Manufacturing biofuels from food crop by-products such as straw could be made quicker and cheaper thanks to the work of scientists in the UK and France.

Researchers at York University, working with colleagues in France, have discovered variant straw plants whose cell walls are more easily broken down to make biofuels, but which are not significantly smaller or weaker than regular plants.

The discovery could help ease pressure on global food security as biofuels from non-food crops become easier and cheaper to make.

The impact of carbon emissions on global warming is driving the need for carbon neutral biofuels. However, as many existing biofuels are produced from crops which can be used for food, increases in production displace food crops, requiring new areas to be farmed, which can drive up food prices and accelerate atmospheric pollution and biodiversity loss.

One potential answer to reduce the impacts of so-called first-generation biofuels on food security and the environment is to make fuels from woody, non-food parts of plants such as straw. These are rich in polysaccharides (sugar chains) which can be broken down into simple sugars and then fermented into ethanol for fuel.

Such biofuels are currently too expensive because of the cost of digesting the woody tissues into simple sugars, but researchers at York's Centre for Novel Agricultural Products, led by Professor Simon McQueen-Mason, may have come up with a solution. The scientists screened a large collection of variants of the model grass species Brachypodium for digestibility. Screening variants in this way allows rapid assessment of the range of natural diversity that can be found in a species.

Using the screening approach, PhD student Poppy Marriott identified 12 independent plant lines with highly digestible straw, but which grew normally and showed no decrease in straw strength. Analysing these plants showed that increased digestibility can be achieved through a range of changes in the cell wall, where the majority of sugar is contained in woody biomass.

By identifying these plant variants with straw that is easier to digest, but which retain their size and strength, the cost and complexity of biofuel production could be reduced, according to the York team.

Professor McQueen-Mason commented, "This work sets the stage for identifying similar high-digestibility lines in commercial crop species that will pave the way to more cost-effective and sustainable biofuels.

"Using plant by-products such as straw provides a double benefit as we can harvest the food from the plant, then use the straw to produce a carbon neutral fuel."