How to preserve jalapeños in olive oil 

In this brief guide, we are going to answer the question “how to preserve jalapeños in olive oil.” We will also look at how to pick the best jalapeños and how to identify if jalapeños have gone bad.

How to preserve jalapeños in olive oil

Jalapeños can be preserved for the short-term by completely immersing in olive oil and then refrigerating or freezing.

Jalapeños are medium-sized, mildly hot peppers originating from Mexico. Jalapeños are used to flavor a variety of dishes such as salads, nachos and salsa. Jalapeños are now cultivated worldwide and used in Mexican as well as Asia and fusion cuisines. Jalapeños are also stuffed and then deep-fried to make delicious appetizers.

Chili (Capsicum spp.) is a commonly cultivated vegetable worldwide, with a production of 36,771,482 t. Worldwide chili yield has increased from 15.5 t ha−1 in 2008 to 18.5 t ha−1 in 2018. This increase is consistent with the goals of world food security programs because it is estimated that the food demand per capita should grow 4% for the next decade. ‘Jalapeño’ peppers (Capsicum annuum) represent a third of Mexican pepper production (31%) and are sold fresh. In 2010, 33,000 ha were planted with ‘Jalapeño’, but this area decreased by 11.2% in 2020 (1).

How does olive oil preserve jalapeños 

Jalapeños have been traditionally preserved in olive oil. Once the jalapeños are immersed in olive oil, the oil acts as an adhesive and reduces the exposure of the jalapeños to oxygen. This reduces the growth of aerobic microbes that cause spoilage. 

However, jalapeños are a low acid food and therefore it is not safe to preserve them in non-acidified oil for more than 4 days. Several cases of botulism have been associated with home-prepared vegetables and herbs stored in oil. These products also should be made fresh, with leftovers refrigerated for use within 4 days, or frozen for longer storage. Vegetables have a high water activity level which further encourages the growth of C. botulinum bacteria in an anaerobic environment. Even when dried, there is still the potential for risk, unless the vegetable has been acidified to a pH of 4.6 or lower. The safest recommendation is to freeze vegetables or herbs stored in oil. If the product is not frozen, it should be refrigerated and then either consumed within four days or discarded (2).

Jalapeños are low in acidity and adding olive oil creates a low acidic, oxygen-free environment. However, some microorganisms can grow under these conditions, including Clostridium botulinum (2).

Some harmful microbes thrive in this environment and they can cause spoilage.

Refrigerating or freezing the jalapeños will slow down the growth of harmful microbes, thereby increasing the shelf-life.

Commercially produced jalapeños in olive oil are shelf-stable because they have been acidified by the addition of preservatives or vinegar.

How to prepare jalapeños in olive oil

Storing in olive oil is a short term storage method to preserve jalapeños (4). 

Jalapeños preserved in olive oil will have a milder hotness compared to fresh or frozen jalapeños .

The following method describes how to store jalapeños in olive oil.

  • Wash the jalapeño peppers with cool, clean water and dry them with a paper towel. Make sure to discard the bruised and damaged peppers.
  • Roast jalapeño peppers. Roasting is done to soften the peppers and to help them absorb more olive oil.
  • Jalapeños can be roasted in an oven. Roast the jalapeños at 232°C until they become soft and the skins darken.
  • Skin the jalapeños. The jalapeños can be broiled to ease the removal of skin. Broil the jalapeños by placing them inside a covered bowl for a few minutes. After broiling, gently peel off the skin.
  • Slice the jalapeños into the desired thickness. At this point, the seeds can be removed from the jalapeños if you prefer reduced hotness.
  • Season the jalapeños with salt, pepper and a choice of spices.
  • Transfer the jalapeños into a clean glass jar and add enough olive oil to cover all the jalapeños.
  • Seal and label the jars and place them in the refrigerator or freezer.

Shelf life of jalapeños in olive oil

Jalapeños in olive oil must be refrigerated to obtain a shelf life of 4 days, when not acidified. Like garlic, peppers are low acidic and therefore, their storage in oil can be hazardous. Vegetables and herbs in oil provide four conditions necessary for botulinum toxin production: (a) a likely natural presence of Clostridium botulinum spores, (b) an anaerobic environment, (c) a pH greater than 4.6, and (d) a water activity (aw) greater than 0.85. Studies of documented outbreaks of botulism have identified vegetables and herbs in oil as the food source, with most outbreaks traced to home-prepared versions (2,5).. 

Jalapeños in olive oil can also be frozen for up to several months (5).

Frozen jalapeños in olive oil must be thawed before use. Thaw the jalapeños by placing them in the refrigerator. Thawing will make the jalapeños mushy and this could be unappetizing (6).

To get the maximum shelf-life from jalapeños in olive oil, sterilize the jars used to store the jalapeños. The jars can be sterilized by immersing them in boiling water for 10 minutes or by using an oven or a microwave.

Jalapeños can also be preserved for long term storage by pickling in vinegar solution and by making hot sauce (3).

How to pick the best jalapenos 

  • Color: Jalapeños are dark green when plucked from the trees. They eventually turn into a bright red color as they mature. Red jalapeños are hotter than green jalapeños. So pick the jalapeños depending on the recipe. For example, green jalapeños are perfect for stuffed peppers or olive oil preservation while red peppers are great for spicy hot sauces.
  • Striations: Striations or stretch marks develop in jalapeños as they age. The more striations you see, the hotter the jalapeño. Once again pick the jalapeños as how hot you want the dish to be. 
  • Size: Smaller jalapeños are generally hotter than larger ones, but that depends on the variety (7).
  • Texture: Pick firm jalapeños. Avoid jalapeños with mushy spots.
  • Discolouration: Avoid jalapeños with black spots and this may indicate bruising or spoilage.

How to know if jalapeños in olive oil have gone bad

We cannot see, smell, or taste pathogenic microorganisms but, we can see or smell some signs of food spoilage. Jars with unsealed lids, bulging lids, or a loose lid could indicate signs of food spoilage or the presence of pathogens. Other signs of food spoilage include rising air bubbles (gas), leaking, foam, foul odor, unnatural colors, sliminess, dried food on top of jars, and cotton mold growth (white, blue, black, green) at the top or under the lid (8).

  • Aroma: Jalapeños that have gone bad will smell rancid and have an unpleasant aroma.
  • Appearance: Spoiled jalapeños may have signs of mold and bacteria growth on them.


In this brief guide, we answered the question “how to preserve jalapeños in olive oil”. We also looked at how to pick the best jalapeños and how to identify if jalapeños have gone bad.

 If you have any questions or comments, please let us know.

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Sánchez-Toledano, Blanca Isabel, et al. Preferences in ‘Jalapeño’Pepper Attributes: A Choice Study in Mexico. Foods, 2021, 10, 3111. 


Nummer, B. A., et al. Current food safety issues of home-prepared vegetables and herbs stored in oil. Food Protec Trend, 2011, 31, 336-342.  


Van Laanen, Peggy. Preserving Peppers. Texas FARMER Collection. 2000.


Hill, M., and P. Kendall. Making pickled peppers. Food and nutrition series. Preparation; no. 9.314, 1998.


Papageorge, Lisa M., Roger F. McFeeters, and Henry P. Fleming. Factors influencing texture retention of salt-free, acidified, red bell peppers during storage. J Agric Food Chem, 2003, 51, 1460-1463.


McCullough, K; Webb, M; Bunning, M. Jalapenos pepper. 2018. Colorado State University.


Zlotorzynski, S. Signs of Food Spoilage. 2021. Pennsylvania State University.