Abstract
Brown rice is recently used as a healthy food ingredient, because of its high nutritive value, although it contains relatively large amount of phytic acid. Owing to its mineral chelating property, phytic acid has negative effects on the bioavailability of essential minerals especially in the children and women in pregnancy. In this study, an attempt to reduce the phytic acid content of brown-rice bread by addition of Aspergillus niger phytase was done. For the analysis of phytic acid in these bread, white rice, brown rice and soy bean products, an anion-exchange HPLC and a post-column detection method with Wade reagent were used. From the preliminary experiment, it was found that the loaf volumes of brown-rice breads were reduced, especially in 50% brown-rice one. Thirty % brown-rice bread, therefore, was used in the next experiment, where the additions of 0.2g and 1.0g of the phytase (per 521g of bread material) to the doughs and breads during mixing, fermentation, and baking were done. The results suggest that the addition of 0.2g of the phytase to 521g of total material before baking can reduce the phytic acid content in brown-rice bread, with less negative effect on appearance of bread than the addition of 1.0g of the phytase.
