Yeast interactions and wine flavour.

The winemaking process includes two main steps: lactic acid bacteria are responsible for the malolactic fermentation which follows the alcoholic fermentation by yeasts. Both types of microorganisms are present on grapes and on cellar equipment. Yeasts are better adapted to growth in grape must than lactic acid bacteria, so the alcoholic fermentation starts quickly. In must, up to ten lactic acid bacteria species can be identified. They belong to the Lactobacillus, Pediococcus, Leuconostoc and Oenococcus genera. Throughout alcoholic fermentation, a natural selection occurs and finally the dominant species is O. oeni, due to interactions between yeasts and bacteria and between bacteria themselves. After bacterial growth, when the population is over 106CFU/ml, malolactic transformation is the obvious change in wine composition. However, many other substrates can be metabolized. Some like remaining sugars and citric acid are always assimilated by lactic acid bacteria, thus providing them with energy and carbon. Other substrates such as some amino acids may be used following pathways restricted to strains carrying the adequate enzymes. Some strains can also produce exopolysaccharides. All these transformations greatly influence the sensory and hygienic quality of wine. Malic acid transformation is encouraged because it induces deacidification. Diacetyl produced from citric acid is also helpful to some extent. Sensory analyses show that many other reactions change the aromas and make malolactic fermentation beneficial, but they are as yet unknown. On the contrary, an excess of acetic acid, the synthesis of glucane, biogenic amines and precursors of ethylcarbamate are undesirable. Fortunately, lactic acid bacteria normally multiply in dry wines; moreover some of these activities are not widespread. Moreover, the most striking trait of wine lactic acid bacteria is their capacity to adapt to a hostile environment. The mechanisms for this are not yet completely elucidated. Molecular biology has provided some explanations for the behaviour and the metabolism of bacteria in wine. New tools are now available to detect the presence of desirable and undesirable strains. Even if much remains unknown, winemakers and oenologists can nowadays better control the process. By acting upon the diverse microflora and grape musts, they are more able to produce healthy and pleasant wines.

Lactic acid bacteria in the quality improvement and depreciation of wine

Scombroid poisoning: a review.

Biogenic amines have undesirable physiological effects when absorbed at too high a concentration. Several kinds of food and beverages contain biogenic amines. Lactic acid bacteria can decarboxylate amino acids. Since winemaking involves the growth of lactic acid bacteria for malolactic fermentation, biogenic amines may occur. However, not all bacterial strains carry these activities. In the same wine-producing area, some wines may contain very low amounts of biogenic amines while others may have relatively large quantities. It is now possible to detect the presence of undesirable histamine-producing strains by PCR test or DNA probe based on the presence of the gene encoding histidine decarboxylase. Other strains have the ornithine and/or tyrosine decarboxylase. When biogenic amine-producing strains are present, the winemaker is encouraged to inoculate selected malolactic starters to replace the indigenous microflora.

https://www.profpc.com.br/Qu%EDmica%20do%20Vinho/lactic_acid_bacteria.pdf

Biogenic amines in wines: role of lactic acid bacteria.

M.-L. NIKU-PAAVOLA, A. LAITILA, T. MATTILA-SANDHOLM AND A. HAIKARA. 1999.New types of antimicrobial compounds were identified in the culture filtrate of Lactobacillus plantarum VTT E-78076. Activity was detected in the low molecular mass fraction separated by gel chromatography. This fraction totally inhibited the growth of the Gram-negative test organism, Pantoea agglomerans (Enterobacter agglomerans) VTT E-90396. Characteristic compounds from this fraction were identified by GC/MS-analysis and the identification was confirmed using pure commercial reference compounds in identical chromatographs and in antimicrobial tests. The active fraction included benzoic acid (CAS 65‐85‐0), 5methyl-2,4-imidazolidinedione (CAS 616‐03‐5, methylhydantoin), tetrahydro-4hydroxy-4-methyl-2H-pyran-2-one (CAS 674‐26‐0, mevalonolactone) and 3-(2methylpropyl)-2,5-piperazinedione (CAS 5845‐67‐0, cyclo(glycyl-L-leucyl)). These compounds in concentrations of 10 ppm inhibited growth of the test organism by 10‐15% when acting separately, but 100% when all were applied together with 1% lactic acid. The inhibition was 40% by 1% lactic acid alone. The compounds were also active against Fusarium avenaceum (Gibberella avenacea) VTT D-80147. The inhibition was 10‐15% by separate compounds in concentrations of 10 ppm and maximally 20% in combinations. Fungal growth was not inhibited by lactic acid. Inhibition by unfractionated Lact. plantarum culture filtrate was 37% and by the low molecular mass fraction, 27%.

New types of antimicrobial compounds produced by Lactobacillus plantarum

Populations of Leuconostoc oenos were harvested from wines containing a relatively high concentration of biogenic amines. Cultivation of the biomass in synthetic media and wine showed that it consisted of histamine-producing strains. Histamine levels after culture depended on the quantity of precursor available and on the presence of yeast lees, which certainly enriched the medium in histidine. Ethanol and pH, which control bacterial growth rate and total population, were also significant factors: pH and low ethanol concentration enhanced histamine production. Strain Leuc. oenos 9204 was isolated and studied since it retained its ability to produce histamine after several transfers. In synthetic medium this strain produced large amounts of histamine especially in the poorest nutritional conditions (no glucose, no L-malic acid). These results clearly demonstrate that Leuc. oenos involved in wine-making might play a role in biogenic amine production. The vinification method might also influence the final amine concentration in wine.

Histamine production by wine lactic acid bacteria: isolation of a histamine-producing strain of Leuconostoc oenos.

In addition to ethanol, the fermentation of grape must by yeasts produces fatty acids as secondary metabolites which inhibit growth of lactic acid bacteria. The degree of inhibition depends upon the fatty acid concentration and chain length and on the composition of the medium.

Inhibition of malolactic fermentation of wines by products of yeast metabolism

A. LONVAUD-FUNEL, A. JOYEUX AND O. LEDOUX. 1991. Total DNA extracted from lactic acid bacteria commonly found in musts and wines was randomly labelled with digoxigenin. It was assayed for the detection of several species by dot-blot hybridization. The method proved to be specific as there was no cross-hybridization between most of the species belonging to the genera Leuconostoc, Pediococcus and Lactobacillus, homofermentative and heterofermentative (Lact. plantarum, Lact. casei, Leuc. mesenteroides, Leuc. oenos, Ped. damnosus, Ped. pentosaceus). However, it failed for some Lact. brevis strains which strongly hybridized with Lact. hilgardii.



Colony hybridization was performed directly on plates soon after enumeration. Eight probes of the most common species were used; it was possible to follow the evolution of each species during the vinification of two red wines. According to the phase of alcoholic fermentation, then malolactic fermentation, the predominance or regression of bacilli and cocci could be established.

https://sfamjournals.onlinelibrary.wiley.com/doi/pdf/10.1111/j.1365-2672.1991.tb03824.x

Annick Joyeux

Papers

Histamine production by wine lactic acid bacteria: isolation of a histamine-producing strain of Leuconostoc oenos.

Inhibition of malolactic fermentation of wines by products of yeast metabolism

Specific enumeration of lactic acid bacteria in fermenting grape must and wine by colony hybridization with non-isotopic DNA probes

Antagonism between lactic acid bacteria of wines: inhibition of Leuconostoc oenos by Lactobacillus plantarum and Pediococcus pentosaceus

Speciation of lactic acid bacteria from wines by hybridization with DNA probes