Addition of Soybean Lipoxygenase to All-Purpose Flour and its Effects on Dough Gluten Strength and Bread Quality

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Virginia Tech

The goal of this research is to determine the effects of added soybean lipoxygenase (LOX) on bread dough rheological properties and physical properties of bread loaves compared to controls, and to determine sensory attributes of bread loaves using quantitative descriptive analysis (QDA). Protein fractions were obtained through the use of isoelectric precipitation. The pH 4.8 precipitate was found to yield the greatest LOX activity when compared with other fractions (p<0.05). The addition of pH 4.8 precipitate improved rheological properties of bread dough, examined in a farinograph, when compared to the all-purpose control (p<0.05). Addition of soy flour also increased the gluten strength of all-purpose flour (p<0.05). The addition of pH 4.8 precipitate to all-purpose flour did not improve bread loaf volume or texture. Sensory panelists described pH 4.8 supplemented bread as having firmer crumb when compared with controls (p<0.05). There were slight color differences among the loaves. The crust and crumb of bread flour loaves was lighter in color than any other sample. It was concluded that the addition of pH 4.8 precipitate to all-purpose flour greatly improved the rheological properties when compared with all-purpose flour alone.

yeast bread, soy flour, gluten, lipoxygenase