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Influence of Added Enzymes and Bran Particle Size on Bread Quality and Iron Availability

¹Cereal Group, Institute of Agrochemistry and Food Technology (IATA-CSIC), Av. Agustín Escardino 7. Parque Científico, 46980 Paterna-Valencia, Spain. ²Microbial Ecophysiology and Nutrition Group, IATA-CSIC, Av. Agustín Escardino 7. Parque Científico, 46980 Paterna-Valencia, Spain. ³Corresponding author. Phone: +34 96 390 00 22. Fax: +34 96 363 63 01. E-mail: mharos@iata.csic.es

The aim of this investigation was to study the influence of different bran proportions and particle sizes, addition of fungal phytase, and α-amylase addition on bread quality and phytate levels, and how these treatments affect availability of iron to intestinal epithelial (Caco-2) cells. Potential mineral contributions to dietary reference intakes and phytate-to-mineral molar ratios were also evaluated. Wheat bran supplementation significantly affected bread quality. Smaller bran particle size affected crumb firmness negatively, whereas the use of α-amylase, in some cases in combination with phytase, could improve technological bread quality. The use of phytase in the formulation significantly reduced the level of phytates, and phytate hydrolysis also led to smaller bran particle size. Increasing the bran proportion used in the bread formulation increased the iron concentration in bread samples by 18.9%. Phytase addition proved to be a useful strategy to improve iron dialyzability; however, incomplete dephytinization still had an inhibitory effect on iron uptake, with the exception of samples formulated with 10% bran. The inhibitory effect of phytate could be predicted from the values of the phytate-to-iron ratios. Reduction of particle size did not improve iron availability or uptake by Caco-2 cells.