Crawfish carotenoproteins and chitin are obtained by a combined process based on flotation-sedimentation and in situ lactic acid production. The carotenoprotein PF(1) obtained has a high content in essential amino acids, w-3-fatty acids, and carotene (mainly astaxanthin) and constitutes an excellent nutritional source for patients with malnutrition. The carotenoprotein PF(2) has a lower nutritional quality but with a substantial carotene content can be used as a feed for animals where coloration is required, such as salmon and trout bred under aquaculture. Chemical and spectrometric (FTIR and (13)C NMR) characterization shows the obtained chitin to be of high quality, similar to that available commercially, for medical and nutritional uses.