Comparison of anthocyanin and polyphenolics in purple sweetpotato (Ipomoea batatas Lam.) grown in different locations in Japan

ABSTRACT The health benefits of purple sweetpotato, which is used as an edible food in its natural state and in processed foods and as a natural color pigment, have been recognized. In Japan, sweetpotato has been economically produced in regions below 36°4ʹN latitude; however, cultivation areas are beginning to expand further north. The anthocyanin and polyphenolics in three purple sweetpotatoes cultivated in different locations; I (42°92ʹN, 143°04ʹE) and II (31°72ʹN, 131°03ʹE), were compared over two years. Total anthocyanin and polyphenolic contents in purple sweetpotatoes tended to be high in location I. The anthocyanin and polyphenolic compositions differed between locations. The peonidin/cyanidin ratios were higher in location II compared with I in all varieties. The relative amount of 3,4- and 4,5-di-O-caffeoyolquinic acids were higher in location II. Their contents and composition also differed between years. These results suggest that the variability of the anthocyanin and polyphenolic content and composition was influenced by climate conditions, probably temperature during cultivation. This study indicates that northern areas in Japan are an alternative production area and may yield higher amounts of anthocyanin and polyphenolics. Graphical abstract