|Abstract Title:||Microwave-assisted hydrolysis of Alginic Acid|
|Session Choice:||Energy & the Environment|
|Presenter Name:||Mrs Tiffani Bouanati|
|Co-authors:||Prof Pascal Gerbaux|
Dr Juan Carlos Cabrera
Abstract Information :
Oligosaccharides are extensively studied for their potential biological activities and they are developed, for example, as prebiotics, drugs carriers, biostimulants... . Only few oligosaccharides are naturally produced and therefore some strategies need to be developed to prepare them either by organic synthesis or upon degradation of naturally occurring polysaccharides. Oligosaccharide synthesis is by far more complex than the preparation of other polymers due to the numerous combinations, the anomericity and the configuration of the carbohydrates. Since the past decades, different methods for producing oligosaccharides by depolymerization have thereby been investigated such as chemical degradation (acid hydrolysis or depolymerization by hydroxyl free radicals), physical degradation (microwave, radiolysis by UV light or γ irradiation, ultrasonic or thermal treatment and enzymatic degradation).
Physical methods, particularly microwave treatments, appear promising and fulfill the fundamental rules of green chemistry. Hydrolysis of carageenan in aqueous solution by microwave treatment was achieved by G.Zhou and oligocarrageenans are obtained after 2 and 10 minutes at 10 or 15 bar, corresponding respectively to temperatures at about 175°C and 200°C.
In the context of a large project dealing with polysaccharides from algae, and for testing the hydrolysis of polysaccharides in water by microwave treatment, we select a commercially available alginate, approximative Mn = 100,000g/mol , extracted from algae.
An aqueous solution of alginate at a concentration of 1mg/ml under stirring was prepared. Alginate being hardly soluble in water, continuous stirring was applied to keep alginate in suspension. After 24h of stirring, solution was placed and sealed in a specific vial for microwave treament. The experience is repeated several times at different temperatures and reaction times. The hydrolysate is then characterized by different methods, such as MALDI-ToF mass spectrometry and reducing sugar quantification.