Researchers uncover benefits of wheat-based packaging

Plant physiologist Gregory Glenn of the Agricultural Research Service (ARS)​ Western Regional Research Centre in California is working with EarthShell, an innovator of potato-starch-based foodservice products, to fine-tune manufacturing of the wheat-starch disposables.

The scientists are confident that these could eventually provide a more environmentally friendly option than today's petroleum-based, polystyrene foam products, and that the concept could be extended to include cups, bowls and plates as well as food packaging.

Glenn's research has proven that the biodegradable products are just as attractive, sturdy, convenient to use and leak-proof as their polystyrene counterparts. But, because they biodegrade easily, the starch-based disposables lessen the burden on America's already overstuffed landfills.

This is the first important consideration. The food processing industry is a major contributor to industrial waste. In the UK for example, the Environment Agency has estimated that the food and drink sector produces between seven and eight million tonnes of waste per year, second only to the construction industry.

The second point is competitiveness. Glenn believes that having a selection of different starches - such as wheat, potato or corn - to choose from gives manufacturers of biodegradable products some purchasing flexibility. That flexibility could help them keep their prices competitive with polystyrene items.

This will be of great interest to packaging firms. Chemical giant BASF recently increased the prices for its plastic material Styrolux by €200 per metric ton in Europe as of 1 August, blaming the rising cost of raw materials.

The price hike for Styrolux, a styrene-butadiene copolymer used in extrusion applications in food packaging, reflects an industry-wide increase in the cost of packaging materials. A month ago, BASF announced that it was to raise its European price for polystyrene (PS) by €200 per metric ton in response to what it calls totally unsatisfactory margins and earnings.

Polystyrene, a standard polymer in BASF's range of styrenic plastics, is used extensively in refrigerator linings and food packaging. As with Styrolux, one of the main raw materials for polystyrene is benzene, which is used in the production of styrene, the pre-cursor of polystyrene.

The price for benzene has now reached historically high levels. This provides an opportunity for biodegradable materials to get into the packaging market.

ARS says that the manufacture of wheat-based containers is a relatively simple process. They can be made in presses or moulds that work something like a giant waffle iron.

The process begins with pouring the wheat-starch batter onto the heated mould, which is then closed and locked. Moisture in the batter generates steam that, in turn, causes the batter to foam, expand, and fill the mould. The steam is vented and, when the 'baking' is finished, the mould is opened, the product is removed and the cycle starts again.

The entire process takes less than a minute. A water-resistant film, added later, helps the container keep its strength and shape.

Research into biodegradable packaging has taken off as scientists look for a cost-effective alternative to polystyrene-based products. Researchers at Oregon State University's department of Food Science and Technology have already designed an edible film made from natural ingredients that protects foods coated in the material from spoiling.

The film can also hold vitamins and other nutrients within it to boost the nutritional value of the food.

The scientists combined chitosan, a fibre found in crab and shrimp shells, which is also a raw material for nutraceutical products, and the protein from egg whites, lysozyme, to create an anti-microbial food wrap. The product looks like a sandwich wrap yet is thin enough to have no effect on the texture of the food it covers.

And a recently published report in the Journal of Agricultural and Food Chemistry reported that herb basil, when incorporated into plastic wrapping, can enhance food safety. The basil, which has long been known to contain bacteria-fighting properties, is incorporated into the plastic wrapping to preserve foods.

The extracts methyl chavicol and linalool ooze out of the wrapping and slow the growth of eight types of lethal bacteria including E. coli and listeria. Experiments showed the wrapping extends the shelf life of cheese and most likely of meats, fish, baked goods, fruits and vegetables.

ARS is the US Department of Agriculture's chief scientific research agency. The recent research into wheat packaging is described in the September issue of Agricultural Research​ magazine.