黑豆蛋白和扁豆蛋白对小麦淀粉理化性质的影响

Effects of black bean protein and lentil bean protein on physicochemical properties of wheat starch

为低血糖指数功能食品的开发提供理论依据并改善淀粉类食品品质,将不同添加量的黑豆蛋白和扁豆蛋白与小麦淀粉混合,对其粒径、糊化、老化、冻融稳定性、质构及微观结构的变化进行分析。结果表明:黑豆蛋白和扁豆蛋白的添加均能增大小麦淀粉-蛋白复合物的粒径,结合激光共聚焦结果推测,蛋白质能与小麦淀粉糊化过程中渗出的直链淀粉发生相互作用,覆盖在小麦淀粉的周围或表面使复合物的粒径增大;黑豆蛋白和扁豆蛋白的加入能使淀粉的起始温度(T_(o))和相变终止温度(T_(c))升高,糊化焓降低(除添加10%扁豆蛋白外),使之不易发生糊化;黑豆蛋白能抑制小麦淀粉回生,而扁豆蛋白能促进小麦淀粉回生,黑豆蛋白添加量为20%时,小麦淀粉的老化度从11.87%降至2.59%;2种蛋白质均能改善小麦淀粉的冻融稳定性,黑豆蛋白添加量为40%时,小麦淀粉的析水率从60.24%降至49.13%;2种蛋白质均能使小麦淀粉凝胶的硬度增加,黑豆蛋白对其弹性无显著影响,扁豆蛋白则使小麦淀粉的弹性显著增加。2种蛋白质均能改善淀粉的冻融稳定性,抑制淀粉糊化,且影响程度与蛋白质添加量有关;黑豆蛋白能显著抑制淀粉回生,扁豆蛋白则与之相反。

Although starch is widely used in industry,starch-based food is usually energy-intensive and prone to lack of protein and can rapidly increase blood sugar after meal.Therefore,protein is often used in combination with starch to prepare nutritionally balanced,low GI foods.Therefore,this study screened two plant proteins,black bean protein and lentil protein.Through evaluating their effects on some processing characteristics of wheat starch,proteins suitable for adding into starch-based foods were selected.To explore the effects of black beans protein and lentils protein on the physicochemical properties of wheat starch,different concentrations of black beans and lentils protein were mixed with wheat starch.The parameters,including size,pasting,aging,freeze-thaw stability,quality and structure and the change of microstructure were determined.The results showed that the addition of black bean protein and lentil protein could increase the grain size of wheat starch-protein conjugate,and the D_(10),D_(50) and D_(90) of wheat starchprotein conjugate tended to increase.Combined with confocal laser images,the two proteins were observed to fill the gap or cover the surface of starch particles,indicating that the two proteins could interact with wheat starch.In the study of the thermodynamic properties of wheat starch,the addition of black bean pro tein and lentil bean protein could significantly increase the initial temperature T_(o) and the transition termination temperature T_(c) of starch,and decrease the gelatinization enthalpy,indicating that the addition of two kinds of proteins made wheat starch less gelatinized.Black bean protein could inhibit the regeneration of wheat starch,while lentil egg could promote the regeneration of wheat starch,and the aging degree of wheat starch could be reduced from 11.87%to 2.59%when the addition of black bean protein was 20%.When the addition concentration of lentil protein reached 40%,the retrogradation enthalpy value decreased and the promoting retrogradation effect weakened,indicating that different levels of the same protein had different effects on the retrogradation properties of starch.Both proteins could significantly improve the freeze-thaw stability of wheat starch.When the concentration of black bean protein was 40%,the water extraction rate of wheat starch decreased from 60.24%to 49.13%.The two proteins could increase the hardness of wheat starch gel,black bean protein had no significant effect on its elasticity,while lentil protein significantly increased the elasticity of wheat starch.Adhesion and adhesiveness were also significantly increased with the addition of the two proteins.These results indicated that the two proteins increased the cross-linking of wheat starch molecules and enhanced its network structure.Therefore,both proteins could improve the freeze-thaw stability of starch and inhibit starch gelatinization,and the degree of influence was related to the concentration of protein.Black bean protein could significantly inhibit starch retrogradation,while lentil protein exerted an opposite effect.