Physical, biochemical, densitometric and spectroscopic techniques for characterization collagen from alternative sources: A review based on the sustainable valorization of aquatic by-products

Collagenous biopolymers can be analyzed using physic-chemical, densitometric, and spectroscopic analysis to obtain their main characteristics, aiming at their biotechnological manipulation. Collagen extracted from fishery resources is a product of high added value, with potential use in food, biopharmaceutical and cosmetic industries. Some factors make the use of the polymer from fishery resources promising, such as: high availability; greater ontogenetic distance between fish and humans; absence of sociocultural barriers; and absence of toxicity. The collagen extraction method (acid-soluble, pepsin-soluble, electrodialysis, ultrasound, isoelectric precipitation) will directly influence its properties. Thus, this work aims to provide an overview of the extraction methods, characterization techniques (solubility, zeta potential, viscosity, thermogravimetry, differential scanning calorimetry, SDS-PAGE, densitometry, gel strength, centesimal composition, color, aminogram, hydroxyproline determination, X-ray diffraction, circular dichroism, ultraviolet, Raman, and FTIR spectroscopy), and potential analysis with a focus on aquaculture and fisheries sources, through a compilation of scientific information that can be useful to guide aquatic biotechnology professionals, considered that its properties are similar to collagen extracted from mammals. (C) 2020 Elsevier B.V. All rights reserved.