Effects of the extraction technology on pomegranate juice quality

Abstract

Pomegranate juice is a rich source of phenolic components; its consumption has considerably increased throughout the world in recent years, due to its nutraceutical properties. Commercial juice production involves pressing the fruits. The aim of this study was to assess the influence of the pressing stage on pomegranate juice properties, in terms of value, duration of the applied pressure and juice yield in order to examine the influence of pressure level on volatiles and nutraceutical properties of the juice. Pomegranate fruits cv. Wonderful One were manually harvested and mechanically processed for extracting the juice by means of a shelling machine, a peristaltic pump and a pneumatic press. Chemical analytical determinations were performed on the juice samples corresponding to the dierent pressure levels applied. They did not show a univocal trend with respect to the increase in pressure; total phenol content values gradually increased as the pressure applied increased, conversely the highest total anthocyanins value was obtained in the first step of the process (552 mg L-1), afterwards a 40% decrease occurred. More than forty Volatile Organic Compounds were identified in the obtained pomegranate juices. The results showed a significant increase in the values in some compounds, particularly for pressure values higher than 0.7 bar, while in others there was a significant decrease as pressure increases. Therefore, the application of different pressure values during pomegranate juice extraction process allowed to obtain products of different quality.