ABSTRACT
In this study, the quality of minimally processed different Iranian pomegranate genotypes was investigated during storage at 4 °C for 14 days. The results showed that at the end of storage time, the lowest microbial count was found on the arils of "Torsh Syabe Lorestan" genotype. There was a significant difference in titratable acidity, total soluble solids, total anthocyanin, catechin, and quercetin content in most genotypes after 14-day cold storage; while no difference was found between studied genotypes in antioxidant capacity, total phenolic, and flavonoid content. In general, total phenolic content and antioxidant capacity of pomegranate arils gradually decreased over storage time. Diphenolase activity of polyphenol oxidase (PPO) enzyme with dopamine hydrochloride substrate and peroxidase (POD) decreased over storage time, whereas diphenolase activity of PPO with pyrocatechol substrate significantly increased. The lowest diphenolase activity with dopamine hydrochloride and pyrocatechol substrates, as well as POD activity was found in Torsh Syabe Lorestan. The results suggested that the genotype of Torsh Syabe Lorestan, which showed the lowest microbial count on the arils and enzymes, could be more appropriate for minimal processing technology.
ABSTRACT
BACKGROUND: Chitosan edible coating was used in an attempt to extend the storage life of pomegranate arils during 12 days at 4 °C. Prior to storage, treated arils were dipped in 0.25, 0.5 and 1% (w/v) chitosan aqueous solutions and 1% (v/v) acetic acid for 1 min, while control arils were dipped in distilled water with 1% (v/v) acetic acid. RESULTS: Chitosan coating inhibited bacterial and fungal growth on the surface of arils. The water content of arils coated with 0.5 and 1% chitosan was maintained during 12 days of storage. Chitosan reduced the increase in total soluble solids (TSS) and titratable acidity (TA) of arils during storage. The lowest TSS and TA were detected in arils coated with 0.5 and 1% chitosan, which maintained the highest TSS/TA ratio after 12 days of storage. In contrast, application of chitosan delayed the decrease in total phenolics, total anthocyanins and antioxidant capacity during storage. The results also showed that chitosan coating suppressed the monophenolase activity of polyphenol oxidase (PPO) with pyrogallol substrate and the diphenolase activity of PPO with dopamine hydrochloride substrate, but the diphenolase activity of PPO with pyrocatechol substrate increased during storage. CONCLUSION: The results suggest that chitosan coating has the potential to extend the storage life of pomegranate arils by reducing the microbial population on their surface.
