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A simple and reliable method for the quantitative evaluation of anthocyanin adsorption by wine yeasts

Echeverrigaray, Sergio, Menegotto, Morgana, Delamare, Ana Paula Longaray
Journal of microbiological methods 2019 v.157 pp. 88-92
adsorption, anthocyanins, biomass, breeding programs, cell walls, color, fermentation, grape must, grapes, quantitative analysis, screening, wine yeasts, wines
Yeast pigments adsorption can modify wine color intensity and is considered an important trait in wine yeasts. The existing methods for the evaluation of yeast adsorption are laborious, time consuming, need confirmation experiments, or are difficult to apply for a large number of strains generated in breeding programs. In this study, a new test is proposed to measure yeast pigments adsorption and wine color in a single experiment. The optimized method included the microfermentation of grape musts obtained by thermal extraction, digital determination of yeast biomass color, and spectrophotometric wine intensity evaluation. Results showed significant negative correlation between yeast pigments adsorption and wine color intensity. Pigments adsorption occurs from the middle to the end of fermentation, indicating cell wall changes and/or anthocyanins modifications over the process. Significant differences were observed on anthocyanins adsorption and wine intensity among yeast strains independent of the grape variety, and yeasts could be grouped as low, medium and high adsorption strains. The proposed method showed high reproducibility and allows the concomitant screening of hundreds of yeast strains in a short period of time.