加工精度对小麦粉淀粉体外消化特性的影响及机制研究

    Effect of processing accuracy on starch digestive characteristics in vitro of wheat flour and mechanism

    • 摘要: 研究加工精度对小麦粉淀粉体外消化特性的影响可为开发低血糖生成指数面制品提供思路。以系统粉、次粉和麸皮为原料,基于膳食纤维含量-累计出粉率配制系列加工精度(出粉率55%~95%,其中出粉率55%~75%为高加工精度,75%~95%为低加工精度)小麦粉,测定淀粉消化特性,结合湿面筋含量、膨胀势、糊化特性、热特性等指标与相关性分析,阐明加工精度影响淀粉消化特性的机制。结果表明:随着加工精度的降低,淀粉水解率和快消化淀粉含量降低,慢消化淀粉和抗性淀粉含量升高;高加工精度小麦粉的淀粉最大水解度降幅高于低加工精度小麦粉;所有加工精度小麦粉,抗性淀粉含量与峰值黏度、回生值等呈极显著负相关(P<0.01);低加工精度下,膳食纤维含量与湿面筋、游离巯基含量的相关性更强。低加工精度小麦粉的淀粉更耐消化,这与较高的膳食纤维含量加剧了面筋网络的劣化显著相关。

       

      Abstract: In order to provide insights into developing low-glycemic index (GI) flour products, this study focus on the effect of processing accuracy on the in vitro digestion characteristics of starch in wheat flour. A series of wheat flours with different processing accuracy (flour yield of 55% to 95%, with 55% to 75% considered as high processing accuracy, and 75% to 95% as low processing accuracy) were prepared based on dietary fiber content and cumulative flour yield using different system powders, middling, and bran as raw materials. The starch digestion characteristics were determined using the in vitro Englyst method. Combined with the determination of wet gluten content, swelling power, pasting properties, thermal properties, and correlation analysis of those with the starch digestion characteristics, the mechanism of processing accuracy affecting starch digestibility was elucidated. The results showed that as the processing accuracy decreased, the in vitro hydrolysis rate of starch and the content of rapidly digestible starch decreased, while the content of slowly digestible starch and resistant starch (RS) increased. The decrease of maximum degree of starch hydrolysis of wheat flour with high processing accuracy was higher than those with low processing accuracy. For all wheat flours with different processing accuracy, RS content showed a significant negative correlation with peak viscosity and setback value (P < 0.01). At low processing accuracy, the correlation between dietary fiber content and wet gluten, as well as free sulfhydryl content, was stronger. The starch in wheat flour with low processing accuracy is more resistant to digestion, which is significantly correlated with the deterioration of gluten network exacerbated by the higher dietary fiber content. For wheat flour with high processing accuracy, dietary fiber and gluten synergistically competed with starch for water absorption, which had a certain physical barrier effect on starch granules, limited starch swelling, inhibited amylose leaching, and limited the movement of starch chains, thereby improving the resistance to enzymatic hydrolysis. For wheat flour with low processing accuracy, dietary fiber deteriorated the gluten network, resulting in a decrease in the barrier effect of gluten on starch granules decreased, and the starch digestibility decreased slightly.

       

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