Hydrolysis Process Optimization And Characteristics Study Of Low-bitter Almond Protein Ptptides

Almond meal is the residue of almond oil extraction,which contains a large amount of protein.The protein extracted from it will be used in food processing.At present,enterprises treat almond meal and make it into animal feed or almond protein powder,which leads to the reduction of the added value of almond meal and the low comprehensive utilization rate,resulting in the waste of resources.If we can make good use of it,it will greatly enhance the added value of almond meal.Almond protein peptide is the product of enzymatic hydrolysis of almond,which has the functions of lowering blood pressure,reducing blood lipid,and resisting oxidation.Studies have proved that small molecular peptides prepared under high degree of hydrolysis have stronger activity than large molecular peptides,but high degree of hydrolysis also causes bitter taste,which affects the taste of almond protein peptide.In order to increase the added value of almond meal,prepare more small molecular peptides and reduce the bitter taste of almond protein peptide,this experiment takes almond protein as the research object,and the main results are as follows:1.The almond protein was hydrolyzed by alkaline protease,and the hydrolysis conditions were optimized by orthogonal experiment with the degree of hydrolysis as the index.The optimum hydrolysis conditions were obtained as follows: the substrate concentration was 4.5%,the ratio of enzyme to substrate was 6000U/g,the temperature was 53℃,the p H value was 9,and the bitterness value was 9 after sensory evaluation.The almond protein hydrolysate with high degree of hydrolysis(31.09%)and high bitterness(9)was obtained.2 Taking the hydrolysate of alkaline protease as the next research object,in the first experimental group,alkaline protease and acid protease were used for step-by-step enzymolysis.Taking the degree of hydrolysis and bitter value as the indexes,the technological conditions of acid protease were optimized by orthogonal experiment,and the optimal technological conditions were obtained: the ratio of enzyme to substrate was 1700U/g,the time was 120 min,the p H was 5,and the temperature was 43℃.At this time,the degree of hydrolysis was 39.14%,and the bitter score was 3.8.In the second group,alkaline protease+aminopeptidase was used for step-by-step enzymolysis.Taking the degree of hydrolysis and bitter value as the indexes,the optimum technological conditions of aminopeptidase were obtained by orthogonal experiment: the ratio of enzyme to base was 2300U/g,the time was 120 min,the p H was 8,and the temperature was 55℃.At this time,the degree of hydrolysis was 37.48%,and the bitter score was 4.4.3 Experimental group 1 was hydrolyzed by alkaline protease+acidic protease+aminopeptidase,while experimental group 2 was hydrolyzed by alkaline protease+aminopeptidase+acidic protease.The effects of different adding order of two exonuclease on the degree of hydrolysis and bitter value were studied.It was found that the degree of hydrolysis of almond protein peptide prepared by experimental group 2 was 43.76% higher and the bitter value was 2.08 points lower than that of single enzyme hydrolysis and double enzyme hydrolysis.4 By comparing the low bitter almond protein peptide prepared in Chapter 2(degree of hydrolysis 43.76%,bitter value 2.08)with the high bitter almond protein peptide provided by the enterprise in four indexes: polypeptide amino acid composition,polypeptide molecular weight,amino acid sequence,the type and number of hydrophobic and basic amino acid residues at N and C terminals,it is found that there are certain differences between high and low bitter almond protein peptides in four indexes,and it is concluded that the four indexes have important influence on the bitter taste of almond protein peptide.5 By studying the functional characteristics of the low bitter almond protein peptide(degree of hydrolysis 43.76%,bitter value 2.08)prepared in Chapter 2 and the almond protein before enzymolysis,it was found that the low bitter almond protein peptide had better functional characteristics than almond protein,which provided a theoretical basis for its processing and utilization in the future.Through the antioxidant research of the two peptides,it was found that the low bitter almond protein peptide had certain antioxidant activity,which was better than almond protein,and it could be developed into antioxidant products to improve it.