摘要
【目的】蛋白质和淀粉的热转变特性对食品加工有重要的理论指导价值,系统研究蛋白质-淀粉共混体系的热转变特性,优化热加工参数,控制食品质量和节能。【方法】以大豆分离蛋白、玉米淀粉和小麦谷朊粉为研究对象,采用差式扫描量热技术,在20—130℃,水分含量为30%—70%,升温速率为10℃·min-1条件下,测定大豆分离蛋白-玉米淀粉、大豆分离蛋白-谷朊粉、谷朊粉-玉米淀粉和大豆分离蛋白-玉米淀粉-谷朊粉混合体系在0—100%比例范围时的热转变特性。【结果】随着水分含量从30%增加至70%,大豆分离蛋白11 S亚基的热转变起始温度和峰值温度分别从105.17℃降至94.80℃,从113.75℃降至99.49℃;峰宽从20.72℃降低至10.59℃,焓变从2.79 J·g^(-1)增加至6.18 J·g^(-1);玉米淀粉的热转变焓值从3.62 J·g^(-1)增至14.14 J·g^(-1)。谷朊粉则无热转变现象。增加水分含量促进了蛋白质和淀粉分子链的运动性是大豆蛋白热转变温度降低,焓值升高,玉米淀粉热转变焓值升高的主要原因。当物料含水率为50%,相对于单一体系,大豆分离蛋白-玉米淀粉混合体系中大豆蛋白11S亚基的热转变焓值显著降低,平均降低1.41 J·g^(-1);混合体系中玉米淀粉的热转变起始温度和峰值温度显著升高,分别平均升高14℃和13℃。大豆分离蛋白-谷朊粉混合体系仅显示大豆分离蛋白的热转变,11S亚基热转变的焓值呈降低的趋势,与未添加谷朊粉相比,平均降低了2.40 J·g^(-1)。谷朊粉-玉米淀粉混合体系仅显示玉米淀粉的热转变,与未添加谷朊粉相比,玉米淀粉热转变的峰值温度和峰宽显著升高,平均增加12℃。大豆分离蛋白-玉米淀粉-谷朊粉混合体系中,当玉米淀粉和谷朊粉等比例增加时,大豆蛋白11S亚基与未添加玉米淀粉和谷朊粉相比,其热转变起始温度、峰值温度、焓值和峰宽均显著降低,分别平均降低4℃、5℃、1.64 J·g^(-1)和3℃。当固定大豆分离蛋白含量为40%,和添加40%谷朊粉相比,添加40%玉米淀粉的11S亚基热转变起始温度和峰值温度均显著降低了3℃。蛋白质与淀粉竞争水分可能是导致混合体系中淀粉热转变温度升高的主要原因,而玉米淀粉和谷朊粉分子的空间位阻是导致大豆蛋白11S亚基热转变焓值下降的主要原因。【结论】添加玉米淀粉或谷朊粉能降低大豆蛋白热转变焓,添加大豆分离蛋白或谷朊粉能增加玉米淀粉热转变温度。
[ Objective ] Thermal transition properties of protein-starch mixtures, which are not fully understood, are important for the food processing, such as optimizing the thermal treatment parameters, controlling final product quality and even saving the processing energy. [ Method] Soybean protein isolate (SPI), corn starch (CS) and wheat gluten (WG) were selected as raw materials.The mixtures of SPI-CS, SPI- WG, WG-CS, SPI-CS-WG were blended at the range of 0-100%. Their thermal transition properties were determined using differential scanning calorimetry (DSC), with water content of 50% and heating rate of 10℃·min^-1 over 20 to 130℃. [Result] With an increase at the water content from 30 to 70%, onset temperature (To) and peak temperature (Tp) of SPI 11 S subunits decreased from 105℃ to 95℃ and from 114℃ to 99℃, respectively, meanwhile, thermal transition enthalpy (ΔH) of 11 S subunit increased from 2.8 to 6.2 J·g^-1. ΔH of CS increased from 3.6 to 14.1 J·g^-1. No thermal transition was observed in WG at 20 to 130℃. It was probably due to the high moisture increasing the molecular mobility of protein or starch. When the moisture was 50%, compared with 100% ingredient, ΔH of 11 S subunit in SPI-CS mixtures significantly decreased by about 1.41J·g^-1 in average, meanwhile, To and Tp of CS remarkably increased by about 14℃ and 13℃, respectively. Only thermal transition of SPI was observed in SPI-WG mixtures. To and ΔH of 11 S subunit decreased by 2.40J·g^-1 in SP1-WG mixtures compared with those of 100% SPI. Similarly, only thermal transition of CS was observed in CS-WG mixtures. In WG-CS mixtures, Yp of CS dramatically increased by about 12℃ compared with 100% CS. In SPI-CS-WG mixtures, when CS:WG was 1 : 1, To, Tpand AH of 11 S subunit obviously decreased by about 4℃, 5℃ and 1.64J·g^-1, respectively, compared with 100 % SPI. Competition between protein and starch for absorbing water was probably the reason for the increasing of thermal transition temperature of CS, and steric hindrance of WG or CS may be the reason for the decreasing thermal transition enthalpy of 11 S subunit. [ Conclusion ] Addition of wheat gluten or corn starch could decrease thermal transition enthalpy of soybean protein and addition soybean protein isolate or wheat gluten could increase thermal transition temperature of corn starch.
出处
《中国农业科学》
CAS
CSCD
北大核心
2016年第18期3618-3627,共10页
Scientia Agricultura Sinica
基金
农业部"948"项目(2016-X31)
关键词
大豆分离蛋白
玉米淀粉
谷朊粉
差式扫描量热
热转变
soybean protein isolate
corn starch
wheat gluten
differential scanning calorimetry
thermal transition property