Nano Materials' Slow Ascent

Aug. 28, 2015
Adoption of new technology usually inches along. In the case of nanotechnology in food, the timeline is measured in even smaller increments.

A catchy phrase can catapult manufacturing issues to buzz status — think Internet of Things or Six Sigma — but like yesterday’s news, their shelf life is limited.

Nanotechnology enjoyed buzz status not too many years ago, but its star power has lost some luster. Partly, that’s a consequence of the vagueness of the term and the different definitions attributed to it.

A technician applies a micro-coating with nanoscale tunnels for heat trapping to a steam pipe at a Grupo Modelo brewery. Photo: Industrial Nanotech Inc.

Food scientists focus on possible improvements in bioavailability, but they recognize that advocacy would pose a public relations minefield. Microbiologists are pursuing “lab on a chip” detection of foodborne pathogens, although commercial development is still years away.

In a sense, nanotech didn’t go away, it just went underground.

Take, for example, Owlstone, a British firm that is a pioneer in field asymmetric ion mobility spectrometry, a technology that miniaturizes ion spectrometry for detection of chemical signatures such as diacetyl, a flavor indicator in fermenting beer and wine. When Owlstone began developing electronic noses for food & beverage products a decade ago, it happily wrapped itself in a nanotech cloak.

Today, not so much. “I’d steer away from defining what we do as ‘nanotechnology,’” the firm’s communications director wrote in an email. “The presence of the word in our web domain is (mostly) a historical accident.”

Nano particles in packaging materials are potential game-changers. Three years ago, Nanox Tecnologia S/A received approval from the Brazilian government to include nanoscale silver ions in a polyethylene matrix for packaging. According to Gustavo Simoes, CEO of the São Carlos, Brazil, firm, the silver particles measure about 0.2 microns, a tenth of the size of the particles in other manufacturers’ antimicrobial silver ions but just as effective.

The silver coats silica particles measuring about 7 microns, and the powder then is added to preforms prior to blowmolding or injection molding. The silica carrier helps stabilize the color and transparency of the plastic, while the silver causes bacterial plate counts to gradually go down. “It’s a physical process,” says Simoes.

Most milk sold in Brazil is UHT processed and shelf stable for four months. Fresh milk is minimally pasteurized and usually only good for a few days. A handful of Brazilian dairies are using Nanox’s particles in high-density polyethylene containers and flexible pouches, boosting refrigerated shelf life to 10 days from four.

“It’s usually very difficult to show consumers the benefits of auto-sterilant containers,” Simoes acknowledges, but extended freshness is easily understood.

Nanox is a spinoff of the Multidisciplinary Center for the Development of Ceramic Materials, a government research initiative. Migration tests on the silica and silver composite determined that it is below the threshold set by Brazilian health authorities. The material is registered with the FDA, but winning EPA approval for an antimicrobial often is a lengthy and expensive process. Simoes says the firm is trying to attract U.S. investors to fund the petition process.

Slippery when wet

Nanoscale coatings for food contact surfaces are among the more active development areas, and although the food safety benefits of preventing biofouling usually drive the work, the benefits in a production environment go beyond safety.

Researchers at the University of Massachusetts have used an electroless nickel plating process to co-deposit fluorinated nanoparticles on the interior of stainless steel plates of a heat exchanger. Five layers of the polymeric coating measure less than 100 nanometers and reduce the need for machine shutdowns to address fouling caused by biofilms.

A similar benefit is delivered with slippery liquid-infused porous surfaces (SLIPS), a surface chemistry from Harvard University’s School of Engineering and Applied Sciences. SLIPS is a fluorinated oil that is immobilized on a surface and resists attachment by anything, giving rise to the term “omniphobicity” to distinguish it from nanostructured superhydrophobic surfaces that biofilm can adhere to.

