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Are all Sulfites in Wine Created Equally?

Sulfites, often misunderstood, are compounds naturally present in grapes or added during winemaking to preserve freshness and prevent spoilage. However, not all sulfites are the same.

 

What type of sulfites can you find in wine?

In ancient Greece, humans infused gypsum (a mineral rich in sulfur) to keep wine for longer. Eureka! Welcome to the birth of sulfites.

Sulfites exist in various forms, sulfur dioxide (SO2), bisulfite (HSO3-), and sulfite (SO3^2-) are the most common types in wines. They play an important role in maintaining wine quality and stability, especially over time. Any level above 10 mg/l (miligrams per litre) needs to be reported on the label and can be only certified organic if they are less than 100mg/l per 2g of sugar. These are typical types of sulfites present in wine: 

 

Sulfur Dioxide (SO2): This is the most common form of sulfite. It acts as an antioxidant and antimicrobial agent, protecting wine from oxidation and bacteria.

Bisulfite (HSO3-): Formed when SO2 reacts with water, bisulfite contributes to the sulfite content of wine. It is seen as the guardian of a wine’s color, flavor, and aroma.

Sulfite (SO3^2-): In its ionized form, sulfite is less common in wine. Its presence is mainly for preserving wine freshness.

 

Are natural wines sulfite-free?

No. All wines contain sulfites. 

Natural wines are crafted with minimal intervention, they have sulfites but in lower levels, as winemakers rely on natural fermentation and minimal additives. Natural wines embrace the terroir and showcase the expression of the grapes and the environment. There is a growing trend to explore the limits of intervention-less wines and RawWine.com, lists almost 14000 wines today, with over 5000 having less than 20mg/l of sulfites.

 

Classic wines may be engineered with sulfites. Usually, the higher sulfite levels occur due to processing techniques and the addition of preservatives to express a specific flavor profile and consistency. White and rosé wines tend to have more sulfites than reds and the consensus is that around 1% of the population is sensitive to sulfites.

 

Do sulfites affect quality?

The short answer is yes. Yet they can affect positively or negatively and there is no consensus on what levels are too high. For example, in the EU a red wine cannot have more than 150 mg/l, yet in the USA any dry wine can have up to 350 mg/l. The best practice is to adapt wine to the target audience and style by analyzing it and contextualizing it in its category and market. At @Meron Quality Institute we have a database of over 350k wines and can help you understand if your wines, or the wines you sell are in line with the expectation consumers will have for a certain type of vintage in a specific market.

 

Have you evaluated what would be the optimal level of sulfites for you? 

EU Regulation on Sulfites in wine

EU Regulation on Sulfites in wine

 

Willem Schouten

Without temperature control, analysis would be unreliable and inconsistent. This environment allows for precision in identifying faults, understanding structure, and documenting development.

Why Wine Should Be Analysed Throughout Transport and Storage

A bottle might leave a winery in perfect condition, but its journey isn’t always smooth. Transport and storage environments vary wildly. From cargo containers to shop shelves, wines encounter heat, cold, vibration, and light. Each of these variables can influence flavour, aroma, texture, and ageing potential.

We have seen it happen: a wine that passed initial testing at the winery can taste very different after a long-haul shipment or poor storage conditions. That’s why it is smart to analyse wine at different points: before release, after transport, mid-storage, and pre-consumption. These stages reveal how the wine holds up in real-world conditions.

Wine Analysis Journey

Best Timing for Wine Analysis at Meron

The timing depends on your role in the wine’s journey as a producer, distributor or retailer.

  • Pre-release: Understand how the wine is evolving in bottle.
  • After shipping: Check for heat damage or cold stress.
  • During storage: Monitor consistency across different batches.
  • If something tastes off: Confirm whether changes in profile are due to environmental factors.

Our fully certified lab and independent testing can help identify what happened, how it happened, and whether it’s reversible or if it’s time to rethink storage or shipping protocols.

Does Temperature Define Wine Quality?

Temperature is not the only factor affecting a wine’s performance, but it is one of the most unforgiving. It can’t fix a wine’s flaws, but it can highlight or mask them. And once heat damage sets in, there’s no way back.

Handled well, temperature can bring out a wine’s complexity and balance. Mishandled, it flattens, distorts, and disappoints. Whether you’re sipping by the pool or sending a new vintage across the globe, a few degrees can change everything.

Before you raise your next glass, take a moment to check the temperature. It might just be the detail that lets the wine speak for itself.

How do you serve your wine? Here is how Anna Niepoort and other industry leaders see it: 

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