And between shifts and during breaks, workers resanitize all surfaces that touch the thousands of pounds of ham, roast beef and bologna.
"In order to control problems, such as listeria, it takes a lot of effort and a lot of extra cost in terms of quality-control personnel," said Louis Eni, one of three siblings running the company, which was founded by their grandfather in 1939.
High-profile recalls by two poultry processors in the Philadelphia area this fall have made the Enis and other local meat processors hesitant to talk publicly about the issue of contaminated meat for fear of being associated with the problem in any way.
Even so, the Enis said they have nothing to hide.
"We've never had a recall, and we've never had a product test positive for listeria or for any pathogen that would require a recall," Louis Eni said.
"In the scheme of things, it's well worth every penny," he said about the cleaning regimen.
An upsurge in meat recalls nationwide - to 95 last year from 25 in 1996 - has led to a tougher stance by the U.S. Department of Agriculture's Food Safety and Inspection Service, which regulates the production of meat, poultry and egg products.
The department has argued recently that recalls should not be relied on as the primary safety mechanism, and that processors must to do a better job of keeping their factories free of bacteria so they do not get into the meat in the first place.
Starting today, hot dog and deli-meats producers that do not already test their plants - equipment, drains, tables and other surfaces - for listeria and other bugs and share the results with the government are going to be tested by government inspectors.
The Enis said Dietz & Watson has been testing its Philadelphia plant - as opposed to merely testing products - and sharing the results with the USDA for at least a decade.
"They have a very good plant up there," said Michael Rose, a 25-year veteran of the USDA, who now works as a food-safety consultant.
Louis Eni, Chris Eni and Cindy Eni Yingling talk about Dietz & Watson with such a passion that there can be no doubt that they have completely thrown themselves into the business, which employs 800 in Philadelphia and Baltimore and has more than $150 million in annual sales.
The Eni siblings said they, along with their mother, Ruth Eni, run the company as equals, hashing over major decisions until they reach consensus.
The approach is reflected on the siblings' business cards, which have no titles. Nevertheless, each has responsibility for a different aspect of the operation.
Louis Eni, 49, takes the lead on marketing, quality control and product development. Chris Eni, 46, oversees the design and operation of the company's plants. Cindy Eni Yingling, 44, handles the finances.
"I was very fortunate that all three were interested in the business," said Ruth Eni, daughter of the founder.
Gottlieb F. Dietz was a German sausage-maker who came to the United States in 1921 to escape the economic malaise in Germany after World War I.
He worked for several meatpackers in the region before striking out on his own in 1939, buying the nearly bankrupt Watson Meat Co. Dietz combined the names because he liked the sound. The seller, Walter Watson, stayed on to handle sales.
Dietz died in 1964. By then, Dietz & Watson had developed a loyal following in Philadelphia for items produced in its former plant on Vine Street between Front Street and Second Street.
When that property was condemned for the construction of a Center City exit from Interstate 95, Dietz & Watson moved in 1975 to its current site, a former slaughterhouse.
A major turning point came in 1972, when Pennsylvania turned over meat-inspection responsibilities to the federal government. Federal inspection meant Dietz & Watson could sell its goods anywhere in the country. The company now distributes its goods in 38 states.
The market for fresh deli meats sold in supermarkets is worth about $5 billion, according to Fresh Look Marketing Group, a Chicago company that tracks the sales of perishables in grocery stores.
The Enis said Dietz & Watson's chief national competition is Boar's Head Provisions Co. Based in St. Petersburg, Fla., Boar's Head is also family-owned, and declined to give any information about its operations.
Dietz & Watson's sales growth - 10 percent to 12 percent a year, according to the family - has been helped by a shift toward more expensive deli meats and the spread of supermarket deli counters from the Northeast to other parts of the country.
In 1997, 89 percent of new grocery stores nationwide included a deli. By 2000, that had climbed to 97 percent, said Michael Diegel, a spokesman for Grocery Manufacturers of America, an industry trade group.
The shift to federal inspection was also meant to raise the bar on meat safety. Indeed, the nation's meat supply has become dramatically safer.
For example, from 1989 to 1999, the share of hot dogs testing positive for listeria monocytogenes fell from 8 percent to less than 2 percent, according to the USDA.
Rose, the food safety consultant, said factory designs have improved dramatically over the last decade.
New plants, such as Dietz & Watson's new poultry operation in Baltimore, are set up so that raw meat comes in one end and proceeds straight through until it leaves as a finished, packaged product. That prevents raw meat from contaminating cooked meat.
Dietz & Watson has that layout for the most part in the much older Philadelphia plant, Rose said.
For example, Dietz & Watson's hot-dog production line works its way from one end of the plant to another, with sharp delineations between the raw and the cooked areas.
During a tour of the Philadelphia plant, Louis Eni said Dietz & Watson tries to distinguish itself from major competitors by using only natural spices and certain old-world preparation techniques.
The meat and other ingredients for the Dietz & Watson hot dogs and other sausage products, for example, are prepared in German sausage machines that use arrays of curved knives rotating 3,600 times a minute to chop the thick batter into very fine particles with slightly different shapes.
And Louis Eni said that, when the hot dogs are cooked, the tiny particles interlock in a way that "gives us the snap and bite of a European sausage."
Contact Harold Brubaker at 215-854-4651 or firstname.lastname@example.org.