Your most basic peanut butter contains just peanuts and some oil to help the peanuts blend together into a smooth paste. There are two distinct types of peanut butter: “regular” and “natural”. “Regular” is the term I’ll use to define your standard peanut butter and jelly sandwich peanut butter, and a category that includes most easy to find national brands. It’s creamy and thick, even at room temperature, and usually has salt and sugar in addition to peanuts in the recipe. “Natural” peanut butter is much thinner than regular peanut butter at room temperature, and tends to be extra firm when chilled. It rarely has extra ingredients added to it and it separates easily into the oil and peanuts used to make the butter.
When it comes to baking, I tend to use what is on hand, but there will often be some differences in recipes made with natural peanut butter instead of regular. Most recipes (unless otherwise specified) are written with the assumption that you’ll use regular peanut butter. The salt and sugar from that regular peanut butter can add a lot of flavor to a recipe, and the thickness of the peanut butter translates into less spread for peanut butter cookies, for instance. Natural peanut butter is often unsalted, so you may need to add additional salt to a recipe. It might also seem saltier than regular peanut butter because of the lack of sugar in the mix, so you might want to cut back on the salt in the recipe by 1/4 tsp if you are very sensitive to it. Natural peanut butter cookies tend to spread out more, and frequently have a crispier texture (this is often do to a higher proportion of oil in the mix) than cookies made with regular peanut butter. Since they spread out more, they sometimes need a slightly shorter baking time.
Most recipes will deliver a similar result no matter which type of peanut butter you use – even if you do have to make a tiny tweak or two due to a lack of salt or sugar in your product – so you can still use whatever is on hand. But watch out for a recipe that specifically calls for one or the other and be aware of the slight differences that exist between the two types.
Now, there are a few types of low fat, low carb or reduced something-or-other peanut butters out there as well (other types of nut butter work the same way as natural peanut butters). If you’re going to use these in baking, check the ingredients list first. The more that it differs from standard peanut butter, the greater the chance that you’re going to have some differences in taste and texture in your finished recipe. That isn’t to say that whatever you’ve made won’t still be tasty. It just might not be the same as using your standard peanut butter, so keep that in mind when tasting the results.