Niranjnai Wickramasinghe
Curtin University, Australia
Title: Phytoestrogen content of fermented lupin (tempeh and natto)
Biography
Biography: Niranjnai Wickramasinghe
Abstract
Natto and tempeh are indigenous Asian soya fermented foods which were originated in Japan and Indonesia, but now also being consumed in all over the world. Importantly these soya based fermented foods are rich in phytoestrogens genistein and daidzein. Phytoestrogens are plant derived isoflavone compound which has similar structure and antagonize human estrogens. While some of previous research indicates that phytoestrogen may act as anti-carcinogenic agents and inhibits tumor growth in patients with breast cancers, some of the other scientific literature says that “they stimulate tumor growth and therefore leading to practical issue for safety of food with phytoestrogen such as soya. Also some of research data say that phytoestogens have increasing attention due to the beneficial effect on glucose, lipid metabolism (protection against cardiovascular diseases), osteoporosis and complications related to menopause. However these health benefits of soya and phytoestrogens are controversial issue as number of research findings has indicated inverse results as well. Moreover contrasting results have been recorded on its cancer protection ability (hormone dependent cancers such as breast and prostrate) and due to these negative findings health authorities of some countries have indicated maximum daily intake level for phytoestrogen. Therefore preparation of indigenous Asian fermented legume foods such as natto and tempeh using other comparable legume is an interesting alternative to avoid overdosing above mentioned compounds. The aim of this study was to determine the amount of genistein and daidzein content of lupin and fermented lupin (lupin natto and tempeh) and whether fermentation time affected the genistein and daidzein content of lupin. Lupin tempeh and lupin natto were prepared using either whole seed (WS) or de-hulled seed (DHS). Analysis for genistein and daidzein content was conducted using HPLC for time points zero, 12 h, 24 h, 36 h, 48 h and 72 h after fermentation. Repeated measures ANOVA with source of lupin as between-subject factor was independently run for lupin tempeh and lupin natto. Results revealed that the amount of genistien and daidzein significantly increased with time in both tempeh and natto. Both isoflavones peaked at 48 h in lupin tempeh and earlier at 36 h in lupin natto. WS tempeh and WS natto had significantly more genistein than WHS tempeh and WHS natto. Diadzein content of WHS tended to be higher than WS across both products. It is concluded that, lupin and fermented lupin have very low amount of genistein and daizein compared to soya bean. Therefore, it is safe to consume without risk of phytoeastrogen overdosing. Fermentation time increased the amount of genistein and daidzein content in both lupin tempeh and natto and the form of lupin raw material used affected the genistein level and to some extent the daidzein content of fermented products.