Stable Cloudy Passion Fruit Juice Production Using Enzymes And Hydrocolloids

Passion fruit is a small egg-shaped tropical fruit, which is also known by the name of Purple Granadillas. Passion fruit (Passiflora edulis) is produced in most tropical and sub-tropical areas of the world as well as in few temperate zones. Juice extracted from this fruit is of high nutritional value and of great importance to human health. Because of its unique intense flavor and high acidity, passion fruit juice has been described as a natural concentrate. When sweetened and diluted, it provides a high quality palatable beverage and the flavor blends well with other juices. Nowadays juice production becomes a competitive activity, therefore passion fruit juice processors need to improve the quality of the final product to compete at the fruit juice market.The objective of this research was to develop an enzymatic technology for processing cloudy passion fruit juice and apply hydrocolloids to ensure the juice stability. The main results are as follows:Some physico-chemical properties of passion fruit were investigated, the dominant component of fresh passion fruit were carbohydrates. The soluble solids content was 17.5°Brix and pH was 3.06. The results indicated fair vitamins, minerals and essential amino acids in passion fruit pulp.With regard to the processing technology of cloudy passion fruit juice, Response Surface Methodology (RSM) was used to optimize conditions of enzymatic liquefaction of passion fruit pulp. These conditions were Pectinex Ultra SP-L dosage 0.0136% w/w, Amylase AG XXL dosage 0.0024% w/w, temperature 49℃, pH 3.8 and time 25 min. Under the optimum conditions, juice yield extracted from enzyme treated passion fruit pulp was 95.02%, with turbidity 724 NTU and viscosity 1.84 cP corresponding to the increase in yield and turbidity by 23% and 31.63% respectively with 0.56 cP decrease in viscosity compared to the control juice sample. The resulting juice exhibited an improved cloudiness and more stabilized color, with an optimum retention of its components through the manipulation of some influencing factors. The effect of hydrocolloids such as Guar gum (GU), xanthan gum (XA), gellan gum (GE), sodium carboxymethylcellulose (CMC), and the mixture of gellan gum and xanthan gum (GX) on color, viscosity and cloudiness of cloudy passion fruit juice was investigated. The results obtained after 30 days storage of juice samples with different concentrations of hydrocolloids at room temperature revealed that hydrocolloids used slowed down the speed of juice settling, but not every one was able to maintain the stability of colloidal system. Visual observation, color and cloudiness measurements indicated that Xanthan gum 0.10% w/w and the mixture of 0.010% w/w Gellan gum and 0.06 %w/w xanthan gum was able to stabilize cloudy passion fruit juice at satisfactory level.Finally, sensory evaluation showed that cloudy passion fruit juice stabilized by 0.010% w/w Gellan gum mixed with 0.06% w/w Xanthan gum was more acceptable to panelists than the cloudy passion fruit juice stabilized by Xanthan gum 0.10% w/w.