Effects of Spent Craft Brewers’ Yeast on Fermentation and Methane Production by Rumen Microorganisms

Abstract

Saccharomyces cerevisiae is a key component of beer brewing and a major by-product. The leftover, spent brewers' yeast from large breweries has been used as a protein supplement in cattle; however the possible advantages of spent yeast from smaller craft breweries, containing much higher levels of bioactive hop acids, have not been evaluated. Hops secondary metabolites from the hops (Humulus lupulus L.) used to make beer are concentrated in the yeast during brewing, and have antimicrobial activity against Gram-positive bacteria. Uncultivated suspensions of bovine rumen microorganisms produced less methane during fructose fermentation when exposed to inactivated, and freeze-dried spent craft brewers' yeast than a bakers' yeast control. The experiment was repeated with caprine rumen microorganisms and ground grass hay as the substrate. Likewise, in the presence of craft brewers' yeast less methane was produced (2.7% vs. 6.9% CH4). Both experiments also revealed a decrease in acetic acid production, but not propionic acid production, when craft brewers' yeast was included. These results indicated that spent yeast could represent a co-product for craft breweries, and a feed supplement for ruminants that has a favorable impact on methane production.

Effects of Hops (<i>Humulus lupulus</i> L.) Beta-Acids on Short Chain Fatty Acid Production from Complex Carbohydrates by Rumen Microbiota

“…There is interest in brewery ruminant co-products with high levels of hop phytochemicals. Some results have shown that spent brewers' yeast inhibited rumen ammonia and methane production [25] [26]. Another DOI: 10.4236/aim.2019.912063 990 Advances in Microbiology study indicates that older stored hops are adequately antimicrobial for feeding applications even after they are no longer desirable by brewers [27].…”

Inhibition of Growth and Ammonia Production of Ruminal Hyper Ammonia-Producing Bacteria by Chinook or Galena Hops after Long-Term Storage

“…However, hops bitter acids inhibit rumen methane production, as well [4]. Even residual hop acids in spent craft brewers' yeast inhibited methane production [23] and ammonia production [24]. It is highly likely that older hops will also inhibit methane.…”

Aprendiz Do Campo: Estimulando a Sucessão Rural Através Do Cooperativismo No Município De Teutônia - Rs

“…Embora os óleos essenciais sejam os aditivos não antibióticos mais comuns, há outras opções que podem ser utilizadas com a mesma finalidade, como as leveduras e os probióticos. Neste contexto, Pszczolkowski et al (2016) avaliaram a eficácia da ação antimicrobiana dos ácidos α e β do lúpulo (Humulus lupulus L.), compostos presentes nas leveduras do resíduo de cervejaria. Para avaliação foram incubadas amostras de feno de gramíneas com líquido ruminal proveniente de cabras, em um dos líquidos havia a presença de leveduras do resíduo de cervejaria enquanto no outro apenas leveduras isentas dos ácidos.…”