Smart packaging was a phrase concocted during the 1970s to describe a fantasy product that would sense some environmental tremor and actuate some package element to trigger an action that would benefit the contained product. Conceptually sensational in practice, smart packaging was difficult to implement. Time-temperature integrators, with their deficiencies, streaked across our consciousness. Quality and spoilage indicators intrigued us. And then came moisture and oxygen scavengers—and imbedded antimicrobials— the visionary answers to all our packaged food deterioration issues (well, not quite…).
Microelectronics were being developed in parallel universes and smashed into our lives with obviously tremendous effects. Breathes there a teenager not inextricably linked to the outer world by some magical black or pink or green or silver box adhered to fingers or ears? Some few applications have been used for package pricing and self-checkout. But, as small as these Droids, iPads, iPods, and tablets are, they have not yet been able to significantly alter our food consumption behavior.
But, food packaging fans, peruse some of the possibles—many of which you have seen headlined—but very few of which have yet disrupted us astronomically.
Because of the inherent variability of microwave ovens, cooks have sought to measure and control the microwave reheating process by applying data sources on packages to link electronically with the individual oven’s characteristics and control the heating. This has met with excellent success in the laboratory and experimental kitchen, but it is still cost-prohibitive for both oven operators and food packagers. But aren’t they printing multidimensional QR (quick response) codes on food packages for consumers to study? The microwave oven sensor can read the code from the package and adjust the heating time, etc., to integrate the package and the specific oven characteristics. And then there are the smart meters that integrate with the conventional or microwave oven and adjust behavior to accommodate to time or the electric power grid (www.geappliances.com ).
Also, do not overlook the ability of a smart phone to link with the food storage components and activate passive RFID (radio frequency identification) codes to alert the consumer to the nutritional value of the food or to allow the retailer or distributor to better control inventory. Eventually, RFID may also serve as an indicator of product quality. RFID devices are capable of receiving and transmitting signals related to food age, spoilage, temperature history, and location, and so when the economics are ready, so also will the capability to link with the consumer.
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Incorporating Active Packaging
Antimicrobials built into plastics are in production today, albeit in tiny quantities. The almost archaic model of coating the antimicrobial natural or synthetic chemical on the plastic surface and depending on migration from surface to surface will persist, but the incorporation of the active component into the package structure has emerged. Previously, we reported on Multisorb’s(www.Multisorb.com) incorporation into plastics. More recently, antimicrobials are being incorporated into non-woven materials that can function something like emissive absorbent pads in contact with foods—or even better—as sources for antimicrobial vapors that permeate foods to destroy sensitive microorganisms. And from Clemson University Packaging Department come the inklings of extrusion of antimicrobials into plastic sheet ([email protected] ).
As all who are intimate with food packaging are cognizant, spanning the processing and distribution components of the food system is critical. Packaging machinery is indispensable to the successful fulfillment of the multiple roles of packaging, and the growing functionalities of machine vision and its control aspects will be serving the packager well.
The Multiscan Technologies unit from Spain can classify olives by ripeness, external color, and internal defects at an incredible rate of 15,000 pounds per hour. The machine’s artificial vision measures using a combination of infrared and ultraviolet radiation, lasers, and X-ray technologies to maximize the information gained.
Their machines are now used to sort cherry tomatoes and macadamia nuts, with future systems targeting the interiors of packages (www.technologyreview.com/spain/food).
Hot and Cold Foods
Every experienced food packaging guru was spellbound by the ever-present self-heating and self-cooling food packages that emerged during the early 2000s. Some have even experienced the chemical thermodynamic technologies that were the basis for canned coffee, soup, hot chocolate, and beer barrel packaging.
Exothermic calcium and magnesium salt reactions, fluorocarbon technologies, and water vapor evaporation technologies peppered the media. Military and civilian applications were targets as large and heavy as the temperature-changing packages were. Safety and efficacy issues emerged during the early commercializations, and soon all disappeared from the market to the great disappointment of backpackers and on-the-go consumers.
Way back during the infant days of space travel, we who were involved sought means to provide a pleasant eating experience for the astronauts— sometimes not too successfully. But one of the mechanisms was thermoelectric technology, a device that could generate heat if the electric polarity were in one direction and remove heat when the polarity was reversed. The chunky machine we engineered and built was smaller than a refrigerator but larger than a breadbox —suitable at that time for hotel rooms, which is where they finally settled.
