Effect Of Nano-microjet Homogenization On The Stability And Storage Quality Of Walnut Meal Protein Beverage

Walnut meal is a by-product in the production process of walnut oil and is rich in nutrients,but in the actual production process it is often treated as waste,resulting in waste of resources.This article used walnut meal as a raw material to make a walnut meal protein beverage,choosing the nano-microjet homogenization to homogenize the beverage and comparing it with ordinary homogenization to explore the effect of different homogenization methods on the stability of walnut meal protein beverage and predicting the shelf life.The main findings are as follows:(1)Determining the processing technology of walnut meal protein beverage and preparing beverage.Using viscosity and centrifugal sedimentation rate as evaluation indicators,single-factor test was performed on the type and amount of stabilizer added in walnut meal protein beverage,and the optimization range of stabilizer added in walnut meal protein beverage was determined as follows: xanthan gum added amount was 0.03-0.05%,CMC-Na added amount was 0.05-0.15%,high ester pectin added amount was 0.05-0.15%.Based on the single-factor test results,the response surface optimization test was performed to obtain the optimal stabilizer formulation added to the walnut meal protein beverage as follows: xanthan gum added 0.04%,CMC-Na added 0.11%,high ester pectin added 0.10%;taking homogenization pressure and homogenization frequency as a single factor,and using the particle size,particle size distribution and instability index as evaluation indicators,the optimal homogenization pressure and homogenization frequency of the walnut meal protein beverage were determined 20 MPa and 2times.(2)Extracting walnut protein from walnut meal and preparing walnut protein emulsion to explore the influence of different homogenization methods on its stability.The homogeneity of the nano-microjets detected by the nano-particle size analyzer made the walnut protein emulsion molecular size smaller and more uniformly distributed;the covalent bonds between the proteins were destroyed,resulting in an increase in the number of negative charges in the emulsion,so the absolute value of the Zeta potential was high;in the walnut protein emulsion homogenized by the nano-microjet,the net charge density of the protein molecules increased and the electrostatic repulsion between the protein molecules increased,the molecular chain becomes more relaxed,and the apparent viscosity of the emulsion increased;the reduction of protein particles made more protein molecules adsorb on the oil-water interface to maintain the stability of the emulsion,which can form a steric hindrance between the water phase and the oil phase,which has better stability;the homogenized walnut protein emulsion of nano-microjet made the protein molecules denature and stretch,and the binding ability with the water solvent was enhanced,the protein molecules were further denatured and aggregated,thus breaking the combination of the protein molecules and the water solvent,making it more difficult to expand,large,thus having higher thermal stability.(3)Comparing and analyzing the stability and shelf life prediction of walnut meal protein beverage by different homogeneous methods during the beverage storage period,the results showed that after 63 days of storage,compared with ordinary homogenized and non-homogenized beverage,the walnut meal protein beverage after the nano-microjet homogenization treatment can better maintain the color of the walnut meal protein beverage.With the extension of storage time,the L value decreased,a and b value increased,the brightness becomes deep dark,red,yellow and darker,the increase in ?E value means that the color difference became larger,and the low temperature storage combined with nano-microjet homogenization treatment can better maintain the color of walnut meal protein beverage;walnut meal protein beverage homogenized by nano-microjet under low temperature conditions have lower difference of stability coefficient,viscosity and centrifugal sedimentation rate than ordinary homogenized and non-homogenized beverage,and the p H and acidity value were more stable.It showed that the nano-microjet homogenization has a good performance in maintaining the emulsion p H and emulsion stability.The nano-microjet homogenization treatment and low temperature storage can extend the shelf life of walnut meal protein beverage.The Arrhenius equation was used to predict the shelf life of walnut meal protein beverage.After the homogenization treatment by nano-microjet homogenization,the shelf life of walnut meal protein beverage was 175 days(25 weeks)at 4?,yhe shelf life predicted value at 25? was 98 days(14week),the predicted shelf life value at 37? was 73 days(10 weeks)and the predicted shelf life value at 55? was 49 days(7 weeks).This study provided an experimental basis for the application of nano-microjet homogenization technology in vegetable protein beverage,and also provided greater possibilities for walnut processing enterprises to process walnut meal.