青方腐乳发酵过程中大豆异黄酮的转化研究

Soy Isoflavone Transformation during Grey Sufu Fermentation

本文比较了青方、红方、白方和低盐红腐乳中大豆异黄酮组成和含量差异,并对青方腐乳发酵过程中大豆异黄酮含量和构型变化规律进行研究。结果表明,四种类型腐乳中大豆异黄酮基本以苷元形式存在,青方腐乳大豆异黄酮含量明显低于其他类型腐乳,仅为红方腐乳的33.01%,从单一异黄酮来看,大豆苷元和染料木素在四种类型腐乳中的含量明显高于黄豆黄素;青方腐乳发酵过程中大豆异黄酮转化研究发现,白坯中大豆异黄酮以糖苷型为主,染料木苷含量高于大豆苷和黄豆黄苷,前酵过程中糖苷型大豆异黄酮转化为苷元型大豆异黄酮,盐腌过程中糖苷型大豆异黄酮含量有轻微降低,发酵过程中苷元型大豆异黄酮总量在后酵前30 d显著下降,其中大豆苷元可能部分转化为雌马酚,导致青方腐乳大豆异黄酮含量明显低于其他类型腐乳,对其转化物质需进一步鉴定。

Soy isoflavone composition and content were compared between grey, red, white, and low-salt sufu(or fermented tofu). Changes in soy isoflavone content during the fermentation of grey sufu were also investigated. The results showed that soy isoflavone glucosides were almost completely converted to aglycones in all four types of sufu. Isoflavone content in grey sufu was significantly lower than that in the other types of sufu, in addition to being only 33.01% of the content in red sufu. Additionally, daidzein and genistein content was significantly higher than that of glycitein in all four types of sufu. Monitoring soy isoflavone conversion in grey sufu during the fermentation process showed that glucosides were the main forms of soy isoflavone in pizi, among which, genistein content was higher than daidzein and glycitin content. Soy isoflavone glucosides were converted to soybean isoflavone aglycone during the pre-fermentation process. There was a slight decrease in soy isoflavone glucoside content during the salting process. The total amount of soybean isoflavone aglycone decreased significantly at 30 d post-fermentation. Among soybean isoflavone aglycones, daidzein might be partially converted to equol, which resulted in the lower content of soy isoflavones in grey sufu than in other types of sufu. It remains to be seen if the transformed substance was equivalent in the four types of sufu.