Comparison of standard moisture loss-on-drying methods for the determination of moisture content of corn distillers dried grains with solubles

Abstract

This study quantified the variability among 14 standard moisture loss-on-drying (gravimetric) methods for determination of the moisture content of corn distillers dried grains with solubles (DDGS). The methods were compared with the Karl Fischer (KF) titration method to determine their percent variation from the KF method. Additionally, the thermo-balance method using a halogen moisture analyzer that is routinely used in fuel ethanol plants was included in the methods investigated. Moisture contents by the loss-on-drying methods were significantly different for DDGS samples from three fuel ethanol plants. The percent deviation of the moisture loss-on-drying methods decreased with decrease in drying temperature and, to a lesser extent, drying time. This was attributed to an overestimation of moisture content in DDGS due to the release of volatiles at high temperatures. Our findings indicate that the various methods that have been used for moisture determination by moisture loss-on-drying will not give identical results and therefore, caution should be exercised when selecting a moisture loss-on-drying method for DDGS.