Equipment Corner: Why use a blender instead of a food processor?

Food processors do everything blenders do and more, such as mincing, chopping, grating, slicing, and shredding. So it would be perfectly reasonable for a cook to ask, "Well, why bother with a blender, then?" As multitalented as food processors are, blenders are better at processing liquids and solids together to form a fine, smooth, well-aerated puree and at liquefying solids. A blender, for instance, will process cooked vegetables and broth into a finer puree than a food processor, making the texture of the finished soup silky. Blenders are also better than food processors at combining ice, fruit, juice, and yogurt to make smoothies. A food processor will leave small chunks of ice, whereas a blender will break up the ice and fruit into particles tiny enough for the drink to live up to its name.

Several design elements account for this. One important factor is the shape of the blender jar. Because food processor workbowls are relatively wide and low, the food that gets thrown off the moving blade tends to stick to the sides of the bowl. By comparison, tall, narrow blender jars force the food up because there is less space for it to move laterally. This upward motion, combined with the rapid spinning of the blades, creates a vortex within the jar that allows for the incorporation of more air, which gives the end product a fluffier, smoother consistency. In our experience in the test kitchen, blender jars also form tighter seals than food processor bowls--another benefit when processing liquids. A rubber gasket forms a seal between the base of the blender jar and the blade assembly, and a tight-fitting lid seals the mouth of the jar. (Despite its secure seals, you should not fill a blender jar more than halfway; this ensures that the contents will have ample room to move as they are blended.)

John Rousso, engineering manager for Windmere Durable Holdings (parent company to Windmere and Household Products, the makers of Black & Decker Household Products), stressed the importance of one component of blender jar design--the flutes. Flutes are vertical protrusions on the inside of the blender jar, which, in Rousso's words, "collapse the vortex" inside the jar, thus redirecting the material being thrown against the jar walls back down onto the blade. This fosters increased contact between the food and spinning blades.

Kristin Verratti, product manager of food products for Household Products, reported that the configuration of the blade assembly also matters. Most food processors have a blade with two cutting edges at different levels, one tight against the bottom of the workbowl and one that is elevated slightly. The blades on most blenders, on the other hand, have four cutting edges oriented on two, and sometimes three or four, planes (usually, two of the cutting edges reach down toward the base of the jar and two reach up toward the top). This way, the material in the jar hits four cutting edges instead of two.