Study On The Preparation Process, Digestion And Antioxidant Activity In Vitro Of Composite Nutrition Powder Of Walnut Peptide, Buckwheat And Quinoa

Walnut,buckwheat and quinoa are recognized as green healthy foods.In this paper,high-protein walnut powder was obtained through peeling technology and supercritical CO₂ extraction,walnut peptide was obtained by enzymatic hydrolysis with the walnut powder as raw material.Used non-biological protein nutrition evaluation method,walnut peptide,buckwheat and quinoa were scientifically compounded to obtain the compound nutritional powder rich in walnut peptide and small molecule sugar,which was obtained through gelatinization,liquefaction and saccharification.In addition,the digestion and antioxidant activity in vitro of the composite powder were studied in this paper.This study provided certain theoretical guidance and reference value for the deep processing and development of relevant products.The results are as follows:1.The optimal process of walnut peeled was determined by single factor and orthogonal experiment,the NaOH mass concentration was 8mg/mL,temperature was 100?,time was 2 min,the score of the peeling effect was 96.0 at this time,the quality of walnut was good;The optimal extraction technology of supercritical CO₂ fluid was determined by single factor and orthogonal experiment,extraction pressure was 35 MPa,temperature was 50?,time was 4.5 h,the extraction rate was 96.42%,the walnut oil was nearly extracted completely,the fine walnut powder had a protein content of 84.79%and an oil content of 2.37%.2.Walnut peptide was obtained by enzymatic hydrolysis with the high protein walnut powder as raw material.The preparation process of walnut peptide was optimized on foundation of the method of response surface analysis,which was adopted with the peptide mass concentration and degree of hydrolysis as the response value.The best enzymatic hydrolysis conditions was as follows:pH was 7.10,temperature was50?,enzyme dosage was 8000 U/g,time was 3.0 h.The peptide mass concentration was 10.01 mg/mL and the degree of hydrolysis was 11.45%,which was close to the theoretical value.3.Walnut peptide,buckwheat and quinoa were used as raw materials,which were mixed at different proportions,The optimal formula was 0.7:13:5,which was obtained through the determination of score of ratio coefficient of amino acid?SRCAA?,the SRCAA was 95.15%,which closed to the protein reference model.The optimal gelatinization conditions of the composite powder of buckwheat and quinoa were determined by single factor analysis:the ratio of solid to liquid was 1:9,temperature was 80?and the time was 50 min.The best liquefaction and saccharification conditions of the mixed powder of the buckwheat and quinoa were studied by single factor and orthogonal test with the target of the mass concentration of reducing sugar.The optimal parameters were?-amylase at 7 U/g,60?,50 min and?-amylase at 150U/g,55?,2.5 h,the mass concentration of reducing sugar was 20.03mg/mL under this condition.The walnut peptide powder was obtained by spray drying.Walnut peptide,buckwheat and quinoa powder were scientifically compounded and obtained by spray drying,this compound nutritional powder rich in walnut peptide and small molecule sugar,whichwasobtainedthroughgelatinization,liquefactionand saccharification.4.The digestion and antioxidant activity in vitro of the composite nutrition powder of walnut peptide,buckwheat and quinoa were studied in this paper.The content of peptide,reducing sugar,flavonoid and polyphenol was increased with time in the digestion process simulated in vitro,especially,the content of the rapid digestible starch?RDS?was64.19%,the slow digestible starch?SDS?was 27.12%,the resistant starch?RS?was only 8.70%in the digestion process of the small intestine,which indicated that the starch hydrolysis was much more thorough after gastrointestinal digestion;The antioxidant activity in vitro of the composite powder was proved by experiment:the reducing power(IC₅₀=5.04 mg/mL),the scavenging activity of the DPPH·(IC₅₀=0.67 mg/mL),the scavenging activity of the·OH(IC₅₀=62.32 mg/mL),the scavenging activity of the^O2^-?(IC₅₀=13.07 mg/mL)and the total antioxidant capacity?27.63 U/mL?.A kind of composite powder rich in walnut peptide,buckwheat and quinoa was developed in this paper,which was not only easy to digest and absorb but also had antioxidant activity.