Flexible Packaging Takes the Heat

Specially engineered pouches and bags keep things cooking at home and in the plant.

By Kate Bertrand Connolly, Packaging Editor

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The combination of flexible packaging and thermal processing techniques — from home microwaves to large-scale, in-plant pasteurization — is coming of age. The products taste better than ever, while delivering the convenience consumers have come to expect.

For consumers, innovative new package structures are taking microwave cooking beyond vegetables and into the realm of raw and frozen meat and fish, with restaurant-quality results. Last fall, grocery retailer Aldi (www.aldifoods.com), Batavia, Ill., launched six frozen entrees in a microwavable pouch engineered to cook like a Dutch oven, only quicker.

Aldi's new Bremer Select private-label entrees, some of which contain frozen raw seafood, are packaged in a form-fill-seal pouch made from a flexible packaging material that incorporates a patterned microwave susceptor between layers of polyethylene terephthalate (PET) and kraft paper.

The package, known as the Smart Pouch, is designed to combine steaming with susceptor cooking for superior results when microwaving frozen entrees that contain raw protein. According to Smart Pouch LLC (www.smartpouch.com), Fayetteville, Ark., creator of the package, this is the first steam pouch to use susceptor technology.

In the course of microwave cooking, susceptor patterns deposited on the packaging material absorb microwave energy, which is then used to heat the entree. Even cooking — the elimination of overdone edges — is a key benefit of susceptor cooking.

Proteins such as beef, poultry, pork and seafood "need higher temperatures in order to achieve a tender texture," says Sterling Tucker, managing partner of Smart Pouch LLC. "To increase the protein cooking temperature in a microwave oven, you need another source of heat introduced into this closed system. This is where the susceptor comes in."

Adding susceptor technology to the steam pouch enables cooking at temperatures higher than 212°F, the thermal limit for steaming. The susceptor assures that proteins cook to an internal temperature of at least 165°F. And steam created by sauces in the Smart Pouch keeps the protein from drying out, despite cooking at a higher temperature. The natural juices and flavors retained in the pouch during cooking produce a highly palatable product.

Tucker credits his partner, Kay Wright, with inventing the patented Smart Pouch technology, which is also compatible with conventional-oven cooking. Marietta, Ga.-based Graphic Packaging International Inc. (www.graphicpkg.com), Smart Pouch's exclusive licensee, makes and markets the Smart Pouch film.

In the frozen seafood aisle
Safeway Inc. (www.safeway.com), the Pleasanton, Calif.-based supermarket chain, uses a different type of microwavable pouch for a selection of frozen, raw fish products within its private-label Waterfront Bistro line.

Waterfront Bistro Santa Fe Style Alaskan Salmon, for example, is sold in a matte-finish stand-up pouch containing two microwavable pouches. Each microwavable pouch contains one salmon fillet. The microwavable pouches are supplied by WaveQuick Technology Co. Ltd. (www.wavequick.com), Tainan, Taiwan.

The self-venting, steam-in pouch technology uses a two-phase cooking method. In the initial phase, microwave energy heats the frozen fillet and turns the moisture in the product into steam, "cooking the food from the inside out," according to WaveQuick. In the second phase, steam builds up inside the pouch, producing a pressure cooker environment that cooks the product from the "outside in." The breathable multilayer film from which the pouch is manufactured regulates the inner pressure.

Flexibowl
The FlexiBowl pouch, introduced at Pack Expo last fall by Ampac Flexibles, allows consumers to microwave or boil the product in the pouch, then eat directly out of the package.

The consumer does not pierce the airtight pouch prior to microwaving, and a tear notch makes it easy to open after microwaving. The cooking technique delivers a high-quality microwaved product, which supports the brand's positioning as a fast, restaurant-quality option.

Cook, tear and eat

Complementing these packaging developments for raw proteins is a new pouch that improves the convenience aspect of heat-and-eat microwaveable products such as soups, stews and rice.

