Does butter need to be refrigerated?

In this brief guide, we will answer the query, “Does butter need to be refrigerated?” and will discuss some tips to properly store butter on the counter.

Does butter need to be refrigerated?

Yes, butter does need to be refrigerated. The unsalted and whipped butter should be refrigerated if you want to avoid rancidity and spoilage caused by bacteria or yeasts. You should store butter in the refrigerator or freezer if the temperature in your kitchen rises beyond 70 degrees Fahrenheit, even if you want to keep it for a few months.

Is it possible for butter to go bad if it is not kept in the refrigerator?

Butter is often used as a spread and in baking. You must, however, soften or melt it before using it if you want to keep it in the refrigerator. So, rather than keeping butter in the refrigerator, some people keep it out on the counter.

However, butter can be spoiled by psychrotrophs, coliforms, yeasts, and lactic acid bacteria. Bacteria can cause five types of spoilage in butter: First, the surface taint (putrid), which is caused by Shewanella putrefaciens, P. putrefaciens, and Flavobacterium spp. at chilling and refrigeration temperatures within 7–10 days. Second, the rancidity of butter, which is caused by hydrolysis of butterfat with liberation of free fatty acids, by the growth of P. fragi and P. fluorescens. Third, flavor formations, which is caused by Lac. lactis subsp. lactis var. multigenes. Fourth, discoloration caused by growth of molds, yeasts, and bacteria on the surface of butter. Dark, smoky, or greenish color on butter are caused by Alternaria and Cladosporium, small black color by Stemphylium and P. nigrificans, green color by Penicillium, bright reddish-pink color by Fusarium culmorum, and black color by Torula spp. Fifth, the formation of excessive viscosity in buttermilk and sour cream with the growth of encapsulated, slime forming Lactococcus. The spoilage caused by microorganisms can be avoided by adding salt to the butter (1).

Butter contains a lot of fat.

Dairy products, such as butter, are derived from animal milk, generally that of cows. To create buttermilk, milk or cream is churned until it separates into buttermilk and butterfat.

Only butter has such a high-fat content, making it unique among dairy products. With just over 3% fat in milk and almost 40% fat in heavy cream, butter has more than 80% fat content. The remaining 80% is mostly composed of water.

It’s low in carbohydrates and protein compared to other dairy products (0.4% carbohydrates, 0.6% proteins,and 2.5% ash, and can be salted or unsalted). Butter’s thick and spreadable consistency is due to its high-fat content. When refrigerated, it becomes much more difficult to spread out. Butter may be stored at room temperature, which maintains the right consistency for cooking and spreading.

Milk fat contains more than 400 different fatty acids, including saturated fatty acids (66%), monounsaturated fatty acids (30%) and polyunsaturated fatty acids (4%) (4).

Butter Doesn’t Go Bad as Fast as Other Dairy Products

When it comes to dairy products, butter has a higher fat content and lower water level, making it less likely to encourage bacterial development. Salting the butter further reduces its water content, therefore reducing the likelihood of germs flourishing.

The high salt concentration in the serum-in-lipid emulsion of butter limits the growth of contaminating bacteria to the small amount of nutrients trapped within the droplets that contain the microbes. However, psychrotrophic bacteria can grow and produce lipases in refrigerated salted butter if the moisture and salt are not evenly distributed. Microbial lipases remaining in the butter can hydrolyze the fat even during frozen storage (2).

Bacteria Cannot Grow on Salted Foods. Only one species of a bacterium can live in salted butter, according to the US Food and Drug Administration (FDA). While most germs can thrive in unsalted butter.

Bacteria were put to butter in a study to assess the butter’s shelf life, and researchers found that a variety of bacteria thrived. Bacterial levels were much lower than expected after three weeks, indicating that butter does not promote the development of the majority of bacteria.

As a result, even when stored at room temperature, ordinary, salted butter poses little danger of bacterial infection. Butter is made with the knowledge that it will not be refrigerated, which is why it is so expensive. On the other hand, unsalted and whipped varieties have their own set of problems.

However, sodium chloride has been shown to be a lipid pro-oxidant factor in different foods and food systems, and chloride has been identified as the active component in this reaction. Commercial salt also contains metal ion impurities that enhance its pro-oxidant effect; metals act as catalysts lowering the activation energy of the lipid oxidation reactions, thus increasing the rate at which these reactions take place. That means, even if, when stored at room temperature, the salted butter may not suffer bacterial spoilage, it is prone to suffer rancidity caused by oxidation of fatty acids (4).

