Comparison between microwave hydrodiffusion and pressing for plum juice extraction

Microwave (MW) hydrodiffusion and gravity, a process initially developed for extraction of phytonutrients, can be adapted for production of an organoleptically pleasant juice, which is compared here with classically extracted juice.Clear and cloudy juices were produced from plums cv. ‘Najbolia’ by enzymatic treatment and pressing. Juice yield were 550 g kg−1 for clear juice, from 670 to 684 g kg−1 for cloudy juice with or without ascorbic acid (AA), and from 344 to 461 g kg−1 for MW juice.MW juice was richest in procyanidins (334 mg kg−1) while the cloudy juice and clear juice with AA were richest in anthocyans (80 and 90 mg kg−1 respectively), and phenolic acids (from 450 to 510 mg kg−1 respectively).The MW process was clearly more rapid and simpler, though yields were lower. This process could be an alternative to produce fruit juice where professionals of juice are confronted to extraction problem.

► We studied two process of juice extraction with plum fruit.
►  A new process using microwave versus classical enzyming and pressing.
►  Technological: microwave was faster and easy to use.
►  Biochemical: compositions of juices were different concerning the polyphenols.
►  Energy requirement: microwave extraction used more energy.