Modified Atmosphere Packaging of Foods

Food manufacturers are increasingly using cleanroom design to minimize bacteria counts in new food products. The mechanics of modified-atmosphere packaging (MAP) are simple:  First, a specified gas mixture is flushed into a package; then the product is sealed inside that gas-containing package. The modified atmosphere (gas mixture) retards the spoilage-causing effects of such factors as oxygen level, respiration rate, and enzymatic activity. Extended shelf life carries obvious benefits, especially in association with the consumer's growing insistence on fresh, natural, and value-added products. MAP is applicable to a diverse range of product categories. MAP varieties of fresh and processed meats, fish and fowl, fresh produce, bread and bakery foods, cheese, and fresh pasta are being marketed.

Although used fairly commonly in Europe for high acid foods and beverages, sterile atmosphere plastic blow molded containers have only been used by a few pharmaceutical manufacturers in the United States.

In Europe, the filling of yogurt into plastic cups is being accomplished under cleanroom conditions and the result is long shelf life of the product without the extensive use of chemical preservatives.

Control de Contaminacion de Colombia (C4), a South American company that specializes in building clean environments for the food, pharmaceutical and industrial areas, has added a Class 100 and Class 1,000 cleanroom for aseptic filling for beer, juices and soft drinks to its portfolio. Tunnel-type pasteurization in the traditional system submits the product to varying high temperatures, which generates a product with varying characteristics. Aseptic filling with controlled pasteurization and lower thermal punishment, by contrast, improves the product in several ways. In beer, it improves the organoleptic characteristics such as the aroma profile and freshness. It also ensures greater product stability, which results in longer shelf life. Juices are spared from denaturalization resulting from exposure to high temperatures for long periods, which occurs with tunnel pasteurization. As a result, orgnoleptic characteristics such as aroma, taste and color are improved.

The cleanroom comprises five areas:  a Class 100 area with vertical laminar flow, modified with sectored air returns that control negative air flows and provide distributed protection considering the location of the product, the operator and the critical zone;  a Class 1,000 cleanroom for the bottle transportation areas that goes from the washer to the entrance of the filler; this is an open cleanroom with unidirectional air flow based on bottle flow;  a technical area for conditioning (temperature and relative humidity) filtering and air handling;  a viewing area, which was created to limit access to the Class 100 area;  modular and acoustic manufacturing was incorporated to attenuate the reverberations and to allow visibility; an area of access and air locks. The cleanroom is controlled by an automatic system based on a programmable logic controller with a standby function that controls filter and room pressure, relative humidity, temperature and air flow 100 percent of the time.

Dairy Farmers of America (DFA) and Stork Food & Dairy Systems announced a joint venture aimed at developing aseptic processing and packaging technologies for all types of products and containers, including plastic. Known as ASEP-TECH USA, the partnership will install a pilot plant next to the DFA Technology Center for developing and testing in-container sterilization, extended shelf life (ESL) and aseptic processes. Food processors will be able to rent the plant for product development and test-market runs of ESL and shelf-stable low-acid or high-acid products.

Stork equipment to be installed includes a Sterideal tubular UHT system; an aseptic surge tank; a lab-scale glove-box aseptic filler; a linear aseptic filler for test-market runs which fills plastic cups, plastic bottles and glass bottles at rates up to 3,000 per hour; and a prototype in-container sterilizer which treats sterilized product filled in non-sterile containers with a mild thermal process. 

At Pacific Foods of Oregon Tetra Pak’s VTIS steam-injection system combines with its TBA/21 packaging machine to aseptically process and package soy drinks, milk & soy blends and 100 percent lactose-free milk in the first U.S. application of Tetra Pak’s new “1 liter square” aseptic container with plastic screw cap. Tetra Pak’s Jeff Kellar envisions aseptic processing and packaging combining with the l liter square package for long shelf-life milk products which can be distributed without refrigeration to cut costs for dairy processors, yet marketed as refrigerated products in a consumer-accepted package. The Aldose system can aseptically dose heat-sensitive ingredients such as flavors, vitamins and colors after the thermal process to prevent their degradation during sterilization.

Moovers, the first plastic-packaged ESL (extended shelf life) milk products in the U.S. were unveiled last year by Smith Dairy Products, Orrville, OH. The products are UHT processed in an APV steam-infusion system and packaged under HEPA air filtration.

Food manufacturers are looking for more flexibility in aseptic systems. APV, for example, engineers aseptic processing systems isolated by custom-designed valves from aseptic surge tanks that supply the filler. This allows the processing system to be cleaned and sterilized for the next production run while filling operations continue.