Refrigeration: Chilling tales of technology

Thank freeze-drying, IQF and MAP for quantum leaps in the quality of foods.

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Individually quick freezing (IQF) is another technology that has dissolved into the invisibility of the consumer’s everyday expectations.

Before the advent of IQF, frozen fruits, vegetables and seafood often came frozen in lumps. Freshness, taste, and product integrity suffered for the cause of preservation. Frigoscandia Equipment, today a Northfield, Minn., unit of FMC FoodTech, introduced the technology with the FloFreeze IQF freezer, and it has changed the image of frozen food quality ever since.

IQF has made it easy to assemble attractive frozen meals and "looks as if it were made from scratch" meal components.
This revolutionary process eliminated blocks and frozen clusters of product. It enabled processors to clean, trim and freeze-in the nutrients of fruits and vegetables sometimes within hours of harvest. The process arrested the natural degradation process, making the frozen product at times superior to fresh.

But by preserving the product and integrity of the raw food item, it also enabled accurate and high-quality portion control. Thanks to IQF, not only are frozen meals easily and attractively assembled, but so are the popular “cook it yourself as if you had made it from scratch” component meals as well.

“Product can be frozen in bulk, individually divided up and mixed into component packages,” explains Jeff Barach, vice president of special projects and technology tracker for the National Food Processors Assn. Barach touts IQF quality and the way it has enabled easy, high-quality meal assembly and compartmentalization. “New applications of IQF include prepared meals for folks with special dietary needs such as low-fat, low-carb, or any type of special meal,” he says.

A slightly different tack is taken at Graceland Fruit (www.gracelandfruit.com), Frankfort, Mich. “Graceland started innovating during a year when the cherry crop was so large that we decided to experiment by drying the excess cherries,” says Donald Nugent, president and CEO. Experimentation led Graceland to become a supplier of fruit and vegetable ingredients to food processors, and to provide them using several processes.

Graceland’s Soft-N-Frozen process combines fruit with sugars and a natural stabilizing system, which binds and controls the free water in fruit pieces, inhibiting ice crystal formation. The result is a fruit ingredient that will not completely freeze, remaining soft and scoopable, while retaining fruit piece identity and natural color.

Unlike IQF fruits, these fruits can be added directly to consumer products with minimal thawing, the company says. The Soft-N-Frozen process preserves the integrity and character of delicate fruits, plus the pasteurization process ensures very low microbe counts.

A healthy atmosphere

Just a few degrees warmer than the freezer, refrigerated cases for more than a decade have carried the invisible technology of modified atmosphere packaging. MAP controls the internal environment of fresh products such as raw meats and vegetables to extend freshness and shelf life.

MAP helps maintain the visual as well as microbiological assurance of freshness. Yet the consumer sees nothing of the technology other than the plastic overwrap, which appears no different than films consumers have encountered for decades.

NOTE TO PLANT OPS:

Knowledge of the ingredients and their properties is critical in maintaining the quality, freshness and shelf life in your packaged refrigerated product. Discuss with Plant Operations and especially Packaging how the ingredients vary with regard to respiration, maintaining fresh appearance and texture, and microbial response with different gas mixes and films.

Fresh beef requires oxygen to maintain the red color equated with freshness. Yet oxygen accelerates degradation in vegetables, which yield oxygen as a waste product.

It really gets tricky when you mix widely varying ingredients, as in a fresh salad. The various components may have different gas preferences, and finding the right balance to provide the best atmosphere for the mix requires knowledge not only of the ingredients themselves, but of the packaging materials influencing the atmosphere.
Maintaining the optimum mixture of gases – evacuating some and sealing in others -- is the key to the technology.

“The challenge of MAP has always been finding the right mix of gas,” says NFPA’s Barach, “plus selecting the packaging material with appropriate breatheability for moisture control with respiring vegetables.”

Determination of both is not an easy task, and the technology has a long history of study, punctuated by trial and error. The atmosphere in a bag of respiring mixed vegetables, for example, is constantly changing. Vegetables emit gases as they age, and each vegetable varies in its pattern of respiration and moisture retention.

“You also have a safety factor,” explains Barach. “With mushrooms, you need a certain amount of breathability. That’s why you often find holes in the film. You don’t want dangerous anaerobic bacteria like clostridium botulinum to develop.”

In other products, the mere presence of oxygen is sometimes the biggest threat to shelf life. Oxygen scavenging technologies today are recruited to meet the challenge.


The latest generation of Cryovac (www.cryovac.com) oxygen-scavenging films absorb oxygen at a 10- to 20-percent faster rate than their predecessors. The polymer-based film has a scavenging component that is coextruded as an invisible package layer, which preserves the clarity of the film. The result is improved freshness, color and nutrient preservation, not to mention a better microbiological safeguard. It is particularly valuable with light-sensitive products.

Nestle’s Buitoni brand of Italian food products incorporates Cryovac OS (oxygen scavenging) film into the lid packaging on its fresh refrigerated pasta products. The companies claim a 50-percent increase in shelf life.

Of course, products like fresh meat need to keep oxygen in to prolong the appearance of freshness. Case-ready meats make major use of modified atmosphere packaging, primarily with multi-layer barrier containers. Often these consist of polypropylene (PP) with an added ethylene-vinyl alcohol (EVOH) layer, the latter keeping oxygen or nitrogen in while keeping ambient air out.

Eastman Chemical (www.voridian.com), Kingsport, Tenn., has introduced its VersaTray Dual-Ovenable crystallized PET and Voridian APET, an amorphous (non-crystalline) polyethylene terephthalate, touting the combination as a more cost-effective alternative to more expensive PP-EVOH containers in MAP applications. The manufacturer claims its products have better gas barrier properties and can be easily sealed.

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