Between a growing demand for convenient foods meant to suit a busy lifestyle and the expectations of international food quality standards, food packaging has been making strides in advancements in order to meet both safety guidelines and preserve the food to look as attractive as possible. To achieve this, different types of coatings for food packaging is used to protect food from oxygen degradation, water vapor, and aromas so that the actual packaging can still be easy and convenient to open.
Food Coating Uses
Coatings of a food package are applied to the substrates of the package, which is the underlying layer just below the surface of the packaging. This coating creates a barrier that is effective at keeping out gases like oxygen and other aromas or liquids like water vapor, oils, and grease. However, this barrier also works in reverse, preserving the aroma of the food within the packaging and trapping the existing moisture within the food so that it takes far longer to dry out. To this end, the shelf life of packaged food is safely extended in both how it tastes and how the food appears.
Aesthetics of packaged food is considered equally important to how safely edible it is. Potential consumers have certain expectations for what food is supposed to look like, and even if a packaged food is safe to eat, it’s likely to be left untouched if it doesn’t meet the aesthetic expectations. Not being able to live up to this ideal of what food should look like results in a lot of wasted food. This is also why many food packages are made with a transparent material, so that consumers can physically see the food and identify its attractive qualities, making them more likely to gravitate towards the product. The most attractive quality to food aesthetics is the color. Color is heavily associated with the quality of foods, such as how a fruit’s color changes as it ripens or how food loses its color as it goes bad. Thankfully, the types of coatings for food packaging aid in retaining desired colors when the shelf life is extended by preventing food from becoming rotten or stale.
As an example, O2 scavengers are a type of coating added to food packaging in order to reduce O2 reactions with the food itself. The O2 scavenger coating absorbs the oxygen trapped within the packaging. They don’t create a perfect vacuum within the packaging, of course, but it helps to reduce the amount of oxygen coming into contact with the food itself.
Barrier Types and Materials
In order to choose the right internal coating, the deciding factors are based upon the region in which the food packaging is being produced, accessible materials, and what the packaging itself is made from. The most commonly used internal coating is an epoxy-based resin that makes up most of all coatings used. Epoxy-based coatings have been the most common since the 1950s because they are strong, flexible, and resistant. This is accomplished by containing many cross-linked monomers in the resin that join together to form a strong lattice of bonds that is very resistant to damage. In addition to being the popular standard, epoxy-based resins are the cheapest coating to make. The downside, however, is that epoxy-based resins make use of the chemical compound bisephol-A which has been found to be linked to toxic effects in humans by disrupting the human endocrine system. For this reason, manufacturers have been trying to look elsewhere for coatings, while others have been adjusting the epoxy-based resin formula to correct this issue.
However, while epoxy-based resins are still the de facto standard, internal coatings can largely vary in order to meet the needs of various products and the region they are produced in. The coatings used in food packaging varies around the world; in fact, and that’s when custom toll processing services like Capital Resin Corporation can be a valuable resource to tailor specialty chemicals in accordance with customer-made formulas. So, while epoxy-based resins are useful on their own, internal coatings can always be tweaked to exact specifications and ensure the coating meets every little need for the best possible food packaging protection.
Nanotechnology has been applied to internal food packaging coatings in recent years. This nanotechnology is used to improve the gas barrier properties of a coating by dispersing a nanoclay within the barrier coating. This alters the platelet orientation within the coating to form tighter together, and while it can’t completely block out gases, it makes the “path” for gases to get into the packaging much more difficult. This creates a very thin and effective gas barrier.
As environmental consciousness increases, manufacturers of food packaging have prioritized recyclability, environmental friendliness, and sustainability. As a result, this has given the opportunity to develop new packaging materials and improvements on the internal coatings used within.
An example of some of the materials being used for packaging that is environmentally friendly is a plastic film to replace aluminum foil. This plastic is fully recyclable but lacks a strong gas barrier. To make up for this weakness, a coating of metalized aluminum and transparent oxide is commonly applied to the plastic film to create a usable barrier against oxygen and moisture. However, this creates a new issue, as these coatings are not heat-sealable. To compensate, the coating is instead used in multilayer film constructions.
These more environmentally friendly plastic films are projected to continue growing at high rates despite their flaws in protecting from oxygen and moisture in comparison to aluminum foil, as the plastic film is attractive for stand-up pouch applications, meat pack lidding, and microwavable and dry food packaging. To continue compensating for the lacking aspect of the plastic films, new internal coatings are still being developed to not only compensate for the heat and gas barrier but to also produce resistant properties and create a transparent or glossy appearance.
With this shift to environment awareness, expect to see food packaging coatings to evolve and mold to the needs of greener materials, meaning new specialty chemicals will be produced by professional chemical manufacturers like Capital Resin Corporation.