Effect of pasteurization process and storage on color and shelf-life of pomegranate juices

The effects of two heat processes LTP (low-temperature pasteurization: 65 °C, 30 s) and HTP (high-temperature pasteurization: 90 °C, 5 s) on color quality of pasteurized cloudy and clarified or centrifuged pomegranate juices were evaluated during prolonged storage at room temperature (25 °C) and under refrigeration (5 °C). Both heat treatments combined with refrigeration prevented microbial growth for 120 days. Although processing and storage of pomegranate juice had a decisive impact on the degradation of anthocyanin compounds and the consequent formation of brown pigments, storage temperature was the main factor affecting both browning index (BI) and red color loss in pasteurized pomegranate juices. Samples stored at 5 °C had a lower and slower loss of red color than those stored at 25 °C. Results showed that BIs increased rapidly with time in juices stored at 25 °C, being not acceptable (>1.00) after 7 days. The juices stored at 5 °C showed less browning regardless of pasteurization treatment they were subjected. In particular LTP-treated cloudy and clarified juices stored at 5 °C for 90 days exhibited BI values of 0.93 and 0.85, respectively.