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.