Changes in quality attributes during production steps and frozen-storage of pomegranate juice concentrate

Abstract

In this study, changes in critical quality attributes of pomegranate juice that was evaluated in juice processing line for obtaining clarified pomegranate juice concentrate were investigated. To achieve that juice samples collected from each production steps throughout juice processing line were analyzed. Moreover, the obtained pomegranate juice concentrate was kept at frozen conditions and monitored quality changings (color and anthocyanin compounds) for six months. The turbidity of the samples showed a significant decrease especially after filtration processes. The color parameters decreased remarkably after ultra-filtration. In pomegranate juice, six anthocyanin compounds were detected and the most abundant one was cyanidin-3,5-diglucoside (117 mg/L). The decrease of TMAC in pomegranate juice was 27.8 % at the end of processing line, compared to fresh juice. Moreover, as colorless phenolics, fourteen compounds were identified and the most abundant one was ellagic acid (122 mg/L) and followed by gallic acid (108 mg/L) in fresh juice. Ellagic acid and gallic acid were respectively decreased by 25.7 % and 41.0 % at the end of processing line. The predominant organic acid and mineral were citric acid (17.4-25.5 g/L) and K (2648 - 3005 mg/L) in all production stages, respectively. The results showed that the main phenolic compounds in pomegranate juice affected dramatically during processing stages, especially after clarification and filtration processes. However, high stability for anthocyanin compounds was determined during frozen storage of the juice concentrate.