Maillard-flavor-enhancing Peptide Producets Preparation Using The Enzymatic Soybean Meal

Soybean meal was used as the raw material in this study,and the optimum enzymatic conditions of soybean meal and the conditions of Maillard reaction were determined.In addition,the effect of peptide molecular weight?MW?on the flavor of Maillarad reaction productions?MRPs?,and in vivo effect of MRPs were investigated.Then,a kind of seasoning salt with health benefits was developed.1.The optimum enzymatic conditions determined using the degree of hydrolysis?DH?and sensory scores as indicators.The soybean meal solution was hydrolyzed by Alkaline protease?5000 U/g?at 50?for 3 hours with initial pH of10 at the protein ratio of 6%.Then,pH was adjusted to 6.5,and the soybean meal solution was mixed with a complicated enzyme including of Papain?5500 U/g?,Neutral Protease?5500 U/g?and Flavourzyme?800 U/g?for a 4-hour reaction at 55?.Finally,the DH of substrate protein was 35.57%,and the 1-3 kDa peptides were the main ingredient in the hydrolyzed product,which accounted for 30.35%.2.The optimum conditions for the Maillard reaction were determined using the sensory scores and pH changes as indicators.The mixture solution of peptide,L-cysteine and xylose?5:1:2,w/w,initial pH was 7.4?was heated at 120? for 120 minutes at the protien concentraon of 20%.3.The effects of molecular weight of peptide on Maillard reaction were analyzed.Four peptide fractions?PFs?were isolated from soybean hydrolysate by ultrafiltration method,and they were PF1?>5 kDa?,PF2?3-5 kDa?,PF3?1-3 kDa?and PF4?<1 kDa?.Then,unfiltered hydrolyzed peptide?PH?and PFs were reacted with D-xylose and L-cysteine at 120? for 2 h,respectively.The molecular weight distribution?MWD?,pH,colour,browning intensity,DPPH radical-scavenging activity,free amino acids of corresponding MRPs?MRPF1,MRPF2,MRPF3,MRPF4 and MRPH?were evaluated,and sensory characteristics of MRPs were analyzed by electronic nose and electronic tongue.The results showed that smaller peptides showed higher contribution to the changes of pH,colour and browning intensity by Maillard reaction,and MRPF4 showed highest DPPH radical-scavenging activity in all MRPs.After Maillard reaction,the content of bitter amino acids in the reaction system decreased significantly,while the content of umami amino acids significantly increased,and MRPF4 had both the highest content of umami amino acids and bitter amino acids.Electron nose and electronic tongue results showed that MRPF3 has better sensory characteristics with strongest meat taste but lowest bitter taste.4.In vivo effects of MRPF3 were studied in this section.The model of aging mice was established by subcutaneous injection of D-galactose(1000 mg.kg^-1/day).The mice were treated with MRPF3 at 800,400 and 200 mg.kg^-1/day as high,medium and low dose groups,respectively.Vc and fructooligosaccharides(400mg.kg^-1/day)were given to the other two groups as positive controls.The results showed that after feeding with MRPF3,the measured indexes of food intake,body weights and organ index of the mice returned to normal,and the content of MDA in the liver was significantly decreased,as well as the activities of SOD and GSH-Px were significantly increased,besides,the total antioxidant capacity of serum was also significantly improved.In addition,the abundance ratio of Fibrobacteria and Bacteroidetes was reduced significantly in MRPF3 groups,and the abundance of Lactobacillus were significantly increased,while the potentially pathogenic bacteria such as Porphyromonadaceae were significantly decreased.5.A kind of seasoning salt was developed with the addaiton of MRPF3.The formula of seasoning salt was preliminarily determined by single factor experiment and orthogonal test using the sensory scores and DPPH radical scavenging rate as indexes,and the thermal stability of the seasoning salt were also studied.The best formula of the seasoning salt was determined as followed,sodium chloride 6.0 g,potassium chloride 3.0 g,sodium glutamate 0.4 g,yeast 0.2 g,inosinic acid 0.02 g,guanylate 0.02 g,MRPF3 0.3 g,anthocyanin 0.075 g,Vc 0.075 g,garlic powder0.125 g,pepper powder 0.06 g,ginger powder 0.10 g.The stability results showed that the seasoning salt had good thermal stability,and the DPPH radical scavenging activity was still higher?80.1%?even after a 30-min heating treatmeng at 100?at the conencentaron of seasoning salt of 20 mg/mL.