Combined Effect of Mild Heat Treatment by Warm Sodium Hypochlorite Aqueous Solution and Active MAP on Browning of Fresh-Cut Celery

Abstract

The combined effect of mild heat treatment during the decontamination process (HT) and active modified atmosphere packaging (active MAP) during cold storage (MA) on browning of fresh-cut celery was examined in this study. A sodium hypochlorite aqueous solution at 50℃ was used for the decontamination treatment and regarded as the medium for the mild heat treatment. The initial gas composition and concentrations of active MAP were 9.0% O₂, 13.0% CO₂, and 78% N₂. The results for 9 days of storage showed that the aerobic plate count (APC, Log₁₀CFU/g) during storage for the solo-MA and HT+MA combination was under 6 and comparatively lower than that of the control and solo-HT. This result indicated that solo-HT had a lower role in reducing bacterial growth. In contrast, solo-HT, similar to solo-MA and HT+MA combination, moderated the variation of the hue angle (H°), which is an index of the degree of browning fresh-cut celery surface during storage. Additionally, the solo-HT and HT+MA combination prevented phenylalanine ammonia-lyase (PAL) activity and the relative increase in apparent polyphenol content, which is associated with the reduction of browning during storage. These results showed that the HT+MA combination could extend the storage stability of fresh-cut celery.