parameters and mixolab pasting properties of sprouting-treated wheat kernels. Compared to normal kernels, the contents of total amino acids and total protein (dry basis) significantly increased in sprouting-treated kernels. Mixolab torque parameters such as protein weakening (C2), starch gelatinization peak (C3), starch gelatinization minimum (C4), starch retrogradation minimum (C5) of wheat dough all decreased for sprouting-treated kernels. In comparison to unsprouting wheat kernels, the total free amino acids released by Bacillus amyloliquefaciens protease containing endo- and exo-types, as well as the content of water-soluble total sugars, showed unmarked changes for sprouting wheat kernels of six tested varieties. Except for one wheat variety, five tested wheat varieties had an increase in their total free amino acids released by Aspergillus protease only containing endo-type, and in their contents of water-soluble reducing sugars after sprouting treatment. The content of damaged starch in the flours of six wheat varieties changed inconsistently after sprouting treatment. It is concluded that total free amino acids and the mixolab dough pasting parameters such as protein weakening (C2), starch gelatinization peak (C3), starch gelatinization minimum (C4) in wheat flour can be used to detect and evaluate the sprouting of wheat kernels. Key words: Wheat sprouting kernels, total free amino acids, damaged starch, starch gelatinization, water-soluble reducing sugars, mixolab dough pasting properties