Effect of different storage temperatures on the physicochemical, phenoliccontent and microbiological qualities of the reconstituted pomegranate juiceafter thermal and aseptic processing

This study investigated the effects of ambient (25±2°C) and chilled (4±1°C) storage on the quality of reconstituted pomegranate juice (RPJ) after thermal pasteurization at 95℃ for 30 s and aseptic bottling. The quality parameters analyzed included pH, total soluble solids (TSS), colour, total phenolic contents (TPC), and microbiological inactivation. The analysis was conducted at intervals of 7 days over a period of 49 storage days. Results showed that while both storage temperatures resulted in satisfactory microbial inactivation, the ambient sample exhibited greater fluctuations in pH (ranging from 2.90 to 3.07) compared to the chilled sample (stable range of 3.04 to 3.12). The colour difference was more evident and occurred faster in the ambient, due to the significant changes in CIE L and CIE b caused by browning, which was accelerated at warmer temperatures. The ambient sample also exhibited a greater TSS variation (23.5 to 26.9) compared to the chilled sample (23.9 to 26.5), suggesting ongoing chemical reactions affecting the sugar content. While TPC values remained stable at 4°C throughout storage (no significant difference, p=0.082), the ambient sample showed significant changes in TPC (p=0.00). Interestingly, TPC levels remained high (>2000 mg GAE/L) for both ambient (2207.06 to 3909.89 mg GAE/L) and chilled samples (2491.81 to 3148.59 mg GAE/L) throughout the storage period. In conclusion, the study recommended chilled storage to maintain juice quality and the functional properties souring from phenolic contents. However, if ambient storage is chosen, implementing a faster time-to-consumer strategy is crucial to minimize quality degradation and ensure market acceptability.