The dish on detergents.(Buyers Guide)

It's a minor purchase compared with a can make a big difference in how clean dishwasher, but the detergent you buy your dishes get. The best products removed nearly all the cooked-on soil from plates; the worst left them quite dirty. As with so many products, however, the choice of which one to buy becomes more complicated as formulas are tweaked and new types are introduced.

More and more detergents include enzymes, which dissolve starches and proteins so that they can be washed away. The trend is noteworthy: The most effective deter-gents in our test have enzymes. If present, enzymes are usually, but not always, listed on the container, either among the ingredients or near the cautions.

Two other recent innovations, from Electrasol, are of less benefit. A version of that brand's tablets incorporates a "powerball," a pellet of Jet-Dry rinse agent that is supposed to eliminate water spots. The detergent cleaned excellently but left water spots as often as most other products.

Electrasol also introduced single-use Deep Cleaning Gelpacs. They sound convenient but aren't. Because the squishy pouches of gel are supposed to dissolve in water, your hands have to be very dry before you handle them or they'll stick to you. And their zipper-lock plastic bag has to be closed after each use.

For a very tough test of the detergents' cleaning power, we used a concoction only our engineers could love: a mix of canned soup, corned-beef hash, chocolate pudding, cola, cheese spread, rice, and powdered egg yolk. We whipped those ingredients together in a blender, spread the goo on glass plates, added a dollop of raw egg yolk, heated the plates in a microwave oven, let the dirty plates sit for hours, then put them in one of four identical dishwashers. We washed the dishes in hard water, using the recommended amount of detergent, and did not add a rinse agent. We also tested whether each detergent would stain silverware.

Overall scores ranged widely, but the top seven detergents were excellent or very good at both removing soil and keeping it from resettling on plates. Any of those would make a good choice. Great Value, from WalMart, is A CR Best Buy.

The Ratings comments can help narrow your selection if you have special concerns. Some products stained silver. A few left glassware slightly but permanently hazy after 23 hours of continuous high-temperature washing in soft water (haze is most likely to be a problem where water is soft). A final point: A powerful name may not ...