Relationship between muscle texture and the crosslinking degree of collagen fibers from octopus (Octopus vulgaris), guitarfish (Rhinobatos productus), and cazon (Mustelus lunulatus)

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.