Low cost is part of SLIPS’ attraction, and economic feasibility is a prerequisite for any metal coating that might be used on food equipment and contact surfaces, points out John Dutcher, director of the nanoscience program at University of Guelph in Guelph, Ontario. “Nanotoxicology is a real concern,” he adds, and extensive research is ongoing to understand what occurs at a molecular level when engineered nanoscale materials enter the environment or the human body.

Coatings for equipment that does not come into contact with food are less contentious. Energy losses from steam pipes and condensate lines, ovens, bottle washers and other equipment drive up production costs, but insulating them with rock wool usually isn’t an option in a food plant, where moisture will turn the insulation into a bacteria incubator.

An epoxy coating from Industrial Nanotech Inc. relies on porous tunnels to trap heat in microscopic layers. A typical application involves six coats with a total thickness of 300 microns, or 0.3 mm.

A project involving a European soft drink manufacturer began with six coats of the firm’s EPX-4 epoxy, followed by two layers of Translucent GP coating, a water-based acrylic that is registered with NSF International for incidental food contact. According to Francesca Crolley, vice president-business development at the Naples, Fla., firm, the bottler realized a 13-month ROI on the project.

Industrial Nanotech is careful to avoid comparisons to insulating R value. There is a European standard that equates the bottler’s coating to about 3 inches of rock wool. That equates to R9-R12 insulating value.

A more compelling ROI was realized last year at Blue Line Brewery, a microbrewery in the Adirondacks of upstate New York. Six coats on an 85-gallon brew kettle accelerated wort boiling time to 45 minutes, according to owner Mark Gillis. A 65-gallon uncoated kettle takes 2 hours to reach boil.

Dental candy

If Gillis ever considered adding nano ingredients to the hops and malt inside his kettles, a maelstrom of protest undoubtedly would ensue. That helps explain the cold shoulder Robert Karlinsey has received to date from confectioners and other food companies he has approached about adding to their products a teeth whitening and restorative agent he developed.

A former director of the nanotech program at the Indiana University School of Dentistry, Karlinsey relies on a nanoscale fusion process to combine calcium and phosphate ions that build enamel-like material on a tooth’s surface. “Basically, it’s a tooth healing agent,” explains Karlinsey, president of Indiana Nanotech LLC, Indianapolis.

The engineered material has been used in a line of professional oral-care products from 3M since 2007. It’s also incorporated in Clinpro Tooth Crème, a retail product. The ingredient panel describes the material as tri-calcium phosphate, a deliberately benign name.

“It’s a big selling point to use calcium phosphate instead of fluoride,” he believes. “We were the third or fourth company to put calcium phosphate into a dental product, but we are the most effective.” Noting that the active ingredient in many pharmaceuticals is necessarily nanoscale in order to pass through cell membranes, Karlinsey says increased bioavailability would be beneficial in better-for-you foods as well as confections, although public perceptions remain a stumbling block.

Public nano resistance is widespread. Friends of the Earth is lobbying the European Health Commissioner to declare a moratorium on nano materials in food supplements and food-contact materials, while also insisting they should be redefined to include materials three times larger than the currently accepted maximum size to be considered nano (100 nanometers).

“We see the same arguments against nano ingredients as we see with GMOs,” muses Rickey Yado, dean of the Faculty of Land and Food Systems at the University of British Columbia in Vancouver. “Medicine is a life-and-death must,” and that shields pharmaceutical manufacturers from criticism over nano ingredients. “Food is something we celebrate with. It has emotional aspects that touch on freedom of choice,” Yado continues, and that makes a nano backlash all but inevitable.

FDA, Health Canada and other regulatory bodies have provided some general guidance for nano ingredients in food, but until there are clear standards, definitions and regulations, he expects food manufacturers to steer clear of them, lest they be vilified. Likewise, use of nano components in active packaging will be sidelined until there are definitive answers about the potential danger of leeching into the food itself.

In the meantime, coatings of one type or another will be the greatest benefit to food manufacturers from this dynamic area of material science.

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