Electrostatic effect on freshness preservation and quality evaluation of yam (Dioscorea alata) tuber during cold storage

Abstract

This study investigated the changes in the quality-related parameters and physicochemical properties of yam (Dioscorea alata L. var. Dasan) harvested after 260 d. The stem tip, middle, and bottom sections of yams were stored at room temperature (20 °C ± 2 °C) for 16 weeks. Samples were taken every 2 weeks and analyzed to determine the changes in physicochemical properties during storage. α-Amylase and PPO activities were highest in the stem tip section. A positive correlation between enzyme activities and storage time was observed in all groups. polyphenol oxidase (PPO) peaked during week 10 of storage and gradually decreased. No significant correlation was found between α-amylase activity and starch content. Moreover, similar to free sugar content, α-amylase activity reached its maximum value during week 14 of storage. All sections of the yams showed reductions in cooking loss rates with the prolongation of storage and reached their minimum cooking loss during week 10 of storage. During the storage, the middle sections of the yams exhibited the most consistent quality, presenting minimal changes in hardness and color stability and the lowest rate of cooking loss. The quality of yam tubers, particularly in enzymatic browning after slicing, post-cooking hardness, cooking loss, and free sugar content, was affected by fluctuations in α-amylase and PPO activities during storage. Therefore, these factors should be considered when evaluating quality and determining optimal storage and handling procedures. The results of this study may serve as a reference for determining the quality of yams during postharvest storage and are important for companies and researchers seeking to optimize yam storage for maximum yield and profitability.

Keywords

• α-amylase
• Enzymatic browning
• Polyphenol oxidase (PPO)
• Shelf-life
• Yam