Development Of Compound Fruit-vegetable Juice Made From Gannan Navel Orange

China is a big country of navel orange production.However,at present,navel orange is mainly consumed fresh,and its deep processing and utilization is inadequate.The reasons for insufficient deep processing and utilization of navel orange is that it will produce obvious"after bitterness"during the processing,which seriously restricts the processing and utilization of navel orange.Based on overcoming the influence of after bitter on acceptability of navel orange juice,mango juice with high sweetness,passion fruit juice with rich variation in aroma,and wax gourd juice with soft flavor and navel orange juice were selected for proper compounding to improve the after bitterness of juice.Taking juice yield,soluble solid(TSS)content,pH value,vitamin C(V_C)content,titratable acid(TA)content,total sugar content and limonin content as indexes,the effects of picking period on the quality of navel orange fresh juice and processed fruit juice were studied,and the optimum harvest time of raw materials of compound fruit-vegetable juice was identified.By comparing sensory scores and physicochemical indexes,the effect of compound fruit-vegetable juice addition on the quality of compound fruit-vegetable juice was analyzed,and the optimal proportion of raw materials of compound fruit-vegetable juice was further optimized.In addition,the key processing parameters of compound fruit-vegetable juice were studied,and the ideal processing technology of compound fruit-vegetable juice was determined.The main results are as follows:1.Analysis of juice characteristics of navel orange at different picking stages.The juice yield,TSS content,pH value,V_C content,TA content,total sugar content and limonin content in fresh juice and processed juice of navel orange collected from November 7,2020 to January 7,2021were analyzed.The results showed that the juice yield,total sugar content,TSS content and V_Ccontent in fresh juice and processed juice of navel orange picked in the middle of December were the highest,while limonin content was at a low level.At this time,navel orange juice had better quality.2.Determination of the proportion of juice raw materials.Single factor analysis was used to study the effects of mango juice,passion fruit juice and wax gourd juice on TSS content,pH value,TA content,total sugar content and sensory score of compound fruit-vegetable juice.The optimal ratio of raw materials of compound fruit-vegetable juice was further optimized by orthogonal test.The results showed that the optimum formula was 5%passion fruit juice,10%mango juice,10%wax gourd juice,and 75%navel orange juice.3.Determination of homogenization parameters of compound fruit-vegetable juice.Different homogenization times(non homogenization,1 time,2 times,3 times,4 times)and homogenization pressure(0MPa,10MPa,20MPa,30MPa,40MPa,50MPa,60MPa)were set as homogenization parameters to determine Sc and viscosity of compound fruit-vegetable juice,and then response surface experiment was carried out according to the single factor results to determine the best combination of process parameters.The results showed that with the increase of homogenization pressure,Sc and viscosity of compound fruit-vegetable juice,first increases and then slightly decreases.When the homogenization times were in the range of 0?4 times,Sc increased first and then decreased with the increase of homogenization times,Sc of compound fruit-vegetable juice was the highest when the homogenization times were 2,The viscosity of compound fruit-vegetable juice increased with the increase of homogenization times.The optimal combination of process parameters is:homogenization pressure 40.4 Mpa,homogenization times2 times.4.Determination of sterilization process parameters of compound fruit-vegetable juice.The compound fruit-vegetable juice was sterilized in water-bath at 65?,75?,85?and 95?for 5 min,10 min and 15 min respectively.The total number of colonies and escherichia Coli,Vc content,TSS content,pH before and after pasteurization was determined.The results showed that the optimal sterilization parameters of compound fruit-vegetable juice were temperature 85?and time 10 min.