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Methods for Preserving Food Quality

Restaurant operators have options when it comes to preserving food quality, which is not only important from a customer standpoint but also helps control food waste.

“From a consumer perspective, one of the key drivers is their initial perception of food and beverages, and what drives perception is the product quality,” says Warren Solochek, professor at Chicago-based DePaul University’s business school and a foodservice consultant. “If I go into a place for a sandwich and the operator says they have the freshest ingredients in town, I will want to see those ingredients when ordering. Secondly, I want the food to taste fresh and have good flavor.”

Two main types of food preservation methods in commercial foodservice include cook-chill and sous vide.


Created in the 1960s, cook-chill was initially used by caterers seeking a way to safely produce large quantities of quality food in advance. Today, operators use this food preparation and preservation method to create bulk product in high-volume segments, including schools, hospitals and correctional facilities.

“To sustain food quality over time, vacuum-packaged foods preserve and prolong shelf life,” says Walter Zuromski, culinary director/owner of Chef Services Group in Rotonda West, Fla. “This method minimizes microbial growth counts. Cook-chill is similar in the way it works.”

Cook-chill improves food quality, maintaining a product’s taste, texture, color and aroma. It also helps retain food’s cellular structure for optimum mouthfeel. It offers other benefits, too. “Cook-chill maintains food safety,” says Matthew Taylor, senior manager, NSF Food Safety Consulting, Ann Arbor, Mich. “It is widely used in the industry, but more for institutional applications or for bulk prep.”

By precooking and rapidly chilling food for future use, operators can prepare large batches, save time and have better control of the production process. Closely monitoring the cooking and chilling process can enhance food safety. Cook-chill also allows operators to control waste since this approach often produces consistent portions. In addition, this method minimizes labor as it is typically used during downtimes.

Operations such as hospitals or universities, in addition to chain restaurants, can create meals or elements of menu items like sauces in a central kitchen, storing the food in bags and delivering it to individual sites for storage and use. When food is ready to be prepared, the bags are placed directly in boiling water or in a steam table to heat to the appropriate temperature.

Cook-chill equipment requirements depend on the size of the operation. Smaller restaurants can utilize a ring stand, an impulse sealer and an ice bath, while larger operations will typically employ 75- to 400-gallon steam-jacketed kettles, pump fill stations for dispensing food into flexible packaging, tumble chillers, and blast chillers. The latter two pieces of equipment cool product quickly to less than 40 degrees F for safe storage prior to heating and serving.

Other cook-chill supplies may include plastic pouches, which can be heat-sealed or fastened with aluminum clips, as well as labels, crates and dollies.

Three-part fully automated cook-chill systems incorporate both cooking and chilling in the same unit and also include a quench system that stops cooking when foods are done.

Recipe management systems that store and monitor hundreds of recipes for added control and consistency are available. This may help operators navigate such challenges as unskilled labor or high turnover.

Sous Vide

Created in France in 1971 to produce a more tender roast beef, the sous vide technique cooks foods in vacuum-sealed bags with strictly controlled temperatures. Like cook-chill, this results in an improvement of the food’s taste, texture and nutritional value.

“Sous vide is increasingly used to preserve food and extend its shelf life,” says Taylor. “This is a technique applied not only to extend shelf life but also to remove organisms or pathogens and prevent spoilage.”

Sous vide works by first vacuum-sealing food in airtight, food-safe plastic bags, then submerging the bags in cook tanks or water baths. The water baths slow cook the bag’s contents at low temperatures. The technique is versatile in terms of applications and is commonly used with meat, eggs, seafood and vegetables. The slow cooking process often produces tender food. Sous vide can also be used as part of cook-chill production.

“For liquids, such as soup and marinades, there’s cook-chill pasteurized processing to cook foods to safe temperatures in the kill zone,” Zuromski says. “This entails 3-millimeter bags, which hold hot product and are sealed hermetically in a food-grade bag. Hot filling is at around 160 degrees F to 165 degrees F. While still hot, the bags are put in an ice water bath or a refrigerated water bath with a temperature of 34 degrees F to cool the liquid down within an hour. This generally drops the temperature fast to below 38 degrees F.”

With this method, operators can get as much as a 30-day shelf life for soup. However, this isn’t the case with foods such as dairy products, seafood and other more perishable items.

“[When preserving food quality with these methods], you’re trying to control mold growth and rancidity while also limiting oxygen exposure in the bag,” Zuromski says. “There are different kinds of preservatives that can help extend shelf life.”

Food appearance serves as a strong indicator of how well it has been preserved. Because customers eat with their eyes, this is just as important as taste. For example, product sitting under a heat lamp for too long may have a diminished appearance. “If you don’t have good storage and the product looks old, the customer won’t have a good perception of food quality,” Solochek says. “The number one thing students tell me is that they believe food is healthy when they walk down the line and see each of the ingredients, so display is important. Number two, is it fulfilling my expectation that hot food is hot?

“One example where the perception of food quality is evident is with the newer heated storage units the pizza operators use,” Solochek notes. “Customers can order pizza, staff then puts it in a locker, and it will be warm and fresh when it’s picked up as opposed to having to grab premade pizzas that are in a stack of boxes [on the counter].”

This line of thought applies to a variety of food. “Whether it’s premade sandwiches or prepared food that’s added onto a bigger plate, people expect restaurant food to be of high quality,” Solochek adds. “Perception is key; operators need to have equipment checked out frequently to ensure proper temperatures are maintained.”

“Cook-chill at the foodservice level should be used more by chefs, and sous vide is growing by leaps and bounds,” Zuromski says. “When done properly, these methods preserve and sustain food quality.”