Manufacture technology of the dry leaves for extracting the purplish red coloring matter contained in kinjisou (Gynura bicolor DC.)
2005
Hayashi, M.(Ishikawa-ken. Agricultural Experiment Station, Kanazawa (Japan)) | Ota, R. | Miwa, S. | Michihata, T. | Enomoto, T.
Kinjisou (Gynura bicolor DC.) is a traditional vegetable of Ishikawa Prefecture, and contains much amount of anthocyanin. Previously, dryness of the leaves was tried for extracting using the purplish red color. However, it was not successful to extract the color from the leaves. We were examined about new manufacturing process for the dryness in order to extract the color sufficiently. Because the dryness Kinjisou can use coloring matter at any time and long-term preservation was possible. Accordingly, before carrying out hot wind dryness of Kinjisou, performing steamy heat-treatment for about 3 - 5 minutes was done. It became possible to extract coloring matter simply and efficiently from the dryness Kinjisou manufactured by the new processing method. The influence of steam heating on the anthocyanin content of the hot water extract of the dryness Kinjisou was examined with HPLC. When the steam heating were done, the peak of anthocyanin detected with 520nm was admitted though it was not admitted when the steam heating were not done. As a result, it was confirmed to be able to extract anthocyanin of Kinjisou by the steamy heat-treatment. Antioxdative activity was assayed by using DPPH (1,1-diphenyl-2-picrylhydrazyl radical-scavenging activity. The extract of steam heating Kinjisou showed more effective antioxdative activity than that of not steam heating Kinjisou. Moreover, when the dryness Kinjisou was sealing to a plastic bag and saving in a refrigerator for six months, the extract from the leaves kept the purplish red color, indicating that the new method is useful for extracting the purplish red coloring matter contained in Kinjisou.
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