Chemical–structural properties and crosslinking degree (lysyl oxidase [Lox] enzymatic activity and pyridinoline [Pyr] content) of collagen isolated from the muscle of octopus (Octopus vulgaris), guitarfish (Rhinobatos productus), and cazon (Mustelus lunulatus) are reported and related with the muscle texture. Histological analysis revealed more collagen fibers stained in the tissues from octopus, which also showed greater shear force (SF) (191.9 ± 38.2 N) compared with the guitarfish (19.7 ± 5.3 N) and cazon (26.2 ± 14.3 N) muscle. The extent of cross‐linked collagen decreased in the order: octopus > guitarfish > cazon. An increase in the total enzymatic activity of the Lox, Pyr content, and insoluble collagen (IC) extraction yield matched with an increase in the SF (p < .01). The Lox activity and Pyr content affect the firmness of the octopus, guitarfish, and cazon muscles, showing the higher crosslinking degree in collagen fibers on octopus. Practical applications The collagen crosslinking degree has been related with the muscle texture of marine organisms. Therefore, the determination of Lox activity and Pyr content may be useful, in a near future, as an indicator of freshness and postcapture development.

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To perform improvements in food science, it is fundamental to understand the physicochemical properties of proteins since their interaction with other macromolecules plays an essential role in food systems. Collagen and paramyosin help in the maintenance of the matrix structure cells, the textural behaviour and the technical functionality of the protein concentrates; because of this, their identification and characterisation are necessary. Cephalopods species have shown differences in the distribution of its muscle fibres. The amino acid profile of jumbo squid showed a high content of glycine and hydroxyproline, while octopus showed a high content of acidic amino acids. The thermal profile of jumbo squid showed an endothermic transition at 117°C, which octopus did not present. Moreover, the proteomic identification confirms the identity of paramyosin with 33% coverage to paramyosin from Dosidicus gigas and a 4% coverage to collagen type II from Sepia pharaonis on octopus and jumbo squid, respectively.

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