Effects of water requirement and substitution level on wheat-rice noodles with hydrocolloids

Substitution of wheat flour with rice flour in noodles can increase rice flour utilization, reduce cost, and lower the allergenicity of wheat gluten. High-AM rice flour (32.5%) was used to dilute high-protein wheat flour (14.8%) on account of its excellent gel-forming properties. Target noodles should obtain qualities comparable to noodles made from all-purpose wheat flour (10.4% protein). RSM technique was applied for optimization of substitution level, water requirement and hydrocolloid level. The coefficient of determination (R(2)) showed that only substitution level and water requirement could predict textural characteristics and lightness (L*) of cooked noodles. Increased amounts of rice flour resulted in a decrease in all cooked noodle textural qualities but an increase in L*. Water absorption of rice flour was significantly higher than that of wheat flour; therefore, increased water content of substituted wheat noodles was necessary. However, water requirement should correspond well with rice substitution level. CMC was observed to be more appropriate for use in wheat-rice noodles. Wheat-rice noodles were not significantly different from wheat noodles at 30-47% substitution, water requirement 43.5-59%, and 1.2-1.5% CMC. The addition of 1.5% Na(2)CO(3) resulted in a significant improvement in cooked wheat-rice noodle texture (p <= 0.05).