Microbiological and chemical monitoring of Marsala base wine obtained by spontaneous fermentation during large-scale production

The present work was undertaken to evaluate the effect of the natural winemaking onthe microbial and chemical composition of Marsala base wine. To this purpose, alarge-scale vinification process of Grillo grape cultivar was monitored from harvestingto the final product. Total yeasts (TY) showed a rapid increase after must pressing andreached values almost superimposable to those registered during the conventionalwinemakings. Lactic acid bacteria (LAB) were registered at the highest levelssimultaneously to yeast growth at the beginning of the process. Saccharomycescerevisiae was the species found at the highest concentrations in all samplesanalysed. Several strains (n= 16) was registered at high levels during the alcoholicfermentation and/or aging of wine; only two of them were detected on the grapesurface. Lactobacillus plantarum was the LAB species most frequently isolated duringthe entire vinification process. Ethanol content was approximately 14% (v/v) at the endof vinification. The value of pH did not greatly vary during the process and the volatileacidity (VA) was detected at low concentrations during the entire transformation. Theconcentration of malic acid rapidly decreased during the AF; on the other hand, lacticacid showed an irregular trend during the entire process. trans-caffeil tartaric acid wasthe most abundant hydroxycinnamoyl tartaric acid and volatile organic compounds(VOC) were mainly represented by isoamylic alcohol and isobutanol.