A Comparative Study of Stout Beer Batch Fermentation Using Free and Microencapsulated Yeasts

Abstract

Because many questions arise regarding the use of immobilization technology to consistently produce a high quality beer, this work focuses on the effects of using an immobilization matrix in the fermentation process. The aim of this study was to explore the feasibility and potential uses of immobilization on sensorial characteristics such as color, flavor, and headspace compounds of stout beer, when using batch fermentation. Batch production of beer was conducted as a standard ale process for stout beer production. For the immobilized yeasts fermentation, cells were microencapsulated in alginate, by using the Thiele modulus procedure for microcapsule design. Glucose concentration, cell multiplication, cell viability, specific gravity, pH, Brix, and ethanol were monitored throughout the fermentation process. Both, sensorial analysis (statistic triangle tests) and instrumental methods (gas chromatography to measure headspace compounds and visible spectrophotometer to quantify the color) were used to evaluate characteristics of the beer that was produced from immobilized and free yeast fermentations. Free and immobilized yeasts fermentation showed no significant difference (p> 0.05) for all variables of interest. The profile of headspace compounds was different, perhaps because of changes in yeast's behavior and the presence of secondary metabolites. However, immobilization did not have a significant impact on the beer flavor, as detected by the sensorial triangle test.

Aroma formation by immobilized yeast cells in fermentation processes

“…Additionally, according to Andrade Neves et al (), fermentation with yeast cells immobilized in calcium alginate could be associated with the thermovinification technique for the production of acceptable young wines from cabernet sauvignon and pinot noir grape varieties. Alginate beads have been also used in green beer production in a fluidized‐bed bioreactor operated by means of a circulating wort system (Wang et al, ), as well as for stout beer production (Almonacid et al, ). Lager‐brewing yeasts, encapsulated in alginate/chitosan matrix, have been found to produce beers comparable to conventional ones, with higher levels of total higher alcohols and esters and slightly lower amounts of aldehydes at different original wort gravities (Naydenova et al, ).…”

High gravity primary continuous beer fermentation using flocculent yeast biomass

“…Any continuous fermentation system depends on high concentrations of yeast, often attained by immobilized cell technology (ICT). Two methods are usually applied in ICT bioreactors: attachment of yeast to solid carriers for biofilm formation ; and forced physical entrapment of yeast cells into semi‐rigid matrices . For both of these methods the yeast carrier price often limits further applications of the technology.…”

Yeast Immobilization Systems for Alcoholic Wine Fermentations: Actual Trends and Future Perspectives

“…Most attempts were made for the utilization of alginate gels for the second fermentation in order to improve the technology of sparkling wine and have been commercially applied ( Busova et al, 1994 ; Colagrande et al, 1994 ; Fumi et al, 1988 ). Immobilization of yeasts in organic supports has also been successfully applied to the following: mead production ( Pereira et al, 2014 ), pomegranate winemaking ( Sevda and Rodrigues, 2011 ), wine made from the tropical fruit cagaita ( Oliveira et al, 2011 ), wine from Cabernet Sauvignon or Pinot noir grape varieties ( Andrade Neves et al, 2014 ), green beer production ( Wang et al, 1989 ), stout beer production ( Almonacid et al, 2012 ), lager-beer ( Naydenova et al, 2013 ), and cider ( Nedovic et al, 2000 ).…”