peanut butter brownie

Peanut butter in everything – Peanut butter science & brownies

It definitely is an American thing, although you do see the phenomenon creeping around the globe somewhat: adding peanut butter in everything. That is, almost everything. Definitely anything that is sweet and baked or very cold and creamy. Peanut butter is omnipresent in the US so discussing the science of peanut butter isn’t something we can skip on here on FoodCrumbles.

Why is peanut butter in everything?

Somehow, peanut butter has grown into this ingredient that can be put in just about any baked good (we’re focussing on the US here). There’s peanut butter cookies, peanut butter sandwiches, peanut butter dressings, peanut butter cakes, peanut butter ice creams and plenty plenty more. Even though the Dutch eat quite a lot of peanut butter (though most of it on sandwiches), it seems that it’s the Americans that have made peanut butter really really big. There’s a ton of different brands and it’s used everywhere.

So where and when did it get its fame? The peanut is native to South America where scientists thing it has been growing for thousands of years. When the Europeans came to Central America in the 16th century they quickly liked and adopted the peanut into their diet. Since peanuts travel well they were a great food for long sea voyages and that way ended up on West Africa (according to the latest theories) where people adopted them rapidly. It is thought that from there on they ended up in the US through slave ships. Peanuts were an essential provision during the civil war in the US and good marketing strategies kept them popular.

Peanut butter didn’t enter the stage until the late 19th century when ground up peanut paste started to be sold and caught on well with consumers. It of course works great on sandwiches. Peanut butter really got big during the subsequent two world wars. Its high protein content makes it a decent meat replacer in times of scarcity and what’s better, it still tastes good. From then on it really took off!

peanut shelled and unshelled

Making peanut butter

The process for making peanut butter is actually quite simple. It consists of the following steps:

  1. Shell the peanuts and remove any debris, etc.
  2. Roast and possibly blanch the peanuts, this will remove the skins and will be a first step in killing off unwanted micro organisms. It also gives flavour to your peanuts. A darker roast (as is the case for coffee) will give a stronger, more in-depth roast flavour. Cool the peanuts to ensure no further flavour & colour development takes place.
  3. Grind the peanuts into a smooth paste. For a smooth, creamy peanut butter manufacturers will grind the peanuts small enough you for not to taste any more particles.
  4. Mix in the other ingredients such as fats, sugar, salt (we’ll discuss them each in more detail below).
  5. Mix back in peanut pieces for crunchy peanut butter! Yes, indeed, they are mixed back in. Have you ever noticed how uniform in size the pieces in chunky peanut butter are? This is impossible to achieve if you grind the peanut butter as a whole and is why the pieces are added back in after grinding!
peanut butter at room temperature, flows back instantly
Peanut butter, stored at room temperature. Even though we only just put a knife in there to take some peanut butter out, it has flowed back to a smooth surface immediately.

All the types of peanut butter

You can make peanut butter from just peanuts. All you have to do is grind down nuts and you’ve got your peanut butter. By grinding down the nuts you release the oil in the peanuts, which peanuts contain quite a decent amount of. By freeing up the oil and reducing the size of the peanuts, you end up with a nice paste.

Despite peanut butter being so simple, there are a lot of different types of peanut butter for sale nowadays (not even to mention the blends with others nuts). All of them have peanuts as their base, of course and vary from there on.

Just peanuts

The simplest peanut butter is made from peanuts and nothing else. This type of peanut butter is not very stable in its appearance though. Over time, during storage, a liquid layer will form on top of the peanut butter. This is perfectly fine, you can just blend it in again. The reason the fat separates is that a lot of the peanut fat is actually liquid (learn more about fats & oils here). Just as would happen in a chocolate milk, the peanut particles will settle down into the liquid over time. Resulting in some liquid on top.

Natural peanut butter gets its flavour entirely from the peanuts it is made from. Peanuts are often roasted before being made into peanut butter. Roasting is great for flavour development and it’s a way for manufacturers to differentiate their product.

This natural peanut butter is great for baking, giving you full control on the amount of sugar and salt you’re adding. Since this type is a little more liquid than others it might impact your dough or batter. However, chilling the dough for a while in the fridge will help prevent this separation.

Peanuts with additional fat

In order to stabilize that fat manufacturers realized they could add another solid fat to help prevent those particles from settling out. We’ve discussed this in a post dedicated on the topic before so won’t dive into the details here. You will recognize these peanut butters by the addition of a fat to the label aside from the peanuts.

