Making banana flour is straightforward: peel green bananas, slice them thin, dry the slices until completely brittle, then grind them into a fine powder. The entire process takes about 10 to 12 hours, mostly hands-off drying time, and yields a versatile, gluten-free flour packed with resistant starch. Here’s how to do it right.
Why Green Bananas, Not Ripe Ones
The single most important decision is using green, unripe bananas. Green bananas contain roughly 70% starch on a dry basis, with up to 74% of that starch being resistant starch, the type that passes through your small intestine undigested and feeds beneficial gut bacteria. Ripe bananas have converted most of that starch into sugar, which means the flour won’t behave the same way in recipes and loses the nutritional advantages that make banana flour worth making in the first place.
Resistant starch acts as a prebiotic, supporting gut health, and has been linked to better blood sugar control and improved satiety. Green bananas contain the highest concentration of resistant starch of any unprocessed food. They’re also rich in potassium (ranging from about 290 to over 1,000 mg per 100 g of flour depending on the variety), along with minerals, carotenoids, and antioxidants. Choose bananas that are firmly green with no yellow patches. If you can only find bananas that are starting to turn, pick the greenest ones available.
Step-by-Step Process
Peel and Slice
Wash the bananas under running water and peel them with a sharp knife. Green bananas don’t peel as easily as ripe ones, so you’ll likely need to score the skin lengthwise and pry it off in sections. Slice the peeled bananas into uniform rounds about 5 mm thick (roughly 3/16 of an inch). Consistency matters here: slices of different thicknesses dry at different rates, and thicker pieces that retain moisture can develop mold.
Green banana flesh oxidizes quickly and turns brown when exposed to air. To keep your flour lighter in color, you can dip the slices briefly in a bowl of water with a squeeze of lemon juice before arranging them for drying. This step is optional and mostly cosmetic, but it does produce a more appealing finished product.
Dry the Slices
Arrange the slices in a single layer with space between each piece so air circulates freely. You have several options for drying:
- Food dehydrator: Set it to 140°F (60°C). Expect 8 to 10 hours of drying time. This is the most reliable home method because it provides consistent, even airflow.
- Conventional oven: Set your oven to its lowest temperature, ideally around 140°F (60°C). If your oven doesn’t go that low, use the lowest setting and prop the door open slightly with a wooden spoon to let moisture escape. Oven drying can take up to twice as long as a dehydrator, so budget 16 to 20 hours. Flip the slices halfway through.
- Sun drying: Possible in hot, dry climates, but slower and riskier. You need consistent heat, low humidity, and good airflow. Cover the slices with cheesecloth to keep insects off. This method takes one to three days depending on conditions and carries a higher risk of mold if humidity spikes overnight.
The slices are done when they snap cleanly in half rather than bending. If they’re leathery or flexible at all, they still contain too much moisture. Keep drying. Residual moisture is the enemy of shelf life: it invites mold growth and causes clumping during storage.
Grind Into Flour
Let the dried slices cool completely, then grind them in a high-speed blender, food processor, or spice grinder. Work in small batches for a finer result. After grinding, sift the flour through a fine mesh sieve. Any larger chunks that don’t pass through can go back into the blender for another round. A standard kitchen sieve works well, though commercial production uses a 40-mesh sieve for a very fine, consistent texture.
How Much Flour You’ll Get
Expect a significant reduction in volume. Green bananas are mostly water, so drying removes the bulk of their weight. As a rough guide, about 5 to 6 pounds of fresh green bananas will yield approximately 1 pound of flour. The exact ratio depends on the banana variety, how green they are, and how thoroughly you dry them. Don’t be surprised by the small pile of flour at the end. The nutritional density is concentrated: 100 g of green banana flour contains around 81 to 85 g of carbohydrates, 3.5 to 4.3 g of protein, and less than 1 g of fat.
Storing Your Banana Flour
Transfer the flour to an airtight container or resealable bag and store it in a cool, dry place away from direct sunlight. A mason jar, vacuum-sealed bag, or zip-top bag with the air pressed out all work. Properly dried banana flour stored this way keeps well for several months at room temperature.
If you notice any off smells, clumping, or visible discoloration over time, the flour likely absorbed moisture. Starting with bananas that were very green and fresh helps: research on green banana storage found that bananas stored longer than about 9 days before processing produced flour with noticeable color changes. For the best results, process your bananas within a few days of buying them.
Using Banana Flour in Recipes
Banana flour behaves differently from wheat flour. It absorbs more liquid, produces a denser texture, and has a mild, slightly earthy flavor that isn’t strongly banana-flavored (unlike ripe banana products). You generally need less banana flour than wheat flour in a recipe because of its higher absorption.
For baked goods, partial substitution works best. Research on doughnuts and cookies found that replacing 10% of wheat flour with banana flour in doughnuts and up to 20% in cookies produced results that tasters rated just as highly as the all-wheat versions. Going beyond those levels started to affect texture and taste in ways people noticed and liked less. So if a recipe calls for 2 cups of wheat flour, try swapping in about 3 to 4 tablespoons of banana flour for some of the wheat and adjust from there.
For fully gluten-free baking, banana flour works well in pancakes, flatbreads, and recipes that don’t rely on gluten for structure. You’ll often want to combine it with a binding agent like eggs or xanthan gum, since banana flour has no gluten to hold things together. It also works as a thickener for soups, sauces, and smoothies, where a tablespoon or two adds body and a dose of resistant starch without altering the flavor much.