Study On Preparation,Separation And Antioxidant Activity Of Almond Peptides

Almonds has been recognized as a good source of bioactive peptides because of rich in protein. In this study, the extraction procedure of almond protein was optimized, and then The double-enzyme hydrolysis assay was applied for almond peptide preparation and the process conditions were researched. the almond peptide was purified and its antioxidant activity of each composition were investigated. the results were shown as follows:1.The extraction of almond protein:four single factors of the pH of protein solution, solid-liquid ratio, extraction time and centrifugal velocity which influenced on almond protein extraction yield were analyzed. The results showed that almond protein extraction rate can reach75.22%in the condition of pH10.0, solid-liquid ratio25, time for60min, the centrifugal speed of4000r/min. The pH influence on almond protein extraction yield is very significant difference (P<0.01), solid-liquid ratio and extraction time on the influence of almond protein extraction rate is significantly (P<0.05), the centrifugal speed influenced on almond protein extraction yield difference is not significant (P>0.05).2. Double enzyme hydrolysis of almond peptides preparation:Compound protease hydrolysis was determined by the single factor experiment. The optimal hydrolysis conditions for almond protein:the substrate concentration was3%,the enzyme ratio is4%, pH value of8.5, hydrolysis temperature is50℃, hydrolysis time was180min, the hydrolysis degree of almond protein can reach20.27%. The optimal hydrolysis conditions of Flavor protease were as follows:the substrate concentration was3%,the enzyme ratio is6%, pH value of6.5, temperature is50℃, time was120min, the hydrolysis degree of almond protein can reach14.54%. The hydrolysis degree of almond protein can reach25.83%in condition of double-enzyme hydrolysis finally.3. Separation of Almond peptide and the molecular weight of the peptide was determinated:four components (API, AP2, AP3, AP4)were obtained and the molecular weight of principal constituents of almond peptide were about679.22KDa,35.19KDa,2985.64Da and414.91Da by the Sephadex G-25gel chromatography.4. The antioxidant experimentation of almond peptide in vitro showed:The effect of AP on DPPH free radical scavenging was obvious with the IC50value of1.43mg/mL.AP3scavenging effect was best with the IC50value of0.67mg/mL. The almond peptide also has scavenging activity against hydroxyl free radicals, the IC50were2.31mg/mL. AP4scavenging effect was best, the IC50value wasl.56mg/mL.The AP also has scavenging activity against uper anion free radicals, its IC50value was2.77mg/mL. the IC50value was1.93mg/mL of AP4. The almond peptide of high concentrations also showed good reducing ability, the reducing ability of AP4was the strongest, the absorbance value is0.562in6mg/mL.The molecular weight of main components of the almond antioxidant activity peptide should be in400～3000Da.