Does Jelly Need to Be Refrigerated? Food Scientists Settle the Debate

Thanks to their sweet-tart flavor and satisfying texture, jams and jellies are staples in the kitchen. It also doesn't hurt that they pair well with a wide range of foods, from toast to vanilla ice cream. But like many essential ingredients and condiments, these fruity spreads aren't something you finish right away. This means you need to know how to store them correctly to ensure they stay fresh in between uses. We spoke to food scientists to learn whether or not you need to refrigerate jams and jellies. These experts also share how long you can expect them to last before and after you've opened them.

The Best Way to Store Jam and Jelly

To protect the shelf life and quality of your jams and jellies, it's best to store them in the refrigerator. The cold temperature will significantly slow down the growth of microorganisms, says Alvin Lee, Ph.D., associate professor of food and nutrition at Illinois Institute of Technology.

You can technically store opened jams and jellies at room temperature—but only in a cool, dark place and for about a week after opening, says Lee. Here's why: Jams and jellies have high sugar and acid levels, which protect against spoilage. But there are still certain microorganisms, called osmophiles, that are resistant to these conditions and can cause spoilage over time, he explains.

Jam and jelly will deteriorate quickly when stored outside the fridge. This is especially true if the ambient (air) temperature is high, which can cause rancidity or separation of ingredients.

It's worth noting that different products will degrade at different rates at room temperature. Those with more sugar (which, again, acts as a preservative) will deteriorate more slowly than low-sugar versions, says Lee. Jams or jellies made with high-acid fruits (think lemon or lime) will also last longer than low-acid versions, as the acidity provides another barrier to stop microorganisms from growing.

How Long Opened Jars Last 

An opened jar of jam or jelly will last for about six months in the refrigerator, per the USDA. But it's still a good idea to eat it as soon as possible, says Lee. "Once opened, jams and jellies will be exposed to air, which contain mold and bacterial spores. These will grow over the six-month time period in the jam [or] jelly," says Lee.

And while most of these microorganisms are harmless and only degrade the quality of the product, some can cause illness or produce toxic compounds, he says. What's more, potentially harmful microorganisms can enter the jam or jelly from non-sterile utensils.

How Long Unopened Jars Last 

An unopened jar of jam or jelly can be stored in the pantry for up to 12 months. This long shelf life is due to the sugar content in the product, which acts like a preservative, says Lee. Essentially, bacteria need water to grow, but during the manufacturing process, sugar binds with most (if not all) of the water, making it unavailable to the bacteria. Plus, the production of jams and jellies usually involves heat, which also kills some microorganisms, says Lee. 

After about 12 months in the pantry, the quality of unopened jams and jellies will likely degrade, says Bryan Quoc Le, Ph.D., a food consultant and the author of 150 Food Science Questions Answered. That's because the sugar-resistant yeasts and bacteria will start fermenting the sugars into alcohol and other flavors, he explains. However, the jar of jam or jelly will still be safe to eat, so long as it wasn't opened.

Homemade Jams and Jellies

Homemade jams vary greatly in terms of preparation and ingredients. A product that was correctly canned can last for about 12 months, but if another method was used, it will have a shorter shelf life.

Signs Jams and Jellies Have Gone Bad

Regardless of the type of jam or jelly you have on hand, it's important to know the signs of spoilage. According to Lee, this may include yeasty off-odors, fermented alcohol-like flavors, and mold growth, which may appear as white fuzzy patches inside the jar or on the product itself. Another tell-tale sign is the separation of ingredients, which means the sugar and water in the product have broken apart, says Lee. If you notice any of these signs, toss the jam or jelly to be safe.