The U.S. Department of Agriculture has finally caught up with those unscrupulous ham processors who were regularly pumping more water into their products than the legal limit. This past spring, the Department began operating under a new regulation that replaces outdated laboratory methods with a more precise technique for checking added substances in cured pork products.

Under the "protein fat free" (PFF) regulation, as it is called, USDA inspectors will indirectly measure water content and other additives in hams by keeping track of the amount of protein in the lean part of the finished product: The more water and other added substances in a product, the more diluted the protein content.

The new regulation does away with the old categories that distinguished hams by the type of packaging they came in -- either cans or plastic packaging. "With the introduction of PFF, we have opened up the possibility of more types of hams being in the marketplace," says John McCutcheon, deputy administrator for technical services at USDA's Food Safety and Inspection Service. Here is what the new categories mean:

*Top-of-the-line traditional ham products without added water are labeled simply "ham" and contain 20.5 percent protein.

*"Ham with natural juices," labeling that previously could be found only on cooked, canned hams, can now appear on hams in any type of packaging that have a minimum protein content of 18.5 percent. (The "juices" are mostly water, and with the spices, add an extra 8 percent of weight to these hams.)

*"Ham -- Water Added" products, which traditionally have been marketed in plastic wrapping and could retain up to 10 percent added water in addition to spices, must have a minimum protein content of 17 percent under the new regulations.

*Hams with more than 10 percent added water must be labeled "ham and water product." These products may retain an unlimited amount of water and additives, as long as it is stated in the product name that, for example, 30 percent of the weight is water and other ingredients.

Package flexibility was not the only reason USDA revised its standards for ham. The old method of keeping track of the added ingredients by weight became outdated by new technology. Today, the production of quick-cure hams often involves "massaging and tumbling" techniques that assure deeper penetration of the curing solution and better retention of the water and other additives.

"Our compliance methods were not as precise with massaging and tumbling procedures," says McCutcheon, who acknowledges that the agency regularly had received complaints from ham producers that their competitors were filling "water added" hams with 18 percent water -- and getting away with it.

Using such methods, processors could add more weight to their hams with sweeteners and flavorings, because under the old rules USDA had placed no limits on these substances. In some cases, according to USDA officials, additives could account for another 15 percent of the weight of the hams, and extra salt was added by processors just to mask the intense sweetness of some of these products.

According to USDA figures, "water added" hams and those with unlimited amounts of water make up two-thirds of the market, while traditional hams and canned hams make up the other third. Why would anyone want to buy a "ham" with so much water?

"Americans prefer a more moist ham," says Bob Wynne, a senior microbiologist at ABC Research Corp. in Gainesville, Fla., a consulting firm that helps meat processors test and develop new products. That preference, he says, is the reason why "water added" hams became popular in the first place.

Wynne beleves the "ham and water product" will be fairly popular, especially with smaller processors, since it will help to make them more competitive with the big, established firms. USDA says such hams also will be cheaper.

However, Wynne doesn't like the fact that the ham and water products probably will be sold to consumers at the deli counter, minus the wrapper, and labeled by retail personnel as "ham." "In actuality, you are buying something different. But there's no way to know in that situation," he says. The ham and water product will also be sold in restaurants and to institutions where its label will be out of the consumer's sight.

The PFF regulations still may not completely prevent cheating. Since hams must contain a minimum amount of protein some processors may attempt to boost the protein content using other types of protein, such as plasma protein, that can't be detected with current laboratory methods. The problem may be more acute in imported hams, where inspectors are not in the processing plant, looking over the processor's shoulder.

Nevertheless, most agree that the regulation is a definite improvement over the previous rules that will better protect the consumer. "The PFF regulation is excellent. It's something we've needed for a long time," says Wynne, noting that it was 10 to 12 years in the making. And, he predicts, it won't be too long before USDA begins utilizing the same method to control water and additives in other processed meat products, such as sausages.