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United States Department of Agriculture

Agricultural Research Service

Title: Effects of Yeast and Bran on Phytate Degradation and Minerals in Rice Bread

Authors
item Kadan, Ranjit
item Phillippy, Brian

Submitted to: Journal of Food Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: May 9, 2007
Publication Date: May 9, 2007
Citation: Kadan, R.S., Phillippy, B.Q. 2007. Effects of yeast and bran on phytate degradation and minerals in rice bread. Journal of Food Science and Technology. 72(4):C208-C211.

Interpretive Summary: Rice bread may be an alternative for those who are sensitive to, and cannot adequately absorb nutrients from wheat bread. Phytic acid is a chemical constituent of rice, occurring predominantly in the bran that binds to minerals and decreases their bioavailability. The amounts of rice bran and yeast in rice bread were varied to determine the best rice bread recipes from a nutritional standpoint. Rice bread appears to be a good source of minerals, such as, magnesium, iron, and zinc that could improve the nutrition of the 1-2 million people in the United States who are intolerant to wheat bread.

Technical Abstract: Rice bread is a potential alternative to wheat bread for gluten-sensitive individuals. Incorporation of rice bran into bread made from white rice flour adds flavor, but also phytic acid, which can reduce the bioavailability of minerals. Breads with varied amounts of defatted bran and yeast were prepared to determine their effects on the phytate and mineral contents of the bread. A completely randomized factorial design was used with bran levels of 3.7, 7.3, and 10.5% of the dry ingredients, and yeast levels of 1.6, 3.2, and 4.7%. Phytase from grain and from yeast can degrade phytate during breadmaking. Increasing the amount of bran decreased the phytate degradation from 42% at the lowest level of bran to 10% at the highest, and the amount of yeast had no significant effect. The bran contributed substantial amounts of magnesium, iron, and zinc. Breads with the lowest level of bran had phytate to zinc molar ratios between 5 and 10, which suggest medium zinc bioavailability. Rice bread is a tasty and nutritious food that is a good dietary source of minerals for people who cannot tolerate wheat bread.

Last Modified: 12/19/2014
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