The Effect Of High Pressure Processing On Texture And Quality Of Fruits And Vegetables

In recent decades,many researches have been done on the application of high pressure processing(HPP)technology in fruit and vegetable products at home and abroad.Many products have come out,such as vegetables,jams and so on.They are very popular with consumers.At present,the research of HPP fruit and vegetable products are mostly fluid state,but HPP products with fruits or vegetables flesh is few.This paper studies this kind of products.Compared with other HPP solid foods,the structure of fruit and vegetable has the characteristics of less pressure resistance.Therefore,this product contains two parts: fruit or vegetable and liquid medium.In this paper,fruits and vegetables with different properties and structures were selected as the object to study.The effects of different HPP treatment conditions on the texture,color and quality of different types of fruits and vegetables were studied.At the same time,we considered the interaction between fruits or vegetables and liquid medium.We also stusdied the effect of different media on the quality of fruits and vegetables.Moreover,by comparing with heat treatment,the characteristics and advantages of HPP fruit and vegetable solid products are evaluated more comprehensively.The main work and conclusions of this paper are as follows:1.To research the influence of HPP on different varieties of fruits and vegetables,as a measure of density,hardness and other parameters,we chose pears,apples,grapes,litchi,and carrot as samples.After HPP under different conditions,we researched the change of fruit and vegetable structure through texture analysis and SEM analysis.We also studied fruits and vegetables quality stability by color analysis and enzyme activity analysis.The study showed that the structure of different fruits and vegetables will change differently after HPP.Those with greater hardness and density were more affected by HPP.At the same time,long holding time was unfavorable to the quality stability of samples.2.The properties of liquid media could affect the structure and quality of fruits and vegetables.By the analysis of orthogonal test,we found sugar degree,pH and color-protecting reagent was three main factors that influenced the samples.Results indicated that three positive factors influencing comprehensive score showed the following order as: sugar degree,pH and color-protecting reagent.p H could affect the germicidal efficacy and color change during storage.However,low pH is not conducive to maintain the color of samples.Sugar degree had significant effect on samples texture.However,High degree of sugar could also aggravate the sample browning during storage.Adding color-protecting agent could maintain the color stability of products during storage.3.The paper research sterilization of HPP and heat treatment under different conditions.And we selected 4 sterilization conditions which could reduce the number of microorganisms by 6 orders of magnitude.The conditions were 80? 6min,90? 4min,400 MPa 15 min and 500 MPa 9 min.Results showed that heat treatment would greatly affect the color,quality and structure of litchi,and HPP can better maintain the quality of the product.