Winetech vine and wine innovation watch: The use of fumaric acid to control malolactic fermentation

New wine additive

Fumaric acid has been declared legal for use by the European Union (Commission Delegated Regulation (EU) 2022/68) as an additive to wine to delay or prevent malolactic fermentation (MLF). It was previously approved by the OIV in July 2021 (Resolution OIV-OENO 581A-2021).

What is fumaric acid?

Fumaric acid occurs naturally in various biological systems since it is an intermediary metabolite in the citric acid cycle, also known as the Krebs cycle. The cycle is used by all living organisms that respire, as opposed to those that ferment. Fumaric acid used in the food industry is industrially produced from maleic acid. Maleic acid is not to be confused with malic acid; they are two different organic compounds.

Where is it already used?

Fumaric acid is used as an acidity regulator in various foods. It is denoted by the E number: E297. Examples of use include certain dairy-based products, certain beverages, breakfast cereals and processed meats and spreads, and salt and vinegar potato chips.

The research behind its use

Research into the use of fumaric acid in wine is not new. Already in 1974 professors Ough and Kunkee from UC Davis published a paper in which they evaluated and recommended the use of fumaric acid in wine, especially in warm viticultural areas. Fast forward 45 years, Morata and co-workers (2019) published a study that investigated:

• The acidification produced by fumaric acid.
• The inhibitory effect of fumaric acid on MLF compared to SO₂, lysozyme and lactic acid.
• The ability of fumaric acid to stop an active MLF.
• The sensory effect of fumaric acid addition to wine.

Results obtained:

• Depending on the dosage of fumaric acid used, the pH was reduced from 3.6 to 3.4 – 3.3. Fumaric acid showed a similar reduction as obtainable by citric acid, a better reduction than malic and lactic acids, but weaker than tartaric acid. The authors conclude that fumaric acid addition can be used as a complementary addition with other acidifying agents. It is not strong enough to be the only acidifying agent.
• Dosages of ≥50 mg/L of SO₂ and ≥300 mg/L fumaric acid added to wine had the same effects on bacterial populations and malic acid concentrations. The inhibitory effect of fumaric acid is, however, more stable over time, since free SO₂ is transformed into bound forms, reducing its inhibitory effect.
• In this study lysozyme was not effective to inhibit MLF at dosages of 200 and 500 mg/L. A high turbidity was also observed in the red wine used for the experiments, most probably due to precipitation of the lysozyme with phenolic compounds.
• Lactic acid was as effective as fumaric acid to inhibit MLF, but at much higher dosages. The authors proposed the use of fumaric acid in conjunction with the yeast Lachancea thermotolerans as complementary agents for the inhibition of MLF.
• Fumaric acid was able to successfully stop an active MLF at a dosage of 600 mg/L.
• The addition of fumaric acid to wine either had no, or very little effect, on the sensory characteristics of the wines. During the triangular tests panellists could not tell the difference between treated wines and controls. During the preference sensory test comparing wines treated with 600 mg/L fumaric acid and controls, panellists detected slight increases in acidity and body in the fumaric acid wines.

Permitted and recommended dosage

The use of fumaric as an additive is permitted in the European Union since February 2022 at dosages of 300 – 600 mg/L. It is only allowed to be added after fermentation completion i.e., in wine. The objectives for its addition are to control the growth and activity of lactic acid bacteria responsible for MLF in wine, to reduce sulphur dioxide dosages and to preserve malic acid. Fumaric acid addition to wine is also permitted in the USA and New Zealand.

Is it legal for use in South Africa?

Not yet, an application to have it incorporated into South African legislation must be lodged with the Department of Agriculture by an intended supplier of the product.

Can it be measured in wine?

Yes, it can be measured using the same sophisticated instruments (HPLC and capillary electrophoresis) commercial laboratories use to quantify the different organic acids (malic, lactic, tartaric, citric, acetic and succinic) in wine. A commercial enzymatic test kit that requires only a spectrophotometer and volumetric glassware, is used by some wineries for the quantification of some organic acids. Recently, in the light of fumaric acid addition being legalised, researchers developed an addition to the L-malic acid test kit by including one new step in the process – the addition of fumarase enzyme. Fumarase converts fumaric acid into malic acid, which is then measurable by the kit. The kit can easily measure concentrations between 0 and 1.5 g/L fumaric acid (maximum dose permitted by the OIV: 0.6 g/L).

Significance for winemakers

Winemakers will have another tool in their winemaking additives and processing aids toolbox. Fumaric acid is a potential alternative to lysozyme to delay, prevent or stop MLF. It does not affect wine sensorially, nor does is affect wine colour, turbidity and stability.

It can be used in high pH, low acidity wines from warm climates to inhibit MLF, thereby retaining freshness and improving shelf-life. It serves as an extra safety measure to ensure microbial stability in bottled wines in addition to SO₂. Take note, however, fumaric acid is only inhibitory to lactic acid bacteria and not acetic acid bacteria.

The OIV is currently evaluating the use of fumaric acid for the primary application of lowering wine pH. Currently it is only authorised to delay or prevent MLF.

Where can I find out more?

1. Commission Delegated Regulation (EU) 2022/68 of 27 October 2021 amending Delegated Regulation (EU) 2019/934 supplementing Regulation (EU) No. 1308/2013 of the European Parliament and of the Council regarding authorised oenological practices. https://eur-lex.europa.eu/legal-content/EN/TXT/PDF/?uri=CELEX:32022R0068&from=EN
2. Resolution OIV-OENO 581A-2021: Treatment with fumaric acid in wine to inhibit malolactic fermentation. https://www.oiv.int/public/medias/8084/en-oiv-oeno-581a-2021.pdf
3. Fumaric acid – Wikipedia. https://en.wikipedia.org/wiki/Fumaric_acid#:~:text=As%20a%20food%20additive%2C%20it,as%20the%20acid%20in%20leavening
4. Citric acid cycle – Wikipedia. https://en.wikipedia.org/wiki/Citric_acid_cycle#:~:text=The%20citric%20acid%20cycle%20(CAC,carbohydrates%2C%20fats%2C%20and%20proteins
5. Fumaric acid – ATPGroup. https://atpgroup.com/product/fumaric-acid-3/
6. Ough, C.S. & Kunkee, R.E., 1974. The effect of fumaric acid on malolactic fermentation in wines from warm areas. American Journal of Enology and Viticulture 25(4).
7. Morata, A., Bañuelos, M.A., López, C., Song, C., Vejarano, R., Loira, I., Palomero, F. & Suarez Lepe, J.A., 2020. Use of fumaric acid to control pH and inhibit malolactic fermentation in wines. Food Additives and Contaminants (Part A) 37(2): 228 – 238. Doi: 10.1080/19440049.2019.1684574. PMID: 31697220. https://www.tandfonline.com/doi/full/10.1080/19440049.2019.1684574
8. 27 CFR § 24.182: Use of acid to correct natural deficiencies. https://www.law.cornell.edu/cfr/text/27/24.182
9. New Zealand winegrowers international winemaking practices guide. https://issuu.com/nzwine/docs/nzw_winemaking_guide_2013_web_version
10. Fernández-Vázquez, D., Rozès, N., Canals, J.M., Bordons, A., Reguant, C. & Zamora, F., 2021. New enzymatic method for estimating fumaric acid in wines. OENO One 55(3): 273 – 281. https://doi.org/10.20870/oeno-one.2021.55.3.4825

– For more information, contact Karien O’Kennedy at karien@winetech.co.za.

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