Process Optimization Of Production Of Soybean Peptide From Soybean Meal By Enzymatic Hydrolysis

Soybean peptide is a mixture of small molecule oligopeptides fermented or hydrolyzed from soybean protein.As a kind of bioactive peptides,it has been widely concerned and used in the fields of food,feed,medicine and daily chemical,because of its good physicochemical and functional properties.At present,the soybean peptides in the market were mainly made from soybean protein isolate or soybean protein concentrate,which were expensive.Soybean meal,a by-product of grain and oil industry,contains abundant proteins and is an appropriate raw material for the production of soybean peptide.Producing soybean peptide using soybean meal as materials can reduce cost effectively and promote the high-value utilization of soybean meal.In this paper,the soybean peptide was produced from the low temperature soybean meal by enzymatic hydrolysis with a patent protease on the basis of the previous research.It is expected to establish a set of perfect production technology and produce soybean peptide that meets the national standard and expends lower,through optimizing the pretreatment processes,the conditions of enzymatic hydrolysis,and post-treatment processes.The main results were described as following:1.Through optimizing the pretreatment process of raw materials,the optimum technological conditions were determined.The soybean meal was crushed to particle diameter less than or equal to 0.088mm,and washed with washing liquid A at 90 ? for 20 min,twice.After pretreatment,the peptide conversion rate of unit quality protein which was subjected to enzymatic hydrolysis increased by more than 1.6 folds.2.The optimum enzymatic hydrolysis conditions were determined as:temperature was 60 ?,substrate concentration was 10%,the amount of enzyme 3500 U per gram of soybean meal,initial pH 9.0(adjusting the pH to above 8.5 every 3 hours),and the enzyme solution time 8 h.Under these conditions,the conversion rate of the unit quality protein was up to 67.88%and the enzymolysis time was shorter by 20%than before.3.Several downstream technologies were determined by selecting and optimizing the post-treatment process.Solid-liquid separation using a framefilter press,purification with continuous microfiltration or ultrafiltration device,concentration with reverse osmosis membrane,desalination with nanofiltration membrane(Type B),and drying with spray drying tower were performed,in succession.The optimal technological parameters of spray drying were as follows:the inlet temperature 190 ? outlet temperature range from 85 ? to 90 ?,feed concentration 200%of the original solution concentration,under these conditions,the product appeared as white or light yellow powder,and the moisture content is 3.89%,which are in line with the national standard requirements.4.The analysis of product quality showed that the soybean peptide powder contains crude protein 91.12%,peptide 87.69%and ash 4.40%,in accordance with the national standard of soybean peptide powder requirements.