Alkaline extraction of seaweed carrageenan hydrocolloids using cocoa pod husk ash

Abstract

The cocoa industry in Ghana is the second largest in the world, and it generates huge amounts of cocoa pod husks, which currently represent a disposal problem as no significant use has been found for them. The husks are rich in potassium, which may be used for alkaline hydrocolloid extraction from red seaweeds. Chemical and rheological properties of κ-carrageenan from Kappaphycus alvarezii and the Ghanaian red seaweed Hypnea musciformis extracted by KOH (benchmark) or by a cocoa pod husk ash solution were compared. Similar extraction yields and successful modification of the seaweed hydrocolloids with 3,6-anhydro-galactopyranose and sulfate contents of 37–38 and 16–17%, respectively, were obtained with cocoa pod husk ash and KOH extraction. Gel strengths of the κ-carrageenans were also similar: G′ at 25 °C were 5780 Pa with cocoa pod husk ash and 5930 Pa with KOH. These findings have implications for industrial waste biomass utilization and sustainable green growth development of seaweed hydrocolloid processing in Ghana.