TITLE:
Vintage Effect on the Strain Dependent Dynamics of Ethanol Production in Vineries of Tokaj
AUTHORS:
Zoltán Kállai, Gyula Oros
KEYWORDS:
Yeast, Vinification, Mixed Fermentation, Ethanol Production, Dynamics, Tokaj
JOURNAL NAME:
Advances in Bioscience and Biotechnology,
Vol.12 No.1,
January
29,
2021
ABSTRACT: The dynamics of ethanol production of local strains
of three yeast species and their ternary mixtures was examined in two Tokaj
vineries. Although, the performance of them diverged significantly in first
etaps of vinification—up to the utilization of half of the sugar content of
grape juice—the variations vintages per vintages surpassed the strain-dependent
alterations. The divergence in the latter aspect diminished during the last
etap, and the ethanol concentration in young wines fermented by Saccharomyces
cerevisiae, S. uvarum and Starmerella bacillaris (2 local
strains of each) and their mixtures did not vary considerably (c.v. 4.2%). The
vinification of grape juice performed more rapidly in fermentors inoculated
with strains of S. cerevisiae, S. uvarum and St. bacillaris as well as with their mixtures than in spontaneously initiated ones by wild
mycoflora in each vintage. The strains responded in different manners to
conditions vintage per vintage, however, their ternary mixtures always
fermented more intensively the grape juice than the strains alone. The strains
affected the dynamics of alcohol production to different extents, but the alterations
between them exceeded the variation between the average effects of the species.
The circumstances of vinification significantly influenced the subsequent
events of fermentation, but the maximum intensity of ethanol production was
inversely proportional to the time required to start alcohol production (p > 0.05), similar to that
observed in the laboratory under strictly controlled micro-vinification
experiments. The maximum intensity of ethanol production (MIE) varied between
0.64 - 2.59 mM ethanol per hour.
The coefficients of second-order polynomial equations describing the dynamics
of alcohol production in both laboratory micro-scale and medium-scale experiments in cellars revealed similar
correlations regarding the interaction of factor groups regulating the
process: the constant (time-independent)
and secondary (time-dependent) coefficients of these polynomes counteracted to
the primary (time dependent) ones strictly in the strain-dependent manner, and
the role of these three factors groups varied also in a strain dependent manner
during the vinification process independently of the varying circumstances in
three vintages.