**6.2.1 Mechanical properties**

The acid soluble collagen from jumbo squid induces modification of crosslinking reaction in chitosan films affecting their mechanical properties (Table 6). In general, the presence of acid soluble collagen from jumbo squid on chitosan films induces the formation of more flexible and less rigid films (Arias-Moscoso et al., 2011; Uriarte-Montoya et al., 2010).

According with Arias-Moscoso et al., (2011) the general trends of the stress-strain curves of acid soluble collagen-chitosan films are characteristic of elastic films. However, these tensile properties vary with the collagen content on the film. It was detected that the tensile strength values of most of ASC/chitosan films evaluated were within the acceptance range of low density polyethylene food packaging (4 and 78.6 mPa42). Meanwhile, the elongation at the break of chitosan films with 20% of ASC was comparable to cellophane and also comparable to polypropylene when contained 50% of ASC, which for some specific applications is a desirable attribute.


Adapted from Arias-Moscoso et al. (2011)

Table 6. Mechanical properties of acid soluble collagen from jumbo squid-chitosan (ASC/CH) and chitosan (CH) films.

It is known that the mechanical properties are dependent on the distribution and intensity of inter- and intramolecular interaction; therefore, when the content of ASC increases, the collagen molecules also increases, and this may reduce chitosan interaction, inducing high possibilities of movements, producing films more flexible and less rigid.
