Evaluation of water-holding capacity for wheat-soy flour blends

The water-holding capacities (WHC) of wheat flour when partially replaced with defatted soybean flour (DSF) or low-fat soybean flour (LSF) were evaluated. Wheat flour was replaced at 2, 4, 6, 8, 10, and 12% levels with DSF or LSF based on sample weight and/or soybean flour protein content. WHC (g water/g flour) was quantified after centrifuging hydrated samples at 1592xg (3,000 rpm) and/or 4,424xg (5,000 rpm) for 30 min. Results showed that at both centrifuge speeds, all wheat-soybean flour blends had WHC greater than wheat flour with the exception of 2% blends based on weight. Wheat-soybean flour blends had lower WHC at 5,000 rpm than at 3,000 rpm. In general, the WHC increased as the proportion of soybean flour increased. Differences in WHC were greatest between the samples containing 2 and 12% soybean flour. WHC values among the 6, 8 and 10% samples were not significantly different for both wheat-DSF and wheat-LSF blends. Blends containing LSF were observed to have comparable WHC to wheat-DSF blends.