Protein enhancement of DDGS from conventional and enzymatic dry grind processes

Abstract

Conventional and enzymatic (E-Mill) dry grind processes were used to produce distillers dried grains with solubles (DDGS). In the conventional process, slurry used whole ground corn and fermented. In the E-Mill process, germ and pericarp fiber were recovered prior to fermentation. Protein concentrate, protein isolate and sieving processes were applied to increase DDGS protein and decrease fiber contents.

For conventional DDGS, protein contents of protein concentrate, protein isolate and sieved products were 33, 37 and 40%, respectively, compared to conventional DDGS (34%). The protein concentrate process yielded more protein (66%) compared to the protein isolate process (15%). Protein yield of sieving process (29%) was higher than the protein isolate process but lower than the protein concentrate process. For E-Mill DDGS, protein contents of protein concentrate, protein isolate and sieved products were 49, 52 and 51%, respectively. Compared to E-Mill DDGS (42%), the three processes increased E-Mill DDGS protein contents. The protein concentrate process yielded more protein (63%) compared to the protein isolate process (11%). Protein yield of sieving process (40%) was higher than the protein isolate process but lower than the protein concentrate process. Lower protein contents with conventional DDGS were due to higher oil and neutral detergent fiber (NDF) contents in conventional DDGS.

For the E-Mill process, NDF content of protein concentrate (3.8%) was higher than original DDGS (1.7%). However, NDF contents of protein isolate (1.3%) and sieved product (1.8%) were not different from DDGS (1.7%). For the conventional process, NDF content of protein concentrate (27.1%) was higher than original DDGS (17.1%). NDF contents of protein isolate (11.6%) and sieved product (9.6%) were lower than DDGS.