Increasing the Production of β-Glucan from Saccharomyces carlsbergensis RU01 by Using Tannic Acid

In this study, we increased β-glucan production from brewer’s yeast, Saccharomyces carlsbergensis RU01, by using tannic acid. High-pressure freezing and transmission electron microscopy (HPF-TEM) revealed that the yeast cell wall obtained from yeast malt (YM) medium supplemented with 0.1% w/v tannic acid was thicker than that of yeast cultured in YM medium alone. The production of β-glucan from S. carlsbergensis RU01 was optimized in 3% w/v molasses and 0.1% w/v diammonium sulfate (MDS) medium supplemented with 0.1% w/v tannic acid. The results showed that MDS medium supplemented with 0.1% w/v tannic acid significantly increased the dry cell weight (DCW), and the β-glucan production was 0.28±0.01% w/v and 11.99±0.04% w/w. Tannic acid enhanced the β-glucan content by up to 42.23%. β-Glucan production in the stirred tank reactor (STR) was 1.4-fold higher than that in the shake flask (SF) culture. Analysis of the β-glucan composition by Fourier transform infrared (FTIR) spectroscopy showed that the β-glucan of S. carlsbergensis RU01 cultured in MDS medium supplemented with 0.1% w/v tannic acid had a higher proportion of polysaccharide than that of the control. In addition, β-glucans from brewer’s yeast can be used as prebiotic and functional foods for human health and in animal feed.

Fruit preservation with bioethanol obtained from the fermentation of brewer’s spent grain with Saccharomyces carlsbergensis

Brewer’s Spent Grain (BSG) is renewable lignocellulosic biomass generated from the beer brewing process. It serves as a substrate for various biotechnological applications. BSG was used as the main substrate for bioethanol production with Saccharomyces carlsbergensis in submerged fermentation. Saccharification and fermentation studies were performed for the production of bioethanol. A sterilized fermenter was loaded with 50 g L-1 of BSG at 29±2 °C and an agitation speed of 180 rpm. pH was adjusted to 6.0 before the addition of 500 mL of yeast culture for 7 days under submerged and optimized conditions. The fermented product was concentrated using a rotary evaporator at 66±1 °C, and ethanol was qualitatively determined by the dichromate method. Bioethanol yield was 22%, with a specific gravity of 0.8 at 28 °C. Fourier-Transform Infrared Spectroscopy (FTIR) confirmed the presence of -CH3 stretch, -OHstretch and -CH2stretch in bioethanol. For the preservative test, Staphylococcus spp., Erwinia spp., Lactobacillus spp., Bacillus spp., Xanthomonas spp., Pseudomonas spp., Micrococcus spp. and Corynebacterium spp. were the bacteria isolated from fruits examined from different regions of Osun State. The genera of fungi isolated were Aspergillus, Colletotrichum, Penicillium, Fusarium, Alternaria, Rhizopus, Candida, Saccharomyces, Geotrichium and Pichia. Bioethanol produced from BSG inhibited the growth of microorganisms with zones of inhibition range from 7.0 mm to 11.5 mm, and thus, selected fruits were preserved. Hence, the fermentation technology of agro-industrial wastes with microorganisms can be adopted to convert waste biomass to useful resources.

Yeast selection for non-alcoholic and low-alcoholic beverages based on wort

A series of wort fermentations with eight yeast strains were carried out in laboratory conditions. The strains used were: Saccharomyces cerevisiae (2 strains), Saccharomyces diastaticus (3 strains), Saccharomyces carlsbergensis (1 strain), Saccharomyces lactis (1 strain), Saccharomyces sake gekkeikan (1 strain). Selection of yeast strains has been performed in order to study the possibilities for their aplication to obtain fermentable non-alcoholic and low-alcoholic beverages based on wort. Three yeast strains (two of Saccharomyces cerevisiae and one Saccharomyces diastaticus), were selected based on their good growth in the used medium and the pleasant organoleptic profile formed as a result of the fermentation carried out. The accumulated alcohol values varied between 0.05 and 0.22 % (w/w).