Week 29: Peanut Butter and Mayonnaise

Peanut Butter and Mayonnaise

Decide how much you use and store accordingly.

Peanut Butter is a staple in many homes when it comes to basic sandwhiches, and many even use peanut butter in their cooking. Mayonnaise is also a commonly used product, especially on sandwiches, as a condiment, and in various salad recipes. These two products have a fairly short shelf life and therefore, I don't specify how much to store. Personally, I like to store a couple jars of mayo (about 2 quarts each, so 4 quarts total) and 4 large jars of peanut butter (2 lbs each, so 8 lbs total). But your needs are going to vary. If you're not sure, start by storing one jar of each. You'll learn soon enough how fast you go through it. Store what you use and use what you store.

Peanut Butter

Peanut butter is a food paste made from ground roasted peanuts. It is popular throughout the world and used mainly as a sandwich spread.

Health Benefits:

Peanut butter may protect against cardiovascular disease due to high levels of monounsaturated fats and resveratrol. Butter prepared with the skin of the peanuts has a greater level of resveratrol and other health-aiding agents. Peanut butter (and peanuts) provide protein, vitamins B3 and E, magnesium, folate, dietary fiber, arginine, and high levels of the antioxidant p-coumaric acid.

There is a Peanut butter based food that helps children with malnutrition in famine stricken countries called Plumpy’nut. It can be stored unrefrigerated for 2 years, and requires no cooking or preparation.

Health Concerns:

For people with a peanut allergy, peanut butter can cause reactions including anaphylactic shock which has led to its banning in some schools. At least one study has found that peanut oil caused relatively heavy clogging of arteries. Peanut butter can also harbor salmonella and cause salmonellosis, as in the salmonella outbreak in the United States in 2007.

Peanut butter is available in smooth, chunky (with small bits of chopped peanuts), natural, reduced-fat, no sugar added, and even swirled with jelly for those time-challenged consumers.

Commercial varieties are usually a blend of ground, shelled, roasted peanuts mixed with vegetable oil (usually hydrogenated) and a bit of salt. Some varieties also contain sugar and additives as stabilizers to prevent oil separation and to also enhance flavor. Natural peanut butter normally contains only peanuts and oil, and will often separate requiring stirring.


  • Homemade peanut butter should be refrigerated in tightly-sealed containers and ideally used within a couple of weeks. Turn the container upside-down occasionally to help redistribute the oils.

  • Natural peanut butters should be refrigerated after opening and can be kept up to six months.

  • Commercial varieties require no refrigeration and can be kept up to six months after opening. Unopened jars can be stored up to one year or longer in a cool, dark location. I find it best to observe the 'Best By' date on the container, which is usually 12-18 months from the date of purchase. Peanut butter is not a good candidate for freezing.


Peanuts are susceptible to mycotoxins out of which aflatoxins are the most well-known. The key to good peanut butter storage is to ensure that it’s not kept in a place that is not wet or humid. Peanut butter should always be stored in air tight containers that are made of plastic or metal.

Kids tip:

A common, simple outdoor bird feeder can be made by coating a pine cone with peanut butter and then covered with birdseed.


Mayo is a thick condiment made primarily from vegetable oil and egg yolks. Whitish-yellow in color, it is a stable emulsion formed from the oil and the yolks. Mayonnaise is a good source of vitamin E, depending upon the type of oil used. The fats in mayo come from eggs, which are a good source of healthy fats such as omega-3 fats. Since mayo doesn’t keep very long, you decide how much you need to keep on hand, depending on how fast you go through it.


Mayo is very sensitive to storage conditions. Mayo can turn bad fairly quickly if stored in warmer areas, but will last much longer in cooler storage conditions. So, store in a cool, dry area. The “Best By”, “Best if Used By”, and “Use By” dates on commercially packaged foods sold in the United States represent the manufacturer’s estimate of how long the product will remain at peak quality. In most cases, the unopened mayonnaise will still be safe to consume after that date, as long as it has been stored properly and the package is not damaged. Pay attention to the “Use by” dates for mayo. It’s generally ok if it’s a few months past, but not much more than that. The mayo containers will usually be dated 6-12 month’s out from the date you purchased it. This is definitely a food item you’ll want to rotate through. If your mayonnaise develops an off odor, flavor or appearance, it should be discarded.

Many people store those little single-serve Mayo packets that you get from restaurants. While this is tempting, be careful with this practice. The packaging degrades fairly rapidly, so they are NOT a good long-term storage solution.

Page updated: 10/13/20