Bio-ionic liquid promoted selective coagulation of κ-carrageenan from Kappaphycus alvarezii extract

Suitability of seven different bio-based ionic liquids (Bio-ILs) namely choline fumarate (Ch-Fu), choline adipate (Ch-Adi), choline caproate (Ch-Cap), choline caprylate (Ch-Capl), choline capriate (Ch-Capr) and choline laurate (Ch-Lau) to selectively coagulate kappa-carrageenan from Kappaphycus alvarezii seaweed extract obtained with both water and alkali was investigated. Among the Bio-ILs, only Ch-Capr and Ch-Lau were able to selectively coagulate the polysaccharide from both the water and alkali extract of the seaweed. However, a higher extraction yield (14.8 +/- 0.5%) of the polysaccharide was observed from the alkali extract of the seaweed with the addition of optimized 6% w/v Ch-Lau. The physicochemical as well as rheological properties of kappa-carrageenan isolated using these two ILs was similar to the one obtained using the conventional method. Considering the ability of the ILs to selectively bind with the target polysaccharide as well as their bio origin, the reported coagulation method can be considered as a suitable alternative for the eco-friendly downstream processing of the carrageenophytes.

Automated summary

Seven different bio-based ionic liquids were investigated for their ability to coagulate kappa-carrageenan, with two showing promising results in terms of polysaccharide extraction yield and properties similar to the conventional method. This coagulation method using bio-based ionic liquids may serve as a suitable alternative for eco-friendly downstream processing of carrageenophytes.