Genetic and physiological characterization of yeast isolated from ripe fruit and analysis of fermentation and brewing potential

Abstract

'Wild' and spontaneously fermented beers are growing in popularity in the craft beer industry. Most of these beers are fermented by the use of either pure cultures of unconventional yeast and bacteria or spontaneous fermentation using mixed local microflora. This study examined the potential of using pure strains of new isolates of wild yeast in the fermentation of a unique beer. The microbial communities from the fruit of pindo palm, loquat, hackberry and blackberry were collected in liquid culture, then plated for isolation. Ten isolates were selected for further analysis. Strains were identified by restriction fragment length polymorphism (RFLP) analysis and analysed for growth in a simple liquid media, fermentation in a complex media, alcohol tolerance and acid tolerance. Despite identification of some strains as the same species, they displayed a wide range of physiological properties. All strains were tolerant of pH values as low as 2.4, but none were tolerant of pH 1.9. Alcohol tolerance of different strains varied from 6 to 12%. Several strains had properties that suggest potential as primary fermenters, including the alcohol fermentation of a beer wort. Organoleptic properties of beers fermented with several of the strains demonstrated potential for commercial brewing.

Analysis of Growth Inhibition and Metabolism of Hydroxycinnamic Acids by Brewing and Spoilage Strains of Brettanomyces Yeast

“…Eight strains were isolated from environmental sources. Strains 1–4, 6, and 7 were previously described isolates from ripe fruit [26]. Strains 5 and 8 are new isolates from Florida seagrape ( Coccoloba uvifera ) and blueberry ( Vaccinium sp.…”

“…Commercial strains are deemed suitable for brewing as advertised. The environmental isolates were used to brew pilot batches and judged by experienced tasters [26]. Strain 6 has been used routinely by a microbrewery for 100% Brettanomyces fermentations.…”

Review: Pure non‐Saccharomycesstarter cultures for beer fermentation with a focus on secondary metabolites and practical applications

“…This is a result of an increased global interest in craft beer and larger brewers seeking different yeasts, often non-traditional yeasts, to innovate new beers. However, since non-Saccharomyces yeasts represent undomesticated strains, their fermentation characteristics can be variable and they can affect the consistency and quality of the produced beers (5,8). However, since non-Saccharomyces yeasts represent undomesticated strains, their fermentation characteristics can be variable and they can affect the consistency and quality of the produced beers (5,8).…”

“…Wild and undomesticated non-Saccharomyces yeast strains can provide different aroma and flavour characteristics that result in alternative and new beer variations and styles (6). In contrast to non-Saccharomyces strains, the domestication of Saccharomyces yeasts for brewing has taken several millennia for brewers to produce consistent beers and control more desirable aromas, flavours and fermentation conditions (1,5,9). In contrast to non-Saccharomyces strains, the domestication of Saccharomyces yeasts for brewing has taken several millennia for brewers to produce consistent beers and control more desirable aromas, flavours and fermentation conditions (1,5,9).…”

Identification and Characterization of Yeast Strains Associated With the Fermented Rice Beverages of Garo Hills, Meghalaya, India

“…NGL4A NGL1B RNS4C RNS1C RNL1A In the present study, primer ITS1 and ITS4 were used for amplification conserved regions of 5.8S rDNA, resulted in product of >1.5kb fragments confirming that the isolate was yeast (Table 2). Similarly, Esteve-Zarzoso et al, (1999) and Lentz et al, (2014) also used 5.8S rDNA for the strains identification upto the species level. The tentative phenotypic identification of all six isolates was confirmed by genotypic characterization in which 5.8S rDNA sequence analysis of these isolates as NGL3A, NGL4A, NGL1B and RNS4Cconfirmed the strains S. cerevisiae, whereas rest two isolates were identified as W. anomalus (RNL1A) and R. Mucilaginosa (RNS4C).The electrophenogram data for 5.8S rDNA sequence was validated using Chromas 2.33 software.…”