If liquid oil splits from the peanut butter it does make the peanut more prone to spoilage because of oxidation. The additional fat can therefore extend the shelf life.

Peanut butter with salt

Peanut butter can be stored indefinitely from a food safety perspective. Peanut butter contains so little moisture (very low water activity) that micro organisms cannot grow within (but if they’re already there, they might just survive!). So the addition of salt to your peanut butter is not because of shelf life. Instead, it is there primarily for flavour. Salt is great at enhancing and lifting up flavours and it does just that in peanut butter.

If you eat the peanut butter as is, peanut butter with salt might just be to your liking. However, if you’re using peanut butter as an ingredients you should consider the salt already present in the peanut butter to balance out the overall recipe.

Peanut butter with sugar

For those sweet lovers there’s also peanut butter with sugar (or molasses). Personally, I really do not like sweetened peanut butter, but it’s a huge part of the peanut butter space in supermarkets so I guess I’m a minority in that regards. So why is sugar added? Two reasons:

  1. Costs: sugar is cheap, definitely cheaper than peanut butter, adding sugar (and it’s often present in quite high amounts) definitely helps make peanut butter cheaper
  2. Flavour: some (just not me) prefer the sweeter peanut butter

Again, you can definitely use peanut butter with sugar in most recipes. As with the salt, beware of the sugar already in there. It might make your food overly sweet if the recipe does not call for sweetened peanut butter.

peanut butter brownie close up
Peanut butter brownie

Peanut butter with glycerides

You may have noticed that some peanut butters contain glycerides as well. These molecules help to get the peanut butter and the different fats mixed well together.

Using peanut butter

You can mix in peanut butter with so many different things: cookie dough, ice cream, brownies (see below) and much more! When working with peanut butter though, there are a few things to remember. Peanut butter may seem very fluid and liquid (especially the natural one), but that does not mean there is any moisture in there. Peanut butte ronly contains a little bit of moisture. So if you need moisture for your dough to come together or to form a gluten network, peanut butter is not the solution.

Instead peanut butter contains a lot of fat (often >50%), proteins and some carbohydrates (some sugars, some fibers). If you don’t have enough moisture in the recipe, the peanut butter might actually dry it out a bit more. But, the high fat content will make your products richer and creamier. It will also make them softer. Especially in the case of cookies this might be an important consideration if you’re looking for crispy as opposed to soft cookies. A lot of peanut butter will make the crispy cookie very challenging.

Peanut butter brownies

Peanut butter brownies

Yield: about 16 portions
Prep Time: 30 minutes
Cook Time: 25 minutes
Total Time: 55 minutes

As we discussed before, there are a lot of different ways to make brownies. You could probably use any style and just add peanut butter on top before placing it in the oven. As we've said several times by now (for Americans) peanut butter works with anything :-)!

The recipe below is inspired by Laura's Bakery.


  • 60g butter
  • 150g sugar
  • 75g brown sugar
  • 100g milk chocolate (or dark if you prefer it less sweet)
  • 80g cocoa powder (add less for a slightly less bitter brownie and for a more liquid batter)
  • 2 eggs
  • 100g flour
  • 2 tsp baking powder
  • 2 big spoonfuls of peanut butter (at least 30g, or more, we used a lightly salted smooth peanut butter, but go wild and choose whichever type you like!)


  1. Add the butter, sugars, chocolate and cocoa to a small pan and gently heat until all the chocolate and butter have melted.
  2. Leave to cool down slightly until it's cool enough to add the eggs without cooking them.
  3. Mix in the eggs and then add the flour and baking powder. Fold it in, but don't mix too much.
  4. Spread the mix in a square tray (max. 20x20cm), it will be quite stiff due to the cocoa powder. If it's really too thick, add a tablespoon of water or milk at the time to soften it.
  5. Add the peanut butter on top of the brownie and use a fork or toothpick to spread it out.
  6. Bake in a pre-heated oven at 190°C for 25 minutes


Gastropod, Peanuts: peril & promise, June 20, 2017, link (Gastropod is a great podcast, a tip if you’re into food & podcasting)

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

Taste of the Past, EPISODE 119 A History of Peanut Butter with Author Jon Krampner, Nov-29 2012, link (yet another podcast!)

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