The 16th General Assembly of the International Organisation of Vine and Wine (OIV), which met on 23 November 2018 in Punta del Este (Uruguay), adopted a total of 20 resolutions.
Decisions on viticulture and the environment
• In the field of viticulture, the OIV adopted a recommendation to encourage research and study relating to the use of plant extracts, specific sustainable fertilisers, hormones, agronomic practices and chemical products as alternatives to synthetic dormancy-breaking products used in table grape production (Resolution OIV-VITI 607-2018).
• A recommendation to encourage research and study relating to the use of biological-control agents, anti-microbial natural plant extracts, physical agents or treatments for sustainable decontamination and agronomic solutions as alternatives to sulphites and other preservatives in the production of table grapes and dried grapes (Resolution OIV-VITI 608-2018).
• OIV protocol for the sustainable use of water in viticulture (Resolution OIV-VITI 569-2018). This protocol defines good water management practices based on sustainability principles, taking into account the consequences of limited supply of water in some areas or regions and in some years, as well as the need to ensure its more efficient use in vitivinicultural production. Sustainable use of water can be achieved through the appropriate selection and management of the vineyard, planting material, soil and cover crop, as well as by ensuring the availability of appropriate and timely water supply, by limiting losses as much as possible.
• The OIV adopted a recommendation on OIV good practices for the minimisation of the impacts associated with plant protection product application in vineyards (Resolution OIV-VITI 592-2018). These good practices constitute the basis for reasoned use of the optimum plant protection products and technical recommendations relating to the application of these products in the vineyard. The criteria suggested are based on the different official protocols enacted by OIV members and are intended to reduce as far as possible the risks for humans and the environment, within the framework of responsibility and sustainability. These guidelines should be revised periodically.
Decisions on oenological practices
Several resolutions relating to new oenological practices will be added to the International Code of Oenological Practices of the OIV, in particular:
• The OIV has continued work on the differentiation of substances already permitted by the OIV from substances used as additives or as processing aids, particularly with regard to glutathione (Resolution OIV-OENO 567B1-2018) and tannins (Resolution OIV-OENO 567C-2018). This distinction will help to establish better harmonisation among the international organisations and to facilitate the international trade of grape wines.
Decisions on specifications of oenological products
The following monographs have been added to the International Oenological Codex, in particular:
• The monograph on the determination of hemicellulase activity in enzymatic preparations (Resolution OIV-OENO 573-2018). Hemicellulases catalyse the degradation of hemicelluloses. The hemicelluloses of the cell walls of grape berries are mainly composed of xyloglucans and arabinoxylans; these two polysaccharides represent nearly 90% of grape hemicelluloses. The hemicellulase activity of enzymatic preparations is evaluated by measuring the 1,4-β-xylanase activity. Enzymatic preparations containing hemicellulase activities are used during grape maceration, and in the clarification and improvement of the filterability of musts and wines.
• The monograph on potassium carbonate (Resolution OIV-OENO 579-2018), which may be used for the deacidification of musts and wines. Detailed specifications accompany this monograph, including that the product intended for oenological applications should contain a minimum of 98% potassium carbonate.
• The monograph on yeasts with guaranteed glutathione levels (Resolution OIV-OENO 603-2018), which supplements the oenological practice. Glutathione is used for its antioxidant properties that can fight against oxidation phenomena in musts and wines and protect aromatic compounds. Detailed specifications accompany this monograph, including those regarding the reduced glutathione, cysteine and gamma-glutamylcysteine contents.
• A revision of the monograph on oenological carbon, relating to the level of ashes when the carbon is agglomerated with bentonite (Resolution OIV-OENO 604-2018).
Decisions on methods of analysis
During this same session, it was decided that new methods of analysis will be added to the OIV analytical corpus. These include, in particular:
• The update of the method for the determination of sulphur dioxide, distinguishing the method for the determination of free sulphur dioxide, a Type IV method (Resolution OIV-OENO 591A-2018) from that for the determination of total sulphur dioxide, a Type II method (Resolution OIV-OENO 591B-2018). The principle of these methods is based on the entrainment of sulphur dioxide by a current of air or nitrogen; it is fixed and oxidised by bubbling through a dilute and neutral solution of hydrogen peroxide. The sulphuric acid formed is determined by titration with a standard solution of sodium hydroxide.
