Why sous-vide makes sense

Prepared Foods, July, 1992 by Rick Lingle

The sous-vide processing/packaging of bulk meats at Idle Wild Farm, Pomfret Center, Conn., provides superior product quality, 20% to 30% improvements in yields, and corresponding cost savings. But that's only the tip of the chilled foods iceberg here, for what is essentially "bag cooking" of bulk meats is also a steppingstone to a grander goal.

"We've proved sous-vide works for our bulk meat operations," says Lou Cooperhouse, director of technical services. "Now we're preparing to take sous-vide into foods for retail sale."

Cooperhouse is bullish on sous-vide, and not only at IWF. "Sous-vide will be the predominant technology for chilled foods sold at retail by the year 2000," he says. This statement seems a heady forecast for a method that has traveled a bumpy road in the marketplace and shares the chilled foods market with the more established technologies of cook/chill and controlled/modified atmosphere packaging (CAP/MAP). No major producer of branded foods has committed to sous-vide - yet.

But few know the chilled foods area as thoroughly as Cooperhouse. He helped Campbell Soup launch a refrigerated product line in 1985, played a pivotal part in commercializing the product line of U.S. sous-vide pioneer Culinary Brands, and has consulted for other companies launching sous-vide products. He bases his projection on the technology's well-documented product quality pluses and its equally impressive manufacturing benefits.

Beginning in December 1991, IWF committed totally to internal utilization of sous-vide or its meat processing operations, about 2 million pounds of product a year.

"We're at every stage of negotiation with several companies in sous-vide development," says Cooperhouse of co-packer IWF, a supplier of frozen meals to non-retail markets including restaurant chains, airlines and institutions. Part of IWF's commitment to sous-vide includes refurbishing the former Kraft General Foods facility located adjacent to IWF's current facility, which housed production for Culinova and Chillery brands of chilled foods. IWF will use the facility as its sous-vide processing center beginning this fall.

Says Cooperhouse: "Several major food companies, now working on sous-vide, are going to make a dramatic impact in the market over the next 12 months. And, with the right package, sous-vide will take root in retail." IWF and Cooperhouse believe they have developed the light package, a prototype that Cooperhouse says is "the ideal sous-vide package for retail" - a vacuum skin packaged (VSP) tray. This approach combines the benefits of sous-vide methods in a package form - the tray - that consumers are familiar with. For its microwavable tray, IWF plans an easy-open peel seal.

VSP also provides high contact clarity, so the foods' visual appeal - enhanced because of the minimal thermal degradation afforded by the sous-vide technique - is maximized. The VSP tray negates other adverse quality connotations consumers perceive in CA/MA packages, including condensation and moisture migration.

BETTER THAN CAP/MAP

Technically, sous-vide is a CAP/MAP method. What sets it apart from other CAP/MAP methods is the post-packaging pasteurization step, which provides another advantage.

"A CAP/MAP product gradually deteriorates over time beginning with the day it's packaged. For a sous-vide food, product quality on day 21 is the same as it was on day one," says Cooperhouse. This also relates directly to food safety.

The benchmark 21-day shelf life used for many refrigerated foods is based on research contracted by Culinary Brands at the University of California-Davis in 1987-1990. Researchers determined that Clostridium botulinum spores inoculated at levels 10,000 times those ever found in nature didn't grow for at least 21 days and, in some cases, didn't grow after 60 days in sous-vide samples. It was also shown that the sous-vide process destroys listeria with a 6.72 decimal (D) reduction and salmonella with a greater than 8 D reduction.

"This reduces 10 million bacteria colonies to one. That's tremendous," says Cooperhouse. "You can't say that for a CAP/MAP product." He adds that incorporating barriers" in the formulation (such as natural acidulants), in the process, in the packaging and in distribution temperatures will allow a sous-vide product to safely achieve a 60-day shelf life.

Because the cooking process occurs after the package is sealed, similar to canning, sous-vide has no post-process opportunities for contamination. The pasteurization time and temperature differ for each food, with the temperature ranging from 135 [degrees] to 185 [degrees] F, says Cooperhouse. The specific conditions, which meet or exceed USDA cooking requirements, are different for every product.

MANUFACTURING YIELDS TO 100%

The sous-vide preparation room at IWF comprises meat processing equipment and vacuum pouching machinery. The double-sided unit is lowered to vacuumize and seal the clear, coextruded multilayer barrier pouch.