By Shubhendra Singh*
Packaging is a crucial aspect of the food processing process and plays a major role in preventing and minimizing waste in food supplies. Packaging helps to preserve world resources by preventing spoilage and waste of items and by safeguarding products until they fulfill their role. One of the methods of packaging or increasing the shelf life of food products is Vacuum Packaging. The product is placed in an airtight pack, the air is removed and the package is sealed. By removing air from around the product, the oxygen content in the packaging is decreased, thereby preventing spoilage microorganisms from growing and degrading the goods. The oxygen scarcity also lowers the spoilage due to oxidation which can leads to browning in apples and bananas.
The combination of vacuum packaging, mild heat, and chilled storage, greatly helps in extending the shelf-life of products. This was the basis of sous-vide (a French word for ‘cooking under vacuum’) cooking as a method of manufacturing high-quality foods for restaurant use with a shelf life of 42 days when stored below 3°C. Since the original sous-vide pasteurization concept at 70°C for 40 min, the thermal process has changed, and the target procedure now stands at 90°C for 10 min.
An additional method is the “Cryovac” skin-type vacuum bag packaging, which permits a vacuum packaging that adheres entirely to plastic material and product: these bags are composed of shrinkable plastic which is immersed in a hot water for a few seconds at 90°C. The wide range of applications of vacuum packaging goes from raw meat to ready-to-eat (RTE) products whereas Cryovac is suitable for Vienna sausages and cooked ham. Application of high temperature inactivates some of the on-surface microorganisms and are described as measurements of prolonged shelf life and close surface contact prevents the formation of wrinkles.
Benefits of Vacuum Packaging
Due to its various advantages, vacuum packaging is a widely accepted method in food packaging such as:
Preservation: Vacuum packaging enhance the storage period of many different types of food, ranging from cheese to soup. Meat, for example, does not last more than six months with typical freezer procedures but vacuum-sealed meat can be stored in a freezer for 2-3 years.
Savings: The ability to preserve food for a longer period of time helps in minimizing food spoilage and waste. Vacuum sealing technology also helps companies to buy and store food in bulk at a lesser price.
Protection: Vacuum sealing protects the food against extraneous components such as bacteria and molds. The risk of dehydration and freezer burn injury is also lessened.
Taste: As the food products are kept in an absence of air, their nutritional value such as moisture, texture, and flavor remain intact.
No Additive: Many conventional methods of preservation use strong chemical substances or additives. In contrast, the usage of any dangerous external element is not required in vacuum packaging.
In the absence of oxygen, as in packed or canned goods, a hazardous bacterium known as Clostridium botulinum, which cannot be observed by sight or smell, may develop. Even at low temperatures, some species can develop slowly, yet at room temperature, it grows best. Any food might be contaminated with it because it is found everywhere. The prolonged shelf-life of vacuum packaged products may permit harmful microorganisms or pathogens to grow slowly, even at cooling temperatures, over a longer period. This could be particularly problematic since food can hardly remain below safe cold temperatures (<5ºC). every time in transit, in stores, shops, and in consumer homes.
Its Applications in Food Products
Not only the packaging material itself can influence shelf life but the way the product is filled in the container is equally significant. For instance, with roasted and ground coffee, a vacuum filling into metal canned cans will take 95% or more of the O2 out of them, compare to a gas flush pack in a laminate plastic foil pouch to eliminate 80% to 90% of the O2 from the pack. The leftover O2 in the package will have a considerable impact on shelf-life, irrespective of the O2 barrier characteristics of the packaging.
Vacuum packaging is commonly used to store dry foods over a long period, such as cereals, nuts, cured meats, cheese, smoked fish, coffee, and potato chips (crisps). A packaging product with low oxygen permeability and vacuum packaging is particularly required for foods like fatty fish. The lower level of oxygen in the package lead enhance shelf life when fresh beef is packaged in a vacuum, however, the color of meat becomes violet because myoglobin is reduced to the form with which most of the customers are unaware. Foods are cooked in a vacuum in sealed evacuated stable heat pouches as well as in thermoformed trays for sous-vide processing.
|Food||Stored In||Normal shelf life||Shelf life of Vacuum packaged product|
|Cheese||Refrigerated||1-2 weeks||4-8 months|
|Cookies, crackers||Room temperature||1-2 weeks||3-6 weeks|
|Flour, sugar, rice||Room temperature||6 months||1-2 years|
|Nuts||Room temperature||6 months||2 years|
|Oils with no preservatives like canola, safflower, corn oil||Room temperature||6 months||1-1.5 years|
Table 1: Shelf life of Vacuum Packaged Foods