Abstract
In this study, methods for the extraction of nasunin, delphinidin-3-(p-coumaroylrutinoside)-5-glucoside, an antioxidant anthocyanin contained in eggplant peel, were investigated. Extracts were obtained by treating the peel with 0.5% acetic acid, after washing the peel 3 times in order to reduce the content of chlorogenic acid. About 80mg of nasunin (86.5% purity) was obtained as the Sep-pack C18 cartridge-absorbable fraction of the extracts from 185g of peel. When the obtained nasunin was dissolved in McIlvaine buffer (pH 4.5) and incubated for 2 weeks at 4°C in the dark, its concentration was reduced to 65.1%. On the other hand, when nasunin was collected as a nasunin-casein complex from the extracts, using isoelectric point precipitation, nasunin showed enhanced stability. Using this method, 60.8% of nasunin was recovered from the extracts. After 2 weeks incubation at 4°C in the dark, no significant reduction in nasunin content was observed. Furthermore, when freeze-dried, the nasunin-casein complex was relatively stable, remaining 89.4% stable even at room temperature. From the results, it was concluded that the nasunin-casein complex can be used for effective preparation of stable nasunin-containing food material from the extract of eggplant peel.
