The West Coast rock lobster <i>Jasus lalandii</i> as a valuable source for chitin and astaxanthin

Abstract

Estimates are made of the maximal amount of chitin and astaxanthin that can potentially be retrieved from material of the South African West Coast rock lobster Jasus lalandii. Three different sources were investigated: (a) industrial waste from lobster processing factories, i.e. the cephalothorax plus legs, (b) whole lobsters, to represent material available on the beaches after mass strandings caused by red/black tides, and (c) exuvia, i.e. the entire exoskeleton that is shed during moulting (exuvia will be available regularly once industrial mariculture of J. lalandii is established). Industrial lobster waste contains 36g chitin kg^–1 wet weight and 18mg astaxanthin kg^–1 wet weight; whole lobsters have 43g chitin kg^–1 and 13mg astaxanthin kg^–1; and exuvia yield 159g chitin kg^–1 and 63mg astaxanthin kg^–1. The total theoretical amounts available from source (a) is 3.6 tons chitin and 1.8kg astaxanthin, from (b) 86 tons chitin and 27kg astaxanthin, whereas the amount available from (c) depends, of course, on the exact extent of lobster in mariculture; once this industry is established, material from this source will form a substantial part of the available amount of chitin and astaxanthin. Each of these sources is too small to support a permanent industry but, if astaxanthin and chitin are extracted, and other crustacean sources (e.g. shrimp waste, South Coast rock lobster waste) are also utilised, temporary harvesting could increase profitability of existing lobster processing, alleviate the need for imports of these compounds and create much-needed jobs in remote areas. Currently, established chemical methods are used to extract chitin from the exoskeleton; astaxanthin is destroyed in this process. Therefore, to extract both chitin and astaxanthin from the same source, the established method must be replaced by biochemical methods that do not destroy astaxanthin. Preliminary data with the protease papain, show that treatment with this enzyme allows the extraction of intact astaxanthin at a 22% higher yield than untreated material. The stability of astaxanthin that was extracted in organic solvents can be increased by antioxidants, such as butylated hydroxyanisole and butylated hydroxytoluene; the loss of astaxanthin was reduced to 6–7% during 6 months of storage with the antioxidants.

African Journal of Marine Science 2005, 27(1): 257–264