| Walnut is a dried fruit with high nutritional and economic value.Its fat content reaches 60%～70%,so the deep processing products of walnuts are usually walnut oil,but walnut meal,as a byproduct after oil extraction,tends to be used mainly in animal feed or crop fertilizers after a simple processing treatment,and the walnut meal is still rich in nutrients such as protein and vitamins,thereby causing waste of resources.Tofu as a traditional food in China,the main material is soybean,and its variety is less.So combining walnut meal with soybean,both improve the comprehensive utilization of walnut meal and enrich varieties of bean curd.In this thesis,three kinds of walnut tofu were prepared with walnut meal and soybean as raw materials and brine,sour pulp and glucolactone as coagulant.The effects of single factor coagulant addition,walnut meal addition,material water ratio,coagulation time,coagulation temperature and pH of sour pulp on the texture,production rate and sensory of tofu were studied.The processing technology was optimized by response surface test according to the results of single factor test.Finally,the quality of walnut tofu and soybean bean curd,prepared by the best processing technology were compared.The main results are as follows:1.Through the study of processing process of marinated walnut bean curd,the optimal processing technologies of marinated walnut bean curd is as follows:15%addition of walnut meal,1:8 material to water ratio,and 7%addition of coagulant.under the conditions,marinated walnut bean curd has the highest production rate of 205.41%.And the condition got tofu has the unique aroma of walnut,and the taste is fine.2.Through the study of the processing process of acid slurry walnut bean curd,the optimal processing technologies of acid slurry walnut bean curd is as follows:15%addition of walnut meal,24%addition of acid slurry,1:9 material to water ratio,and 3.6 pH of acid slurry.under this condition,acid slurry walnut bean curd had the highest production rate of 232.66%.And the tofu obtained under this condition has a unique aroma of sour pulp.3.Through the study of the processing process of lactonated walnut bean curd,the optimal processing technologies of lactone walnut bean curd is as follows:22%addition of walnut meal,0.3%addition of lactone,1:7 material to water ratio,85℃ coagulation temperature,under this conditions,the taste of lactone walnut tofu is tender and smooth,with an intact shape,and it has the unique aroma of walnut and the highest sensory score,which is 93.32.4.Comparison of the quality of marinated walnut bean curd,acid slurry walnut bean curd,lactone walnut bean curd prepared by the optimal processing technique and commercially available soy bean curd is shown in:(1)Compared with commercially available soy tofu,the protein contents of marinated walnut bean curd and acid slurry walnut bean curd were increased by 2.53%,2.98%,respectively.The protein content of lactone walnut bean curd was reduced by 4.67%;(2)Compared with commercially available soy bean curd,the fat content of marinated walnut bean curd and acid slurry walnut bean curd were reduced by 2.04%,1.88%,respectively.Lactone walnut bean curd had 3.82%higher fat content;(3)The total amino acid contents were as follows:soy bean bean curd(12.72 g/100 g)>acid slurry walnut bean(12.27 g/100 g)>marinated walnut bean curd(12.08 g/100 g)>lactone walnut bean curd(4.36 g/100 g).And the total number of colonies and the number of coliforms in their microbial indicators were within the safe limits. |
