Advances in Bioscience and Biotechnology | 2021
Vintage Effect on the Strain Dependent Dynamics of Ethanol Production in Vineries of Tokaj
Abstract
The dynamics of ethanol production of local strains \nof three yeast species and their ternary mixtures was examined in two Tokaj \nvineries. Although, the performance of them diverged significantly in first \netaps of vinification—up to the utilization of half of the sugar content of \ngrape juice—the variations vintages per vintages surpassed the strain-dependent \nalterations. The divergence in the latter aspect diminished during the last \netap, and the ethanol concentration in young wines fermented by Saccharomyces \ncerevisiae, S. uvarum and Starmerella bacillaris (2 local \nstrains of each) and their mixtures did not vary considerably (c.v. 4.2%). The \nvinification of grape juice performed more rapidly in fermentors inoculated \nwith strains of S. cerevisiae, S. uvarum and St. bacillaris as well as with their mixtures than in spontaneously initiated ones by wild \nmycoflora in each vintage. The strains responded in different manners to \nconditions vintage per vintage, however, their ternary mixtures always \nfermented more intensively the grape juice than the strains alone. The strains \naffected the dynamics of alcohol production to different extents, but the alterations \nbetween them exceeded the variation between the average effects of the species. \nThe circumstances of vinification significantly influenced the subsequent \nevents of fermentation, but the maximum intensity of ethanol production was \ninversely proportional to the time required to start alcohol production (p > 0.05), similar to that \nobserved in the laboratory under strictly controlled micro-vinification \nexperiments. The maximum intensity of ethanol production (MIE) varied between \n0.64 - 2.59 mM ethanol per hour. \nThe coefficients of second-order polynomial equations describing the dynamics \nof alcohol production in both laboratory micro-scale and medium-scale experiments in cellars revealed similar \ncorrelations regarding the interaction of factor groups regulating the \nprocess: the constant (time-independent) \nand secondary (time-dependent) coefficients of these polynomes counteracted to \nthe primary (time dependent) ones strictly in the strain-dependent manner, and \nthe role of these three factors groups varied also in a strain dependent manner \nduring the vinification process independently of the varying circumstances in \nthree vintages.