Modeling of Saccharide Utilization in Primary Beer Fermentation with Yeasts Immobilized in Calcium Alginate

Abstract

Immobilized beer fermentation was studied using an industrial bottom-fermenting yeast strain Saccharomyces cerevisiae. The yeast cells were immobilized in 2.5% calcium alginate gel and used for brewing in a five-vessel cascade reactor. The fermentation was performed at 15 degrees C at various flow rates. A nonstructured mathematical model was developed to simulate the performance of continuous primary fermentation of lager beer. The model was based on the following variables: maltose, maltotriose, glucose, fructose, ethanol, and cell concentration. Experimental values of these variables were determined in samples taken at regular intervals. For experimental data fitting a nonlinear regression was used. Substrate consumption was characterized by specific substrate consumption rate and saturation constant. The values of these two parameters were optimized for all four substrates. Inhibition effects of substrates and product were analyzed using various inhibition patterns. Only the inhibition effect of maltose on maltose consumption was clearly identified. A good-fitting relationship for maltose inhibition was found, and inhibition constants were calculated.

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

“…Others authors have published similar values (Tanaka et al 1984;Hannoum and Stephanopoulos 1986). Parameters r M and K, used in the design, were those reported by Smogrovicova et al (2001) for beer fermentation with immobilized yeast into alginate (r M =0.35 g/g DW h and K=19.4 g/L). Then, the design variable "X O " was calculated in 25 g DW /L.…”

“…However, if no diffusional restriction is present, one can estimate the glucose uptake (first fermentable sugar for yeast consume) as follows (Smogrovicova et al 2001):…”

“…Parameters r M and K were those reported by Smogrovicova et al (2001) for immobilized beer fermentation.…”

“…The microcapsules were left 1 h in a calcium solution and washed them in sterile distilled water (Smogrovicova et al 2001). Then, a sample of ten microcapsules was inspected with a microscope that was adapted with a digital camera (Nikon, Tokyo, Japan).…”

“…This has attracted much attention during the last few decades. Various systems of immobilized fermentation have been developed and used (Pilkington et al 1998;Smogrovicova et al 1997): attachment to a surface (Cashin 1996;Van Iersel et al 1998Reddy et al 2010), self aggregation (Karel et al 1985), or entrapment within a porous support, e.g., gel microencapsulation, in which food-grade alginate is the main biopolymer used for that purpose (Nedovic et al 2001;Smogrovicova et al 2001).…”