title: Changes in main nutrients and medicinal composition of Chinese yam (Dioscorea opposita) tubers during storage.
abstract: The changes in the main nutrient and medicinal components during the storage of the Chinese yam (Dioscorea opposita) tubers were studied. The harvested tubers were stored under ambient conditions (10 °C to 18 °C, 60 % to 80 % Relative Humidity) and cold temperature and packaged conditions (4 °C, 60 % to 65 % Relative Humidity) for 45 day. The allantoin, starch, total alcohol-soluble sugar, reducing sugar, protein, and moisture contents of the samples were evaluated. Their amylase activities were also investigated. Results of ambient conditions indicated that, during storage, moisture decreased by 67.96 % to 56.51 %, and total sugars, reducing sugars, and protein increased by 6.49 % to 9.81 %, 1.7 % to 2.27 %, and 13.02 % to 14.55 %, respectively. Starch and enzyme activities increased during the early days of storage and progressively decreased, and the content of allantoin changed in volatility. The changes were more significant at cold temperatures and packaged conditions than at ambient conditions. This result suggests that after-ripening occurred in the early stages of Chinese yam tubers, which positively affected the nutritional potential of the tubers by a marked increase in nutrients. Low-temperature sweetening greatly affects the nutritional potential of tubers by a series of complicated interactions between starch and sugars at 4 °C.
authors.affiliation: School of Pharmaceutical Science and Technology, Tianjin University, Tianjin, 300072 China.
authors.forename: Zhidan
authors.initials: Z
authors.lastname: Zhang
authors.affiliation: School of Pharmaceutical Science and Technology, Tianjin University, Tianjin, 300072 China.
authors.forename: Wenyuan
authors.initials: W
authors.lastname: Gao
authors.affiliation: School of Chinese Medicine, Tianjin University of Traditional Chinese Medicine, Tianjin, 300193 China.
authors.forename: Renfang
authors.initials: R
authors.lastname: Wang
authors.affiliation: Institute of Chinese Matetria Medica, China Academy of Chinese Medicinal Sciences, Beijing, 100200 China.
authors.forename: Luqi
authors.initials: L
authors.lastname: Huang
keywords: After-ripening; Chinese yam; Low temperature sweetening; Nutrients; Storage