Increasing public concern with sulfite content in wine as well as wine quality loss by high sulfite additions has created the need for new winemaking tools and practices to reduce sulfite use. SOâ‚‚ has been one of the most used wine additives for centuries because of its antioxidant and antimicrobial activities. For winemakers, reducing SOâ‚‚ means greater commitment of time and responsibility in avoiding the risk of exposing an unprotected wine to chemical and microbiological changes.

Lamothe-Abiet offers options able to replace SOâ‚‚ for its anti-oxidant, anti-oxidasic, and anti-microbial activities and produce quality, low or SOâ‚‚–free wines. The entire process of winemaking must be reviewed, especially sanitation and oxygen protection, using appropriate equipment and sanitation protocols.

WHY WE USE SOâ‚‚:

1.  Protect grapes, juice, and wine from oxidation
2.  Reduce oxidases enzyme (PPO and laccase) activities
3.  Control microbial growth, activity, and contamination to limit juice and wine spoilage

ALTERNATIVES TO SOâ‚‚ - ANTI-OXIDANT AND ANTI-OXIDASES ACTIVITY

Oxidation is one of the main concerns for a winemaker as it affects wine stability and sensory properties of wine causing browning, loss of flavor and aroma, and unbalanced mouthfeel. Grape and juice oxidations are mostly happening via enzymatic reactions while wine oxidation reactions are chemical. Enzymes responsible for phenolic compounds oxidation in juice are polyphenol oxidases (PPO) and laccase in Botrytis-infected grapes. PPO's, in presence of Oâ‚‚, transform phenolic compounds and catechins into quinones, strong oxidants responsible for juice browning. This reaction is very fast and occurs within about 15 minutes beginning from when the berries are in contact with air (open, damaged, or crushed), thus making the respect of berry integrity during processing essential. In wine, chemical oxidation reactions are much slower and highly impacted by the redox potential of the wine and temperature. Very similar reactions, involving the formation of quinones from oxidation of phenolic compounds, not via enzymatic activities but starting with an activation of the oxygen into a radical via redox reactions.

SOâ‚‚ ALTERNATIVES FOR MINIMIZING OXIDATIONS:

For enzymatic oxidation to happen, oxidases, Oâ‚‚, and phenolic substrates must be present.

1. Reducing Oâ‚‚ Solubilization in Juice and Wine. Limiting exposure to air to prevent the solubilization of oxygen in juice and wine is the first step to prevent oxidation. In addition to using inert gas, and inert press such as Bucher Inertys, chemical inertization is possible using compounds that quickly react with oxygen and oxygen radicals before they enter the oxidation mechanism. Gallic and ellagic tannins have a high capacity for Oâ‚‚ consumption and can be used to replace SOâ‚‚ on this action.
   - Tanin Gallique a l’alcool for white/rose grapes and juices 
   - Pro Tanin R for red grapes
   -  Tan & Sense Volume for wines during racking, transfer
2. Reducing Oxidase Enzyme Activity. With 50 mg/L SOâ‚‚, it is possible to decrease up to 90%the PPO activity but higher dosages are necessary to effectively inhibit laccase, resulting in negative consequences for alcoholic and malolactic fermentation and wine quality. Gallic and ellagic tannins have a strong affinity with proteins, so they can bind with enzymes, thus inactivating PPO and laccase.
   - Tanin Gallique a l’alcool for whites/roses 
   - Pro Tanin R for reds
3. Removing Phenolic Compounds. Phenols are the main substrate of oxidation. Removing phenolic compounds with fining agents is an efficient way of minimizing the oxidation process and stabilizing wine. Juice fining can help produce wines with a fresher color, higher content of aromatics, and less sensitivity to oxidation.
   - Polymix (PVPP, Casein) or Polymix Natur (PVPP, yeast extracts, bentonite)
4. SOâ‚‚, Glutathione and Cysteine derivates can react with quinones formed during the oxidation process, producing the "Grape Reaction Product" (GRP). As GRP is no longer a potential substrate for further oxidation, the reactions of oxidation are stopped. Protecting grape's glutathione and using yeast derivates rich in glutathione and cysteine can be an alternative to SO2 to reduce oxidation reactions.
   - OptiThiols in juices
   - Aroma Protect in wines

ALTERNATIVES TO SOâ‚‚ - ANTI-MICROBIAL ACTIVITY

The anti-microbial activity of sulfur dioxide is mainly due to the molecular form whose concentration depends on free sulfur content, pH, temperature, and alcohol content. Each micro-organism has a different sensitivity to SOâ‚‚, therefore, the quantity necessary to inhibit their growth and activity is specie dependent.

SOâ‚‚ ALTERNATIVES FOR CONTROLLING MICROBIAL DEVELOPMENT:

1. On grapes and juices, it is possible to inhibit the development of spoilage microbes by bio-protection, using 'positive' microbes to colonize the environment and inhibit the development of others, while respecting a natural microbial equilibrium.
   - Excellence B-Nature 
2. Chitosan's anti-microbial activity is highly effective, non-specific (can control both yeast and bacteria), and not dependent on juice and wine pH, which makes it a reliable alternative to SOâ‚‚. It works by contact: the positive charges present on its surface attract negatively charged microorganisms in juice. It alters the permeability of the cell membranes, causing micro-organisms to die and then precipitate.
   - KillBrett
3. As most of the spoilage microbes live in aerobie (especially acetic acid bacteria), scavenging oxygen radicals and maintaining wine in a low redox potential limit nutrient availability and limit their development. Ellagic tannins, particularly from untoasted oak, are very efficient in scavenging oxygen radicals.
   - Tan & Sense Volume

https://www.bvnorthamerica.com/news/2021/7/7/low-so2-winemaking