Don’t let your butter get rancid

Butter has a minimal risk of bacterial development, but its high-fat content makes it susceptible to rancidity. You can tell if fat has gone rancid because it will smell bad and may become brown.

Oxidation is the process through which fats grow rancid or decay, altering their chemical structure and releasing potentially hazardous substances. As a consequence, any product created with rancid fats has an unpleasant taste.

Rancidification in butter is caused by lipolysis (release of free fatty acids) and oxidation of the fatty acids, impairs the flavor and lowers the nutritional quality of butter. Lipolytic changes occur in milk fat as a result of the hydrolysis of triacylglycerols by lipases (indigenous milk enzymes and enzymes of microbial origin). Lipolysis triggers the accumulation of free fatty acids (FFA), which can cause off-flavors described as rancid, butyric, bitter, unclean, soapy or astringent. Polyunsaturated fatty acids, which contain multiple double bonds with particularly reactive hydrogen atoms, are prone to oxidation (4).

This process may be accelerated by heat, light, and oxygen exposure. Butter may take anywhere from a few weeks to more than a year to become oxidized, depending on how it is manufactured and kept.

In the Refrigerator, butter lasts longer

Refrigeration is the best option for storing unsalted, whipped, or raw, unpasteurized butter to prevent the formation of microorganisms. Because the danger of bacterial development is so minimal, salted butter does not need to be kept in the refrigerator.

Even if kept at room temperature, butter has a shelf life of many months. However, if it is stored in the refrigerator, it will last longer. This inhibits the oxidation process, which finally leads to rancidity in butter.

In addition, freshly churned salted butter is characterized by an intense cooked/nutty flavor which likely comes from the high heat treatment that the cream receives prior to churning. The most common compounds that characterize the primary fresh aroma of butter flavor are diacetyl, butanoic acid, hexanoic acid, hexanal, acetaldehyde, dimethyl sulfide, δ-octalactone, δ-decalactone, decanoic acid, phenol, p-cresol, and skatole. This flavor is known to rapidly dissipate in butter. However, long storage of butter in the refrigerator may accelerate this flavor loss, when compared to the long storage at freezing temperatures (3).

Because of this, it is typically suggested that butter not be left out for more than a few days or weeks to maintain its freshness. You should also store it in the refrigerator if your residence is warmer than 70–77°F (21–25°C). To keep your butter on the counter but not consume it all in a short period, keep a little bit on the counter and put the rest in the refrigerator. For up to a year, you may preserve huge quantities of butter in your freezer. 

Studies showed that butter prints stored at −18°C and found no deterioration over a 12-mo period. Butter stored for 14 wk at 5°C remained high in quality according to graders, but some slight changes in flavor were observed for some packaging types. It was concluded that −10°C was the best storage temperature in terms of convenience and butter quality (3).

Butter Storage Tips On the Counter

While certain forms of butter need to be refrigerated, ordinary, salted butter may be left out on the counter. If you want to keep your butter fresh at room temperature, here are some tips:

·         Keep just a little portion of it out on display. Refrigerate or freeze anything you don’t need right away.

·         Use an opaque container or a closed cabinet to keep it out of direct sunlight.

·         It’s best to keep it in an airtight container to prevent odors from escaping.

·         Take care to keep it out of direct sunlight and other sources of heat, such as the stove.

·         Unless the room temperature drops below 70–77°F (21–25°C), keep butter out of the fridge.

·         Many of these requirements may be met by a butter dish, but an opaque plastic storage container is also a good option.

Other FAQs about Butter that you may be interested in.

What is the difference between butter and margarine?

Can you put butter in spaghetti sauce?

How long does butter last in the fridge?

Conclusion

In this brief guide, we answered the query, “Does butter need to be refrigerated?” and discussed some tips to properly store butter on the counter.

References

1. Spoilage of Milk and Milk Products. 2016. In Food Microbiology: Principles into Practice (eds O. Erkmen and T.F. Bozoglu). 
2. Ledenbach, Loralyn H., and Robert T. Marshall. Microbiological spoilage of dairy products. Compendium of the microbiological spoilage of foods and beverages. Springer, New York, NY, 2009. 41-67.
3. Lozano, Patricio R., et al. Effect of cold storage and packaging material on the major aroma components of sweet cream butter. J. Agric Food Chem, 2007, 55, 7840-7846.
4. Méndez-Cid, Francisco J., et al. Changes in the chemical and physical characteristics of cow’s milk butter during storage: Effects of temperature and addition of salt. J Food Comp Anal, 2017, 63, 121-132.