Macrowine 2021
IVES 9 IVES Conference Series 9 Glutathione content evolution during spontaneous alcoholic fermentations of Sangiovese grapes

Glutathione content evolution during spontaneous alcoholic fermentations of Sangiovese grapes

Abstract

Glutathione is a tripeptide (γ-Glu-Cys-Gly), which can occur in grapes, in must and in wine prevalently in the reduced form as well as in the oxidized form as glutathione disulfide. The importance of the reduced form of glutathione lies in its antioxidant activity. In must, it limits browning by reducing o-quinones produced by polyphenol oxidase activity on hydroxycinnamic acids; in wine, it exerts a protective effect on various aromatic compounds. Glutathione concentration in wine is lower than in grape juice and variable as it depends on several factors, ranging from the native content of grapes to winemaking technique. During alcoholic fermentation, Saccharomyces cerevisiae metabolism modifies to different extent the native concentration of glutathione in must, depending on the strain. In this study, the evolution of the glutathione content during three spontaneous alcoholic fermentations of Sangiovese grapes (vintage 2015), carried out at commercial-scale in a winery located in Val d’Orcia (Tuscany), was monitored. From a microbiological point of view, S. cerevisiae dominated all the fermentation phases, since non-Saccharomyces yeast did not reach significant population densities. However, a great intraspecific genetic diversity was found within the S. cerevisiae populations. In freshly pressed musts, glutathione concentration ranged from 4 to 7mg/L, and consisted predominantly of the oxidized form. During alcoholic fermentation, glutathione concentration resulted highly variable: in the first days, in correspondence of yeast exponential growth phase, it decreased, possibly due to the consumption of glutathione by yeast cells in the active growth phase; successively, glutathione content increased until the end of alcoholic fermentation, suggesting a glutathione release from yeast cells in correspondence to cell autolysis into the wine; at the end of alcoholic fermentation, glutathione contents of wines ranged from 19 to 23mg/L, and the reduced form represented about 60% of the total. The results suggest that the final glutathione concentration in wine is mostly dependent on the amount of glutathione released by yeast cells rather than on that derived from grapes at the vintage.

Publication date: May 17, 2024

Issue: Macrowine 2016

Type: Poster

Authors

Silvia Mangani*, Eleonora Mari, Giacomo Buscioni, Martina Cerretelli, Massimo Vincenzini, Simona Guerrini, Yuri Romboli

*Food Micro Team

Contact the author

Tags

IVES Conference Series | Macrowine | Macrowine 2016

Citation

Related articles…

Anthropogenic factors in modulations of fungal populations from grapes to wines and their repercussions on wine characteristics

The effects of anthropogenic activities on vineyard (different plant protections) and in winery
(pressing/clarification step, addition of sulfur dioxide) on fungal populations from grape to wine were studied. The studied anthropogenic activities modify the fungal diversity. Thus, lower biodiversity of grapes from organic modality was measured for the three vintages considered compared to biodiversity from ecophyto modality and conventional modality. The pressing / clarification steps strongly modify fungal populations and the influence of the winery flora is highlighted.

Read More

Microbial stabilization of wines using innovative coiled UV-C reactor process: impact on chemical and organoleptic proprieties

For several years, numerous studies aimed at limiting the use of SO2 in wines (thermal treatments, pulsed electric fields, microwaves …). Processes must be able to preserve the organoleptic qualities of wines with low energy consumption. In this context, ultraviolet radiations (UV-C), at 254 nm, are well known for their germicidal proprieties. In order to inactivate microorganisms in grape juice and wine without affecting the quality of the product, efficiency of UV-C treatment process should be optimized.

Read More

Innovations in the use of bentonite in enology: interactions with grape and wine proteins, colloids, polyphenols and aroma compounds.

The use of bentonite in oenology rounds around the limpidity and the stability that determine consumer acceptability. As a matter of fact, the haze formation in wine reduces its commercial value and makes it unacceptable for sale. Stabilization treatments are, therefore, essential to ensure a long-time limpidity and to forecast the formation of deposits in the bottle. Bentonite that is normally used in oenology for clarifying-fining purpose, shows a natural clay-based mineral structure allowing it to swell and to jelly in water and hence in must and wine.

Read More

Molecular cloning and characterization of UDP-glucose: furaneol glucosyltransferase gene from Japanese

2,5-Dimethyl-4-hydroxy-3(2H)-furanone (furaneol) is an important aroma compound in fruits, such as pineapple and strawberry, and is reported to contribute to the strawberry-like note in some wines. Several grapevine species are used in winemaking, and furaneol is one of the characteristic aroma compounds in wines made from American grape (Vitis labrusca) and its hybrid grape, similar to methyl anthranilate. Muscat Bailey A is a hybrid grape variety [V. labrusca (Bailey) x V. vinifera (Muscat Hamburg)], and its wine is one of the most popular in Japan. The inclusion of Muscat Bailey A in the ‘International List of Vine and Varieties and their Synonyms’ managed by the ‘International Organisation of Vine and Wine (OIV)’ in 2013 has further fueled its popularity among winemakers and researchers worldwide.

Read More

DNA and type of grain: which factor does better explain sensory differences of sessile and pedunculate oaks?

Sessile oak and pedunculate oak have shown several differences of interest for enological purposes. Tannic and aromatic composition among sessile oak or pedonculate oak has been well studied. Sessile oak is generally more aromatic than pedunculated, while the later is more tannic. This scientific point of view is rarely applied to classify oak in cooperages. Most coopers use the type of grain to distinguish wide and thin grain.

Read More