Cellulose made from wood pulp has been added to foods from shredded cheese to salad dressing since the 1970s, but making the wood palatable has required strong acids and the process can produce environmentally challenging effluents. Enter maple fiber: the result of breaking apart wood from red maple trees using nothing except water.
The molecules that create structure in fruits and vegetables and trees are chemically identical. The main issue with eating a tree is our inability to break down the wood fibers. They are impermeable to water, enzymes and chewing in our months. In fact, there are no animals that eat wood. Even in the winter, when food supplies are limited, deer and beavers only eat the bark or growing shoots of trees.
But once freed cellulose, hemicellulose and lignin from wood can provide a valuable source of roughage in processed foods. They can address a chronic lack of fiber in the typical US diet and have some useful additional properties. Cellulose binds water and can help to extend the shelf-life of baked goods. It is also a good emulsifier.
An award-winner whose time has come?
I was in the audience when the Plantrose process, used in the production of maple fiber, won an EPA Green Chemistry Award in 2015. It was fascinating. One of my first jobs on leaving university was working for Courtaulds in the UK developing the Tencel/lyocell process. We worked with N-methylmorpholine N-oxide. A powerful solvent and a potentially explosive process dissolves woodchips. This creates a thick cellulose solution which can be extruded to create a new form of cotton for clothing. I was amazed to learn, decades later, that cellulose could be released just using water!
Stop short of sugar
The original Plantrose process focuses on breaking down cellulose, a glucose polymer, into individual glucose (sugar) units. Supercritical water is used to hydrolyze cellulose, breaking apart the bonds that hold the structure together. The crystalline domains are literally melted using water under extreme heat and pressure.
Conditions are controlled in the maple fiber process so that the cellulose, lignin and other non-starch polysaccharides are released – but they are not completely broken down to sugars. They remain as cellulose polymers. Free from the structure of the wood they are ready to be combined with other ingredients in foods.
Is maple fiber good to eat?
I think so. I noticed maple fiber as one of the ingredients in Nowadays meatless chicken nuggets and was delighted to discover that this was the commercialization of the technology I had admired in that awards ceremony. I’m always interested in trying new plant-based protein foods – and this one is a hit in our house!
- More about cellulose in foods: From McDonald’s To Organic Valley, You’re Probably Eating Wood Pulp (NPR, June 2014)
- Recent work on cellulose in ice cream.
- More about the 2015 EPA Green Chemistry award for the Plantrose process.
- More about the Nowadays meat-free chicken nuggets.