Active packaging

Moisture control

Desiccants are hygroscopic materials used to reduce water vapour inside sealed packages. They are commonly supplied as sachets, canisters, tablets, closures, labels, or components incorporated into packaging materials.

Moisture-control systems are used with foods, pharmaceuticals, electronics, machinery, diagnostic products, and other moisture-sensitive goods. Their performance depends on the initial moisture level, internal package volume, storage humidity, temperature, package permeability, and absorption capacity of the desiccant.

Some pharmaceutical containers incorporate desiccants into bottle closures or internal structures. This reduces the risk of consumers accidentally removing or mishandling a loose sachet.

Corrosion control

Packaging for metal products can contain volatile corrosion inhibitors, also known as vapour-phase corrosion inhibitors. These compounds evaporate within an enclosed package and form a protective molecular layer on exposed metal surfaces.

Volatile corrosion inhibitors may be incorporated into paper, polymer films, foams, oils, emitters, chips, and other packaging materials. Their effectiveness depends on inhibitor concentration, package sealing, storage conditions, metal type, and the volume of the enclosed space.^[4]

Corrosion-control packaging is used for machinery, automotive parts, tools, electronic components, military equipment, and metal products stored or transported in humid environments.

Metal chelation and antioxidant systems

Trace transition metals, particularly iron and copper, can accelerate oxidative reactions in foods and other sensitive products. Metal-chelating packaging contains compounds that bind these metals and reduce their ability to promote oxidation.

Chelating compounds may be immobilised on a polymer surface so that they interact with the product without being directly mixed into it. This approach has been studied as a method for improving oxidative stability and reducing dependence on directly added preservatives.^[5]

Antioxidants can also be incorporated into films, coatings, labels, or sachets. The active compound may remain immobilised on the package surface or be designed to migrate within regulated limits.

Oxygen and atmosphere control

Oxygen scavengers, also called oxygen absorbers, remove residual oxygen from a sealed package. Reducing oxygen can slow lipid oxidation, colour changes, vitamin degradation, mould growth, and the growth of aerobic spoilage organisms.^[6]

Iron-based oxygen absorbers commonly contain iron powder and supporting ingredients that allow oxidation to occur. Other systems use ascorbic acid, enzymes, unsaturated organic compounds, microorganisms, antioxidants, or oxygen-scavenging polymers.

The active material may be supplied in a sachet, card, label, bottle closure, tray, film, liner, or moulded package component. Sachets must be clearly identified and protected against accidental opening or ingestion.

In practical dry-food storage, oxygen-absorber sachets may be placed inside suitable high-barrier Mylar pouches before heat sealing. The food type, moisture level, absorber capacity, seal integrity, and package barrier must be appropriate for reduced-oxygen storage.^[6][7]

The effectiveness of an oxygen scavenger is partly determined by the package's oxygen transmission rate. A low-transmission barrier limits the amount of oxygen entering after the initial oxygen has been removed. A high-barrier film remains passive packaging when used without an active component.

Modified atmosphere packaging changes the concentration of gases surrounding a product. Nitrogen, carbon dioxide, oxygen, or mixtures of these gases may be selected according to the product and its spoilage mechanisms.

Active components such as oxygen scavengers, carbon-dioxide emitters, carbon-dioxide absorbers, and ethanol emitters can help establish or maintain a desired package atmosphere.^[8]

Reduced-oxygen packaging requires product-specific safety controls. A low-oxygen environment may inhibit aerobic spoilage organisms while allowing some anaerobic microorganisms to grow. Product acidity, water activity, processing, refrigeration, storage time, and package integrity must be considered together.

Ethylene control

Fruits and vegetables naturally release ethylene, a plant hormone involved in ripening, ageing, and other physiological processes. Packaging systems that remove ethylene or inhibit its action can delay unwanted ripening during storage and transportation.

Potassium permanganate immobilised on alumina, silica, or another carrier is one of the established ethylene-scavenging systems. Activated carbon, zeolites, catalytic materials, and other adsorbents have also been studied.

