Evaluation of extruded-expelled low-fat soybean flour in flour blends and the effects on bread and dough development

The research detailed in this document focuses on the performance of a partially defatted soybean flour called low-fat soybean flour (LSF). This soybean flour type has not received widespread application as a food ingredient. This has resulted from a lack of information available on the performance of LSF in a variety of food systems. Based upon its compositional and functional properties, LSF has shown potential for use in a flour blend. Past studies have focused on the usage of flour blends containing wheat flour partially replaced by an oilseed or legume flour. Wheat-soy flour blends have mostly been studied for use in yeast-leavened bread production. These blends have been able to enhance the protein content of yeast-leavened breads; however, favorable and unfavorable alterations to dough and bread development have been observed. In an effort to determine whether LSF could make favorable contributions to bread systems when used in a flour blend with wheat, several studies were performed in comparison to blends of wheat and defatted soy flour (DSF). For all experiments, wheat flour was replaced by soybean flour up to 12% based on weight and/or equivalent protein;To understand the protein-water interaction character of LSF in a flour blend, water-holding capacity (WHC) was examined. WHC was evaluated for blends at 2, 4, 6, and 12% replacement of wheat flour based on weight and equivalent protein. Findings showed that wheat-LSF blends had very similar WHC character to wheat-DSF blends. Dough development testing using a 10-g mixograph was performed on flour blends at the replacement levels of 2, 6, and 12%. The parameters of mix (peak) time, rate of development, and shear force during development were quantified. Dough development testing was conducted with and without the use of the dough conditioners, sodium stearoyl-lactylate and calcium stearoyl-2-lactylate. Wheat-LSF blend required longer mixing; however, these mix times were decreased after dough conditioner use. Effects on the physical and sensory properties of yeast-leavened bread were evaluated after making bread using the specified wheat-soybean flour blends at 2, 6, and 12% replacement of wheat flour. The physical properties loaf weight, loaf volume, crumb firmness, and crust/crumb color were evaluated. Sensory evaluation of bread crumb was accomplished using an 11-member sensory panel. Panelists provided sensory perception data for the perceived intensity of the following bread attributes: bread aroma, nutty aroma, crumb firmness, bread flavor and nutty flavor. Nutty flavor was associated with breads that contained soybean flour. Overall wheat-LSF breads had similar physical and sensory properties to wheat bread that did not contain any soybean flour. Most results from this research have been attributed to the presence of approximately 10% oil in the LSF