Influence of cultivation and storage conditions on the quality of the new breed yam 'Kitanebari'
2018
Nakazawa, Y. (Tokyo University of Agriculture, Abashiri, Hokkaido (Japan). Faculty of Bioindustry, Department of Food and Cosmetic Science) | Hirai, G. | Taberi, K. | Yamazaki, M. | Sato, H.
We performed a detailed examination of how the quality of 'Kitanebari' vanes depending on cultivation and storage conditions. The moisture content and viscosity were significantly lower and higher, respectively, in 'Kitanebari' than in Nagaimo. The differences in nitrogen levels in the fertilizer did not affect its moisture content and viscosity. As the nitrogen levels in the fertilizer increased, the polyphenol (PP) contents decreased. The polyphenol oxidase (PPO) activity showed an interaction between varieties and fertilizer nitrogen level. The PPO activity tended to be higher in 'Kitanebari' than in Nagaimo, and it increased with increasing fertilizer nitrogen levels. Nagaimo was more prone to browning when the fertilizer nitrogen levels increased. Excising the vine at an early stage tended to increase water content and decrease viscosity, suggesting that it became an immature rhizosphere. We demonstrated that early removal of vines significantly increased PPO activity and browning. However, harvest time did not affect moisture and viscosity. Changing the harvest time from fall to spring significantly increased PP content and PPO activity. In addition, when changing the harvest from fall to spring, Nagaimo became markedly brown. The storage period did not affect moisture and viscosity, but PP and PPO content significantly increased with storage. Thus, as the duration of storage increased, browning progressed. The degree of browning in 'Kitanebari' was slower than that in Nagaimo.
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