Impact of malolactic fermentation on volatile composition and sensory properties of white and rosé wine from the greek variety moschofilero

Abstract

Moschofilero is a native grape variety, classified as a ‘gris’ type variety, that is cultivated in PDO Mantineia, Peloponissos, Greece. It is used for the production of both white and rosé wines. Due to high altitude of the vineyards, the harvest is done by mid October, and many vintages are characterised by high acidities and low pH values. Besides that, Moschofilero wines record usually low alcohol levels and thus these wines lack body and generally are considered to be ‘medium’ to ‘low’ body wines. The aim of our work was on one hand to evaluate the impact of three different O. oeni strains, to qualitative characteristics of Moschofilero white and rose wine and to check if MLF boosts the mouthfeel of the wines. Laboratory scale alcoholic fermentation (AF) monitoring was performed every day by density measurements, while malic acid degradation was measured with the RQflex reflectometer. Two different S. cerevisiae strains were used to perform AF and three commercial strains of O. oeni for MLF. Classical wine analyses (acidity, sulfite, residual sugars) and organic acid composition (tartaric, malic, citric, lactic, succinic and acetic acid) were performed in all wines after MLF. Fermentative volatile compounds (esters and superior alcohols) were determined by SPME followed by GC–MS and diacetyl concentration was analysed by GC-ECD. All produced wines were evaluated sensorially. All O. oeni strains could perform MLF and degrade the malic acid (2.5 g/L) but had a different effect on wine composition. The major variation was observed for the acetic acid (0.25 g/L, 0.35 g/L and 0.45 g/L respectively for the three strains) as also for the diacetyl production (max 1.5±0.5 mg/L). The volatile compounds levels were found to be slightly different in the produced wines and strain effect was observed for both, bacterial and yeast species. The effect of malolactic fermentation to Moschofilero white and rosé wines depends on the bacterial strains as well as the yeast strain used for alcoholic fermentation. MLF can lead to decreased grassy character, boost the fruity notes and improve the wine mouthfeel, depending on the strain used.