Characteristics of elasmoid fish scales and its fractions, according to FT-IR spectroscopy

Abstract

Elasmoid scales of pike-perch (Sander lucioperca), white amur (Ctenopharyngodon idella), carp (Cyprinus carpio), freshwater bream (Abramis brama) and crucian carp (Carassius carassius) were processed without hydrolysis by “dry” method in order to study the characteristics of the obtained finished product, which determine its further use as additives for food and other purposes. The essence of the method consisted in washing the scales, its subsequent drying, grinding and separation, with obtaining two fractions enriched with both organic (cotton-like product) and inorganic (powder) components. FT-IR spectroscopy was used to characterize the scale samples and their enriched fractions. Characteristic bands known for collagen, in particular for Amide I, Amide II, Amide III, Amide A, were observed in the IR spectra of all the samples studied. The bands (inorganic part) at ~1022 cm–1 and at ~599 cm–1 indicate valence asymmetric vibrations of PO43– groups. Numerous bands for all experimental samples in the wavelength region 3900-3500 cm–1 can be caused by vibrations of OH groups, which is associated with the presence of water in the tested samples. Comparison of the absorption intensity in the region of characteristic frequencies of collagen and hydroxyapatite calculated by the IR method can be one of the approaches for the development of a rapid method for the determination of their quantitative content in fractions obtained from fish scales. Organic and mineral additives from fish scales can be recommended as components of formulations of various food products, as well as raw materials in tissue engineering, orthopedics and dentistry.