Agar extraction from integrated multitrophic aquacultured Gracilaria vermiculophylla: Evaluation of a microwave-assisted process using response surface methodology

摘要

Microwave-assisted extraction (MAE) of agar from Gracilaria vermiculophylla, produced in an integratedmultitrophic aquaculture (IMTA) system, from Ria de Aveiro (northwestern Portugal), was tested andoptimized using response surface methodology. The influence of the MAE operational parameters(extraction time, temperature, solvent volume and stirring speed) on the physical and chemical propertiesof agar (yield, gel strength, gelling and melting temperatures, as well as, sulphate and 3,6-anhydro-Lgalactosecontents) was evaluated in a 2^4 orthogonal composite design. The quality of the extracted agarcompared favorably with the attained using traditional extraction (2 h at 85ºC) while reducing drasticallyextraction time, solvent consumption and waste disposal requirements. Agar MAE optimum resultswere: an yield of 14.4 ± 0.4%, a gel strength of 1331 ± 51 g/cm2, 40.7 ± 0.2 _C gelling temperature,93.1 ± 0.5ºC melting temperature, 1.73 ± 0.13% sulfate content and 39.4 ± 0.3% 3,6-anhydro-L-galactosecontent. Furthermore, this study suggests the feasibility of the exploitation of G. vermiculophylla grewin IMTA systems for agar production.