Potato plates – introduction

Earthpac, previously Potatopak, is an innovative New Zealand company that makes biodegradable products.

Potatoes

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A pile of new potatoes.

Rights: Stephen Rees, licenced through 123RF Ltd.

This introductory article describes why and how Earthpac use waste potato starch to make disposable plates and trays.

Earthpac makes disposable plates and trays from waste starch. These products are biodegradable and sustainable. In contrast, plastic disposable plates and containers are convenient and cheap, but they are not biodegradable and are made from limited petroleum stocks.

Where did the idea come from?

Richard Williams founded Potatopak (later Earthpac) and designed the first potato plates. He had the idea after a staff barbeque, when he became concerned about the environmental impact of all the waste plastic containers that were thrown away.

Getting started

Richard’s prior knowledge of biopolymers helped him to develop and manufacture the potato plate products. He set up Potatopak in Blenheim, New Zealand. As well as manufacturing, Earthpac promotes the environmental benefits of biodegradable products to consumers.

How do you make a potato plate?

Earthpac plates are made from a mixture of potato starch, cellulose and water. These ingredients are mixed and heat pressed into shape. The water and heat cause the starch to expand, creating a honeycomb formation. The high temperature sets the mixture and creates an impervious outer skin. The cellulose strengthens the material. Read Making potato plates to discover the entire process from weighing the ingredients to quality control of the final product.

Sourcing the ingredients

Potato starch is a waste product from chip-making. The starch granules collect in the water used to rinse the potatoes as they are cut into chips. A few companies in Australia extract the starch from the waste water and filter it to remove dirt particles. Earthpac imports the starch from these companies because it is white, clean, fine and safe to eat. In 2008, no companies in New Zealand extract and filter potato starch from chip-making waste water, but as demand for starch grows this may change.

The machines

Richard’s knowledge has helped him to design and build the machinery that makes the potato starch plates and other products. He also uses this knowledge to maintain the machines and optimise their performance.

Ongoing research and development

Earthpac products can be used to store or serve most foods. However, they can’t be used for raw meats or hot liquids, which react with the starch and cause it to break down. Earthpac has working with scientists at Crop & Food Research (now called Plant & Food Research) to develop a protective coating that will stop the starch from breaking down. The coating has to be food safe, 100% biodegradable and free of chemicals. Scientists are close to finding a solution to this problem. In 2011 Potatopak rebranded as Earthpac.

The future

Earthpac is always looking for new uses for their products. One of their earlier innovations is a possum bait station made out of potato starch. They also produce a range of products, including cuterly, carry bags, bin liners and doggy bags.

Take up the challenge

There are two unit plans to aid teachers in the use of these resources:

• Designing a new product from potato starch challenges students to consider sustainability issues and create a design brief for a new product. (If you'd like to try to make a new product, potato starch is available for purchase from earthpac.)

• Promoting potato plates explores product life cycles, environmental impacts and encourages students to take action regarding the use of disposable products.

The unit plans are supported by two student activities: Testing the degradability of potato plates experiment and Promoting potato plates.