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24, chemin de Borde Rouge –Auzeville – CS52627
31326 Castanet Tolosan CEDEX - France

Dernière mise à jour : Mai 2018

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ANR CHITOWINE

ANR CHITOWINE

Research on the origin and the side effects of chitosan stabilizing properties in wine

Fungal chitosan is a polysaccharide made up of glucosamine and N-acetyl-glucosamine and derived from chitin-glucan from Aspergillus Niger or Agaricus bisporus. It has been authorized as an antiseptic agent in wine in 2009 (OIV). Only the fungal chitosan is allowed in wine, with total exclusion of those extracted from crustaceans. At the maximum dose of 10g/hl, it was shown to allow to efficiently eliminating Brettanomyces bruxellensis, a volatile phenol producing yeast and the main spoilage agent in red wines. Although the fungal chitosan is highly renewable, biocompatible (ADI equivalent to sucrose) and non-allergenic, winemakers very often prefer to use sulfites (SO2), though they are classified as priority food allergens. Indeed, fungal chitosan appears as a poorly reliable product because of many conflicting reports and advices on its efficiency and on its side effects towards beneficial wine microorganisms or wine taste. These contradictions could be explained by the heterogeneity of the fungal chitosan lots traded, the diversity of the wines (chemical composition, winemaking route chosen) but also by the recently highlighted huge genetic diversity prevailing in wine microbial species.

The CHITOWINE project is based on the collaboration of three academic partners, a technology transfer unit and an industrial partner. It primarily aims to better demonstrate the potential and limitations of fungal chitosan use as an antimicrobial agent in wine. The work will first enable to better define the spectrum of fungal chitosan through the screening of a large microbial collection representative of the inter- and intraspecific diversity of wine ecosystem (16 species, 200 strains). The chemical characteristics essential to the antiseptic activity of fungal chitosan (degree of acetylation, molecular weight, solubility) and the influence of extrinsic parameters of reaction (pH, temperature, dose) will be evaluated. In addition, the physiological effects of chitosan will be sought through a battery of biochemical, microscopic and transcriptomic tests, to identify, if possible, the molecular targets of chitosan and to understand the sensitivity differences observed, between species and between strains in the same species, and improved use recommendation will be proposed and evaluated. The need for additional treatments (filtration, enzymatic treatments) to completely eliminate B. bruxellensis and the efficiency of fungal chitosan for solving other microbiological issues in winemaking will be examined. The consequences of chitosan treatment on the colloidal stability and organoleptic properties of wines will be studied. Analytical methods to guide chitosan use (for checking the quality of chitosan lots, for the detection of resistant strains, for determination of chitosan residue after wine treatment) will be developed and optimized.

The results will be widely disseminated in an efficient and modern way to a wide audience (scientists, students, wineries wine professions, oenological product purchasers, decision-making bodies such as OIV). If the use of fungal chitosan confirms that it is safe and efficient for treating specific oenological contamination (B. bruxellensis or other), it could, in these specific cases, efficiently replace sulfur dioxide as an antimicrobial agent. This would contribute to lower the dose of sulfites in wines and to consolidate the current approach for more natural and sustainability in the wine industry (challenge 5, focus 4). The economic and societal benefits will be important since this sector is the second largest exporting sector in France and wine a main symbol of French art of living.

Contact : Thierry Doco (thierry.doco@inra.fr)

Parterns

 

partenariat chitowine