OIV adds pulsed electric fields to recognized treatments for must and wine

16 resolutions adopted in Yinchuan

The OIV approved 16 resolutions on October 16 during its 24th General Assembly in Yinchuan, Ningxia. The package updates international standards covering viticulture, winemaking and analytical methods, while adding pulsed electric fields to the practices recognized for stabilizing grape must and wine.¹

The decisions were adopted during the 47th World Congress of Vine and Wine, held in China from October 12 to October 16. More than 600 people from 47 countries participated, including representatives of 42 OIV member states and 5 nonmember countries. The program comprised 420 scientific contributions and 6 technical visits; the presentations are expected to become openly available through the IVES Conference platform in the coming months.¹

Pulsed electric fields for microbial control

Among the changes, 2 resolutions recognize pulsed electric fields, known as PEF, as microbiological stabilization treatments for must and wine. The process produces irreversible electroporation in microbial cell membranes, thereby inactivating organisms responsible for spoilage.¹

In must, PEF may remove or reduce unwanted microorganisms and immediately stop alcoholic fermentation when a producer seeks residual sugar, while allowing lower sulfur dioxide doses. In wine, its stated purposes are to remove or reduce spoilage microorganisms, postpone the onset of malolactic fermentation without sulfur dioxide, or prevent that fermentation.¹

For producers and laboratories handling wine, grape juice and wine vinegar, these revisions could become an important technical reference for microbial control, product stability and origin testing. Because regulators, exporters and wineries often use OIV standards as benchmarks, the changes may eventually influence production choices, compliance activity and trade discussions.¹

Safeguarding grapevine diversity

A resolution on grapevine genetic diversity outlines ways to retain intravarietal variation accumulated in old vineyards and connects that work with climate adaptation and future selection programs. It calls for surveys of old vineyards and conservation of plant material both in situ and ex situ. Varietal identity must be verified and the material tested for freedom from viruses before preservation, with rare varieties receiving priority.¹

New and revised oenological practices

The revised International Code of Oenological Practices permits dimethylpolysiloxane, or PDMS, as an antifoaming treatment during alcoholic fermentation at no more than 10 mg/l. It cannot be used for wines destined for sparkling wine production.¹

Another resolution authorizes functionalized mesoporous silica in must to selectively adsorb and remove unstable proteins. Classified as a processing aid, it must be introduced into the tank discontinuously. Preliminary trials must establish a dose between 20 and 200 g/hl, and the resulting wine must then be filtered at a porosity of 0.45 μm or less.¹

Permitted uses of yeast mannoproteins were also extended. They may now improve stability against potassium bitartrate precipitation, reinforce protein stability in white and rosé wines, and enhance color stability in red wines, subject to a maximum dose of 400 mg/l.¹

A further 2 resolutions establish treatments for white must and white wine using styrene-divinylbenzene adsorbent beads. Must or wine is passed through a bead-filled column at a controlled flow rate to lower browning risk by partially removing polyphenolic compounds, particularly hydroxycinnamic acids and oxidized polyphenols. Before treatment, turbidity must be reduced to 10 NTU or below.¹

Powdered cellulose was added to the materials allowed as activators for malolactic fermentation, expanding a list that already contained microcrystalline cellulose and products derived from yeast.¹

Revisions to the International Oenological Codex

A new codex monograph defines specifications for chelating styrene-divinylbenzene resins carrying an iminodiacetic functional group, intended to reduce metals in aged wine vinegars. Its purity and safety provisions require that no styrene, divinylbenzene or iminodiacetic acid be detectable after migration into a vinegar simulant, and the resins may be regenerated no more than 5 times.¹

The citric acid monograph was also revised. Citric acid, used to acidify wine or reduce the risk of iron haze, now covers 2 forms—monohydrate and anhydrous—under INS 330.¹

Analytical methods and sorbic acid limits

For grape juice, reconstituted grape juice, concentrated grape juice and grape nectar, 1 resolution introduces an enzymatic method to determine low ethanol concentrations from 0.150% to 3.00% alcohol by volume.¹

Another method measures the strontium isotope ratio in wine, which is associated with geological origin. The procedure combines high-pressure microwave digestion, chromatographic separation of strontium and rubidium, and quadrupole inductively coupled plasma mass spectrometry, or Q-ICP-MS. Such analysis may become more significant as producers and regulators seek stronger verification of provenance claims.¹

The OIV also fixed the maximum sorbic acid level in finished wine at 200 mg/l. The limit rises to 250 mg/l for Vitis labrusca and its hybrids.¹

Regulatory simplification

In economics and law, 1 resolution withdraws 43 resolutions deemed obsolete, outdated or redundant. The OIV said the step was intended to make its rules more coherent and easier for member states to apply under the 2025–2029 strategic plan.¹

The OIV corpus contains 1,445 resolutions adopted between 1928 and 2025. The organization had already withdrawn 376 resolutions in 2023 and another 184 in 2024.¹

Classification of oenological tannins

In safety and health, the OIV updated the classification of oenological tannins according to their use. Tannins applied to must are treated as processing aids because they perform no technological function in the finished wine; when used in wine for other purposes, they are classified as additives.¹