Preparation Of Sweet Almond Peptide And Its Meal Replacement Powder

Xinjiang is rich in almond resources.Most of the almonds are used to extract oil,which will produce a large number of by-products(almond meal),and almost all of the meal is used as cheap animal feed.The protein content of cold pressed sweet almond meal is about 50%.The protein denaturation degree is small.But the comprehensive utilization rate is very low.In this paper,sweet almond protein,sweet almond peptide and its meal replacement powder are prepared successively by five methods of protein extraction,double-enzyme method and mixing experiment.The main results are as follows:(1)The rate of sweet almond protein extraction by ultrasonic-enzyme method is the highest.The solubility,foam stability and emulsifying property of the protein prepared by enzymatic method are the best.The protein prepared by alkali-enzyme two-step method has the best water holding capacity and foaming property.The protein prepared by ultrasonic-alkali method has the best oil holding property.The protein prepared by alkali dissolution and acid precipitation method has the best emulsion stability.The protein powder prepared by ultrasonic-enzyme method has the smallest aggregation degree,while the alkali dissolution and acid precipitation method is the largest aggregation degree.(2)The degree of hydrolysis of sweet almond protein is negatively correlated with the initial protein concentration and positively correlated with the initial Alcalase concentration.The constant K2 of enzymatic reaction rate is 27.035 min-1,and the rate of hydrolysis kinetic model of sweet almond protein is:R=(27.035 E0+0.4988 s0)exp[-0.1733(DH)].The kinetic model of degree of hydrolysis and time of hydrolysis is:DH=5.77 ln[1+(4.69 E0/S0+0.086)t],and the constant K4 of enzyme inactivation is 2.992 min-1.(3)The optimal hydrolysis condition of sweet almond protein is:the first step,the substrate concentration of sweet almond protein solution is 3%,pH value is 8.0,temperature is 50?,Alcalase addition is 3000 U/g,and the time is 1 h;the second step,the pH is 7.10,the temperature is 55?,Flavourzyme addition is 4900 U/g,and the time is 2.75 h.The actual almond TCA-NSI under this condition is 68.87%,which is consistent with the model prediction.(4)The optimal formulation of meal replacement powder of sweet almond peptide is:almond peptide 3.74%,stevioside 0.05%,SiO2 1.50%,soy protein isolate powder 37.56%,roasted chickpea powder 49.18%,konjac flour 3.03%and the trehalose 4.94%.The actual sensory score of optimal formulation is 96.12,which is consistent with the model prediction.Through the above experiments,sweet almond protein,peptide and its meal replacement powder are prepared in sequence.The meal replacement powder is a product with high protein content,low fat content,moderate dietary fiber content and enough energy.This paper provides a theoretical basis and support for the effective utilization of byproducts of cold pressed sweet almond and intensive processing of sweet almond protein.