The FlexiBowl pouch, introduced at Pack Expo last fall by Cincinnati-based Ampac Flexibles (www.ampaconline.com), is designed for on-the-go occasions. Consumers microwave or boil the product in the pouch, then eat directly out of the package.

The company's linear tear technology provides a clean, straight tear across the package, so the product doesn't spill upon opening. And "cool grip" tabs give the consumer a comfortable grip on the hot package.

The FlexiBowl pouch can be designed in a variety of formats, but one example incorporates a linear tear notch at the top of the package and a second notch lower on the pouch. The consumer would tear at the top notch, partially or fully, to allow venting during microwaving. After cooking, she would tear at the lower notch to open the pouch into a bowl.

This package concept is useful for retorted applications but can also be used for dry foods such as snacks and cereals. The film used to make the pouch, plus the package shape and placement of cool grips and tear lines, can be customized to suit specific customer requirements. The package is designed to run on existing form-fill-seal packaging equipment at the same line speed as conventional pouches.

Meanwhile, back at the plant
The run of recent flexible-packaging advancements vis-à-vis cooking and heating is not limited to consumer-product packaging. Flexible packaging also is evolving for post-packaging pasteurization of cooked meat in the plant.

For ready-to-eat meat products, it is not uncommon to cook the meat and then apply a secondary operation within the plant, such as browning or smoking. However, that second touch-point makes the product vulnerable to bacterial contamination prior to packaging.

Post-packaging pasteurization, in which the completely processed protein is first packaged in a heat-shrinkable barrier bag and then heated to 200-205°F for several minutes, is used to reduce surface pathogens. This type of pasteurization can add up to two weeks of extra shelf life, a significant plus for the retail delicatessens that purchase this type of ready-to-eat product.

Until recently, processing techniques that created a rough surface on the meat were not compatible with post-packaging pasteurization because they poked holes in the barrier bag.

"There are some products that have a very abusive exterior. They might be coated in cracked peppercorn," says Mike Rosinski, marketing director for smoked and processed meats at the Cryovac div. (www.cryovac.com), Duncan, S.C., of Sealed Air Corp.

Another example is fried turkey breast. Rosinski explains, "With that flavor profile, they hold it in down in the fryer for longer periods of time and it comes out with a very hard, dried exterior. Those nibs or protrusions the come off the product can pop through a bag, particularly if it is rolling along a conveyor."

Cryovac packaging
Cryovac's Heavy bag, here used by Crest Foods, is a heat-shrinkable, multilayer polyolefin bag that can be used for post-packaging pasteurization of products.

To address the issue, Cryovac developed an abuse-resistant barrier bag called the CNP310 Heavy bag. This heat-shrinkable, multilayer polyolefin bag can be used for post-packaging pasteurization of products such as open-rack cooked beef, brisket, fried turkey breast and items coated with roughly textured spices.
The Heavy bag runs on the same Cryovac rotary-chamber vacuum packaging equipment as regular heat-shrinkable bags, and at the same line speeds, to the benefit of processors with legacy equipment.

A separate development from Cryovac streamlines the handling of proteins that the processor cooks in a bag; after cooking, the bag is stripped off the product in preparation for further processing, packaging and, optionally, post-packaging pasteurization. Called the CNZ660 Grip & Tear cook-in bag, the package is made from a non-barrier, multilayer coextruded film.

The bag is designed with finger holes, a tear notch and a straight-tearing feature, allowing workers to easily strip the bag off the cooked product without a knife. Eliminating knives and other tools prevents repetitive-motion injuries and also reduces the possibility of product contamination. The primary applications for the cook-in bag are roast beef and cooked turkey sold in delicatessens.

Both in the plant and in consumers' homes, flexible packaging has come a long way toward achieving parity with other packaging materials when it comes to pasteurizing, cooking and reheating. You could say that films are just getting warmed up.

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