When powdered gelatin is sprinkled on top of a cold liquid and left to stand for several minutes, the gelatin granules will swell with the absorbed liquid. This process is known as blooming. When the gelatin mixture is heated (with the hot maple syrup mixture in this instance), it will dissolve evenly without any blobs of gelatin. Blooming gelatin is necessary to achieve the marshmallows' smooth texture and consistency, and ensures that the gelatin sets properly as the marshmallow mixture dries.