How Long Does Butter Last? | USDA Guidelines

Butter’s ubiquitousness results in most of us having the ingredient in our homes, whether we are heavy or irregular users of this dairy product. Consequently, butter can remain in our fridges for months after purchase and be used without further consideration. However, butter is a dairy-derived product, so how long does it actually last?

The USDA recommends that salted butter is kept for no longer than 5 months when stored in the refrigerator. However, if you have purchased unsalted butter, it will only last 3 months under the same conditions. These time frames apply to butter that has been opened or unopened.

How long butter lasts:

Type	Room Temperature Shelf Life	Refrigerator Shelf Life	Freezer Shelf Life
Salted Butter	Up to 10 days	5 months	Up to 12 months
Unsalted Butter	Up to 2 days	3 months	Up to 6 months

To preserve butter and maintain its freshness, keep it away from air, as the oxygen in it will react with the fats causing them to spoil. Signs that butter has spoiled include discoloration, mold spots, changes in texture, and an alteration in taste.

The rest of the article will go into greater detail about how long butter lasts and provide information about proper storage as well.

What Is The Shelf Life Of Butter?

Butter is a unique dairy product that lasts for longer than its counterparts, such as milk, yogurt, cream, or cottage cheese. Instead of shelf lives that are measured in days and weeks, butter can be safely stored for months. According to the United States Department of Agriculture (USDA), unsalted refrigerated butter will last up to 3 months, and salted butter will start to spoil after 5 months.

These guidelines apply to opened or unopened butter, provided you re-wrap the butter after use. They are also only applicable to butter that has been produced using pasteurized cream. In Europe, butter derived from raw cream (unpasteurized) is the preferred source. Raw butter, due to its bacterial content, will only last around 10 days when stored in the refrigerator. Commercial raw butter is a scarce commodity in the United States; therefore, it is unlikely you will encounter this. If you do, it may be called “raw butter” or “European-style.”

The relatively prolonged shelf life of pasteurized butter is due to its composition, which is high in fat and low in water content. These conditions make it difficult for bacteria to grow due to a lack of food. Salted butter lasts longer as salt is preservative that helps keep the water content low, again adversely affecting the ability of microorganisms to grow. Consequently, bacterial and fungal propagation isn’t the normal pathway for butter to expire. Instead, the fats in the butter degrade, making the product rancid.

The most common pathway for butter to become rancid is through oxidation from being open to the air, exposure to light, and exposure to heat. Due to these modalities, the shelf life of butter is mostly down to how you look after butter during its lifespan. Without proper storage conditions, butter can you rancid on the day you buy it.

If you need to buy butter ahead of time or know you cannot use what you have within the 3-month window, you can freeze butter to extend its lifespan. Freezing butter in the short term (up to a year), should not result in too much change in texture. This is due to the lack of water content in butter, which means that there is little water to expand and develop ice crystals upon freezing.

However, after a year in the freezer, the butter will start to degrade. You can expect the texture and flavor profile to change drastically due to the fats breaking down. Due to the relatively short increase in shelf-life, it is best to buy butter in quantities that you will use within the refrigerated timeline rather than in bulk.

Related Does Coconut Oil Need to Be Refrigerated? | How to Store It.

How To Store Butter

Correctly storing butter is the key to its longevity. To preserve the freshness of butter and prevent bacterial growth and the fats from becoming rancid, you want to keep butter away from air, light, and heat.

Keep Away From Air

The oxygen and moisture in the air are critical factors in butter spoiling. Oxidation is the most common pathway for butter to become rancid, breaking down the butter into glycerol and fatty acids. While oxygen from the air is mostly going to split the butter into components, it also assists any microbes in thriving. The small amount of moisture in the air, especially in humid climates, also contributes to keeping dangerous bacteria hydrated and able to replicate. Therefore, avoiding butter’s contact with the air can only be a good thing.

To prevent these modes of degradation, it is good practice to keep butter enclosed as much as possible. Such precautions as re-wrapping butter after each use will help preserve it. If you like your butter out of the fridge to soften before use, consider buying a butter dish, or even a French butter keeper, which keeps air away better. Other options are resealable plastic bags or a container with an airtight seal.

Protect It From Light

Similar to air, the light will cause oxidation and butter to go rancid quickly. This is why butter dishes are not transparent. For a long time, scientists thought that one of the most affected components of butter that is attacked by light is riboflavin, which is also known as vitamin B2, and it was this that caused the butter and milk to go rancid.

However, B2 doesn’t respond to sunlight as aggressively as once thought. Instead, the chlorophyll from the grass that cows eat and end up in the final product is the cause behind the off-flavor dairy products, including butter, experience when exposed to light.

Chlorophyll is highly sensitive to light, far more so than riboflavin, and was only discovered by scientists in cows milk by chance while studying other compounds. Therefore, light reactions could be affecting other compounds in the butter that we are presently unaware of. Either way, shielding butter from the light will keep it tasting delicious throughout its lifespan.

Refrigeration

Keeping butter refrigerated (below 40 °F) is the first line of defense against it spoiling. Most users report that butter can be kept at room temperature for up to a week in a butter-appropriate container (Amazon Recommendation); however, the USDA disagrees. Instead, the government will only recommend that butter remains safe for only a couple of days at room temperature before it should be discarded.

Keeping the temperature low does two key things to protect butter. First, it keeps the butter away from the food danger zone of 40 °F – 140 °F, which is where most microorganisms thrive and replicate readily. At lower temperatures, any bacteria or fungi in butter will not be able to grow. Additionally, lower temperatures help preserve the fat’s chemical structure inside the butter, which is the primary modality for butter spoilage.

