Sometimes Stainless is More

ENSURING THE CLEANLINESS OF FOOD PACKAGING EQUIPMENT MAY BE AS SIMPLE AS THE METALS CHOSEN AT THE EARLIEST STAGES OF MACHINERY CONSTRUCTION.

By Valerie Burke and Bridget McCrea

Safeline Powerphase PLUS detectors can withstand extreme washdown.

If you want to get something clean, forget about Martha Stewart – ask a food plant maintenance manager. These guys use some of the most aggressive cleaning agents (acids and chlorinated sanitizers) and thorough cleaning routines (often exceeding GMPs and Hazard Analysis Critical Control Points) in any industrial environment.

Maintaining a pristine production and packaging environment is mission- critical for food manufacturers. First of all, they are highly regulated by the Food and Drug Administration (FDA), the U.S. Department of Agriculture (USDA), and other governing bodies in specific food sectors. Also, unsanitary food manufacturing can be disastrous to public health.

The Centers for Disease Control and Prevention (CDC) report approximately 76 million cases of food borne illness a year with an estimated 200 deaths resulting from food-induced anaphylaxis. Not to mention the impact of a contaminated food product recall on a company’s reputation and sales.

It’s easy to see why food manufacturers have set the standard for cleanliness in industry. One of the key features that they look for when purchasing processing and packaging equipment is that it is 100 percent wash-down certified.

“100 percent wash-down certified is necessary for sanitary conditions and helps manufacturers comply with FDA, USDA and 3A requirements,” says Tony Ross, commercial manager at Safeline Inc., in Tampa, Fla., a manufacturer of microprocessor-based metal detection equipment.

One vital issue is bacteria count, which must be controlled to avoid shipping product that will make consumers sick. “We’ve seen a number of major product recalls due to contamination,” says Ronald Downing, vice president of marketing and sales at George Gordon Associates in Merrimack, N.H. “The wash-down capability allows the machines to be sprayed with a water- based cleaning solution that gets rid of the bacteria, and is the only effective way to accomplish the necessary level of cleaning.”

In many food processing plants, especially meat packages, wash-down means the equipment must withstand a rigorous cleaning process, which entails using hot (minimum 140°F), high-pressure (up to 1000 psi) water sprays and caustic, acid-based detergents dispensed through spray and foam systems, in addition to hand cleaning.

“Ease of cleaning and durability are top priorities when we select equipment to purchase,” explained Mark Nouvel, director of poultry engineering for Gold Kist Inc., Atlanta, Ga. Gold Kist is one of the nation’s largest poultry farms with more than 2,300 family farms in the Southeast producing more than 14 million chickens a week.

WASH-DOWN CERTIFIED

The main criterion for wash-down certified packaging equipment is stainless steel construction. Some equipment manufacturers claim their products are "wash-down" Don't be fooled. Only some parts, if any, of the equipment are fabricated out of stainless steel. More commonly, the equipment is constructed from substandard, albeit economical aluminum.

In contrast to anodized aluminum, stainless steel resists corrosion and localized chloride attack from both cleaning agents and aggressive ingredients like high levels of chloride salts and high acid contents such as found in tomato past and ketchup. Stainless steel can be electro-polished for a uniquely flat, mirror-like surface.

According to Downing, the fact that stainless can be polished to a “grainless finish” is a great asset to the sanitation process. “The higher the grain,” he says, “the greater chance to retain microscopic bacteria in the material surface. Polishing, in essence, reduces the surface effect of the grain for the areas that food may touch.”

EASY TO CLEAN

Easy-to-clean equipment translates into cleaner equipment, says Nouvel. Food areas must be thoroughly cleaned to prevent hygiene issues or bacterial problems. For this reason, some companies are moving to all stainless steel processing equipment. “It’s easier to clean, requires less maintenance and doesn’t rust.”

Discussing 304 and 316 grades, Ross says stainless steel is the material of choice for food manufacturers based on its strength, resistance to corrosion and ability to withstand high levels of caustic wash-down. And while very strong salts or acid solutions – when mixed with the chromium oxide – can cause the steel to rust, electro-polishing techniques allow for a bright, shiny surface with greater light reflectivity.

“The process also passivates the material and produces a smoother, more sanitary finish which in turn creates less friction and drag,” says Ross. “The process tends to remove both metallic and non-metallic contamination, thus increasing the chromium to iron ratio, and reducing corrosion.”

There’s a direct correlation between ease of cleaning and productivity – the easier it is to clean and sterilize plant processing and packaging equipment, the more productive the plant.

Whether it comes in direct contact with food or only indirect contact, all processing and packaging equipment must be cleaned frequently – often at the end of every line change, shift and workday.

The USDA’s Food Safety Inspection Service directive states, “all food and non-food contact surfaces of facilities, equipment and utensils used in the operation of the establishment must be cleaned and sanitized as frequently as necessary to prevent the creation of unsanitary conditions and the adulteration of product.” Depending on the size of the plant, type of food produced, and number of shifts, this could add up to 15 to 20 hours or more of mandatory cleaning each week.

At an ice cream plant, for example, it’s not uncommon to find one or two people assigned to the measurement of bacterial count. “They’ll shut the plant down for cleaning the minute the count rises above standard,” Downing explains. “I’d say the least stringent procedure for companies is at least one wash down every shift.”

When selecting equipment, Downing says food manufacturers should factor in the actual “ease of wash down” on the equipment, and not just whether the equipment meets standards or not. If the equipment is accommodating, he adds, then the sanitation procedure it is much more likely to be implemented effectively.

“With food-friendly equipment in place, a manufacturer must then seek out an effective procedure that is also reasonable to accomplish the task,” says Downing. “Lastly, and most importantly, they need to have responsible people on all shifts to carry out the procedure, and have a concern for the objective beyond the limit of the procedure – or the machine design – to truly keep the plant clean.”

Currently, Ross says most manufacturing and/or processing plants either already have, or are in the process of, converting to all stainless steel equipment. “It is unlikely that a substitute for stainless steel will present itself in the near future,” he says.

While easy-to-clean equipment does equate to cleaner equipment, there’s more to it than simply building the equipment out of stainless steel. “A conscious effort must be made during the design stage to produce equipment that has as few ‘trap’ points or flat surfaces as possible,” says Ross.

Markem's stainless SmartDate.

The ability to clean in place (CIP) is another important characteristic for food equipment. “With stainless steels, standard CIP solutions and procedures can be used,” says Fritz. “It takes less time and effort to clean stainless steel equipment in place plus aluminum would be less resistant to some of the standard solutions used for CIP,” he says.

Due to its lower strength, the surface of aluminum alloys is more vulnerable to scrapes, dents and nicks which can be more difficult to clean and serve as initiation sites for corrosive attack by cleaning agents used in the food industry. If the cleaning agent or food ingredient penetrates the normal protective oxides of the metal, bare metal is exposed and there is an increased likelihood for further pitting of the metal.

Once pitting occurs, catastrophic corrosion starts and the metal will deteriorate. It may absorb dangerous bacteria and pathogens from the food, and metallic ions from the alloy will contaminate any food products that come in contact with the equipment.

Overall, the life cycle cost advantages of stainless steel over aluminum outweigh the incremental additional cost. If aluminum is involved, sometimes there are problems, plus costly – OEM-specific – cleaning agents are required. Over time, aluminum gets corroded no matter what you do and it must be replaced while stainless steel can last beyond a line’s life expectancy.

Valerie Burke and Bridget McCrea have written about business and technology issues for more than 10 years.