Opened canned tomatoes and saw bubbles rising immediately. Is that fermentation or spoilage

The amount of dissolved gas can vary depending on factors such as temperature during canning and the specific type of tomatoes used. For example, tomatoes canned at higher temperatures might retain more dissolved gases, leading to more bubbles when opened. This is generally a harmless occurrence, but it’s important to differentiate it from signs of fermentation or spoilage.

Natural dissolved gases are a normal part of the canning process, but it’s crucial to distinguish them from bubbles caused by fermentation. Fermentation in canned foods usually indicates microbial activity, which can be a sign of spoilage. This process can produce gas, leading to bubbling and sometimes even causing the can to bulge.

Fermentation typically involves yeasts or bacteria that feed on sugars, producing carbon dioxide and alcohol. If a can is compromised, either through a faulty seal or damage, these microorganisms might find their way inside, leading to unwanted fermentation. It’s important to assess other factors, such as smell and appearance, to determine if fermentation is occurring.

Safe, normal bubbles are usually small, clear, and dissipate quickly. They often appear immediately upon opening the can and are a result of the release of trapped gases. These bubbles should not be accompanied by any other visual changes to the liquid or tomatoes themselves.

If the liquid remains clear and the tomatoes appear intact and vibrant in color, it’s likely that the bubbles are harmless. This can be compared to the bubbles you might see when opening a carbonated beverage.