INFLUENCE OF ADDITIVES ON THE ENSILING PROCESS OF WET BREWERS’ GRAINS

Abstract

The results of three experiments to study various aspects of, and treatments to improve the preservation of, wet brewers’ grain are reported. In the first experiment, brewers’ grains were sampled in a brewery from the lauter tub and holding tanks. Material from the holding tanks was also ensiled in test-tube silos and sampled at various time intervals during the 18-day study. All samples were analyzed for lactobacillus growth, organic acid and ammoniacal nitrogen content and buffering capacity. Water soluble and total non-structural carbohydrate were determined for material sampled from six separate brews. No lactobacilli were isolated from the grains sampled in the lauter tub; however, lactic acid bacteria were evident in samples from the holding tanks. The lactobacillus population increased sharply during the first 2 days of ensiling, followed by a decline over the remaining 16 days of the experiment. The results of the 18-day study suggested that a silage additive would assist in satisfactory ensiling of wet brewers’ grains. The second and third experiments were designed to study the effects of various treatments on the preservation of brewers’ grains under long-term anaerobic storage conditions. In the second experiment, the 23-liter laboratory silos were ineffective in simulating actual horizontal silo conditions in the time period allocated to the study. The lack of similarity may be related to the cool temperatures under which the laboratory silos were stored. In the third experiment, 160-ml test-tube silos were used. The control silage was poorly preserved, containing high levels of acetic and butyric acid and ammoniacal nitrogen. The material treated with both rates (0.50 and 0.75%) of formic acid and the high rate (0.75%) of the formic–propionic mixture was well preserved. The addition of molasses, although inhibiting butyric acid production, was ineffective in controlling ammoniacal nitrogen production.