Screening low-methanol and high-aroma produced yeasts for cider fermentation by transcriptive characterization

Abstract

The commercial active dry yeast strains used for cider production in China are far behind the requirements of the cider industry development in recent decades. In this study, eight yeasts, including Saccharomyces cerevisiae, Schizosaccharomyces pombe, Pichia bruneiensis, and Pichia kudriavzevii, were screened and assessed by growth performance, methanol production, aroma analysis, and their transcriptive characterization. Saccharomyces cerevisiae strains WFC-SC-071 and WFC-SC-072 were identified as promising alternatives for cider production. Strains WFC-SC-071 and WFC-SC-072 showed an excellent growth capacity characterized by 91.6 and 88.8% sugar utilization, respectively. Methanol production by both strains was below 200 mg/L. Key aroma compounds imparting cider appreciably characteristic aroma increased in cider fermented by strains WFC-SC-071 and WFC-SC-072. RT-qPCR analysis suggested that most genes associated with growth capacity, carbohydrate uptake, and aroma production were upregulated in WFC-SC-071 and WFC-SC-072. Overall, two Saccharomyces cerevisiae strains are the optimal starters for cider production to enable the diversification of cider, satisfy the differences in consumer demand, and promote cider industry development.

Isolation and identification of non‐Saccharomyces yeasts and their flavour characteristics while brewing Yinhong plum wine

“…Selected yeast strains were inoculated separately on YPD solid medium and plum fermentation medium and cultured for 3 days in a constant temperature incubator at 28°C. Subsequently, eight professionally trained assessors (four males and four females) conducted olfactory evaluation 16 to assess the flavour of the medium and fermentation broth. They rated their liking of the sample taste on a scale of 1 to 5, where 1 indicated dislike, 2 indicated tolerance, 3 indicated like, 4 indicated very much like and 5 indicated extremely like.…”

Screening ester-producing yeasts to fortify the brewing of rice-flavor Baijiu for enhanced aromas

“…Osmotolerant yeasts could be screened from high sugar niches, such as molasses, grape must, sugar juice, and syrup, under media with high sugar concentrations [ 5 , 6 ]. The low-methanol and high aroma-producing yeasts could be obtained from samples of Maotai (Guizhou) and Xifeng distilleries (Shaanxi, China) after enrichment under YEPD medium containing apple squares, purification on the YEPD agar plates, and sensory evaluation of resultant cider [ 7 ]. Both Daqu and Xiaoqu are the Kojis and widely applied for the production of fermented foods because of a lot of microorganisms involved that can produce enzymes for starch hydrolysis and aromas production [ 8 ].…”