Quantification of Physical and Chemical Properties, and Identification of Potentially Valuable Components from Fuel Ethanol Process Streams

Abstract

Wider exploration of ethanol coproducts is required as the ethanol industry continues to expand. Currently, process streams such as thin stillage and condensed distillers solubles (CDS) are processed into DDGS and used as animal feeds, but other higher value opportunities may exist. The objective of this study was to identify chemical components in CDS and thin stillage and to quantify physical properties. Analysis of protein, organic acid, and sugar profiles was explored. Physical properties including density, thermal conductivity, thermal diffusivity, and moisture were also examined. CDS had an average density of 1.02 g/cm3, while thin stillage had 1.08 g/cm3. The thermal diffusivity of thin stillage was 0.11 mm2/s, while that of CDS was 0.10 mm2/s. Thermal conductivity of thin stillage and CDS were approximately 0.54 W/m0C0.45 W/m0C, respectively. The moisture content for the thin stillage was found to be 93.28 %wb, while CDS had one of 73.63 %wb. Based on the protein profiles it was determined that the majority of the protein found in both thin stillage and CDS was located in the compounds precipitate. Overall the highest percentage of protein was found to fall between 10 and 15 kDa. Glycerol was found in thin stillage at concentrations of 18.8 g/L and 63.2 g/L in CDS; while acetic acid was found in concentrations of 3.22 g/L in thin stillage and 10.82 g/L in CDS. Quantification of the physical properties and identification of the chemical properties paves way for exploration of new value added uses of thin stillage and CDS.