Protein and fiber fortification of white pan bread using food-grade distiller's dried grains
This entry is also available in the Theses and Dissertations section of Open Prairie.
Distiller’s dried grains (DDG) are a coproduct of ethanol production. DDG has been used historically as animal feed. However, in the past decade, ethanol production has dramatically increased causing a surplus of distiller’s grains and saturating the market. The use of DDG, which is high in both protein and fiber, to fortify baked goods is one option to reduce the excess of DDG while enhancing its economic value. The purpose of this study was first, to evaluate the washing process for DDG to make it food grade, and second to evaluate the effects of incorporation of food-grade DDG from two different sources (DDGS and HP-DDG) on the quality of white pan bread (sandwich bread). HP-DDG was produced using a proprietary fractionation procedure prior to fermentation, while DDGS was produced using a conventional ethanol production procedure. Distiller’s dried grains with solubles (DDGS) and a high protein DDG (HP-DDG) were subjected to a washing process to make them food grade. Processing recovery (percent yield), color, and particle size were evaluated during the washing process. Substitutions of 5% and 10% of both DDGS and HP-DDG were used in all-purpose flour (APF). Dough rheology was tested using a Mixolab and a TA.XTPlus Texture Analyzer. Bread was baked using a modified AACC straight dough process. Loaves were then analyzed for color, volume, density, internal crumb structure and texture profile. Sensory acceptance of breads was evaluated using a seven-point hedonic scale. Yields from the washing process for the DDGS and HP-DDG, averaged 52.7% and 72%, respectively. While color of DDGS and HP-DDG was reduced through the washing process, finished products containing DDG were darker than the control. This led to visible color differences in the crumb of breads containing DDG. Significant differences were noted between washed DDG samples in relation to particle size distribution. Mycotoxins were not detected in either of the washed samples. Incorporation of food-grade DDG into breads led to smaller, denser loaves with fewer air cells. Loaves with 10% food-grade DDG were found to be significantly more firm than the 5% loaves. Substantial increases in protein content were seen at all levels of DDG inclusion, however statistically significant increases in fiber were noted only in the 10% DDGS loaves. Sensory analysis showed that all bread treatments were acceptable to consumers, and that the only significant difference in acceptability of loaves was noted in the appearance scores.