Giancarlo, MOSCHETTI1, Michele, MATRAXIA1, Rosario, PRESTIANNI1, Valentina, CRAPARO1, Vincenzo, NASELLI1, Paola VAGNOLI2, Sibylle KRIEGER-WEBER3, Giancarlo, MOSCHETTI1, Luca, SETTANNI1, Raimondo, GAGLIO1, Antonella, MAGGIO4, Antonio, ALFONZO1, Nicola, FRANCESCA1
1 Department of Agricultural, Food and Forestry Science, University of Palermo, Italy
2 Lallemand Italia, VR, Italy
3 Lallemand S.A., Korntal-Mu¨nchigen, Germany
4 Department of Biological, Chemical and Pharmaceutical Sciences and Technologies (STEBICEF), University of Palermo, Italy
Email contact: giancarlo.moschetti[@]unipa.it
AIM: Malolactic fermentation is a process of decarboxylation of L-malic acid into L-lactic acid and carbon dioxide that leads to deacidification, modification of odors and flavors of wines . Different LAB strains belonging to species Lactiplantibacillus plantarum and Oenococcus oeni are able to diversify wines under the sensory aspect after malolactic fermentation . In this context, the sensory impact of malolactic fermentation conducted on Nero d'Avola grape musts in Sicily using 4 commercial starters LAB was investigated.
METHODS: bunches of Nero d'Avola grapes, after destemming, were aliquoted into ten stainless steel tanks and inoculated with Saccharomyces cerevisiae NF213. Five trials were carried out in relation to the commercial LAB strain used for malolactic fermentation: ML PrimeTM (T13), Lalvin VP41® (T14), O-Mega® (T15) and PN4® (T16). ML PrimeTM was a commercial formulation based on L. plantarum, while Lalvin VP41®, O-Mega® and PN4® contained O. oeni. All LAB strains were added to the must after 24 h of yeast inoculum. An experimental control production was carried out in the absence of LAB starter. During fermentation, physicochemical and microbiological parameters were determined. Furthermore, through interdelta (yeast) and RAPD-PCR (LAB) analysis, the dominance of the starter was determined. After 15 days of maceration, the wines were racked and bottled. Six months after bottling, the volatile organic component was determined and the sensory evaluation of the experimental wines was performed.
RESULTS: A genotypic approach demonstrated a dominance of starter strains of yeast and LAB ranging from 88 to 92%. The initial content of L-malic acid in Nero d'Avola musts was 1.92 g/L. After 2 days from the addition of LAB, malic acid values were the lowest in T13, while in T14, T15 and T16 no significant reductions in malic acid were reached. At the end of alcoholic fermentation, trials inoculated with different strains of O. oeni (T14, T15 and T16) showed a degradation of malic acid up to 3 weeks after the end of alcoholic fermentation, reaching values lower than 0.3 g/L, whereas in T13 malic acid reached values of 0.6 g/L. In the control trial T17, no malolactic fermentations were recorded. VOC analysis allowed ascertaining the presence of alcohols, carboxylic acids and esters in higher quantities. Sensorial analysis showed a higher preference for trial T13, which obtained the highest results in terms of general acceptability. Slightly lower results were obtained in the other wines.
CONCLUSIONS: The use of L. plantarum improved the aromatic complexity of Nero d'Avola wines compared to those obtained with O. oeni. In this context, the use of ML PrimeTM certainly had a positive influence on several attributes, positively enhancing their sensory characteristics.