Evolution of malolactic bacteria and biogenic amines during spontaneous malolactic fermentations in a Greek winery

Nitrogen Sources Added to Must: Effect on the Fermentations and on the Tempranillo Red Wine Quality

Nitrogen supplementation in musts or during the alcoholic fermentation is a common practice to promote fermentations. In this study, the impact of the supplementation of two different sources of nitrogen during Tempranillo red wine elaboration was studied. Mineral and organic nitrogen was added after the exponential yeast growth phase and during winemaking, examining its impact on the alcoholic and malolactic fermentation development, on the aromatic wine composition and on the nitrogenous wine composition. The nitrogen supplementation did not provide neither significant advantages in kinetics and fermentations time, nor differences in the chemical wine composition. The aromatic composition of the wines improved with the addition of inorganic nitrogen, although its organoleptic evaluation was not favored. Moreover, the concentration of amino acids in wines increased slightly after the malolactic fermentation and significantly during the stabilization time, especially with organic nitrogen addition. However, the synthesis of biogenic amines did not increase in wines neither after the malolactic fermentation, nor after the storage period.

Modifications of Phenolic Compounds, Biogenic Amines, and Volatile Compounds in Cabernet Gernishct Wine through Malolactic Fermentation by Lactobacillus plantarum and Oenococcus oeni

Malolactic fermentation is a vital red wine-making process to enhance the sensory quality. The objective of this study is to elucidate the starter cultures’ role in modifying phenolic compounds, biogenic amines, and volatile compounds after red wine malolactic fermentation. We initiated the malolactic fermentation in Cabernet Gernishct wine by using two Oenococcus oeni and two Lactobacillus plantarum strains. Results showed that after malolactic fermentation, wines experienced a content decrease of total flavanols and total flavonols, accompanied by the accumulation of phenolic acids. The Lactobacillus plantarum strains, compared to Oenococcus oeni, exhibited a prevention against the accumulation of biogenic amines. The malolactic fermentation increased the total esters and modified the aromatic features compared to the unfermented wine. The Lactobacillus plantarum strains retained more aromas than the Oenococcus oeni strains did. Principal component analysis revealed that different strains could distinctly alter the wine characteristics being investigated in this study. These indicated that Lactobacillus plantarum could serve as a better alternative starter for conducting red wine malolactic fermentation.

Saccharomyces cerevisiae mixed culture of blackberry (Rubus ulmifolius L.) juice: synergism in the aroma compounds production

Blackberry (Rubus sp.) juice was fermented using four different strains of Saccharomyces cerevisiae (Vitilevure-CM4457, Enoferm-T306, ICV-K1, and Greroche Rhona-L3574) recognized because of their use in the wine industry. A medium alcoholic graduation spirit (<6°GL) with potential to be produced at an industrial scale was obtained. Alcoholic fermentations were performed at 28°C, 200 rpm, and noncontrolled pH. The synergistic effect on the aromatic compounds production during fermentation in mixed culture was compared with those obtained by monoculture and physic mixture of spirits produced in monoculture. The aromatic composition was determined by HS-SPME-GC. The differences in aromatic profile principally rely on the proportions in aromatic compounds and not on the number of those compounds. The multivariance analysis, principal component analysis (PCA), and factorial discriminant analysis (DFA) permit to demonstrate the synergism between the strains.

Genetic and phenotypic strain heterogeneity within a natural population of Oenococcus oeni from Amarone wine

AIMS

To investigate the Oenococcus oeni population occurring during spontaneous malolactic fermentation (MLF) of Amarone wine, a peculiar and hostile environment for malolactic bacteria.

METHODS AND RESULTS

Pulsed-field gel electrophoresis (PFGE) analysis showed a high level of genetic heterogeneity within the O. oeni population involved in MLF throughout an industrial vinification of Amarone wine. The 13 strains with distinct PFGE profile displayed different capability to hydrolyse esters and glycosides, as well as great variability to growth under stress parameters, such as high ethanol content (15% v/v), low pH (3·0) and temperature (15°C), and presence of SO(2). Moreover, polymorphism in the gene sacB involved in exopolysaccharide production was observed among the strains. The strains showed differences to convert l-malic acid into l-lactic acid in wine.

CONCLUSIONS

The occurrence of spontaneous MLF in stressful ecosystems such as Amarone wine is related to the heterogeneity of O. oeni community; biodiversity indexes and strain evolution analyses suggested that its success depends on its initial strain evenness.

SIGNIFICANCE AND IMPACT OF THE STUDY

Remarkable intraspecies complexity within the O. oeni natural population could explain the great versatility of this species as key of successful adaptation to harsh winemaking conditions.

Assessment of the genetic polymorphism and biogenic amine production of indigenous Oenococcus oeni strains isolated from Greek red wines

In the warm climate country of Greece malolactic fermentation (MLF) has received limited attention. Molecular techniques and High Performance Liquid Chromatography (HPLC) were used to study the genetic polymorphism of autochthonous lactic acid bacteria developing towards the end of spontaneous MLF of Greek red wines and for the assessment of their potential to produce harmful biogenic amines. This research revealed that native Oenococcus oeni isolates are very much adapted to specific winery conditions since the majority of spontaneous MLF were driven mostly or exclusively by a single strain of O. oeni. Native O. oeni strains showed only limited dispersion since cluster analysis uncovered only few common genotypes among indigenous isolates from different wineries. The genotype of a frequently used malolactic starter was more than often detected among autochthonous isolates without nevertheless compromising the biodiversity of natural microflora residing in wineries but rather becoming a part of it. For the majority of the wine samples studied, MLF implementation and storage in bottles resulted in negligible changes on the levels of the BA histamine, tyramine, phenylethylamine, cadaverine as well as of ethylamine, methylamine, isobutylamine. We provide evidence that autochthonous O. oeni isolates can only contribute to putrescine accumulation in Greek wines but still the specific trait behaves as strain-specific with a limited dispersion.

Presence of lactic bacteria in the air of a winery during the vinification period

In this paper we have studied the presence and evolution in the winery air of the lactic bacteria responsible for malolactic fermentation. Sampling took place during the winemaking process (between September 2007 and July 2008) in a winery from the Rioja appellation in Spain. The results obtained indicated that the presence of these microorganisms in the atmosphere was detected when grapes were entering the winery, while malolactic fermentation was taking place, and when liquid containing bacteria was manipulated. The species and clones of the lactic bacteria identified were also related to those present in the vinification tanks at any given stage of the process.