Clarification of Pomegranate Juice at Industrial Scale

Manuel Valero

doi:10.4172/2157-7110.1000324

Abstract

The effects of conventional and membrane clarification processes on some physicochemical properties of pomegranate juice such as color, turbidity, Total Soluble Solids (TSS), Total Phenolic Content (TPC), antioxidant activity and bioactive compounds (anthocyanins, ellagitannins and ellagid acid) were evaluated. Changes in color parameters such as absorbance at 520 nm (A520, red color), Total Color Density (TCD) and Browning Index (BI), as well as TPC were negatively influenced by bentonite or albumin concentration in batch processes. However, both microfiltration (MF) and ultrafiltration (UF) processes at the applied conditions did not cause any significant differences on the levels of A520, BI, TPC, and other parameters determined as part of the evaluation study. Moreover, the permeate flux in MF were higher than in UF, which is preferable for commercial application of tangential filtration technology in pomegranate juice industry. MF-clarified juice had physicochemical and nutritional properties similar to those of fresh juice.

Highlights

Pomegranate juice in its original state has a turbid appearance that makes it hard to preserve
For albumin a concentration of 0.25 g/L resulted in a decrease in turbidity which did not vary at concentrations equal or higher
According to Vardin and Fenercioglu [31], the natural clarification of pomegranate juice resulted in a decrease in turbidity of 67.7% at 16 h and 85% at 96 h, 2.5 g/L of gelatin produced a reduction of 80.2% at 16 h

Summary

Introduction

Pomegranate juice in its original state has a turbid appearance that makes it hard to preserve. The main purpose of the clarification is to reduce the turbidity, decrease the astringency of the product [1] and maintain the red color of pomegranate juice. Pomegranate fruit contains considerable amounts of sugars, organic acids, amino acids and phenolic compounds such as gallic acid, protocatechuic acid, chlorogenic acid, caffeic acid, ferulic acid, oand p-coumaric acids, catechin and quercetin [2,3] as well as enzymes, proteins, pectins and insoluble complexes as colloids (polysaccharides). The phenolic constituents give color, astringency and bitterness to the pomegranates juice [4,5]. These compounds with colloids and proteins are responsible for the formation of the cloudy appearance of fruit juices during concentration and storage [6,7,8]. The operational costs of using membrane processes are considerably lower than those of more traditional processes [16,17,18]

Methods

Results

Conclusion