How to Prevent Your Foods from Going Rancid

Oils and fats have different storage times depending on the type of oil and storage conditions. Under normal storage conditions, your oil will last from a few months to three years or more. Sealed, canned shortening powder will last three to five years but does not perform the same as regular oils. You can extend these storage times with a few tricks I’ll teach you here.

What Causes Spoilage?

Oils and fats are vulnerable to the usual causes of food spoilage: microorganisms, oxidation, heat, light, pests, and time.  For properly stored oils and fats, oxidation is the most common cause of rancidity, aided by time, temperature, humidity and light. I’ll cover protecting your oils and fats from all of these causes in this article.

How Long Does Oil Keep?

Unopened oils keep longer in the refrigerator or freezer. Once opened, moisture becomes a factor, so I keep most oils and fats in the pantry after opening. Moisture in the oil can shorten its shelf life as much or even more than the cooler temperature preserves it. If a cool, dry place is available, such as a basement or cellar, that would be a preferred location for storing opened oils.

Shelf Life of Common Oils and Fats

Flavored oils, such as chili oil, truffle oil, and garlic oil, spoil faster than pure oils, so it is best to store oils in their natural state and flavor them as needed or store only enough flavored oil for short-term use.

Related: How To Make Delicious Lard With 2 Years Shelf-Life (+ 5 Tasty Recipes)

Extending Shelf Life – Protecting Oils and Fats from Microorganisms and Pests

Exposure to microorganisms and pests will spoil your fats quickly, so care should be taken to protect oils from these problems. Microorganisms are not usually a problem if you store the oils in a clean environment, properly sealed or covered. Microorganism growth is faster in a warm environment and slowed or stopped by cold temperatures. If you do suspect contamination for any reason, throw it out. Oils spoiled by microorganisms may not exhibit any signs of spoilage but can cause illness.

Pests are more of a problem with oils and fats. If you see any signs of rodents, such as signs of chewing or infiltration, consider the oil or fat spoiled and use it for non-food purposes such as making candles.

To prevent problems with microorganisms and pests, I store my oil in clean, dry, thick plastic buckets or metal cans. Metal is best for preventing rodents but is costly.

Related: What Should You Do With Your Canned Foods After the Expiration Date?

Protecting Oil and Fats from Oxidation, Humidity, Heat, and Light

Oxidation is caused by exposure to air and is accelerated by heat and light. Storing your oils and fats properly slows oxidation.

Preventing Oxidation:

• Store oils and fats sealed, vacuum packed, or flooded with nitrogen to exclude air
• Keep them in a dry, dark location
• Refrigerate or freeze them unopened
• Add an antioxidant when appropriate
• Date and rotate your supplies

If you cannot vacuum pack your oil, or flood it with nitrogen, another way to exclude air is to completely fill the bottle before sealing it. Choose a glass bottle or jar, avoiding metal or plastics, and fill it to the rim. Clean the rim and seal the jar. Check your fill by turning the bottle upside down to observe the size of the air bubble. Ideally, you want no air, but a tiny bubble may be the best you can get, depending on the bottle. Adding an antioxidant before sealing gives you additional protection.

Using an Antioxidant

Antioxidants will prolong the life of your oils by blocking the free radicals that cause oxidation. They won’t prevent oxidation completely, but they will slow it down considerably. I add Rosemary Essential Oil in my oils after opening. Other antioxidant oils include oil of oregano, sage oil, and Vitamin E.

To reduce oxidation, you only need a small amount of antioxidant oil, between .05 to 1 percent. Approximately 3 drops to 2 teaspoons of antioxidant oil per quart of oil. The larger amount is ideal and offers the best protection, but it also adds flavor to the oil. Adding 3 drops or more of rosemary oil per quart gives you a reasonable amount of antioxidant protection without noticeably affecting the flavor.

I use antioxidant oils when transferring oils into smaller containers to increase the shelf life of the opened oil. I’ve discussed this in more detail below.

How to Tell if Oil is Rancid or Spoiled

Oils and fats are usually labeled with a “Best Used By” date rather than an expiration date. Stored under normal pantry conditions your oil should last beyond this date. However, by following our recommendations, you should be able to extend this storage time considerably.

As oil ages, it changes in color, clarity, and texture. These are the beginning of spoilage, but the oil may still be usable. When the oil is rancid, you will notice an unpleasant taste and smell. At this point, consider it spoiled. It won’t make you sick, but it does lose its healthy properties and may become unhealthy over time. It doesn’t taste good either, so you are better off not using it. It might still be useful for purposes other than cooking or eating.

How to Store Fats to Extend the Shelf Life

The best way to store fats and oils is in an airtight container in a cool, dark place. For normal storage, this means in a pantry, away from the stove or other heat sources. You can increase your storage time considerably by storing oil and fats in the refrigerator or freezer if you have the room. They will probably become cloudy and solidify, but this is normal and not a sign of spoilage. Remove them to room temperature for an hour or more before use, and they will return to their liquid state.

I store the oil bottle currently in use in the refrigerator or pantry and my backup supplies in the freezer. My current bottle of olive oil and most vegetable oils are kept in the pantry. Avocado oil, hazelnut oil, walnut oil, and sesame oil have a short shelf life and are always kept in the refrigerator or freezer, along with all flavored oils.

Storing large Quantities of Oils and Fats

To get the best prices on my oils and fats, I usually purchase them in large containers. However, when I am ready to use them, I prefer small containers since the oil spoils faster once opened. I always rotate my oils and fats, but I don’t use them quickly since we limit our fat consumption. I don’t like to have a large open container on the shelf. I get around this by re-packing the oil or fat immediately after opening. I pack the oil or lard tightly into a canning jar and cover it with a warm, dry lid. Then I vacuum seal it to remove the air.

Before vacuum sealing, you can also add an antioxidant oil such as Rosemary Essential Oil, Vitamin E, or Sage Essential Oil to liquid oils, as discussed above. I prefer Rosemary Oil for its pleasant flavor. Be sure to note the addition on the container.

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