Mineral-free biomaterials from mussel (Mytilus edulis L.) shells: Their isolation and physicochemical properties

One of the modern directions of mussel shells utilisation is associated with the production of mineral-free biomaterials that can be successfully used in food production, feed additives production, in biotechnologies, as well as in biomedicine. The objectives of this study are to obtain an organic matrix (conchix) from mussel (Mytilus edulis L.) shells by demineralisation using two decalcifying agents—a solution of hydrochloric acid (HCl) and a solution of disodium salt of ethylenediaminetetraacetic acid (Na2-EDTA), as well as the influence of the decalcifying agent nature on the organic matrix structure. The degree of demineralisation of the obtained conchixes when using HCl reaches 100%. It has been shown that the native structure of the organic matrix proteins is partially destroyed during the demineralisation of the shells in the HCl solution; analysis of IR spectra indicates a 1.5-fold decrease in the number of α-helices compared to the organic matrix obtained by gentle Na2-EDTA-based demineralisation. SEM and TEM studies indicate the destruction of the biopolymer structure of the outer (periostracum) and inner (prismatic and nacreous) layers of the organic matrix obtained using HCl, while this structure is completely preserved when using Na2-EDTA. The results obtained indicate the preference of using Na2-EDTA for the production of biomaterials with potential use in food technology and biomedicine.