焙烤过程对红茶面包淀粉消化特性的影响及其机理研究

Influence Mechanism of Baking Process on the Starch

摘要:

研究了焙烤过程对红茶面包淀粉消化特性的影响，并通过茶多酚HPLC分析、茶色素含量测定及酶活抑制实验，对其机理进行了探究。结果表明：在不同焙烤条件下，红茶面包的淀粉消化特性不同，当焙烤条件设定为190 ℃、15 min时，其葡萄糖释放速率最为缓慢；经焙烤之后，红茶中的儿茶素含量未发生明显变化，茶黄素、茶红素、茶褐素含量均降低，但低极性茶多酚含量增加；红茶经焙烤后，其水提物对α-淀粉酶活力和α-葡萄糖苷酶活力的抑制效果均增强。低极性茶多酚的生成受焙烤过程的影响，其对淀粉消化酶的抑制显著，进而降低红茶面包的淀粉消化速率，因而，焙烤条件是开发低血糖生成指数（GI）焙烤食品的关键因素。

Abstract:

The effect of baking process on starch digestion of black tea bread was studied in this paper. Starch digestion curves showed that the rates of glucose release of black tea bread were different under different baking conditions. The rate of starch digestion was slowest when baking conditions were set at 190 ℃ and 15 min. This paper further studied the mechanism of this phenomenon by using HPLC analysis of tea polyphenols，the detection of tea pigments content，and α-amylase and α-glucosidase activity assays. There were no obvious changes for catechins，but the content of theaflavins，thearubigins，and theabrownins all decreased while the content of tea polyphenols with low polarity increased during baking. Baking process increased the inhibition of black tea on the activity of both α-amylase and α-glucosidase. The difference of starch digestibility of black tea bread may be due to the difference of the content of low polar tea polyphenols under different baking conditions. Therefore it is crucial to choose optimal baking condition to the develop bakery tea foods with low glycemic index（GI） value.