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.
Want to be updated on new food science articles? Subscribe to our weekly newsletter
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 ingredient is helpful. We’ve extensively covered brownies before here. So 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.
- 150g sweet potato puree (or a little more in actual sweet potato)
- 200g cooked black beans (without liquid)
- 45g all-purpose flour
- 50g butter
- 2 tbsp powdered egg replacer OR 2 eggs
- 40g milk (any type of milk) - do NOT add if using eggs
- 75g brown sugar
- 65g chopped nuts (e.g. pecans)
- 1tbsp instant coffee powder
- 40g cocoa powder
- sprinkle of salt
- 2 tsp lemon juice
- 1/2 tsp baking soda
Black bean & Sweet potato puree
- If starting with sweet potatoes: peel the sweet potato and boil until soft.
- If starting with dried black beans, cook in a pressure cooker with sufficient water for 30-40 minutes until soft.
- Blend black beans and cooked sweet potato in a blender to create a smooth paste.
- Mix all ingredients in a bowl. Use a spatula to fold ingredients together.
- Take a greased or lined with parchment paper, square baking tin (20x20 cm or 8x8 inch) and fill with brownie batter. Smoothen out.
- Bake in a pre-heated oven at 350F for 20-25 minutes. To get a more gooey brownie take out just before it's fully cooked, for a drier more cakey brownie, take out when a skwere comes out clean.
This brownie is quite low on the sugar and high on beans and sweet potato. As such, it can't be stored for as long at room temperature as a conventional brownie might be. Store in the fridge for several days or wrap in plastic before freezing.
Did you know, adding sweet potato in your brownie increases the fiber content! Researchers have actually done research on this to better understand how best to use the sweet potato.
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