Effects of Different Storage Periods on the Shelf-life Quality of Fresh-cut Vegetable Yam and Iron Stick Yam

In this study, the effects of storage at 4 ℃ for 0, 30 and 60 d on the phenolic content and browning key enzyme activities of fresh-cut yam during shelf life were investigated using 'Changshan fine hair yam' vegetable yam and 'Henan Wenxian' iron stick yam as test materials. The results showed that the browning index of both fresh-cut yams increased with the extension of shelf life, but with the extension of storage period, the browning index of vegetable yam was lower, while the browning index of iron stick yam was higher. At the 8th day of shelf period, the browning index of fresh-cut vegetable yam stored for 30 d was only 4.6% lower than that stored for 60 days, with no significant difference, while the browning index of fresh-cut iron stick yam for the same period was 8.4% lower than that stored for 60 days, and the difference was significant (P<0.05). Increase in respiration rate, ethylene release, lignin content, phenolics, chlorogenic acid, and browning key enzyme activities during the shelf life of fresh-cut iron stick yam as storage period and shelf life increased. However, the respiration rate and lignin content of fresh-cut yam decreased with the prolongation of storage period, the browning key enzyme activity showed a rising and then decreasing trend with the prolongation of storage period, and the phenolic substances increased in the late shelf stage, and other indicators were more consistent with the change pattern of iron stick yam. Further correlation analysis showed that the phenolic substances and enzyme activities in iron stick yam varied more with the storage time and were positively correlated with the browning index, while the browning index of vegetable yam varied with the storage time and was only positively correlated with the enzyme activity. In conclusion, vegetable yam was more suitable for fresh-cut processing, and the shelf-life of fresh-cut products can reach 8 days after 60 days of storage, while the shelf-life of fresh-cut product of iron stick yam was only 4 days after 60 d of storage.