A presentation sponsored by the Almond Board of California (Modesto, CA) pointed to the use of almond shells as an ingredient in plastics for applications including packaging.
Nutty idea? Literally it is, but figuratively it’s not—the shells enhance the plastics’ performance beyond traditional fillers and materials by increasing the plastic’s strength. The shells are being tested as a partial plastic replacement in plastics trays and pallets and other containers and products.
It’s one of the more interesting aspects of research and development conducted by the Western Regional Research Center (Albany, CA) of the United States Department of Agriculture.
“The team has been working on sustainable agricultural-derived plastics for at least 20 years with a scope well beyond fillers,” notes Bill Ort, USDA research leader in Bioproducts. “We’ve quietly worked with companies like EarthShell, Cargill-Dow (Ingeo), Clorox-Glad, Metabolix and others to create sustainable packaging solutions.”
Because California produces more than 80% of the world's almonds, almond shells come into the picture as a biomass resource.
Currently, almond shells are used for dairy ranch bedding or orchard floor mulching, according to the Almond Board’s Guangwei Huang, associate director, food research and technology, who notes that although current values for shells are down a few dollars a ton from up to $50 per ton a couple of years ago, they are not disposed of in landfills.
“Any use as plastic fillers would add value to shells,” Huang tells Packaging Digest. “We are assessing many potential outlets for almond shells and hulls, more specifically looking at higher-value options. Incorporating torrefied almond shells into recycled plastics is one of the higher value potentials we have identified and investigated for almond shells.”
Additionally, the shells have benefits beyond traditional plastic fillers.
“Using shells as fillers in polymer composites have multiple advantages over commercial additives, e.g., cost, energy consumption, renewability, biodegradability, landfilling,” Orts explains. “However, almond shells are hydrophilic, which limits their incorporation into most polymer matrices. Our research shows we can make stiffer, stronger and more heat-resistant composites (see Heat Deflection Temperature chart) compared to unfilled polymer. We're starting to work with industrial companies to optimize materials to meet their specifications and work towards scaling up.”
The shells are collected and processed and undergo “torrefaction,” described by Orts as process where the shell biomass is heated to 200-300 ⁰C in the absence of air and oxygen.
“Compared to raw biomass, torrefied biomass is more hydrophobic, making it more chemically compatible with polymer matrix, and more grindable, reducing the energy required to mill to a small particle size,” he points out.
The torrefied shells can replace common industrial fillers such as calcium carbonate, talc and carbon black.
The material has its pluses and minuses.
Using almond shells as a filler reduces the amount of petroleum-based plastic, the landfill of almond shells and of course better utilization of almond byproducts. According to Orts, the major disadvantage is that recyclers such as CalRecycle will not recycle the composite material.
You can read the full report at Packaging Digest’s Informa sister publication PlasticsToday.
I’ll close this report with an impression that there was more to IFT18 than technologists and technology, there was also a demographic aspect on display that's worth mentioning. My observation was that IFT18 drew a lot of younger industry professionals and enthusiasts—Millennials and Gen Xers—a high percentage of whom were women, dramatically more than the usual industry trade shows I frequent. That impression was corroborated by a well-traveled, well-networked young female packaging professional who attended last year’s IFT in Las Vegas.
In any event, these appear as indications of a dynamic and inclusive era in food development with all the ingredients that promises a bright today and brighter tomorrow.
MinnPack 2018 (October 31 – November 1, Minneapolis) is part of the Midwest’s largest advanced design and manufacturing event that brings you the latest in materials, automation, packaging and more. ___________________________________________________________________________________