Antioxidative activity and isoflavone composition of the black soybean koji prepared with different starters
Date Issued
2005
Date
2005
Author(s)
Lee, I-Hsin
DOI
zh-TW
Abstract
In the present study, black soybean kojis were first prepared with Aspergillus awamori, Asp. oryzae BCRC 30222, Asp. sojae BCRC 30103, Rhizopus azygosporus BCRC 31158 and Rhizopus sp. No. 2 which are commonly employed as starter organism for the manufacture of oriental fermented foods. Changes of antioxidative activities including α-diphenyl-2-picryl-hydrozyl (DPPH) radicals scavenging effects, Fe2+-chelating ability, reducing power and Trolox equivalent antioxidant capacity (TEAC) and isoflavone content of the black soybean kojis were examined. Besides, effect of cultivation temperature and fermentation periods on the antioxidative activities and isoflavone content of the Asp. awamori-prepared black koji were also investigated.
Results revealed that black soybean is a good substrate for the growth of all the test organisms. Methanol extracts of all the black soybean kojis, excepted that prepared with Rhizopus sp. No. 2, exerted higher DPPH free radical scavenging activity, Fe2+-chelating ability, reducing power and TEAC than did the extract of the unfermented black soybean. Among the various kojis examined, koji prepared with Asp. awamori showed the highest antioxidative activity. A higher aglycone content was also noted in all the prepared black soybean kojis than the unfermented black soybean. The highest content of aglycone was found in the koji prepared with Rhizopus sp. No.2.
Further preparaing the koji with Asp. awamori at different temperatures (25, 30 and 35℃) and for various fermentation periods (1-5 days) revealed that growth of test organism, the enhancing effect of antioxidative activity and the extent on isoflavone deglucosylation were the highest in koji prepared at 30℃. Koji prepared at 30℃ for 3-4 days showed the highest antioxidative activities and aglycone content.
Subjects
黑豆
異黃酮素
抗氧化活性
black soybean
isoflavone
antioxidative activity
Type
thesis
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