The malolactic fermentation in the wines of Naoussa (Greece). Study of lactic acid bacteria

The red wine« Appellation d'Origine Naoussa de qualité supérieure » stemming from the « Xynomavro » vine cultivated in this wine-growing region of western Macedonia (Greece) needs the advantages coming of malolatic fermentation. This wine, in spite of its incontestable qualities has a strong astringent and a high level of acidity, the malic acid contributing essentially to these two characters.Because of the interest malolactic fermentation presents for this region, we have collaborated with the wine-producters to insure, at first, the generally admitted conditions which favour the evolution of malolactic fermentation, then to study it.The latter includes : a) the control of the conversion of malic acid into lactic acid by chromatography paper and b) the enumeration, isolation and identification of lactic acid bacteria.During this two-year-long research, 187 samples have been taken from 50 different tanks during 12 samplings. The isolation of lactic acid bacteria was done by plating dilutions of wine samples and their identification with the API system and other physico-chemical and enzymatic methods.Data processing has been done by computer and given a strain group distribution according to their similarity.The results show that the homofermentative lactic acid bacteria - mainly Lactobacillus plantarum - are more numerous than the heterofermentative ones before the malolactic fermentation. They decrease during the fermentative process and disappear with its completion.The heterofermentative lactic aeid baeteria, whose main specie is Leuconostoc oenos evolves inversely.A low increase of Pediococcus has been observed too after the beginning of malolactic fermentation. A statistical analysis confirms the main points of this research.The application of malolactic fermentation becomes more efficient the second year; it is favoured in press-wines and for temperatures kept at 20-25°C; the bacteria population is also increased.The persued reduction of total acidity in wines, which underwent malolactic fermentation, was considerable.