Fungal wand

How to get maximum out of antioxidants in soy

By Biplab Das
Published: Thursday 30 September 2010

SOY is an enduring favourite of healthfood aficionados. It is known to ward off cancer and reduce risk of brittle bone and heart diseases. The oil seed owes its ability to antioxidants. The trick to exploit these fully is to change the way soy is consumed, say scientists at Banaras Hindu University (BHU) and National Botanical Research Institute, Lucknow. They have found that the antioxidant property of soy gets enhanced when it is fermented with a fungus, Trichoderma harzianum.

Studies have shown fungi can break down the complex protein of seeds, making them easy to digest, and can also enhance the nutritional value of food, including stale grains. For example, Cordyceps sinensis fungus enhances the nutrients present in stale rice. This caught the attention of Harikesh B Singh, professor of mycology and plant pathology at BHU. He wondered if the antioxidant molecules concentrated in soy seeds can similarly be enhanced.

To explore the possibility, Singh along with his colleagues picked a group of fungi, Trichoderma, which is known to trigger the release of antioxidants, phenolic acids and flavonoid compounds, in plant tissues as defence against pathogens. Its effect on soy seeds had never been studied, though. The scientists used Trichoderma harzianum NBRI-1055 fungal strain to ferment soybeans.

During fermentation the fungi secretes enzymes which break down carbohydrates and lignin. Consequently, fermented soybean had higher antioxidants than unfermented soybean. Extract of the fermented soybean protected liver cell membranes, DNA and protein from the onslaught of free radicals. Free radicals react with lipid molecules present on the cell membrane through oxidation and destroy the membrane. Antioxidant molecules stop this oxidation process and protect the cell.

In the August issue of Bioresource Technology, the researchers write that the finding would help tailor soy foods as potential nutraceuticals or functional foods. H N Mishra, a food engineer at IIT Kharagpur, said the safety aspects of using the reported fungi in foods need to be ascertained. Singh and his team now plan to test the fermented product on animals.

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