Simultaneous extraction of chitin and astaxanthin from waste of lobsters Jasus lalandii, and use of astaxanthin as an aquacultural feed additive

This work investigates simple methods for simultaneous extraction of astaxanthin and chitin from industrial waste of the South African West Coast rock lobster Jasus lalandii. Removal of proteins from waste is the critical step to yield intact chitin and astaxanthin. Because common chemical methods destroy astaxanthin and damage chitin, we investigated partial proteolysis by papain followed by removal of adhering tissue/protein by centrifugation. Incubation time of waste with papain, papain concentration, waste:medium ratio, duration of centrifugation and the size of holes in the centrifuge rotor were altered to achieve a complete removal of protein/tissue and at minimum cost. From lobster waste that was deproteinised this way, chitin and astaxanthin could be extracted using existing methods. The most suitable extraction conditions (0.5% papain, 1:10 waste:medium ratio, 24 h incubation, centrifugation for 5 min with 5 mm holes) yielded 2.4 +/- 0.6 g chitin (4.2%) and 3.1 +/- 0.7 mg astaxanthin from 56.8 +/- 5.8 g crushed lobster waste. From deproteinised exoskeleton, astaxanthin was extracted in methanol, transferred into various vegetable oils, and its concentration measured using spectrophotometry. Maximum stable concentration of astaxanthin in oil was approximately 80 mg ml(-1), above which astaxanthin precipitated. Astaxanthin oil prepared from J. lalandii material included in feeds for shrimps Palaemon pacificus and tilapia Oreochromis mossambicus caused deposition in whole shrimps but not in tilapia tissues.