Learn the science behind:
Always looking for a new experiment, I decided to try my hand at some black bean brownies the other day. Looking for a fun variation on brownies, and having some left-over sweet potato, I ended up making sweet potato-black bean brownies.
They turned out great, but it got me wondering. There are a ton of black bean brownie recipes out there, but no brown bean, kidney bean, or lentil brownies. So, why do we use black beans to make a good sticky brownie?
What’s in a black bean?
Black beans, or Phaseolus vulgaris, are one of many types of beans. It is set apart from others by its pitch black color. They, like most other legumes, are rich in proteins, fibers and complex carbohydrates. Cooked black beans contain about 9w-% of protein, a similar amount of fiber and over 10w-% of complex carbohydrates. Black beans also barely contain any fat, and contain only very little fat.
Of course, a black bean is black. When attempting to make something dark like brownies, it helps to create that dark flavor. However, cocoa powder in and by itself is already capable of making brownies pretty dark in color.
Large complex carbohydrates are known to stabilize water in food in a gel like matrix. This increases the viscosity and creates a creamier mouthfeel.
Plenty of reasons for using (black) beans
Brownies are dark brown in color. Using a black bean in your brownie will only darken the brownie, making it a somehow obvious choice. But why even consider to put these beans in your brownies?
Flour free (or reduced flour) brownies
First of all, people are using black beans to take out the flour from the brownies to accommodate the recipe to someone with celiac disease. In that case, the starches from the black beans will help thicken the batter and make it creamy. However, if you’re more into cakey brownies, you might be disappointed. Wheat flour helps create that lighter airy structure. Both the gluten proteins and the starches help set the cake structure. Taking it out will make the brownies more gooey. If you’re more of a gooey brownies person though, this works great.
Researchers have focused on using black beans in brownies to reduce the amount of fat and thus calorie content of the brownies. They replaced shortening with black bean puree. Participants in a study couldn’t change the difference up to 30% substitution, after that they did notice a difference, even though they still found the brownies acceptable.
Black beans, like more legumes, contain more fibers the all purpose flour. Several researchers have looked into this, not necessarily with black beans, but different types of legumes. We humans need sufficient fiber. Especially in the west we often lack enough of it, thanks in part to fiber-less brownies! Adding some brownies in there may just help a little.
Why black beans specifically?
So far, most reasons (apart from the color) aren’t specific to black beans. Other types of beans could have fulfilled those roles. And, in testing out some others (e.g. brown and kidney beans), those worked perfectly fine as well!
We’re curious as to why black bean brownies are more common than other type of bean brownies, because the differences really aren’t that big at all!
Just try it out, use whichever beans you have at hand, follow the recipe below and let us know in the comments how it went!
“Designing” black bean brownies
For now, we’ll be assuming though that you’ll be sticking to your black beans. If you’re planning on using them, a good understanding of both the recipe and ingredients is helpful. Keep in mind that there are several other factors that will determine whether you get a crispy top for instance, or a gooey interior. That said, let’s focus on the black beans here.
Once you have your black beans, consider what they’re made of. Black beans contain a lot of starches and complex carbohydrates, barely any sugar or fat, but again a good amount of protein. Since black beans contain a lot of water you should reduce the amount of moisture you’d normally add to your recipe. Also, the carbohydrates in black beans have already absorbed a lot of moisture. Where flour will still thicken liquids considerably during baking, black beans won’t do that as much.
Using black bean flour
Of course, getting rid of that high moisture content in black beans can be done by using dried, milled black beans: black bean flour. Black bean flour is not as commonly available. But if you decide to use it, you have a few more opportunities to balance the moisture content of your brownies if you otherwise find them too wet. This is especially useful if you’re not using any wheat flour!
Color & flavor
Black beans, are black, of course. This is what makes them ideal for brownies, which are dark in color naturally. If you’re aiming to develop a lighter colored product, you could simply consider another type of legume! Most legumes have similar, though not identical, structural properties. Colors and flavors are very different though, making them suitable for slightly different applications.
Some practical concerns
When you’re looking at using black beans the first aspect to consider is storage capacity. If you’re making brownies at home you can pull open a can of black beans and use them. However, if you’re planning on making these on a larger scale, that becomes more problematic. You will need to transfer to larger packaging formats or even cooking the black beans on site.
English, M.M., Viana, L. and McSweeney, M.B. (2019), Effects of Soaking on the Functional Properties of Yellow‐Eyed Bean Flour and the Acceptability of Chocolate Brownies. Journal of Food Science, 84: 623-628. doi:10.1111/1750-3841.14485
Fleischer, A.M., Acceptability of Brownies Supplemented with Black Bean Puree by College Students at Indiana State University, 2013, link
Uruakpa F. O., Fleischer A. M., Sensory and Nutritional Attributes of Black Bean Brownies, American Journal of Food Science and Nutrition 2016; 3(3): 27-36, link
USDA, Food Central, Beans, black, mature seeds, cooked, boiled, without salt, link
Khemmarat Vongsumran, Wannasawat Ratphitagsanti*, Penkwan Chompreeda and Vichai Haruthaitanasan, Effect of Cooking Conditions on Black Bean Flour Properties and Its Utilization in Donut Cake, Kasetsart J. (Nat. Sci.) 48 : 970 – 979 (2014), link