• The method for the determination of ethanal in wines was adopted (Resolution OIV-OENO 595-2018). The method described is suitable for the determination of the total (free and sulphur-dioxide-bound) ethanal in wines for concentrations of between 0.2 and 80 mg/L. The analyte is identified by derivatisation of the molecule with 2,4-dinitrophenylhydrazine (DNPH), followed by elution using the HPLC technique. Detection is evaluated using the retention time at the wavelength of 365 nm.
• The update of the method for the determination of total acidity in vinegars (Resolution OIV-OENO 597-2018). The principle of this method is based on the neutralisation of acids in sample by alkaline solution. The modification made consists of ensuring that the water used is free from CO2, which produces an acidic reaction and could influence the final result of the titration.
• The method for the determination of L-lactic acid in wines by specific enzymatic analysis using an automatic sequential analyser (Resolution OIV-OENO 598-2018). This method is characterised on a scale of measurement of 0.06 to 1.43 g/L. The principle of this Type III method is based on the reaction of nicotinamide adenine dinucleotide (NAD) with L-lactic acid, which is oxidised to pyruvate. The pyruvate formed is then converted into L-alanine in the presence of L-glutamate. The reduced nicotinamide adenine dinucleotide (NADH) produced is measured thanks to its absorption at 340 nm. It is proportional to the quantity of L-lactic acid.
• The method for the determination of L-malic acid in wines by specific enzymatic analysis using an automatic sequential analyser (Resolution OIV-OENO 599-2018). This method is characterised on a scale of measurement of 0.12 to 2.30 g/L. The principle of this Type III method is based on the reaction of nicotinamide adenine dinucleotide (NAD) with L-malic acid, which is oxidised to oxalate. The oxaloacetate formed is then converted into L-aspartate in the presence of L-glutamate. The reduced nicotinamide adenine dinucleotide (NADH) produced is measured thanks to its absorption at 340 nm. It is proportional to the quantity of L-malic acid.
• The method for the determination of the total D-glucose + D-fructose in wines by specific enzymatic analysis using an automatic sequential analyser (Resolution OIV-OENO 600-2018). The method is characterised on a measurement range of 0.1 to 96.31 g/L, taking into account the introduction of a dilution of the sample beyond 5 g/L. The principle of this Type III method is based on the reaction of nicotinamide adenine dinucleotide phosphate (NADP) with glucose-6-phosphate, which is oxidised to gluconate-6-phosphate. The quantity of reduced nicotinamide adenine dinucleotide phosphate (NADPH) produced directly correlates with that of glucose-6-phosphate and thus with that of D-glucose. Fructose-6-phosphate (F6P) is converted into glucose-6-phosphate (G6P) in the presence of phosphoglucose isomerase (PGI), which is oxidised according to the previous reaction. The reduced nicotinamide adenine dinucleotide phosphate (NADPH) produced is measured by way of its absorption at 340 nm.
• The update of the method of analysis of volatile compounds in wines by gas chromatography (Resolution OIV-OENO 606-2018). This update consists of integrating the results of the inter-laboratory test carried out and classifying the types of methods according to the compounds considered.
• The update of the method for the determination of releasable 2,4,6-trichloroanisole in wine by cork stoppers (Resolution OIV-OENO 623-2018). The modification made concerns the quantity of sodium chloride that may be added in order to increase the effectiveness of extraction and the sensitivity of the method according to the potential matrix effects that may occur. Similarly, a selection of specific ions for quantification by mass spectrometry was specified.
Decisions on safety and health
• Finally, the OIV adopted an update of the decision tree for toxicological evaluation of processing aids and additives used in vine products (Resolution OIV-SECSAN 627-2018). This update was developed with a view to its use during the adoption procedure for an oenological practice involving processing aids or additives.
The full texts of the resolutions adopted are available on www.oiv.int.
– For more information, contact Wendy Jonker at firstname.lastname@example.org.