基于挤压法的高抗性淀粉米粉制备及结构表征

Preparation and Structural Characterization of Rice Flour with High Content of Resistant Starch Based on Extrusion Method

摘要:

为生产具有抗消化性的高抗性淀粉营养米粉,采用挤压法,以碎米(broken rice, BR)为原料,添加月桂酸(lauric acid, LA)和β-乳球蛋白(β-lactoglobulin, βLG),探讨高温挤压、低温挤压结合常温贮藏和低温贮藏处理对米粉中淀粉-脂肪酸和淀粉-脂肪酸-蛋白质复合物的形成、结构及其体外消化性质的影响。以冷却峰黏度、差示热扫描焓值(enthalpies, ΔH)和体外消化抗性淀粉相对含量为复合物形成效果考察指标,探究高抗性淀粉米粉的优化制备方法；以傅里叶红外光谱谱带和X射线衍射V型峰表征复合物结构特性。结果表明:不同挤压和贮藏处理对米粉的糊化、热特性影响较大,低温挤压结合低温贮藏处理的BR-LA-βLG组冷却峰黏度最大(636cP),说明经过低温挤压-低温贮藏处理的BR-LA-βLG组产生的复合物最多,且其热特性中的ΔH和抗性淀粉相对含量最高,分别为27.69J/g和28.08%；短程有序性测定发现,BR-LA组和BR-LA-βLG组在1710cm-1和2855cm-1处出现了红外吸收峰,且BR-LA-βLG组在1710cm-1处的吸收峰强度显著低于BR-LA组；晶体结构分析表明,淀粉与LA和βLG在不同挤压和贮藏温度下形成Va型晶体,低温挤压结合低温贮藏处理的BR-LA-βLG组的结晶度最高,为13.77%。应用低温挤压结合低温贮藏的加工方式可以获得抗性淀粉相对含量较高的营养米粉,研究旨在丰富糖尿病人群的主食来源,并为高抗性淀粉食品原料制备提供一定参考。

Abstract:

In order to produce nutritious rice flour with high content of resistant starch and anti-digestive properties, the extrusion method was used to investigate the effects of high-temperature extrusion, low-temperature extrusion combined with ambient and low-temperature storage on the formation, structure and in vitro digestive properties of starch-lipid and starch-lipid-protein complexes in rice flour, using broken rice (BR) as raw material and with the addition of lauric acid (LA) and β-lactoglobulin (βLG). The optimal preparation method of rice flour containing high resistant starch was explored by taking the viscosity value of the pasting cooling peak, the differential thermal scanning enthalpies (ΔH) and the relative content of resist starch of in vitro digestion as the indicators for the formation effect of the complexes. The structural properties of the complexes were characterized by Fourier infrared spectroscopy bands and V-shaped peaks of X-ray diffraction. The results showed that different extrusion and storage treatments had a large effect on the pasting and thermal properties of rice flour, and the BR-LA-βLG group treated with low-temperature extrusion combined with low-temperature storage had the largest the pasting cooling peak viscosity value of 636 cP, indicating that the BR-LA-βLG treated with low-temperature extrusion-low-temperature storage produced the largest number of complexes, and had the highest ΔH and relative contents of resist starch in the thermal properties, which were 27.69% and 28.08%, respectively. The short-range ordering determination found that the infrared absorption peaks appeared at 1710cm-1 and 2855cm-1 in the BR-LA group and BR-LA-βLG group, and the intensity of the absorption peak of BR-LA-βLG group at 1710cm-1 was significantly lower than that of BR-LA group. The analysis of the crystal structure showed that the Va-type crystals were formed by starch with LA and βLG under different extrusion and storage temperatures. The crystallinity of the BR-LA-βLG group treated with low-temperature extrusion combined with low-temperature storage was the highest, which was 13.77%. The processing method of low-temperature extrusion combined with low-temperature storage could be used to obtain nutritious rice flour with relatively high content of resistant starch. The research aimed to enrich the source of staple food for diabetic people, and provide some reference for the raw material production of food with high content of resistant starch.