Active and intelligent packaging are two forms of smart packaging. Active packaging employs technology that intentionally releases or absorbs compounds from the food or the headspace of food packaging, which extends the shelf life of products by stalling the degradative reactions of lipid oxidation, microbial growth, and moisture loss and gain better than traditional food packaging. Intelligent packaging communicates to consumers and others throughout the value chain. The two types of smart packaging will advance the packaging sector. Scavengers for oxygen, ethylene, and moisture continue to dominate active packaging, but recent growth in active packaging emitters has been dramatic.
Scavengers
Package scavengers in the form of separate packets or sachets have been around for at least 50 years, but now scavenging technology is embedded within the package structure. This integrated approach reduces costs and enables this form of active packaging to be a cohesive process for production operations and consumers. The combination of intelligent technologies with active packaging allows the gathering of information on how a package is performing.
- Oxygen scavengers Oxygen absorbers stall oxidation and inhibit microbial growth. The most common substrate in oxygen scavengers is iron followed by ascorbic acid and other substrates. These substrates are incorporated into polymer structures as light-sensitive dyes or sacrificial unsaturated dienes. Oxygen-absorbing liners on the underside of beer closures, such as the Carlsberg FreshCap, are said to increase the shelf life of beer by 15%. The ability for consumers to activate oxygen scavengers within an opened resealable package is an emerging development in this area.
- Ethylene scavenging products Ethylene scavengers extend the shelf life of produce by slowing the ripening process and senescence. They are typically available in sachet form and can be integrated into the package structure. Regardless of whether ethylene-absorbing sachets contain zeolite or potassium permanganate, they absorb ethylene and moisture to reduce senescence and release sulfur dioxide if water comes in contact with the sachet pads that contain sodium metabisulfite salt. In addition, the compound 1-methylcyclopropene (1-MCP) is commonly used in the washing and processing of fresh produce and to block ethylene receptors and slow senescence. FruitBrite by Hazel Technologies releases 1-MCP to diffuse ethylene blockers within the headspace of packaging during distribution. In addition, the incorporation of 1-MCP in corrugated linerboard eliminates the need for sachets and allows for more seamless and consistent produce distribution. PEAKfresh by PEAKfresh USA, Green Bags by Evert Fresh, Ethyl Stopper by Profresh Systems, and Bio Fresh by Grofit Plastics are other ethylene-scavenging products that are on the market.
- Moisture scavengers Moisture scavengers control moisture in the headspace of a package and absorb liquid weeping from food, which extends product shelf life. Examples of common commercial scavenger pads and sachets that absorb moisture from food include Dri-Loc by Novipax, absorbent pads by Thermasorb, and MeatPad by McAirlaid’s. There are also various types of absorbent packaging, such as MoistCatch films by Kyodo Printing, desiccant packaging by Onyx Specialty Papers, and FreshWell rigid trays by Aptar. Clays, zeolite, humectants, and other compounds in packaging substrates absorb moisture, but adding high-capacity hydrogels to packaging structures allows for more effective moisture control.
Emitters
Active food packaging emitters lessen the effects of deteriorative reactions from microbial growth, oxidation, or uncontrolled ripening via their direct contact with food and diffusing from the packaging. Packaging materials that do not provide a suitable shelf life of foods can be enhanced with active packaging emitters. For example, when an antioxidant is emitted into the headspace of a package, the required oxygen barrier or the degree of headspace modification (via vacuum or gas flushing) may decrease. This is the case with some packaged cereals in which butylated hydroxyanisole or butylated hydroxytoluene emitted from a relatively low-barrier, low-density polyethylene and polypropylene copolymer stalls lipid oxidation. More