Hybridization within Saccharomyces Genus Results in Homoeostasis and Phenotypic Novelty in Winemaking Conditions.

Despite its biotechnological interest, hybridization, which can result in hybrid vigor, has not commonly been studied or exploited in the yeast genus. From a diallel design including 55 intra- and interspecific hybrids between Saccharomyces cerevisiae and S. uvarum grown at two temperatures in enological conditions, we analyzed as many as 35 fermentation traits with original statistical and modeling tools.

Determination of biogenic amines in wine by thin-layer chromatography/densitometry.

Biogenic amines are small-molecular-weight organic bases that can be encountered in all fermented foods, including wine. Ingestion of wine containing biogenic amines, and especially histamine, can result in health nuisances. HPLC is the analytical technique most often employed in the determination of biogenic amines in wine but HPLC-based methods are expensive and time-consuming.

Identification of impact odorants contributing to fresh mushroom off-flavor in wines: incidence of their reactivity with nitrogen compounds on the decrease of the olfactory defect.

Analysis of wines from different grape varieties marked by sometimes intense aromatic nuances of fresh mushroom was performed by gas chromatography coupled with olfactometry. This analysis has led to the identification of several odoriferous zones, which were recalling a fresh mushroom odor. Two trace compounds responsible for these odoriferous zones, 1-nonen-3-one and 1-octen-3-one, have been identified and their content has been determined by using either a multidimensional gas chromatography technique coupled to olfactometry and mass spectrometry detection (in the case of 1-nonen-3-one) or the preparation of the derivative with O-2,3,4,5,6-pentafluorobenzylhydroxylamine hydrochloride in the presence of the deuterated form, as the internal standard (in the case of 1-octen-3-one), then gas chromatography coupled to mass spectrometry detection.

Impact of the Botrytis cinerea strain and metabolism on (-)-geosmin production by Penicillium expansum in grape juice.

Geosmin, an off-flavour of some rotten grapes, has been implicated in wine defects. Botrytis cinerea and Penicillium expansum were the most common among the numerous microorganisms isolated from rotten grapes. P.

Characterization of some mushroom and earthy off-odors microbially induced by the development of rot on grapes.

Grape rot is one of the major causes of degradation of many grape components and, thus, of deterioration in wine quality. In particular, the association of Botrytis cinerea with other, less visible, fungi frequently leads to the development of organoleptic defects in grapes and sometimes in wines. This study examines the nature of the volatile compounds responsible for mushroom, mossy, or earthy odors detected by gas chromatography-olfactometry in organic extracts of rotten grapes and musts.

A CAPS test allowing a rapid distinction of Penicillium expansum among fungal species collected on grape berries, inferred from the sequence and secondary structure of the mitochondrial SSU-rRNA.

Penicillium expansum is a fungal species highly damageable for the postharvest conservation of numerous fruits. In vineyards, this fungus is sometimes isolated from grape berries where its presence may lead to the production of geosmin, a powerful earthy odorant, which can impair grapes and wines aromas. However, the discrimination of P.

Origin of (-)-geosmin on grapes: on the complementary action of two fungi, botrytis cinerea and penicillium expansum.

One of the consequences of rot on grapes is the development of volatile compounds giving fungal, mouldy or earthy odours. Among these compounds, (-)-geosmin (trans-1,10-dimethyl-trans-9-decalol), a powerful aromatic compound with an earthy smell is a persistent defect in grape juice and wines made with at least partially rotten grapes. A microbiota analysis of rotten grapes containing (-)-geosmin was carried out on sites from four French regions from 1999 to 2002, to clarify the involvement in geosmin appearance of Streptomyces spp.

Characterization of Penicillium species isolated from grape berries by their internal transcribed spacer (ITS1) sequences and by gas chromatography-mass spectrometry analysis of geosmin production.

Geosmin (trans-1,10-dimethyl-trans-9-decalol), an earthy-musty compound, has been identified in wines and in grape juice, in which its presence is highly detrimental to the aromatic quality. Geosmin has a biological origin, and the analysis of rotten grape microflora has been done on two grape varieties (Semillon, Cabernet Sauvignon) from six parcels of the Bordeaux region over 3 years (1999, 2000, 2001). Forty-three Penicillium-related species have been analyzed by gas chromatography-mass spectrometry (GC-MS) for their geosmin production.