酿造酱油用豆粕微波真空预处理工艺研究

Study on Microwave Vacuum Pretreatment of Soybean Meal for Brewing Soy Sauce

研究利用微波真空预处理豆粕以提高其作为酿造酱油原料的品质。首先预实验确定最适合微波功率2000 W,以膨化度和可溶性蛋白含量为指标,通过单因素实验确定微波真空处理时间、润水量、真空度的选择范围分别为120~180 s、10~20mL和-40^-80kPa,采用响应面分析法优化确定豆粕微波真空预处理的最佳工艺参数为:处理时间155 s、润水量14.8 mL、真空强度-62 kPa。在该条件下豆粕膨化度可达到1.20,可溶性蛋白含量达到17.21%,并检测发现预处理后豆粕的基本成分除脂肪无显著变化外,水分降低而粗蛋白和总碳水化合物升高,另外总氨基酸和谷氨酸等10种主要的氨基酸含量均有不同程度提高,微观组织较处理前疏松,形成明显的孔道结构。使用优化工艺处理的豆粕作为原料并利用曲精进行酱油成曲培养,与高压蒸煮工艺和挤压膨化工艺处理的豆粕进行比较,成曲的总氨基酸和9种主要氨基酸含量均显著提高。另外,使用豆粕做发酵原料的成曲,其中性蛋白酶活力相比于高压蒸煮工艺和挤压膨化工艺分别提高了18.70%和11.94%,酸性蛋白酶活力为35.77%和20.32%。

In this study,microwave vacuum pretreatment of soybean meal was used to improve the quality of soy sauce.Firstly,the optimum microwave power(2000 W) was determined by pre-experiment,and the selection ranges of microwave vacuum treatment time,moisture content and vacuum degree were 120~180 s,10~20 mL and -40^-80 kPa,respectively,by single factor experiment,taking the expansion degree and soluble protein content as indicators,response surface methodology was used to optimize the parameters of microwave vacuum pretreatment of soybean meal.The optimum parameters were as follows:treatment time 155 s,water content 14.8 mL,vacuum strength -62 kPa.Under these conditions,the swelling degree of soybean meal reached 1.20 and the soluble protein content reached 17.21%.It was found that the basic component of pretreated soybean meal had no significant change except fat.The water content decreased while the crude protein and total carbohydrate increased.In addition,the contents of nine main amino acids,such as total amino acid and glutamic acid,increased in varying degrees.The microstructure of pretreated soybean meal was looser than that of untreated soybean meal,forming obvious pore structure.Soybean meal treated by optimized technology was used as raw material and koji essence was used for soy sauce koji culture.Compared with soybean meal treated by high pressure cooking and extrusion,the total amino acid and nine main amino acid contents of koji were significantly increased.In addition,the neutral protease activity of starter fermented with soybean meal in this study was increased by 18.70% and 11.94% respectively,compared with that of high-pressure cooking and extrusion,and the acid protease activity was 35.77% and 20.32% respectively.