1-Methylcyclopropene does not remove ethylene from the package. It limits ethylene activity by binding to receptors in plant tissue.^[9]

The effectiveness of an ethylene-control system depends on the produce type, maturity, respiration rate, storage temperature, ventilation, humidity, and scavenger capacity.

Antimicrobial packaging

Antimicrobial packaging is designed to inhibit pathogenic or spoilage microorganisms on a product surface or within the package environment.

Antimicrobial compounds may be incorporated into films and coatings, immobilised on a package surface, released into the package headspace, or contained in pads, labels, and separate emitters. Studied agents include organic acids, plant-derived compounds, enzymes, bacteriocins, metal ions, nanoparticles, and synthetic antimicrobial substances.^[10]

The performance of antimicrobial packaging depends on the target microorganism, active-agent concentration, release rate, temperature, food composition, storage period, and contact between the package and the product.

Absorbent pads used with meat, poultry, seafood, and fresh produce can combine liquid absorption with antimicrobial substances or freshness indicators.^[11]

Time and temperature indicators

Temperature indicators show that a specified temperature has been reached or exceeded. Time–temperature indicators respond to cumulative exposure over time and can provide an indication of the thermal history of a product.

Indicators may use chemical, enzymatic, microbial, mechanical, electronic, or colour-changing mechanisms. They are used with foods, vaccines, pharmaceuticals, biological materials, and other temperature-sensitive goods.^[12]

Electronic temperature data loggers can record the time, duration, and extent of temperature deviations. Thermochromic inks provide reversible or irreversible colour changes when particular temperatures are reached.

Freshness and gas indicators

Freshness indicators respond to chemical or biological changes associated with product deterioration. They may react to pH changes, volatile amines, carbon dioxide, oxygen, hydrogen sulphide, humidity, or microbial metabolites.

Gas indicators can show leakage, loss of the intended package atmosphere, or the presence or absence of a target gas. Biosensors combine a biological recognition element with a transducer that converts a reaction into a measurable signal.

Freshness indicators do not replace microbiological testing or required date labelling. The indicator must be designed for the specific product, spoilage pathway, and storage environment.

Radio-frequency identification and smart labels

Radio-frequency identification tags use radio waves to identify and track products, packages, pallets, and unit loads. Passive tags receive power from a reader, while active tags contain their own power source.

RFID tags may be combined with temperature, humidity, shock, or other sensors. They can support inventory control, authentication, cold-chain monitoring, and supply-chain traceability.

Near-field communication tags allow compatible smartphones and other devices to retrieve product information or interact with digital services.

Barcodes and digital links

Linear barcodes and two-dimensional symbols are used to identify packaged products and communicate data. QR codes can connect users to instructions, ingredient information, traceability records, authentication services, recall notices, and accessibility resources.

The GS1 Digital Link standard defines how GS1 identifiers can be represented in web addresses and connected to online information and services.^[13]

A printed barcode or QR code alone does not make a package active. It may be considered an intelligent or connected-packaging feature when it provides access to relevant data, uniquely identifies an item, records interactions, or operates with sensors and information systems.

Digital identifiers can be copied unless they are combined with authentication, encryption, secure graphics, serialisation, or server-side verification.

Security and authentication

Security packaging can include tamper-evident closures, security printing, holograms, digital watermarks, RFID tags, unique serial numbers, covert markers, and forensic authentication features.

These systems help identify counterfeiting, diversion, unauthorised opening, product substitution, and manipulation of the package.

Authentication systems may combine visible, covert, forensic, and digital elements. Scan data from serialised codes can also help identify unusual copying or distribution patterns.

Shock, tilt, and vibration monitoring

Shock indicators, tilt indicators, and vibration monitors can be attached to products, packages, pallets, or shipping containers. They show or record when handling conditions exceed a selected limit.

Digital data loggers can record the magnitude, direction, duration, and timing of shocks and vibrations. The collected information may support product inspection, carrier evaluation, damage investigation, and laboratory package testing.

These systems are used with medical equipment, calibrated instruments, electronics, artworks, industrial components, and other sensitive goods.