冷榨豆粉凝胶特性及其在千页豆腐制作中的应用

Properties of cold-pressing soybean meal gel and its application in the production of Chiba tofu

目的研究不同加热温度(90、95、100℃)、不同加热时间(20、30、40、50、60 min)对冷榨豆粉凝胶特性的影响及其在千页豆腐中的应用。方法以凝胶强度和持水性为指标探究冷榨豆粉凝胶特性;以黏度、储能模量和损耗模量为指标探究冷榨豆粉凝胶在热处理过程中流变学特性变化。采用单因素实验和响应面优化实验对冷榨豆粉基千页豆腐加工工艺进行优化,探讨不同冷冻条件对其品质影响。结果热处理使冷榨豆粉分散液形成弹性凝胶(储能模量大于损耗模量)。冷榨豆粉凝胶黏性、储能模量、损耗模量、随着加热温度的升高及加热时间的延长而增加,凝胶强度和持水性同样随之增加,且分别在100℃加热90 min处达到最大[(130.57±0.02)g、0.99 g/g]。经优化得出冷榨豆粉基千页豆腐最佳工艺条件为:冷榨豆粉添加量100.00 g、冰水添加量575.00%、谷氨酰胺转氨酶(transglutamianse,TG)添加量1.64%、大豆分离蛋白(soy protein isolate,SPI)添加量46.00%。优化后的冷榨豆粉基千页豆腐的硬度为2271.24 g,弹性为0.95。在‒18和‒45℃两种冷冻温度下,千页豆腐中结合水(T2b)含量整体随着冷冻时间的延长而减小,弛豫时间缩短,凝胶网络中的水受到限制。不易流动水(T21)弛豫时间随着冷冻时间的增加先增加后减小,且分别在冷冻7和3 d处达到最大。结论热处理会对冷榨豆粉凝胶特性产生积极的影响。冷冻会使冷榨豆粉基千页豆腐内部结构中的更多结合水向自由水转移,使冷榨豆粉基千页豆腐结构疏松,孔径变大。

Objective To study the effects of different heating temperatures(90,95,100℃)and different heating times(20,30,40,50,60 min)on the properties of cold-pressing soybean meal gel and its application in Chiba tofu.Methods The strength and water holding capacity of gel were used as indexes to investigate the properties of cold-pressing soybean meal gel;the rheological properties of cold-pressing soybean meal gel during heating treatments were investigated with viscosity,storage modulus and loss modulus as indexes.Single factor experiment and response surface optimization were used to optimize the processing technology of Chiba tofu based on cold-pressing soybean meal and explore the effects of different freezing conditions on its qualities.Results The cold-pressing soybean meal solution could form elastic gel(storage modulus was greater than loss modulus)by heating treatment.The viscosity,storage modulus and loss modulus of cold-pressing soybean meal gel increased with increase of heating temperatures and times.The strength and water holding capacity of gel also increased and reached the maximum[(130.57±0.02)g,0.99 g/g]at 100℃for 90 min,respectively.The optimal conditions of Chiba tofu based on cold-pressing soybean meal were following:Cold-pressing soybean meal addition of 100.00 g,ice water addition of 575.00%,transglutamianse(TG)addition of 1.64%,and soy protein isolate(SPI)addition of 46.00%.The hardness and elasticity of optimized Chiba tofu based on cold-pressing soybean meal were 2271.24 g and 0.95,respectively.The overall content of bound water(T2b)in Chiba tofu and relaxation time decreased with the extension of freezing time and water in gel network was restricted at‒18 and‒45℃.The relaxation time of non-flowing water(T21)increased first and then decreased with the increase of freezing time and reached the maximum at 7 and 3 d,respectively.Conclusion Heat treatment has a positive effect on the properties of cold-pressing soybean meal gel.Freezing can transfer more bound water in the internal structure of Chiba tofu based on cold-pressing soybean meal to free water,so that its structure becomes loose and pore size becomes larger.