Key Technology Research In Integrated Processing Of Passion Fruit

Passion fruit pulp has rich aroma and nutrient concentrations,which is widely used in the world’s high-end dining and beverage industries in the form of frozen pulp. To meet the microbiological requirements and try to keep the original nutritional quality of passion fruit pulp, sterilization has became the key technology of frozen fruit pulp. Passion fruit peel is accounted for about 60% of the whole fruit,which wastes a lot of resources and increases costs.Currently,it is the main method of utilizing the passion furit peel by using boiling method to isolate the cuticle layer and a sponge layer. The sponge layer processes into preserved fruit.To reduce preserved fruit browning,polyphenols of sponge layer should be as low as possible. So it is important to optimize boiling to make polyphenols lowest.But the technology system generated a lot of wastewater (peel water),which has not been applied effectively.This study aimed to analyze the reference value of the passion fruit peel water and the availability in fruit juice processing,which provide theoretical basis for using peel water.The main findings were as follows:1.Comparaing the quality difference between the three passion fruit (purple fruit from Nanning,purple fruit from Liuzhou,Tainung No.1),the results showed purple passion fruit pulp from Nanning was accounted for the highest proportion of whole fruit.Vc and carotenoid content also were highest,so its research value was the higher.Passion fruit pulp from Nanning was treated under three pasteurization conditions(80,95℃ and 110℃).Results indicated that different heat treatment can all reduce passion fruit pulp total acid,increase solid acid ratio,deepen color,weaken aroma and active ingredients.All showed different levels of negative impact.However,the quality loss of passion fruit pulp after 110℃ 75s can be reduced to minimum,which keeps the original quality characteristics of passion fruit pulp.2.Using boiling method, when the conditions were higer than water ratio of 1:5 and 90℃ for 10min, it can be easily to artificial peeling off the cuticle layer and the sponge layer.For example,comparing with non-boiled peel,when water ratio is 1:7 and temperature is 95℃ for 15min, the efficiency of artificial going cuticle increased from 98.21Kg/h·person to 590.28Kg/h·person, then sponge layer yield increased from 68.99% to 90.87%,the shear force of sponge layer dropped from 18.79Kg to 4.45Kg.The results showed that optimal conditions were cooking peel at 100℃ for 19min and water ratio of 1:9.The maximum extraction rate of total soluble solids of peel was 5.55%,the extraction rate of polyphenols was 7.27mg/g,the shear force of sponge layer was 3.10Kg.3. Passion fruit peel water contains sugars, organic acids, pectin and soluble substances.Its polyphenols,tannins and flavonoid were 10.23mg/L,108.74mg/g, 2.59mg/g,10.28mg/g,respectively.Hydroxy clearance,ECso values and ORAC values were 0.32mgVc/mg,0.105mg/mL,6.03μmolTrolox/mg,respectively.The results showed that the peel water has rich nutrients and active ingredient, which has antioxidant activity.When the mass ratio of peel water and pulp was 1:9,2:8,3:7 and 4:6, the EC50 values of mixed passion fruit juice drinks was significantly lower than theoretical value. It showed that both complex has antioxidant synergy.Through comparing Vc and polyphenols of samples before and after heat sterilization,experimental results showed that the anti-oxidation synergistic effect of peel water and pulp can protect Vc and polyphenols,which reduced heat loss.In this study, complex passion fruit juice (the mass ratio of peel water and pulp= 4:6)can save more active ingredients and antioxidant ability than passion fruit juice drinks(the mass ratio of water and pulp=4:6).