Influence of additives on short-term preservation of wet brewers' grain stored in uncovered piles

Fresh wet brewers’ grains at 23.0% dry matter and 4.7% total nitrogen (dry matter basis) were obtained from a brewery. The effects of the following additives on the preservation of brewers’ grains, stored in uncovered piles, were compared to an untreated control during a 14-day storage period: 85% formic acid at 0.20 and 0.40%; propionic acid and formic–propionic mixture (1:1) at 0.20, 0.30, and 0.40%; and molasses at 2.00%. Piles of brewers’ grains were placed outside on polyethylene sheeting. The quality of the wet brewers’ grains was determined by measuring pH, organic acid and ammoniacal-nitrogen content of surface and subsurface samples taken at three intervals during the 14-day study. As well, visible surface changes were noted daily during the 2-wk period. A rapid increase in acetic acid in the subsurface samples was detected for brewers’ grains treated with the low and medium rates (0.20 and 0.30%) of both propionic and formic–propionic, 2.00% molasses and the untreated control. As well, extensive mold growth, discoloration and dry matter deterioration were noted for these treatments. The two rates (0.20 and 0.40%) of formic acid and the high rate (0.40%) of propionic acid were effective in reducing subsurface deterioration, but were unable to reduce the amount of surface spoilage. The high rate (0.40%) of the formic–propionic acid mixture effectively reduced all aspects of deterioration to maintain quality material during the 14-day study.