Drying Characteristics of Distillers Wet Grains Under Varying Condensed Distillers Solubles and Drying Temperature Levels

Abstract

Distillers dried grains with solubles (DDGS) has been shown to be an excellent livestock feed ingredient, and it is produced by the fuel ethanol industry, which is primarily located in the Midwest United States. There is a growing need to transport DDGS over long distances via rail, but this can often be hampered by poor flowability when unloading. DDGS is formed by combining condensed distillers solubles (CDS) with distillers wet grain (DWG) and then drying at high temperatures. It is hypothesized that drying conditions can affect resulting DDGS chemical, physical, and flow properties, but there is currently little quantified information about drying behavior of these coproducts. Thus, the objective of this study was to investigate the moisture desorption patterns of DWG for three CDS addition levels [10%, 15%, and 20% wet basis (wb)] at three drying temperatures (1005C, 2005C, and 3005C), to thus produce DDGS. Several mathematical models (Page, Newton, Pilosof, Henderson-Pabis, and others) were used to fit the observed moisture data over time. A new comprehensive model was developed for moisture ratio versus time (the best fit had R 2 = 0.91, SEM = 0.17) using a modified Page model which accounted for varying CDS and temperature levels. The developed model will be useful to predict moisture content values of DDGS for various drying times, CDS addition levels, and drying temperatures, and will thus be a benefit to industrial processing conditions.

Effects of CDS and Drying Temperature Levels on the Flowability Behavior of DDGS

“…These tie in to our previous studies [29,30] where mathematical modeling based on the same drying temperatures and CDS levels were used. In these studies, it was found that temperature had more significant effects on the drying behavior than CDS addition levels.…”

“…Temperature selection was based on interviews and discussions with industry experts, and also based on our previous studies of drying rate and moisture content of DDGS. [29,30] For each temperature=CDS combination, drying was done to reduce all of the experimental samples to a target of 8% (db) moisture content in order to have common baseline moisture content and eliminate its possible influence on the flowability behavior. To achieve this, each treatment combination was dried at different drying times.…”

“…[25][26][27][28] Two studies examined the drying rate and moisture desorption during DDGS production, using varying CDS and drying temperature levels. [29,30] Those studies were able to establish regression models of the drying kinetics and moisture desorption behavior, but no correlational studies between the resulting flowability properties and the effects of drying temperature and CDS addition levels were performed. Understanding these effects on physical and flow properties is an essential step toward improving DDGS flowability.…”

Measurement and Comparison of Glass Transition and Sticky Point Temperatures of Distillers Dried Grains with Solubles (DDGS) with Varying Condensed Distillers Solubles (CDS) and Drying Temperature Levels

“…The drying was done at three selected temperatures (100, 200, and 300°C). Temperature range selection was based on interviews and discussions with industry experts and upon our previous drying studies (Bhadra et al 2011a(Bhadra et al , 2011b. For each temperature and CDS combination, the drying was done for a specified time limit to reduce all the experimental samples to 8% (db) moisture content, so that we had a common baseline in all the samples for moisture content to eliminate its possible influence on the measured properties.…”

“…They are produced by a rapid drying process so that the food molecules do not have much time to align themselves and become crystalline. For DDGS, previous work has reported that the temperature of any typical drying operation ranges from 300 to 1,000°F, and the time taken to produce the dried DDGS is only a few seconds (Bhadra et al 2011a(Bhadra et al , 2011b. Therefore, like other food and milk powders, DDGS also has a high drying temperature and short drying time and, thus, forms an amorphous solid.…”