Thinking inside the Box
While hemp fiber is classically associated with being as a textile fiber such as for t-shirts, there are many other uses. Of course not all hemp fibers are textile grade, such as those that are the stalks from hemp seed crops. Consequently, a European research project is unpacking the properties of hemp into natural, renewable & biodegradable food packaging. And we’re not talking about rough burlap bags or paper forms. It’s a true plastic and is commonly referred to as bioplastic since it’s not derived from petroleum.
The Traysrenew project in the European Union (EU) was a multi-year project involving a consortium of manufacturers drawn from across the supply chain with researchers from Spain and England. The goal was to produce food trays for poultry products that are cost effective, renewable, and higher performance than their conventional counterparts which are made of Polystyrene (PS) or Polypropylene (PP). The food trays would be made from biopolymers which are derived from bast fiber plants including hemp and flax. The poultry sector was chosen due to its high volume, being that it produces approximately 11 million tons of meat annually in the EU, with an average per capita consumption of 50.6 pounds (23 kg) each year.
The interest on this kind of green packaging is being driven by both the industry and consumers. Manufacturers want lower costs and increased shelf life; consumers want fresh and safe food available in addition to products that reflect their values.
Up to now, the use of biodegradable films for food packaging was considered limited due to poor barrier protection from environmental elements including: oxygen, water vapor, dust, light, and air, in addition to weak mechanical properties. The higher costs associated with the use of these materials has also been an ongoing issue.
Fiber-based hemp composites for packaging relies on both nanofibers as well as a specially derived powder that is mixed with other materials. Using a variety of methods the materials are mixed, compacted and melded — commonly by either heat or by letting the composite mix solidify.
Starting work in 2010, Traysrenew created and tested a thermoplastic tray and lid made of 85% biopolymers with 15% hemp / flax based microfibers. Testing showed this tray met all targeted industry performance standards.
As hemp fiber is known to have anti-bacterial properties, adding hemp to food packaging has the additional benefit of increasing preservation. However, technical details on these antibacterial properties are specifically lacking at the time of this writing.
The Traysrenew project touts their trays as having a shelf-life at chill temperatures of 10 days, which matches the typical sell-by date for how long poultry is displayed for sale inside a stores refrigerated display case. Poultry is considered to be easily spoilable by grocers, so anything that adds to the shelf life is welcome in the retail trade.
With this project, industry participants touted the economic benefits to manufacturers, the environmental benefits of using renewable and biodegradable packaging as well as the social benefits of increasing demand for fibers grown domestically on local farms.
It’s an open question as to when and if these trays will be adapted by the European food industry, but it’s likely. According to industry association European Bioplastics, a total of 700,000 tonnes of bio-based plastics were produced globally in 2010, and the market is projected to reach 1.7 million tonnes by 2015. 60% of these were used for packaging, making it the largest application of bioplastics. The growth rate for bioplastics is estimated at 22.5% a year.