**5.1 Stability**

It is known that some environmental conditions may induce degradation of biopolymers, mainly affecting the mechanical properties and limiting their presentation, therefore the stability of the film is also a very important characteristic to evaluate. Lima et al. (2006) detected that a more stable film can be obtained when the chitosan in a collagen-chitosan film reaches 50% because chitosan increases the organization of the microscopic structure of the collagen. The effect of solar radiation on the properties of collagen, chitosan, and collagenchitosan films, have been reported. Research of Sionkowska (2006), Sionkowska et al. (2006), and Sionkowska et al. (2011) indicated that collagen-chitosan blends are more sensitive to the action of UV irradiation or artificial solar light than pure collagen or pure chitosan films.

#### **5.2 Applications of collagen/chitosan blends**

Biomaterials from collagen/chitosan blends with different applications have been successfully obtained (Table 5). However, it is important mentioned that the biological or mechanical properties, as well as stability of the product, depends of the compositions of the blend (Table 5).

this properties could be improved, mainly its elasticity (Suyatma et al., 2005). One strategy to increase chitosan elasticity is to associate it with biodegradable materials. However, the interactions that may occur between biopolymers are very important when the characteristics of any material are considered to be transformed. These interactions depend

Miscibility in polymer blends is attributed to specific interactions between polymeric components, which usually give rise to a negative free energy of mixing in spite of the high molecular weight of polymers (Shanmugasundaram et al., 2001). On the other hand, the interactions between natural polymers of different chemical structures, whether they are hydrogen bonding or electrostatic in nature, considerably improve the mechanical properties of the material obtained from such mixtures (Zhang et al., 1997). Although, most of polymers blends are immiscible with each other due to the absence of specific interactions, TEM micrographs of collagen–chitosan composites have shown that chitosan network can interpenetrate into the collagen network; the chitosan phase is wrapped in the collagen phase and is denser; besides, the amount of chitosan phase grows with the content

The main kinds of interactions that can give rise between the two polymers when they are in contact with water are: an electrostatic complex and an hydrogen bonding type of complex, in the presence of a great excess of chitosan (Taravel & Domard, 1993; Taravel & Domard, 1995). Hydrogen bonds between collagen and chitosan can be formed as follows: between either a carbonyl, hydroxyl, or an amino group from collagen, and either hydroxyl, amino, or a carbonyl group from chitosan. The formation of hydrogen bonds between two different macromolecules competes with the formation of hydrogen bonds between molecules of the same polymer (Mo et al., 2008). Apparently, interactions between collagen and chitosan depend on the structural organization of collagen and the amount and distribution of charges along the polymer chains. These properties are directly related to the pH of the medium, which is of fundamental importance for the study of interactions present between

It is known that some environmental conditions may induce degradation of biopolymers, mainly affecting the mechanical properties and limiting their presentation, therefore the stability of the film is also a very important characteristic to evaluate. Lima et al. (2006) detected that a more stable film can be obtained when the chitosan in a collagen-chitosan film reaches 50% because chitosan increases the organization of the microscopic structure of the collagen. The effect of solar radiation on the properties of collagen, chitosan, and collagenchitosan films, have been reported. Research of Sionkowska (2006), Sionkowska et al. (2006), and Sionkowska et al. (2011) indicated that collagen-chitosan blends are more sensitive to the action of UV irradiation or artificial solar light than pure collagen or pure chitosan films.

Biomaterials from collagen/chitosan blends with different applications have been successfully obtained (Table 5). However, it is important mentioned that the biological or mechanical properties, as well as stability of the product, depends of the compositions of the

on the miscibility of its components.

of chitosan increasing (Zhang et al., 1997).

the biopolymers (Tohni, 2002).

**5.2 Applications of collagen/chitosan blends** 

**5.1 Stability** 

blend (Table 5).


Table 5. Properties of collagen/gelatin-chitosan blends.

By-Products From Jumbo Squid (*Dosidicus gigas*): A New Source of Collagen Bio-Plasticizer? 33

On the other hand, the differential scanning calorimetry (DSC) analysis has been used by different authors to elucidate how the collagen associates to other macromolecules (Privalov & Tiktopoulo, 1970). The glass transitions temperatures (Tg) is an important criteria for the miscibility of the components. In a completely miscible blend of two polymers, only one Tg will appear in the DSC thermograms (Suyatma et al., 2005). Uriarte-Montoya et al. (2010) and Arias-Moscoso et al. (2011) detected that in chitosan-ASC films at 85-15 and 50-50 respectively, the Tg value of was lower than that of the chitosan film. According with the theory of plasticization, those results confirm that chitosan-ASC have good miscibility (Suyatma et al., 2005), and suggests that collagen may

**6.2 Characterization of chitosan/acid soluble collagen from jumbo squid blends** 

Fig. 5. Micrograph and picture of acid soluble collagen obtained from jumbo squid by-

Films produced by mixing collagen from jumbo squid and chitosan are easily obtained by using a casting plate (Arias-Moscoso et al., 2011). These films usually are opaque, soft, with porous structure, and hygroscopic (Figure 5), which also poses poor water barrier properties and slight acidic smell (Arias-Moscoso et al., 2011). The last mentioned properties may produce films not suitable to prevent deterioration in some kinds of products; however, might be suitable for medical or pharmaceutical applications and, to avoid the acidic smell,

act as plasticizer in chitosan film structure.

a neutralization process may be applied.

products-chitosan (A) and chitosan (B) films.
