Effect of condensed distillers solubles and drying methods on selected physico-chemical characteristics of laboratory-prepared wheat distillers dried grain with solubles

Abstract

Abstract. Wheat distillers dried grain with solubles (DDGS) samples were prepared at 15, 30, and 45% condensed distillers solubles (CDS) and dried using forced-air, microwave, and microwave convection methods to examine the effect of CDS level and drying methods on their chemical and physical characteristics. Proximate composition analyses were conducted using AOAC official methods. Physical property measurements included bulk density, particle density, particle size distribution and color. As CDS level in the blend increased, crude protein and ash content increased while crude fat and fiber content decreased. The fat and acid detergent fiber contents were also markedly affected by the drying conditions. Bulk and particle densities increased while particle size decreased as CDS level was increased. These linear physical property trends were consistently observed in forced-air convection-, microwave-, and microwave convection-dried samples. Dryer settings significantly affected the lightness and redness color parameters. Drying at lower air temperature, microwave power, and microwave convection settings tended to produce lighter and less red samples. These results contribute toward better understanding of the underlying causes of product quality variation as well as the potential of alternative drying technologies for wheat distillers grain with solubles.