While most refrigerators have butter compartments in the door, this isn’t the best place to store your butter. The only exception is if you use your butter quickly, that is, within a few weeks. Otherwise, the fridge door should be avoided as the doors encounter fluctuating temperatures as they are opened. To best preserve butter, keep it in the main section of the fridge.

How To Determine If Butter Has Gone Bad

The preservation of butter isn’t always at the forefront of people’s thoughts, as it is a product that doesn’t appear to go bad. However, eating rancid butter will result in lower food quality and can result in an upset stomach along with other digestive issues if consumed. Knowing how to properly care for butter throughout its life will keep your butter fresh for longer.

Butter is something that most of us have in our refrigerators, and we can’t recall when we purchased it. Although sell-by dates are a guide as to how long the butter will be viable, it is always good to know what you are looking for when trying to detect if the butter has expired.

• Discoloration
  Butter should be one consistent color. If you cut into your butter block and the inside is a brighter color than the outside, this is a clear indication that the butter has expired. This change in color
• Mold Spots
  If you detect any black spots on your butter, it indicates that mold has developed on it. Remember, mold is fungi spores, so even if you remove the spore, the fungi are still in the butter, making it unsafe to eat. However, the butter will likely have gone rancid long before mold starts to grow on butter. 
• Texture
  Expired butter will be very soft, even squishy to the touch. If the texture of the butter is softer than it usually is, throw it away. The inverse can also be true. Very hard butter is indicative that it is no longer safe to eat too. 
• Smell
  Butter should be nearly odorless. If you smell your butter and detect a sour aroma, the butter’s fatty acids have significantly broken down. It is also possible that the smell is due to bacterial growth. Don’t eat it and throw it away.
• Taste
  If you eat butter and it has an off-putting flavor, then the fats and oils have probably gone rancid. The unpalpable flavor should prevent you from eating any more of it anyway, but avoid eating butter if it tastes foul. In particular, you are looking for either a soap, baby vomit, or a blue cheese type flavor. It’s a clear indicator that the butter has gone rancid.

Luckily, eating expired butter doesn’t have too many consequences. Unlike eating expired meat, degraded butter will, at most, give you a stomach ache. That is because it is far more likely that that butter will be rancid before it is spoiled due to bacteria. Consuming rancid butter, however, can lower your vitamin E and vitamin B stores. For some, that may be a health concern that is best avoided.

Final Thoughts

Butter is a core ingredient in many foods and is used throughout the world as a fat for cooking. Its creamy flavor profile is also regarded as a spread, used on toast or a pancake. 

Butter is a common ingredient in many foods and cooking processes throughout the world. While each country has its own personalized method of making butter and products derived from it, the most common butter in the United States is butter made from pasteurized cream or milk. If kept refrigerated, this butter will last up to 3 months or 5 months if it is salted.

To achieve these shelf lives, the butter needs to be protected from the air to avoid oxidation of the fats, away from light to protect the fat molecules’ chemical bonds, and at temperatures below 40 °F to prevent bacterial growth and the degradation of the butter molecules. If needed, butter can be frozen for up to a year. However, expect the texture and flavor profile to have changed slightly during the freeze-thaw process. 

Related Questions

How Is Butter Made?

Producing butter is an extensive process involving the churning of milk to separate the butterfat (solids) from the buttermilk (liquids). Churning is the act of stirring or shaking vigorously; for butter, this needs to be between 120-150 RPM for 20-25 minutes. The milk needs to be heated to 65 °F.

For flavor, some kinds of butter use additives such as salt or food coloring to make the product more appealing. It takes 10 to 11 gallons of milk to produce just one pound of butter. Most butter that is purchased uses cow’s milk as the base. However, you can also use goat, sheep, yak, or buffalo milk to make butter. The color, taste, and texture of the butter will be determined by the milk source.

What Are Clarified Butter and Ghee?

Butter that has almost all of its milk and water content removed is clarified butter. It is produced by melting butter (bringing it to its melting point of 90 °C – 95 °C) and then allowing it to return to room temperature. Following this process, the butter will have separated into components that remain in distinct layers due to their differences in density.

• On the top, the lighter components of whey proteins form a skin that can be siphoned off the top.
• The middle layer is the clarified butter layer, which is essentially purified butterfat.
• The bottom layer is the products with the highest densities, which are mostly water and the heavy proteins in the butter, such as casein proteins.

Ghee is made via a similar process to clarified butter, except that during the melting phase, a higher temperature of 120 °C is used. The butter remains boiling or simmering until the milk solids turn brown, and most of the water has been evaporated. The effect of this extra heat is that it flavors the ghee with an aromatic nut flavor, and it produces antioxidants. As oxidation is one of the main processes behind rancidity, these antioxidants help prolong the ghee’s shelf life to around 6 to 8 months.

Related How Long Does Ghee Last and How Should It Be Stored?

What Is The Difference Between Butter And Margarine?

The key difference between margarine and butter is that butter is made from dairy products, e.g., cows milk, whereas margarine is derived from plant oils. All butter sold in the United States must contain at least 80% fat, and as the fat is derived from animals, it is high in saturated fats and cholesterol. Margarine, meanwhile, is made from a combination of vegetable oils, water, salt, and emulsifiers.

Do note that some kinds of margarine can contain a little milk. Akin to butter, margarine must contain 80% fat too, as anything less must be classified as a spread. However, margarine has far less cholesterol than butter and contains more polyunsaturated and monounsaturated fats – both of which are healthier for heart health than saturated fats.

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