peanut butter at room temperature, flows back instantly

How Peanut Butter is Made

All you need to make peanut butter are peanuts and some strong grinding power. Break those peanuts up into small pieces, and a previously hard, crunchy product turns soft and smooth. Pretty amazing isn’t it?

But that’s not all. There are countless ways to spice up your peanut butter and create a wide range of variations. Each requires just a slight tweak of the process or the addition of an extra ingredient.

Basic peanut butter manufacturing process

Of course, peanuts don’t leave the plant shelled, cleaned and roasted. So, before you can transform peanuts into peanut butter they need to be prepped. First of, the shells needs to be removed so you’re left with the peanuts themselves. The shells contain too much fibers to be used in a peanut butter, you just want the peanuts. Once you’ve got your peanuts, you’re ready to start making that peanut butter.

Roasting – for flavor

Technically, peanuts can be ground into peanut butter immediately. However, the resulting peanut butter can be quite bland in flavor. It’s why most manufacturers will roast the peanuts. During roasting, the peanuts are heated for a set period of time using either oil or hot air. Various chemical reactions take place, including the Maillard reaction. These reactions will cause the peanuts to get darker in color, and develop a lot of delicious flavors. This step is key to the final peanut butter flavor.

Another crucial benefit of roasting is that it further dries the peanuts. Even though peanuts are quite dry themselves, with a moisture content of about 5%, roasting brings it closer to 1%. If you’ve roasted peanuts, or other nuts for that matter, at home, you will have noticed that the roasted, cooled-down nuts are crunchier than the unroasted ones. The lower moisture content of the roasted peanuts is a key reason for this change.

peanut shelled and unshelled
Shelling peanuts, most do still contain their dark brown/reddish skins.

Blanching – to remove the skins

Depending on the actual process a peanut butter manufacturer may use, blanching happens after roasting, or just before, or not at all, it depends on the specific process. The main purpose of this step is to remove the skins from the peanuts which is done by heating the peanuts with either water or air. The heat causes the skins to let go and they can be rubbed off quite easily. An additional benefit of this process, as is also the case for roasting, is that the heat can kill certain microorganisms. This can improve the safety of the product.

Grinding – making the actual paste

Then it’s finally time to transform those peanuts into peanut butter! To do so, grinders break down the peanuts into small pieces. Often, the peanuts need to pass through at least two different grinders to break the peanuts into sufficiently small pieces. Think of these grinders as very strong food processors or roller mills. They are extremely strong and can break up the peanuts into very small pieces.

Generally speaking, the smaller the peanut pieces, the smoother the final peanut butter. Peanut butter processors may tweak their grinding settings to ensure they get the consistency they’re looking for. As such, sizes can vary. That said, generally speaking, at least half of the the particles in smooth peanut butter at less than 25 micron (μm) in size. At this size, particles are too small for our tongue to detect them, thus giving a smooth instead of gritty experience in our mouth.

inside of peanut butter
Ground peanut butter, there are still a few small pieces to be seen.
Grinding releases the oils

Keep in mind that peanuts themselves are made of countless cells. Peanuts generally contain over 40% oil. In the whole peanut, this oil is held within the cell structure of the peanuts. However, during grinding, many cells are broken down. As a result, the oil that was previously trapped within, is released. After grinding tiny peanut particles float in oil, instead of the oil being trapped within solid structures. It’s what allows peanut butter to be spreadable, whereas whole peanuts aren’t. But, it’s also why some peanut butters split over time, the oil and peanut pieces may separate again.

Mixing in other ingredients

Even though the main purpose of the grinding step is to break down the peanuts into small pieces, it also happens to be a great mixing step! All the pieces are continuously mixed and blended as they pass through the grinding steps. It’s why a lot of the additional ingredients that may be added to peanut butter such as salt, other oils, flavors, and sugars are added during this step. This way, no separate mixing step is necessary.

Storing peanut butter – stable, but not indefinitely

You can store peanut butter for quite a long time without it spoiling. However, depending on the variety, flavors can change and the peanut butter may even turn a little rancid. This is due to the oxidation of peanut oils. When they get exposed to oxygen, irreversible chemical reactions take place that aren’t great for the overall product flavor. The risk for this happening is biggest in peanut butters that develop a layer of liquid oil on top over time. Aside from these flavor changes, you generally won’t see growth of molds on peanut butter. The peanut butter is simply too dry to allow the growth of most microorganisms. Nor will you see color changes, or other types of common spoilage. Peanut butter is quite stable.

peanut butter at room temperature, flows back instantly
Peanut butter, stored at room temperature.

By the way, most other ‘nut butters’ such as almond or cashew butter are made in a very similar way

The role of non-peanut ingredients in peanut butter

You can make peanut butter from just peanuts. But, a quick glance at the peanut butter offerings out there will tell you that most peanut butters contain at least one or more added ingredients. Even though the underlying production processes are very similar, they do change the peanut butter in some subtle ways.

