Phytosterol Distribution in Fractions Obtained from Processing of Distillers Dried Grains with Solubles Using Sieving and Elutriation

Abstract

ABSTRACTIn an earlier study, the combination of sieving and elutriation was effective in separating fiber from distillers dried grains with solubles (DDGS), the coproduct remaining after ethanol production from corn. To separate fiber, air was blown through sieve fractions in an elutriation column. Material carried by air to the top of the elutriation column was the lighter fraction; material that settled in the bottom was the heavier fraction. Separation of fiber from DDGS resulted in two products: 1) elusieve fiber with high neutral detergent fiber (NDF), which was obtained by combining lighter fractions; and 2) enhanced DDGS with reduced fiber (low NDF) and increased fat and increased protein contents, which was obtained by combining material remaining after separation of lighter fractions. There were no differences in phytosterol distributions (St:E, St, and FPE) among sieve categories. Phytosterol contents of oil from the lighter fractions were higher than or the same as the corresponding heavier fractions. Total phytosterol contents in elusieve fiber and enhanced DDGS were 112–142 and 226–232 mg/100 g, respectively. Phytosterol contents in elusieve fractions were compared with phytosterol contents reported in previous studies for fiber from different corn processing techniques. Phytosterol content of elusieve fiber was higher than wet‐milling endosperm fiber (71 mg/100 g). Enhanced DDGS had higher phytosterol content than dry‐milling fiber (152 mg/100 g), wet‐milling endosperm fiber (71 mg/100 g), quick fiber obtained from steeping without chemicals (215 mg/100 g), and DDGS (216 mg/100 g). Wet‐milling pericarp fiber (241 mg/100 g) and quick fiber from steeping with chemicals (275 mg/100 g) had higher phytosterol contents than elusieve fiber and enhanced DDGS. Phytosterol extraction from elusieve fiber could potentially increase revenues from elusieve process; however the increase in price of elusieve products could not be determined because estimates for the cost of the phytosterol extraction and for the value of ferulate phytosterol esters are not available.