Bleaching and fractionation of dietary fiber and protein from wheat-based stillage

Wet milling procedures developed to separate wheat stillage into fiber-rich and protein-rich fractions were modified to include bleaching with alkaline hydrogen peroxide to improve their potential as food ingredients. Bleaching alone transferred over 40% of the protein in wheat fiber into the bleached wheat protein fraction and, whey followed by a single milling and sieving, reduced the protein in wheat fiber by 58% and increased wheat protein yield to 50% of the dry matter. Bleaching eliminated the dark grey colors of wheat fiber and what protein and enhanced their flavors. The wheat fiber product at 50% total dietary fiber had high water and oil absorptions of 3.3 g/g, while the 57% protein wheat protein product had absorptions of 2.3 and 1.8 g/g, respectively. Oil emulsification values were about 1.0 g/g for wheat fiber and what protein samples. Prolonged wet milling reduced wheat fiber yields proportionally, with a corresponding increase in dietary fiber concentration, while wheat protein yields increased but protein contents remained constant. Essential amino acid analysis showed that stillage and wheat protein products have better protein nutritional quality than raw wheat. An alkaline hydrogen peroxide bleaching treatment and one stage milling in a batch countercurrent system was sufficient to separate wheat stillage into wheat fiber, wheat protein and soluble solids that exhibited acceptable properties as food ingredients.