双螺杆挤压温度对山药粉理化性质和体外消化性的影响

Effects of twin-screw extrusion temperature on physicochemical properties and in vitro digestibility of yam flour

该研究使用同向双螺杆挤出机研究挤压温度对山药粉的理化性质和体外消化率的影响。设定在不同温度(90、100、110和130℃),螺杆转速为180 r/min,物料水分为30%的条件下对山药粉进行挤压处理。结果表明,挤压处理使山药粉的结晶度下降,而且随挤压温度升高而降低,结晶结构发生改变。挤压后山药粉的溶解度更高,膨胀度和糊化焓下降,并且随着挤压温度升高,在130℃时,山药粉的溶解度最高,膨胀度和糊化焓最低。山药粉的动态流变学表现出弱凝胶性质。在频率扫描范围内,山药粉的储能模量(G′)和损耗模量(G″)随温度上升整体呈下降趋势。淀粉的体外消化结果显示,挤压后山药粉的慢消化淀粉含量升高,抗性淀粉含量下降,总体消化率升高,且慢消化淀粉含量随温度升高而增加。因此,当挤压温度为130℃时,山药粉性质稳定,不易凝胶化,水溶性较好,而且慢消化淀粉含量高于未处理山药粉。挤压工艺可能通过影响山药粉的结构和体外消化率提高食品的功能特性和质量。

The effects of extrusion temperature on the physicochemical properties and in vitro digestibility of yam flour were studied by using the same direction twin-screw extruder.The flour was extruded under the conditions of different temperatures(90,100,110,and 130℃)with a screw speed of 180 r/min and the feed moisture of 30%.The results showed that the crystallinity of yam flour decreased with the increase of extrusion temperature,and the crystal structure changed.After extrusion,the solubility of the flour was increased,while the expansion degree and the gelatinization enthalpy decreased.With the increase of extrusion temperature,the highest solubility and the lowest expansion degree and gelatinization enthalpy were obtained at 130℃.The dynamic rheology of yam flour showed weak gel properties.In the range of frequency scanning,the energy storage modulus(G′)and loss modulus(G″)of yam flour decreased with the increasing of temperature.The results of in vitro starch digestion showed that the content of starch with slow digestion properties increased and the content of resistant starch decreased.Meanwhile,the overall digestibility increased after extrusion,and the content of slowly digested starch increased with the increase of temperature.Therefore,when the extrusion temperature was 130℃,the flour was stable and not easy to gelatinization.It had a good water-soluble and the content of slowly digested starch was higher than that of untreated flour.The extrusion process could improve the functional properties and quality of the food by affecting the structure and in vitro digestibility of the flour.