Supermarket shelves are filled with liquids, pacs, powders and tablets that promise to get the even the dirtiest dishes clean.

Consumer Reports’ recent tests of nearly two dozen dishwasher detergents found some that brands stood out among the many in stores.

Several Cascade products cleaned up in CR’s tests gauging how well a detergent removed caked-on, baked-on glop from dishes and pots. They also proved adept at preventing water spots and food redeposits and were gentle on glass and silver.

Top-scoring of all tested products was Cascade Complete, a liquid detergent that costs 17 cents per standard load.

Other excellent detergents from this brand were Cascade Complete With Bleach Hydroclean Action (liquid; 17 cents per load); Cascade 2 in 1 Action Pacs With the Power of Dawn (detergent-filled pacs; 19 cents per load); Cascade Complete With Bleach Hydroclean Action (powder; 12 cents per load); and Cascade 2 in 1 With Bleach Hydroclean Action (pacs; 19 cents per load).

Enzymes – the molecules that break down food deposits – appear important to superior performance.

Indeed, the five lowest-scoring cleaners and one mid-level detergent rated by CR lack them.

Cleaning through chemistry

Three other dishwasher detergents containing enzymes stood out for their very good performance and comparative low price, earning them distinctions as CR Best Buys. Great Value powder (available at Wal-Mart) is the best of this bunch, although Target powder and Kirkland Signature powder (available at Costco) scored nearly as well. All clean at a cost of just 5 cents per standard load.

Each of these detergents, along with the excellent Cascade products, also contain phosphates, which help boost cleaning power, but harm the environment by encouraging algae growth in freshwater.

For a phosphate-free wash that’s strengthened by enzymes, consider Ecover tablets (21 cents per load) or Ecover powder (24 cents per load), Citra-Dish powder (22 cents per load), 365 Everyday Value powder (14 cents per load), and Seventh Generation powder (16 cents per load). All do a good to excellent job of cleaning, although they often trail the higher-scoring Cascade detergents in such measures as preventing food redeposits or water spots.

Machines that measure up

Most of the dishwashers that Consumer Reports recently rated did a solid job of cleaning even the dirtiest dishes. What separates the top-rated dishwashers CR tested from those scoring slightly lower isn’t usually cleaning ability. Rather, differences in measures such as energy and water use, noise, loading flexibility, cycle time and ease of use helped position models in the rankings.

Among midpriced models, standouts include the Kenmore 1374 and the Kenmore 1373 (at $650 and $580, respectively, from Sears, they qualify as CR Best Buys), and the Bosch SHE 45CO ($700). All are well-equipped.

The Kenmore models managed to handle baked-on brownie mix well with their normal cycles. The Bosch has a stainless-steel tub that’s backed by a long warranty. That model and the top-ranked Kenmore 1374 are both very quiet machines.

If you’re interested in a lower-priced dishwasher, consider the Whirlpool DU1100XTP ($500), the GE GLD4600N ($460), the Frigidaire Gallery GLD4355RF ($500), or the Maytag MDB4651AW ($400). While they don’t run as quietly and aren’t as easy to load as some higher-scoring models, these provide good overall cleaning in a basic package.

In CR’s tests, the Whirlpool delivered superior washing performance, the GE and the Maytag were very easy to use, and the Frigidaire and Maytag had shorter cycle times than most – 110 minutes for the normal cycle.