Enhancement of bioavailable iron and calcium contents in fermented linseed (Linum usitatissimum L.) beverages

Linseed (Linum usitatissimum L.) is considered as a nutritious food because of exceptionally high alpha-linolenic acid (ALA) content, dietary fiber, quality protein and phytoestrogens. It is rich in minerals (100 g of seeds contain 350-431 mg of magnesium and 236- 250 mg of calcium) and has very low amount of sodium. It also contains anti-nutritional factors, especially phytic acid that interferes with the bioavailability of nutrients like calcium and iron. Fermentation increases the nutritional quality of foods by reducing anti-nutritional factors. Probiotic cultures viz., Lactobacillus acidophilus, Bacillus mesentericus and lactic acid bacterial isolate LAB-3 were used to produce fermented linseed beverage and the quantity of phytic acid, bioavailability of iron and calcium were estimated. Bioavailability of iron and calcium increased by fermentation. The highest bioavailable iron and calcium were observed in L. acidophilus fermentation (4.40 mg and 250.41 mg /100 g seeds, respectively) followed by LAB-3 and Bacillus mesentericus compared to raw seeds that contain 0.89 mg of iron and 125 mg of calcium /100g of seeds. Phytic acid content was high in raw seeds (1392 mg /100 g seeds) and fermentation with L. acidophilus recorded 856 mg phytic acid /100 g seeds resulting in 38.51 % reduction. LAB-3 and B. mesentericus showed approximately 32 % reduction in phytic acid content. The reduction in phytic acid content is significantly high. Fermentation using probiotic bacteria enhanced the bioavailability of iron and calcium by reducing phytic acid. Hence, this study leads to a conclusion that, microbial intervention can be adopted to reduce the anti-nutritional factors and enhance the nutritional quality of linseed.