Preparation of a natural pigment ingredient containing nasunin from eggplant peel
2013
Hashimoto, K. (Utsunomiya University, Utsunomiya, Tochigi (Japan). Faculty of Agriculture) | Hoharazawa, T. | Itoh, K. | Akutsu, S. | Oyama, T. | Watanabe, T. | Yamazaki, K. | Kakubari, F. | Yoshinari, S. | Arai, K. | Uda, Y.
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 80 mg of nasunin (86.5 % purity) was obtained as the Sep-pack Csub(18) cartridge-absorbable fraction of the extracts from 185 g of peel. When the obtained nasunin was dissolved in McIlvaine buffer (pH 4.5) and incubated for 2 weeks at 4degC 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 4degC 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.
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