Efft Of High Hydrostatic Pressure On Formulaand Rheology Of Jujube Compoud Pulp

Jujube is a delicious fruit which has rich nutrients and it is a unique product in China.However,the skin of jujube is thin,and jujube is easy to spoil in room temperature.As a kind of deep-processing product of jujube fruit,jujube compound pulp has a optimistic development prospect because of the advantage of unique flavor,healthy function and portable storage.Ultra-high pressure technology is able to kill microorganisms effectively and maintain the original nutrition and flavor of the food.In this paper,the quality character of four varieties of jujube were studied firstly.Secondly,the formula of jujube compound pulp was obtained by D-optimal mixing design method.On this basis,the sterilization and enzyme inhibition effect of ultra-high pressure and ultra-high pressure collaborative technology was studied,after that the storage quality of treated jujube compound pulp was researched.Finally,the rheological properties of jujube compound pulp were analyzed and the quality evaluation system was obtained.The result are as follows:?1?The quality indexes such as colour,nutritional component and antioxidant properties of four jujubes were compared.The results showed that there was great differences in color.Four varieties of jujube's total sugar was in range of 11.25%²4.44%,total acid was in range of 0.21%⁰.31%,Vc content was in range of 192mg/100g³26mg/100g,total phenol was in range of358.3mg/100g⁴93.8mg/100g,flavone was in range of 307.92⁴00.35mg/100g.Lingwu jujube had the highest total sugar content.The Vc content,total phenol of Dali jujube was highest.The flavone of Jingyang jujube was highest.Jujube pulp was made from four varieties of jujube,the Lingwu and Dali jujube had good suspension stability,the Vc retention rate of Dali jujube was highest.The Vc of Dali thermal degradation showed that this reaction of jujube pulp conformed to the first-order kinetic equation,the sequence of activation energy was:N₂>avoid light>CK.?2?The effect of the amount of sweet potato,hawthorn and ginger on the sensory characteristics,sugar acid ratio,suspension stability,antioxidant activity and viscosity of jujube pulp were studied.Making use of D-optimization design to devise and optimize the formula of jujube compound pulp and choose sensory score as the only response value.The results showed that the parameters of addition were hawthorn 40%⁵0%,ginger 10%²0%,sweet potato 10%²0%,which can obtain jujube pulp with the optimum sensory quality.The parameters of addition were hawthorn 50%,ginger 20%,sweet potato 30%,which can obtain jujube pulp with the best suspension stability.The parameters of addition were hawthorn 30⁴0%,ginger 10²0%,sweet potato less than 10%,which can improve the antioxidant activities of jujube pulp.The optimum combinations of jujube,hawthorn,ginger and sweet potato were54.54%,27.68%,8.63%and9.15%,respectively.?3?The inlulence of UHP and UHP collaborative treatment on the quality of jujube compound pulp was researched.The results indicated that the bactericidal effect became well,the suppression of enzyme activity was more obvious,the Vc content declined but total phenol content increased,the reducing capacity and DPPH radical scavenging activity raised all along with the increasing of pressure.The total number of colonies was 58.9cfu/mL,the enzyme activity residual rates of POD and PPO were 69.6%and 80.3%on the condition of 25?,15min and400MPa.Ultra-high pressure collaborative treatment can effectively maintain the storage quality of jujube compound pulp.The Ultrasonic-UHP treatment had the best bactericidal effect and suspension stability,the color difference was the smallest as well.When refrigerated for 4 weeks,the sequence of Vc content and total phenol content was:blanching-UHP>ultrasonic-UHP>UHP.?4?The rheological properties of jujube compound pulp which were treated by ultra-high pressure and ultra high pressure co-processing was studied.The result showed that the fluid pattern of jujube compound pulp was in accordance with Herschel-Bulkley model,ultra-high pressure and ultra high pressure co-processing did not change the pattern of fluid but reduced hysteresis loop area,blanching-UHP treatment had the smallest hysteresis loop area.The flow exponent decreased with the increasing of the pressure,the consistency coefficient increased with the increasing of the pressure.The elastic modulus?G'?of all experimental groups were bigger than that of viscous modulus?G''?,which showed that the jujube compound pulp had gel property.Comprehensive equation for the effect of temperature and concentration on viscosity was:?=0.00138e^-0.0932exp(8515.507e^0.02136/RT).?5?Five core quality indexes of jujube compound pulp were selected from fifteen indexes such as sensory quality,physicochemical property and antioxidant activity by means of mathematical analysis?principal component and cluster analysis?.The core indexes of jujube compound pulp were reducing sugar,the value of“L”,reducing power,stable coefficient and Vc content.The mathematical model of jujube compound pulp was established based upon the AHPmodel,whichwasY=0.0580×reducingsugar+0.3978×L^*value+0.0959×reducingpower+0.1761×stablecoefficient+0.2721×Vccontent.Verifying the results between D-optimal test and mathematical model.The fitted equationofD-optimaltestandmathematicalmodelwas Y=0.91787X+1.8905E-6?R²=0.83036?,which means that this mathematical model is able to applied in the quality evaluation of jujube compound pulp.