SORPTION ISOTHERM CHARACTERISTICS OF DISTILLERS DRIED GRAINS WITH SOLUBLES (DDGS)

ABSTRACT. Distillers dried grains with solubles (DDGS) is widely recognized as a highly nutritious animal feed ingredient. With the exponential growth of the fuel ethanol industry in the past several years, significant quantities of distillers grains are now being produced. To effectively utilize these feeds in the domestic market, these coproduct streams have to be transported greater distances and must be stored in various structures until final use. Unfortunately, DDGS flow is often problematic as it frequently becomes restricted by caking and bridging during storage and transport. This issue may arise from a number of factors, including storage moisture, temperature, relative humidity, particle size, and time variations. The objective of this study was to develop sorption isotherms for DDGS with varying soluble levels, in order to provide facility designers and operators with appropriate storage and transport information. Equilibrium moisture contents (EMC) of DDGS with four different soluble levels (10%, 15%, 20%, and 25 % d.b.) were determined using the static gravimetric method at 10C, 20C, 30C, and 40C over four equilibrium relative humidity (ERH) levels of 60%, 70%, 80%, and 90%. The sorption capacity of DDGS increased with increasing temperature and soluble level, and followed a type III isotherm, which is commonly observed in high‐sugar foods. The observed EMC values for 10%, 15%, 20%, and 25 % (d.b.) solubles ranged fro