Field‐Flow Fractionation as Analytical Technique for the Characterization of Dry Yeast: Correlation with Wine Fermentation Activity

Abstract

Important oenological properties of wine depend on the winemaking yeast used in the fermentation process. There is considerable controversy about the quality of yeast, and a simple and cheap analytical methodology for quality control of yeast is needed. Gravitational field flow fractionation (GFFF) was used to characterize several commercial active dry wine yeasts from Saccharomyces cerevisiae and Saccharomyces bayanus and to assess the quality of the raw material before use. Laboratory-scale fermentations were performed using two different S. cerevisiae strains as inocula, and GFFF was used to follow the behavior of yeast cells during alcoholic fermentation. The viable/nonviable cell ratio was obtained by flow cytometry (FC) using propidium iodide as fluorescent dye. In each experiment, the amount of dry wine yeast to be used was calculated in order to provide the same quantity of viable cells. Kinetic studies of the fermentation process were performed controlling the density of the must, from 1.071 to 0.989 (20/20 density), and the total residual sugars, from 170 to 3 g/L. During the wine fermentation process, differences in the peak profiles obtained by GFFF between the two types of commercial yeasts that can be related with the unlike cell growth were observed. Moreover, the strains showed different fermentation kinetic profiles that could be correlated with the corresponding fractograms monitored by GFFF. These results allow optimism that sedimentation FFF techniques could be successfully used for quality assessment of the raw material and to predict yeast behavior during yeast-based bioprocesses such as wine production.

Determination of Viable Yeast Cells by Gravitational Field‐Flow Fractionation with Fluorescence Detection

“…Since 1999, our group has studied yeast strains in wine production, and we have recently developed new methodologies for the characterization of commercial ADWY using FFF (13, 17–20). As demonstrated in a previous work (21), differences in GrFFF peak profiles between commercial yeast strains during fermentation can be related to the different cell growth stage. Moreover, different fermentation kinetic profiles were established from the fractogram changes monitored by GrFFF.…”

Monitoring of Mixed Culture of Saccharomyces cerevisiae and Acetobacter aceti Using Gravitation Field-flow Fractionation and Gas Chromatography

“…GrFFF provides sizebased separation with larger particles eluting earlier than smaller ones. 11,12 GrFFF has been applied for characterization of yeast cells 13,14 as well as to the study of viability and activity of S. cerevisiae strains during fermentation 15,16 GrFFF elution band area can be used as a measure of particle content (or concentration), and thus can be used for monitoring of change in population of cells during incubation.…”

Kinetic Study of Cell Proliferation of Saccharomyces cerevisiae Strains by Sedimentation/Steric Field Flow Fractionation in Situ

“…Classical biochemical methods are not suitable for characterization and kinetic study of the S. cerevisiae strains (2). In the past few years the Field Flow Fractionation technique has been applied for the characterization of yeast cells (3)(4)(5)(6)(7), as well as the study of the viability and activity of S. cerevisiae strains during wine fermentation (8,9).…”