The 17th General Assembly of the International Organisation of Vine and Wine (OIV), which met on 19 July 2019 in Geneva (Switzerland), adopted a total of 18 resolutions.

 

Decisions on viticulture and the environment 

  • In the field of viticulture, the OIV adopted the definition of ‘polyclonal selection’, as well as an OIV process for the protection and conservation of the intra-varietal diversity and the polyclonal selection of vines for grape varieties with wide genetic variability. The procedure is based on principles of quantitative genetics and statistics (Resolution OIV-VITI 564B-2019).
  • The definition and general principles of precision viticulture. This resolution considers the need to identify and compile technical protocols and best practices about precision viticulture techniques that are currently available or in the process of being developed. Precision viticulture privileges a range of information technologies for understanding variability within production systems and for quantifying and mapping intra-vineyard variability in order to target management according to the real needs of each part of each plot (Resolution OIV-VITI 593-2019).
  • The OIV adopted a recommendation on the minimum criteria for establishing a protocol for identification of varieties. The objective of the resolution is to harmonise the international criteria for identification of varieties. These criteria should be used if official recognition and registration of a variety are requested. The OIV protocol may be used in the case of re-examination of existing names of varieties and also defines criteria for the naming of new varieties. The protocol describes technical procedures suggested for the identification of vine varieties by providing minimum guidelines relating to ampelographic and genetic characteristics (Resolution OIV-VITI 609-2019).

 

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 decided to add new objectives to the oenological practice on tannin addition in musts (Resolution OIV-OENO 612-2019) and in wines (Resolution OIV-OENO 613-2019). In particular, objectives regarding antioxidant activity and colour expression were added to accompany those on protein stabilisation and fining.
  • Treatment of crushed grapes with ultrasound to promote the extraction of their components. The objective of this practice is notably to obtain a must with a higher concentration of phenolic compounds and other grape components, while reducing the maceration time compared to a traditional process (Resolution OIV-OENO 616-2019).
  • The update to the oenological practice concerning fermentation activators by the addition of food cellulose to the existing compounds (Resolution OIV-OENO 633-2019).
  • The oenological practice on de-acidification by lactic acid bacteria. The objective of this practice is to reduce the total acidity and real acidity through the use of lactic acid bacteria of the Lactobacillus, Leuconostoc, Pediococcus and Oenococcus genera in order to, on the one hand, develop balanced wines in terms of taste sensations and, on the other hand, obtain the total or partial degradation of malic acid by biological means (Resolution OIV-OENO 611-2019).
  • The treatment of grapes and musts by discontinuous high-pressure hydrostatic processes, with pressure levels higher than 150 MPa, to reduce indigenous microorganisms in grapes and musts. The objectives of this practice are, in particular, i) to reduce the microbial loads of indigenous microorganisms, especially yeasts, ii) to reduce SO2 levels used in winemaking, iii) to accelerate maceration in red winemaking (Resolution OIV-OENO 594A-2019).
  • The OIV adopted a new limit on the use of carboxymethylcellulose in white wines. The dose of carboxymethylcellulose to be used should now be less than 200 mg/L, instead of 100 mg/L previously (Resolution OIV-OENO 586-2019).

 

Decisions on specifications of oenological products

The following monographs have been added to the International Oenological Codex, in particular:

  • A revision of the monograph on colloidal silicon dioxide solutions with regard to the formulation in colloidal solution, in aqueous dispersion or in dry powder form. Some specifications of physicochemical properties were also updated (Resolution OIV-OENO 617-2019).
  • The update to the monograph on potassium hydrogen sulphite with regard to physicochemical properties (Resolution OIV-OENO 646-2019).
  • The update to the monograph on egg albumin with regard to specifications relating to dry matter and pH (Resolution OIV-OENO 650-2019).

 

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 to the method for the determination of phthalates by the integration of validation parameters derived from an inter-laboratory study. Based on the results of the separate analysis of each analyte and according to their reproducibility results, the method is considered as a Type II or Type IV method (Resolution OIV-OENO 596-2019).
  • Method for the determination of potassium polyaspartate in wine by high-performance liquid chromatography coupled with a fluorescence detector. This method is applicable to the analysis of potassium polyaspartate (KPA) in wines at concentrations higher than 40 mg/L. The principle of the method consists of carrying out the determination of aspartic acid before and after acid hydrolysis, by derivatisation with ortho-phthalaldehyde followed by chromatographic analysis coupled with a fluorescence detector. The difference in the aspartic acid content between the hydrolysed sample and non-hydrolysed sample will indicate the level of addition of polyaspartate (Resolution OIV-OENO 619-2019).
  • Determination of acetic acid in wines by automated enzymatic method (Resolution OIV-OENO 621-2019). This method makes it possible to determine acetic acid in wines using an automatic sequential analyser and specific enzyme analysis. The measurement range, which was the object of an inter-laboratory validation, is from 0.2 g/L to 1.14 g/L acetic acid. The principle of the method is based on the conversion, in the presence of ATP, of acetic acid into acetyl phosphate in a reaction catalysed by acetate kinase.
  • Determination of D-gluconic acid in wines and musts by automated enzymatic method (Resolution OIV-OENO 622-2019). This method makes it possible to determine D-gluconic acid in wines and musts by specific enzymatic analysis using an automatic sequential analyser, with concentrations of 0.06 g/L to 5.28 g/L of analyte. The principle of the method consists of the phosphorylation of D-gluconate present in the sample during an enzymatic reaction catalysed by gluconate kinase, followed by the oxidation of D-gluconate-6-phosphate in the presence of NAPD to form NADPH – the NADPH concentration obtained being proportional to the quantity of D-gluconate-6-phosphate, and thus to that of D-gluconic acid.

 

Decisions on limits on contaminants in wines

  • Finally, the OIV adopted a reduction of the limit of lead in wines. A new limit of 0.10 mg/L was set for wines produced from the 2019 harvest year onwards. A limit of 0.15 mg/L was set for liqueur wines produced from the 2019 harvest year onwards. The former limit of 0.15 mg/L now applies to wines and liqueur wines produced from grapes harvested between 2006 and 2018 (Resolution OIV-OENO 638-2019).

 

The full texts of the resolutions adopted are available on www.oiv.int.

 

– For more information, contact Wendy Jonker at wendyj@daff.gov.za.

 

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