The use of phenolic protein precipitates (trub) from beer production in animal feed

Abstract

During beer production, proteins and polyphenols form complexes and fall out of solution. This precipitate is separated from the wort in the form of hot trub at the end of wort production and after cooling but before fermentation in the form of cool trub. The disposal of hot trub with the spent grains and of the cool trub in the wastewater is neither economical nor practical due to their nutritional value.

The experiments show that all types of trub as well as a mixture of trub and spent yeast can be dried using a drum dryer to create a usable livestock feed additive. The composition of the trub-yeast mixture is comparable to that of dried spent yeast. Dried trub consists mainly of non-nitrogenous extract, which is made up mostly of sugars.

The feeding experiments using these dried products show that a combination of trub and yeast can be used in dried protein feed preparations. Even the bitter yeast-trub mixture was acceptable to pigs as feed. This contradicts findings often reported in the literature, which suggest that livestock will not accept trub in their feed.