This green process could be used to valorize other food remains rich in cellulose or lignin
The banana is an excellent source of energy, nutritionists will tell you unanimously. So is the peel, according to Marie-Josée Dumont, but in the fuel sense of the term. The professor from the Department of Chemical Engineering at Laval University and her colleagues at McGill University have just taken a new step towards a fuel based on banana peel by substantially improving the efficiency of an existing chemical process.
Banana peel is rich in cellulose, hemicellulose and lignin," explains Professor Dumont. In theory, it is possible to extract simple sugars, such as glucose and fructose, and convert them by heat treatment into a molecule called hydroxymethylfurfural (HMF). "HMF is a very versatile molecule. It can be used to synthesize fuel or various industrial products, including drugs. The US Department of Energy considers HMF to be one of the most promising source molecules," she says.
The current method of extracting sugars from food scraps such as banana peels involves treating them with solvents and chemical catalysts. The process studied by Professor Dumont and her collaborators instead uses enzymes and mechanical processing. "We put the banana peels in a ball mill, which mechanically crushes the biomass to make it easier for the enzymes to work," says Dr. Dumont.
This process, known as mechano-enzymatic, makes it possible to obtain, in 3 hours, 405 grams of glucose and 172 grams of fructose from 1 kilogram of banana peel. This is respectively 1.2 and 1.9 times more than the process by chemical hydrolysis, without pretreatment and without aggressive chemical treatment. From the same amount of banana peel, the enzyme-mechanical process produces three times more HMF than the chemical process, Professor Dumont and colleagues report in a study published by the journal Bioresource Technology.
The researchers used banana peel to demonstrate the effectiveness of their process, but their real target is broader: fruit and vegetable scraps. "We want to optimize the enzyme-mechanical process so that we can get the sugars from complex and heterogeneous biomass, rich in cellulose or lignin, and convert them into HMF and fuel afterwards. The challenge is to do this at a cost advantage over fossil fuels."
The signatories of the study published in Bioresource Technology are A.K.M. Al Amin Leamon, Mario Perez Venegas, Valérie Orsat and Karine Auclair, from McGill University, and Marie-Josée Dumont, from Laval University.