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Now we are informed that researchers at Intel, Arizona State University, Nextreme, and RTI International have integrated a thermoelectric cooler into a computer chip. The semi-conductor-based device uses electric current to move heat; instead of compressors and coolant pipes, a static nanostructured thin film with thermal properties better than bulk thermoelectric materials uses electrons to pump heat more efficiently.
Such thin film devices are not yet ready for large cooling or heating capacity offered by refrigerators, but they are useful for very small volume refrigeration and are far more compact and very much functional, especially when powered with nanoelectric generators (www.technologyreview.com).
Amusement is reading the daily media releases on the progress of ultra-tiny materials as they edge into packaging-related structures, still bearing that cloud of health concerns. The concept of blending clays into plastic resins to strengthen and enhance has intrigued for years—with many reports on the potential advantages. But ask the scientists intimate with the disciplines, what would be the result if carbon nanotubes themselves were melded into monomaterials, i.e., single-layer structures?
Solutions of carbon nanotubes can be applied to manufacture strong fibers with properties that far exceed those of polypropylene woven into bulk bags or non-wovens or even steel. At Rice University, using technologies applicable to the manufacture of liquid crystals, nanotube fibers are generated—today for conductive materials, tomorrow for spinning extraordinarily lightweight, strong bonded materials. If polymeric liquid crystals approached the properties and economics for food packaging during the 1990s, might we not predict carbon nanofiber food packaging during the current decade?
Coming from a slightly different direction is Nanocomp of Concord, New Hampshire, which is commercially producing (in small quantities) sheets composed of carbon nanotubes. Eschewing the “traditional” approach of mixing nanotubes with resins to create composites, the company has been manufacturing sheets composed solely of nanotubes.
The materials are made by feeding a blend of catalyst and alcohol into high-temperature furnaces to cause the carbon atoms to bind together to form long nanotubes. Emerging from the furnace, the nanotubes tangle together to form networks that accumulate on the surface of a spinning roller in the form of loosely packed nanotubes. Subsequent acid treatment leads to capillary forces pulling together the nanotubes and compressing the sheet to form a shiny mat of closely connected tubes.
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Envision that the miniscule carbon nanotube—long identified as today’s ultimate in material properties for tensile strength, burst strength, barrier, and chemical resistance—has been successfully grown into fibers and sheets apparently bearing the same properties as the individual unit.
Once again, today it is an expensive space material, applicable for cable and weather protection, but in the future it may be cheap enough to threaten steel for cans, aluminum for barrier pouches, and complex polymers for trays and bowls—and made from virtually inexhaustible carbon.
Returning from the as yet inert materials sector to the more active realm of actuation using electricity—to power the RFID, for example, solar cells may now be printed on almost anything. Think flexible package plastic films or even carbon nanotube sheets. Today, the major cost variable in photovoltaic cells is the substrate.
By printing directly on thin materials, the cost of the active components reduces the costs measurably. An MIT technology prints the solar cells at temperatures of 120º C using vapors to produce a uniform layer even on rough surfaces. To produce an array of photovoltaic cells, successive layers are deposited in a vacuum chamber in a process hardly unlike vacuum deposition of aluminum for oriented polypropylene film for snack pouches.
MIT’s Vladimir Bulovic and his associates have calculated that the photovoltaic cells on the “packages” are good enough to “power an electric gizmo”—a scientific description meaning flash a light, sound a clarion call down an aisle, or trigger a message on a passing consumer’s smart phone. And SunPrint does it with acoustic printing to precisely deposit layers of active cell material.
It is not possible to truly conclude this brief on the coming several years because we are not able to even enumerate the kaleidoscope of other electronic innovations that are bursting out of the laboratories usually not frequented by food and food packaging scientists and technologists. Consider the following list: nanoparticles that boost solar power with light-trapping thin film photovoltaics; nanopiezotronic wires that function as nanosensors; Kovio’s lithographically printed flexible chips—for RFID or more information; microscale aluminum oxide composite ceramic for structural materials; and printable 3D parts for complex shapes. All are on the horizon.
We have not yet attempted to predict the roles these technologies will play in food packaging in our foreseeable future, but it is certain that we will be digging deeper into each and learning how to apply one or more to our endless supply of food packaging problems. How much more meaningful fun can you look forward to in your future?
Aaron L. Brody, Ph.D.,
President and CEO, Packaging/Brody Inc., Duluth, Ga.,
and Adjunct Professor, University of Georgia