Influence of Different Extraction Techniques on Yield and Quality of Plums Juices.

Two plums cultivars (Red 'Centerose' and Yellow 'Yabany Zahaby’) were used to produce juice. Several treatments were conducted on plums before juice extraction, including freezing, enzymatic hydrolysis (pectinase), microwave, and steaming (hot water vapor). The obtained plums juices were analyzed for physical and chemical properties. The results showed that addition of 250 mg of pectinase/ 100g plums increased the juice yield to 78.24% and 76.67% for the red and yellow plums, respectively. Also, microwave heating for 20 s and steaming for 60 min enhanced the juice yield for both red and yellow plums. Furthermore, pectinase addition to plums before juice extraction improved nutritional and antioxidant properties of obtained plum juice. Besides, ascorbic acid content in obtained red and yellow plums juices after enzymatic treatment recorded 62.49 and 48.94 mg/ 100 ml, respectively. On the other hand, red and yellow juices obtained after steam treatment had significantly higher values of phenolics, flavonoids and antioxidant activity, when compared to all other treatments. The results indicate that combined freezing treatment with pectinase addition facilitate the production of a nutritious clear juice, which promote its usage for food and beverage applications. [ABSTRACT FROM AUTHOR]