Formation of flavor components by the reaction of amino acid and carbonyl compounds in mild conditions.

This work describe products of reactions between four alpha-dicarbonyl compounds (diacetyl, pentan-2,3-dione, glyoxal, and methylglyoxal) or two alpha-hydroxy ketones, (acetoine and acetol) and amino acids present in wines. The results shows the formation of odorous products or strong-smelling additives resulting from the Maillard and Strecker reaction in a primarily aqueous medium, at low temperature and low pH ( approximately pH 3.5) of the wine.

Role of carbonyl compounds in SO(2) binding phenomena in musts and wines from botrytized grapes.

Carbonyl compounds play an important role in musts from botrytized grapes. Some of them, such as glyoxal and methylglyoxal, may explain a considerable part of bindable SO(2). Others, such as 2- and 5-oxogluconic acids, produced by gluconic acid oxidation in proportions respectively from 2.

Isolation, properties and behaviour of tyramine-producing lactic acid bacteria from wine.

Wines containing high levels of biogenic amines were investigated for the presence of tyramine-producing strains. Two different Lactobacillus brevis (IOEB 9809 and IOEB 9901) able to produce the amine were isolated. None of the isolated strains identified as Oenococcus oeni formed tyramine.

Contribution to the knowledge of malolactic fermentation influence on wine aroma.

In this work, we study two aspects of malolactic fermentation: the use of industrial lactic acid bacteria starter-cultures in a white Sauvignon wine and the effects of the bacterial activity on the composition of wines in terms of volatile substances from oakwood during partial malolactic fermentation in barrels. A sensory evaluation was made by the use of discriminative and descriptive methods. The consequences of bacterial development are thus limited, but it is nevertheless possible to make characteristic observations.

Tyrosine decarboxylase activity of Lactobacillus brevis IOEB 9809 isolated from wine and L. brevis ATCC 367.

Tyramine, a frequent amine in wines, is produced from tyrosine by the tyrosine decarboxylase (TDC) activity of bacteria. The tyramine-producing strain Lactobacillus brevis IOEB 9809 isolated from wine and the reference strain L. brevis ATCC 367 were studied.

Lactic acid bacteria in the quality improvement and depreciation of wine.

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.

Aa-Pri2, a single-copy gene from Agrocybe aegerita, specifically expressed during fruiting initiation, encodes a hydrophobin with a leucine-zipper domain.

The Aa-Pri2 gene, specifically expressed during basidiocarp differentiation of the mushroom Agrocybe aegerita, was cloned. Sequence analysis showed a 525-nt ORF interrupted by three introns (51, 48, 54 bp). One TATA box (-94), two CAAT boxes (-382, -398) and one CT-rich motif (-149) were present.

Cloning and sequencing of the Aa-Pri1 gene specifically expressed during fruiting initiation in the edible mushroom Agrocybe aegerita, and analysis of the predicted amino-acid sequence.

A gene (Aa-Pri1) specifically expressed during fruiting initiation of the basidiomycete Agrocybe aegerita was cloned. The total length of the Aa-Pri1 gene was 492 bp including a class-II intron of 54 bp size located at nt +125; the open reading frame encoded for a 145-aa protein of 16 093 Da. CCAAT (-156) and TATAAAT (- 83) boxes, and T(A)5T(A)2 (+593) and T(A)3T(A)4T(A)6T (+608) putative polyadenylation sequences were identified.