The use of alternative fruits in the apple blackberry crumble tart can significantly impact the overall flavor profile by introducing different levels of sweetness, acidity, and texture. For example, using frozen berries may add a more intense fruity flavor and vibrant color to the tart. Sliced pears or peaches could bring a softer, juicier element that contrasts with the firmer apples. Additionally, incorporating warming spices like cardamom, nutmeg, or orange zest can enhance and complement the natural flavors of various fruits used in the recipe.