Muralidharan Nagarajan

Properties of film from splendid squid (Loligo formosana) skin gelatin with various extraction temperatures.

Properties of film from splendid squid (Loligo formosana) skin gelatin extracted at different temperatures (50-80°C) were investigated. Tensile strength (TS) and elongation at break (EAB) of films decreased, but water vapour permeability (WVP) increased (P<0.05) as the extraction temperature increased. Increase in transparency value with coincidental decrease in lightness was observed with increasing extraction temperatures. Electrophoretic study revealed that degradation of gelatin became more pronounced with increasing extraction temperatures. As a consequence, their corresponding films had the lower mechanical properties. FTIR spectra of obtained gelatin films revealed the significant loss of molecular order of the triple helix. Thermogravimetric analysis indicated that F80 exhibited the higher heat susceptibility and weight loss. Loosen structure was observed in film prepared from gelatin with increasing extraction temperatures. Thus, the temperature used for gelatin extraction from splendid squid skin directly affected the properties of corresponding films.

Film forming ability of gelatins from splendid squid (Loligo formosana) skin bleached with hydrogen peroxide

Properties of gelatin films from splendid squid (Loligo formosana) skin bleached with hydrogen peroxide (H(2)O(2)) at various concentrations (0-8% w/v) were investigated. Tensile strength (TS) and water vapour permeability (WVP) of films decreased, but elongation at break (EAB) increased (p<0.05) as the concentration of H(2)O(2) increased. Among all films, that prepared from gelatin with 2% H(2)O(2) bleaching showed the lowest ΔE(∗)-value (total colour difference), which was concomitant with the highest L(∗)-value (lightness). Generally, higher concentration of H(2)O(2) resulted in increased b(∗)-value (yellowness) of resulting films. Electrophoretic study revealed that α-chains of gelatin in films became lowered with increasing H(2)O(2) concentrations used for bleaching. Thermogravimetric analysis indicated that heat susceptibility and weight loss of different films varied with H(2)O(2) concentrations. Rougher surface was obtained in gelatin films prepared from skin bleached with H(2)O(2) concentrations above 4%. Thus, the concentrations of H(2)O(2) used for bleaching of squid skin prior to gelatin extraction directly affected the properties of corresponding gelatin films.

Properties of Bio-nanocomposite Films from Tilapia Skin Gelatin as Affected by Different Nanoclays and Homogenising Conditions

Fish gelatin films incorporated with hydrophilic and hydrophobic montmorillonite (mmt) nanoclays with the aid of homogenisation using different pressure levels (1,000 to 4,000 lb/in2) and passes (two and four) were characterised. Young’s Modulus, tensile strength and elongation at break of films decreased with increasing pressure levels and number of passes. High pressure homogenisation generally lowered the mechanical properties of nanocomposite films. Additionally, water vapour barrier property became poorer, when high pressure homogenisation was implemented. Films incorporated with hydrophobic nanoclay (Cloisite 20A) exhibited the lower water vapour permeability (WVP) than those with hydrophilic nanoclay (Cloisite Na+). Colour parameters (L*, a*, b* and ∆E*) of nanocomposite films were affected to some degrees by homogenisation conditions. Transparency of films increased when homogenisation pressure and number of passes increased. As revealed by wide angle X-ray diffraction (WAXD) analysis, nanocomposite films prepared using homogenisation had exfoliated nanostructure, whilst those prepared without homogenisation exhibited intercalated nanostructure. Thermogravimetric (TGA) and differential scanning calorimetric (DSC) analyses indicated that thermal stability of nanocomposite films varied with homogenisation condition, being higher in these films than in those without nanoclay. Thus, homogenisation condition and hydrophobicity of nanoclay directly affected the properties of nanocomposite films from fish skin gelatin.

Effects of pHs on properties of bio-nanocomposite based on tilapia skin gelatin and Cloisite Na+

Effects of various pHs (4-8) of film forming suspensions (FFS) on the properties of nanocomposite film based on tilapia skin gelatin and hydrophilic nanoclay (Cloisite Na(+)) were investigated. Intercalated/exfoliated structure of nanocomposite films was revealed by WAXD analysis. Youngs Modulus (YM) and tensile strength (TS) of nanocomposite films increased up to pH 6 (P<0.05). Nevertheless, the further increases in pH levels resulted in the decreases in both YM and TS (P<0.05). The highest water vapour barrier property of the film was observed when the pH of FFS was 6 (P<0.05). Lightness (L*) and yellowness (b*) of nanocomposite films generally increased with increasing pH levels. Transparency of nanocomposite films was affected to some extent by pHs. Homogeneity and smoothness of film surface were obtained for nanocomposite films with pH 6 as confirmed by SEM micrographs. Thermogravimetric (TGA) and differential scanning calorimetric (DSC) analyses indicated that thermal stability of nanocomposite films varied with different pH levels. In general, mechanical and water vapour barrier properties of nanocomposite films were improved when FFS having pH 6 was used. Thus, the pH of FFS directly affected the properties of nanocomposite gelatin films incorporated with hydrophilic nanoclay.

Comparative Characterization of Bovine and Fish Gelatin Films Fabricated by Compression Molding and Solution Casting Methods

Properties and characteristics of films from bovine and fish gelatins prepared by compression molding and solution casting methods were comparatively investigated. Both gelatin films made from compression molding had lower strength, stiffness and tensile toughness, but higher extensibility, water–vapor barrier property and yellowness than those made from casting method (p < 0.05). Moreover, the compression-molded gelatin films exhibited lower thermal stability as indicated by lower glass-transition temperature (Tg) and thermal decomposition temperature (Td), irrespective of gelatin types. This was mainly attributable to the higher thermal degradation of gelatin taking place during compression-molded film-formation at high processing temperature, as assured by Fourier transform-infrared (FTIR) spectroscopic and free-amino group content analyses. Greater degradation mainly contributing to lower inter-molecular interaction, and molecular order and organization, led to lower overall properties of compression-molded films as compared to cast films. In general, with the same fabrication method and condition used, bovine gelatin films exhibited higher mechanical resistance but lower water–vapor barrier properties and more yellowish than fish gelatin films.