Overview
This laboratory study produced chitosan from shells of the invasive Danube crayfish Faxonius limosus using different demineralization and deproteinization routes and tested the chitosans as edible coating matrices. To judge raw-material safety, lead, cadmium and mercury were measured in the dried shell; all were below the EU 0.5 mg/kg limit for crustacean meat. Metal levels in chitin are shown only on a log-scale figure, and the finished chitosan was not reported numerically.
Key numbers
- Crayfish shell: lead 0.183 ± 0.06, cadmium 0.136 ± 0.05, mercury 0.124 ± 0.033 mg/kg (Section 2.7).
- Demineralization cut shell calcium to 2% (pH 1.3) and 0.02% (pH 0.5) of the shell content (Section 2.7).
Methods (brief)
Lead and cadmium by flame AAS after dry ashing; mercury and other metals by AAS. Tests were run in duplicate and repeated three times. No detection limits, reference materials or recoveries are reported.
Evidence Fitness
Only three heavy metal values, all for the shell raw material, with minimal QA. The authors argue chitosan levels should not rise because no metal-bearing reagents are used, but they print no chitosan values. This is a raw-material proxy for chitosan, not a measurement of the ingredient, so the chitosan page is not linked.