**6. Chitosan and acid soluble collagen form jumbo squid by-products blend films**

It has been demonstrated that collagen/chitosan is miscible at any composition range in acetic acid solution and the compatibility will remain even when the solvent is absent, being possible the compatibility in a solid state (Dan et al., 2007). Collagen in acid solution exhibited positively charged groups and it has a molecular interaction with chitosan (Figure 4) with high potential to produce biocomposites with novel properties as was previously described (Liang et al., 2005; Lima et al., 2006; Sionkowska et al., 2006; Wang et al., 2005; Wess et al., 2004). Besides that, acid soluble collagen might be useful as a new source of plasticizer agent in the preparation of biofilms in composites with chitosan (Uriarte-Montoya et al., 2010).

Fig. 4. Schematic presentation of chitosan-collagen fraction molecular interaction.

#### **6.1 Molecular interactions in chitosan and acid soluble collagen from jumbo squid films**

The molecular interaction between acid soluble collagen form jumbo squid (ASC) and chitosan was reported to be mainly due to hydrogen bonding between the two polymers (Uriarte-Montoya et al., 2010). These observations were based on the modification of the amplitude bands in infrared (FTIR) analysis. FTIR spectroscopy is an useful tool to study the hydrogen bonding and other interactions as well as the miscibility of polymer blends (Zhang et al., 2002).

The typical peaks of chitosan are around 2890, 1645, 1563, and 1414 cm-1 which correspond to aliphatic groups (–CH2 and –CH3), amides I, II, and vibrations of –OH groups from primary alcohols, respectively. The amide I arises from C=O stretching; the amide II arises from –NH torsion groups. When a shoulder at 1645 cm1 is detected, it suggests that chitosan comes from a partial desacetylation process (Wess et al., 2004). The addition of ASC to commercial chitosan induced a decrease in the bands around 1645, 1563, and 1414 cm-1 (Uriarte-Montoya et al., 2010) indicating that there is an interaction between the polymers and the compatibility between collagen and chitosan, which results in good film homogeneity.

It has been demonstrated that collagen/chitosan is miscible at any composition range in acetic acid solution and the compatibility will remain even when the solvent is absent, being possible the compatibility in a solid state (Dan et al., 2007). Collagen in acid solution exhibited positively charged groups and it has a molecular interaction with chitosan (Figure 4) with high potential to produce biocomposites with novel properties as was previously described (Liang et al., 2005; Lima et al., 2006; Sionkowska et al., 2006; Wang et al., 2005; Wess et al., 2004). Besides that, acid soluble collagen might be useful as a new source of plasticizer agent in the preparation of biofilms in composites with chitosan

**6. Chitosan and acid soluble collagen form jumbo squid by-products** 

Fig. 4. Schematic presentation of chitosan-collagen fraction molecular interaction.

**6.1 Molecular interactions in chitosan and acid soluble collagen from jumbo** 

The molecular interaction between acid soluble collagen form jumbo squid (ASC) and chitosan was reported to be mainly due to hydrogen bonding between the two polymers (Uriarte-Montoya et al., 2010). These observations were based on the modification of the amplitude bands in infrared (FTIR) analysis. FTIR spectroscopy is an useful tool to study the hydrogen bonding and other interactions as well as the miscibility of polymer blends

The typical peaks of chitosan are around 2890, 1645, 1563, and 1414 cm-1 which correspond to aliphatic groups (–CH2 and –CH3), amides I, II, and vibrations of –OH groups from primary alcohols, respectively. The amide I arises from C=O stretching; the amide II arises from –NH torsion groups. When a shoulder at 1645 cm1 is detected, it suggests that chitosan comes from a partial desacetylation process (Wess et al., 2004). The addition of ASC to commercial chitosan induced a decrease in the bands around 1645, 1563, and 1414 cm-1 (Uriarte-Montoya et al., 2010) indicating that there is an interaction between the polymers and the compatibility between collagen and chitosan, which results in good film

**blend films** 

**squid films** 

(Zhang et al., 2002).

homogeneity.

(Uriarte-Montoya et al., 2010).

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 act as plasticizer in chitosan film structure.
