Blenders have come a long way from soda shops and ice cream parlors. While they still excel at such basic tasks as making a milkshake, manufacturers have tried to add new functions -- everything from ice crushing to grating cheese -- in order to keep this "old-fashioned" appliance current.

The widespread acceptance of food processors in the 1980s sparked many of these changes in blender design. Although manufacturers have kept the basic structure the same (a glass jar sits on a motor that drives a rotating metal blade at the bottom of the jar), blades have been reconfigured (some blades are extremely thick while others are thin and razor-sharp) and blender jars have been reshaped (some jars are still tall and narrow while others are wider and shorter).

In addition to these changes, some companies have experimented with touch pads; a smooth surface is much easier to wipe clean than one cluttered with a dozen raised buttons. Some have tried to muffle the roaring sound while others have expanded the "pulse" function to include a "high-energy" (multispeed) function that adds extra power at any speed. One blender even has an automatic pulse that goes on and off repeatedly until the button is pressed again, while a few retain the old-fashioned single-speed pulse.

Given the many changes in blender technology -- and the fact that some six million Americans bought blenders for home use in 1994 -- Cook's Illustrated decided to evaluate the culinary potential of six "contemporary" blenders and see which were really worth purchasing. We found that some features are clearly more useful than others. A multispeed pulse is better than a single-speed pulse function, for example. However, touch pads that are hard to engage are not an improvement over regular buttons. Likewise, a wide jar design may make the blender sturdier, but it can also cause mixtures to move to the outside perimeter away from the blade's reach.

After working with dozens of bunches of basil, pounds of Parmesan cheese and gallons of soup, we cannot say that a "new" blender is an essential piece of kitchen equipment. After all, there are other tools that can grate cheese (a hand-held Mouli grater, for instance), puree soup (an immersion blender) or make pesto (a mini food processor). However, one good blender can perform all of these tasks and more. If you are already inclined to buy a blender to make milkshakes or frozen drinks, you may as well purchase one with the widest range of culinary applications.

As with most appliances that we test, there are literally hundreds of models on the market. Blenders are generally divided into two categories: those made specifically for use in bars (sometimes with stainless steel jars and often only one or two speeds) and those made for the kitchen (with glass jars and a range of speeds). We focused on the latter category and chose top models from the leading manufacturers.

In addition to general design and construction, we evaluated the performance of blenders on a number of particular tasks. We made milkshakes and frozen margaritas and also tried to crush ice in all of the blenders. Bar blenders generally do a much better job with ice, but all of the kitchen blenders that we tested should have been able to crush small amounts, at least according to the accompanying literature. In truth, only one blender (the KitchenAid Classic 3-Speed Blender, model number KSB3WH) really crushed ice well. Two other blenders (the Krups PowerX Plus 239 and Waring Touch Blend TB201) could crush some ice, but not more than six or eight cubes at once. Three other blenders could not crush any ice at all.

For our culinary tests, we chose tasks that we hate to do in a food processor: grate a small amount of Parmesan cheese until powdery, make a small amount of pesto and puree hot soup. We love our sturdy food processors, but they never grate cheese fine enough, they leak when hot liquid is added to the bowl, and they're too large to make a small amount of pesto. Some blenders were able to handle all three jobs (pureeing soup was the easiest), while others faltered, especially when grating cheese.

After completing these six tests, it was clear which blenders we wanted to own. The Krups and Waring were able to perform all six tasks. The Cuisinart Vari-Speed Blender CB-4, KitchenAid and Hamilton Beach Blend Master 54200 each struggled with at least one task but are acceptable choices, while the Oster Designer 23-Speed Osterizer Power Blend 4102 was unable to complete three of the six tests and was unacceptable.

On design issues, the Krups is the clear winner. This blender has the widest range of speeds with a truly low speed as well as a "power burst" button for top-notch pulsing. An easy-to-use dial adjusts the speed smoothly and makes cleanup quick since there aren't a dozen little buttons that can trap dirt. On the down-side, this blender only does a fair job of grating cheese; the texture was pebbly rather than powdery. On the definite plus side, the Krups blender is so quiet you can actually have a conversation when it is on. The reasonable price is an added bonus.

The Waring blender actually outperformed the Krups model in a couple of areas -- it made the finest grated cheese and smoothest pesto -- but is rated second overall based on its annoying "high-tech" design. The touch-pad buttons are difficult to lock into place. The capacity of this blender is also too small. An automatic pulse function, which turns the blender on and off until the button is disengaged, is a nice feature, but it only works at one speed. Despite these flaws, the Waring blender is still a good second choice because it works well in spite of the design kinks.

The Cuisinart is incredibly noisy, and the plastic lid on the model we tested was warped and difficult to snap into place. The KitchenAid is a great ice crusher but left several small chunks after grating cheese for one minute and made the worst pesto, with large strips of basil and chunks of garlic. The culprit is the wide jar design, which makes the blender especially well balanced but also allows food to stray far from the blade.

The Hamilton Beach is another step down in quality. Fourteen speeds cover only half the territory of the three speeds in the KitchenAid. In addition, the blender left large chunks of cheese ungrated, struggled to crush the ice for the frozen drink and failed to incorporate all of the basil into the pesto. Also, the design is not user-friendly.

The Oster blender seems to have a lot less power than the other models. Cheese stuck under the blade, and the blender began to emit a burning-rubber smell during our tests. As for the pesto, the garlic was sliced, not minced, and the entire mixture was too chunky. CAPTION:TESTERS' NOTES

KRUPS PowerX Plus 239: (best blender) Excellent design and good performance in most areas make this blender the top choice.

WARING Touch Blend TB201: An overly complicated design drops this blender to second place despite good performance at most tasks.

CUISINART Vari-Speed Blender CB-4: Performance varied greatly on this blender, with a limited range of speeds and an airplane-like roar.

KITCHENAID Classic 3-Speed Blender, model number KSB3WH: By far the best ice crusher in the bunch, but the culinary abilities of this blender are uneven.

HAMILTON BEACH Blend Master 54200: Mediocre performance plus confusing design make this blender an unappealing choice.

OSTER Designer 23-Speed Osterizer Power Blend 4102: A poor range of speeds and subpar performance drop this weak blender to the back of the pack.

-- Cook's Illustrated