Enrichment of bread with soymilk using response surface methodology

•The results of this study have demonstrated that soymilk can be a good alternative to water in the bread-making process.•The total substitution of water with soymilk improved the protein content of the bread by almost 15 %.•The inclusion of soymilk in the bread production did not affect the sensory quality.•The inclusion of soymilk in the bread production positively affected the crust color of the bread. Response Surface Methodology (RSM) was used to optimize the substitution of water with soymilk in the modification of bread recipes in Ghana. The moisture, fat, and protein contents and the sensory and color characteristics of the refined bread recipe were evaluated and compared to commercial bread. A simple lattice mixture design was employed with water and soymilk as the independent variables and moisture, fat and protein as the response variables. The optimized formulation was 100 % soymilk substitute bread and the optimum responses were 31.78 g/100 g for moisture, 10.05 g/100 g for fat and 16.26 g/100 g for protein. The instrumental color analysis of the bread samples was assessed using the CIE L* a* b* measuring system. The results showed that the inclusion of soymilk at various levels had a significant (p = 0.01) effect on the overall appearance of the bread samples, thus the bread samples had a darker crust color. The optimized bread had a significantly higher protein content (16.26 g/100 g vs. 14.00 g/100 g; p = 0.032) almost 1.2 times higher than the commercial bread. Soymilk can completely substitute water in the bread-making process to increase the protein level of bread without marked influence on the sensory qualities.