Just peanuts – controlling roasting is crucial

The simplest peanut butter is made from peanuts and nothing else. Natural peanut butter gets its flavor entirely from the peanuts it is made from. Proper control of the roasting process is even more important for these styles!

Keep in mind that peanuts are a natural product and that there are quite some different peanut varieties out there. As a result, there can still be quite large differences between 100% peanut peanut butters. Some peanuts may have more fat, others a different flavor profile for instance. Large-scale manufacturers generally use a blend of at least two varieties to ensure consistency. But, smaller scale manufacturers may see some more variation in their peanut butter products.

Peanut butter doesn’t contain butter

And no, peanut butter does not contain butter, despite the possibly confusing name! Butter contains too much water (close to 20%) to safely add to peanut butter. Also, generally speaking, only vegetable fats are added to peanut butter, excluding butter.

Add salt – for a flavor boost

One step up is the addition of salt. Salt amps up the flavor of peanut butter. It doesn’s necessaribly make it salty. Instead, it can strengthen and highlight the overall flavor of the peanut butter. Manufacturers will generally add it during the grinding process to ensure it gets mixed in properly. Salt doesn’t otherwise impact the peanut butter.

peanut butter from the fridge - keeps its shape
Jar of peanut butter

Other fats – for stability

Peanuts contain quite a lot of fat, and most of that fat is liquid at room temperature. During grinding this liquid oil is set free from the rest of the peanut. It’s what makes peanut butter a peanut butter, but, it also causes some additional challenges… Since the fat is liquid and the peanut particle solid, they will separate over time. That’s just how physics works. This separation of fat used to be a shelf life limiting factor before manufacturers found a way to overcome is.

Nowadays, you will find that many peanut butter manufacturers add a small percentage of other solid fats to the peanut butter. These solid fats help stabilize the liquid ones. If manufacturers do so, you’ll see that represented in the list of ingredients. Either hydrogenated peanut oils have been added, or simply another type of vegetable fat.

Again, to make this peanut butter variation, no fancy process steps need to be added. They can just be mixed in during the grinding process.

pot of peanut butter
A pot of peanut butter, advertising the absence of sugars (zonder toegevoegde suikers).

Sugar – for sweetness & price

The next ingredient does not impact the product’s consistency. Again, it’s a flavor changer: sugar. Sugar, honey, molasses, corn syrup; they can all be added to peanut butter during the grinding process. Generally speaking, they’re added for one of two reasons, or both:

  1. Costs: sugar is cheap, and (a lot) cheaper than peanuts, so it reduces costs
  2. Flavor: sugar sweetens the peanut butter
Honey makes it non-vegan

Most peanut butters are vegan. That is, they’re made from plant based ingredients only. The simpler the peanut butter, the higher the chances for it being vegan. One of the main reasons for a peanut butter no longer being vegan is actually the addition of honey as a sweetener. Most other varieties will be fully plant based.

Peanut pieces – for crunch!

Ever wondered why creamy peanut butter seems to have large pieces within a smooth paste, without really any small or medium sized pieces? It’s definitely not a continuous mix of sizes that makes up a crunchy variety. Also, it seems hard to make a smooth paste, with a few large particles. And that indeed is tricky. It’s why most crunchy peanut butters are a two step process. First, a smooth peanut butter is made. This is the ‘continuous’ phase that will hold the crunchy bits. Next, larger pieces of peanuts, ground using slightly different equipment or different settings, are mixed in.

Glycerides – to help stability

You may have noticed that some peanut butters contain glycerides. These molecules, which are made from fats, help to stabilize the peanut butter with fats mix. Generally speaking, you’ll only see them in peanut butters that also contain added fats.

Peanut butter is not a global phenomenon

Interestingly, whereas the largest fraction of peanuts grown in the United States is used to make peanut butter, those numbers are radically different in the rest of the world. Aside from a few exceptions, such as the Netherlands, peanut butter is not at all that common outside of the US. As a matter of fact, in most of the world, peanut oil is one of the most important products made from peanuts, which happens to be a great oil for frying and baking!


EPA, Peanut Processing, link

Foods and Food Production Encyclopedia. United States: Springer US, 2012, p. 896-900, available at: link

Gastropod, Peanuts: peril & promise, June 20, 2017, link – Gastropod is a great podcast, a tip if you’re into podcasts

Krampner, J., Creamy and Crunchy: An Informal History of Peanut Butter, the All-American Food, 2014, link

Tara McHugh, How Nut and Seed Butters Are Processed, Nov 1, 2016, link

N. H. Mohd Rozalli, N. L. Chin & Y. A. Yusof(2015)Particle Size Distribution of Natural Peanut Butter and Its Dynamic Rheological Properties,International Journal of Food Properties,18:9,1888-1894,DOI: 10.1080/10942912.2014.971184

USDA, Food Data Central, Peanuts, raw, FDC ID: 2515376, link

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