Analysis of physical, chemical, and functionality properties of distillers dried grains with solubles (DDGS) for use in human foods.

摘要

The ethanol industry is currently booming, and extensive research is being pursued to develop alternative uses for distillers dried grains (DDG) and distillers dried grains with solubles (DDGS). The main objective of this research project was to investigate methods to use distillers grains in human foods, which consisted of five unique but connected studies. The purpose of the first component of the research was to survey current practices of U.S. ethanol plants. It analyzed processes, equipment, end products, and desired future directions for coproducts. Approximately one third of plant managers surveyed expressed willingness to alter drying times and temperatures to improve quality. Other managers hesitated to implement changes, based on reasons such as economic incentive, cost and return, and capital investment required. Respondents also reported the desire to see novel uses of DDG and DDGS, including fuels, extrusion, pellets, plastics, and human foods.;The objective of the second component of this study was to examine previous research on bleaching and color removal techniques for various food products and to discuss their potential applicability for distillers grains. Methods that showed promise included hydrogen peroxide, ethanol/butanol extraction, and lipoxygenases. Hydrogen peroxide appeared extremely successful when used under alkaline conditions. Ethanol and butanol have proven color removal abilities; however, it is important to monitor extraction losses. Finally, lipoxygenases, such as those found in enzyme-activated soy flour, appeared to have high bleaching potential for coproducts.;The third component of this project utilized ethanol extraction to remove pigments from DDGS. Independent variables included DDGS particle size (diameter of 0.384 or 0.329 mm), number of extractions (1, 2, or 3), time (agitation = 30, 60, or 90 min), and concentration of ethanol (5, 10, or 15 mL/g). Altogether, the experimental design was a 2x3x3x3 completely randomized design with each treatment combination replicated twice (n=2). Protein content was affected by time and number of extractions. A decrease in lipid content resulted in an increase in protein content. Lipid and pigment analysis indicated similar decreasing trends, signifying that lipid content decreased while time, ethanol concentration, and number of extractions increased. Color analysis (color values) showed ethanol extraction to be a moderately effective bleaching technique for DDGS materials. Chemical property data (protein, lipid, and pigment values) indicated that the treatments were highly effective in reducing lipid and pigment values while increasing protein percentages.;The objective of the fourth component of this study was to quantify, using standard laboratory methods, physical property values for low oil DDGS (i.e. DDGS that had been commercially solvent-extracted). Results showed that moisture content, water activity, thermal properties, bulk density, and angle of repose values were similar to traditional DDGS that has not had the oil removed. However, color was impacted by the oil extraction, as the low oil DDGS was paler compared to untreated counterparts.;The purpose of the fifth component of research was to analyze how various DDGS and sodium stearoyl lactylate (SSL), dough conditioner substitutions levels function in both flour mixture and bread matrices. The independent variables included all purpose and bread flours, DDGS substitution levels (0%, 25%, or 50%) and 3 levels of the SSL dough conditioner (0%, 0.15%, or 0.3%). The dependent variables were expressed on a dry weight basis and included several chemical (protein, lipid, and ash), physical (side height, peak height, width, length, mass, moisture, water activity, strength, stiffness, and Hunter L, a, and b values), and subjective (uniformity, size, thickness of cell walls, grain, moistness, tenderness, softness, and crumb color) measurements of flour mixtures and bread loaves. Overall, as the substitution percentage of DDGS increased, so did protein, moisture, ash, and Hunter-a values. Loaf peak height, side height, width, and length decreased as DDGS quantity increased. Overall, 25-50% DDGS substitution appeared to have negative impacts on physical features despite the fact that the chemical content was enhanced.