Certified master baker and gluten-free baking expert Richard Coppedge Jr. of The Culinary Institute of America in Hyde Park, New York provides insight on this one. Many gluten-free baked goods are made with a large amount of starchy flours, which include potato starch and tapioca starch made from root vegetables. By nature, these ingredients do not have much flavor, particularly after they are processed. And when potato starch and tapioca starch comprise two-thirds or more of the flour blend in a baked product, this ratio naturally contributes to the lack of flavor in the end product. Grain flours such as wheat naturally have more flavor, which is why traditional wheat-baked goods taste and smell so good!
The starches in gluten-free baking are primarily used as agents, meaning they serve a certain purpose for the baked good, either to bring weight and chewiness, or to make the product more airy and promote browning. They are not used for flavor, nor are they used to promote nutritional value. This is why many gluten-free breads become more palatable when toasted. The toasting helps caramelize the starch and boost the flavor. And oftentimes to compensate for the lack of flavor due to the root starches, gluten-free bakers will use sugar in excess.
Luckily, more gluten-free baked goods and recipes are now relying less on the large amount of starches in the flour blend and are incorporating more of the higher-protein, higher-flavor gluten-free flours into the blend, which will naturally improve the flavor. You’ll notice that baked goods that rely more on the grain and seed flours such as sorghum, amaranth, quinoa, teff, corn, and rice have a better flavor and are often closer to capturing the flavor of a wheat-based product.