Ponusa Songtipya

Properties of blend film based on cuttlefish (Sepia pharaonis) skin gelatin and mungbean protein isolate

Blend films based on cuttlefish (Sepia pharaonis) ventral skin gelatin (CG) and mungbean protein isolate (MPI) at different blend ratios (CG/MPI=10:0, 8:2, 6:4, 4:6, 2:8 and 0:10, w/w) prepared at pH 11 using 50% glycerol (based on total protein) as plasticizer were characterized. CG films incorporated with MPI at increasing amounts had the decreases in tensile strength (TS) (p<0.05). The increases in elongation at break (EAB) were observed when CG/MPI ratios of 6:4 or 4:6 were used (p<0.05). Decreased water vapor permeability (WVP) was obtained for films having the increasing proportion of MPI (p<0.05). CG/MPI blend films with higher MPI proportion had lower film solubility and L*-values (lightness) but higher b*-values (yellowness) and ΔE*-values (total color difference) (p<0.05). Electrophoretic study revealed that disulfide bond was present in MPI and CG/MPI blend films. However, hydrogen bonds between CG and MPI in the film matrix were dominant, as elucidated from FTIR spectroscopic analysis. Moreover, thermal stability of CG/MPI blend film was improved as compared to that of films from respective single proteins. Differential scanning calorimetry result suggested solid-state morphology of CG/MPI (6:4) blend film that consisted of amorphous phase of partially miscible CG/MPI mixture and the coexisting two different order phases of individual CG and MPI domains. Thus, the incorporation of MPI into gelatin film could improve the properties of resulting blend film, which were governed by CG/MPI ratio.

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.

Characteristics of film based on protein isolate from red tilapia muscle with negligible yellow discoloration

The properties of film from fish protein isolate (FPI) prepared by prior washing followed by alkaline solubilization process (ASP) from red tilapia muscle were monitored during the storage of 20 days at 50% RH and 25°C, in comparison with those of films from washed mince. Lipid, heme iron and non-heme iron contents in FPI were decreased by 98.8, 36.8 and 91.9%, respectively in comparison with those of washed mince (p<0.05). Films from FPI had higher tensile strength (TS) and elongation at break (EAB) than those from washed mince for both pH (3 and 11) used for film preparation (p<0.05). Film from FPI at pH 3 showed the highest TS, while that from washed mince at pH 11 had the lowest TS (p<0.05). Nevertheless, films from FPI had higher WVP than those from washed mince for both pH used (p<0.05). At the same pH used for film preparation (3 or 11), films from FPI showed the lower TBARS values than those from washed mince (p<0.05). Nevertheless, films from both FPI and washed mince had the higher TBARS values when pH 3 was used for film preparation, compared with pH 11 (p<0.05). Among all films, those from FPI prepared at pH 3 had the highest transparency and no yellow discoloration was observed during the storage of 20 days, in comparison with other films (p<0.05). Conversely, film from washed mince prepared at pH 3 had the higher increase in b*-value and ΔE*-value than other films. Therefore, FPI could serve as a potential material for film preparation with lower contents of lipid and prooxidants, thereby preventing the yellow discoloration of the fish myofibrillar protein-based film during extended storage.

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.

Binding interactions between lysozyme and injectable hydrogels derived from albumin-pH/thermo responsive poly(amino urethane) conjugates in aqueous solution

Injectable hydrogels are alternative materials for drug and protein delivery in biomedical applications, which can potentially eliminate the need of surgical implantation in the treatment procedures. Prior to administration, such hydrogels, in a liquid state, must demonstrate good interactions with the incorporated molecules to maintain the sustain release of active agents and to avoid unappreciative burst release. The injectable hydrogels derived from BSA-pH/temperature responsive poly(amino urethane) conjugates have been reported to demonstrated good sustainability for delivery of lysozyme, both in vitro and in vivo. However, the interactions between such conjugates and the loading lysozyme were not fully understood. In this present work, we reported the binding interactions between the studied complex systems, BSA-pH/temperature responsive poly(amino urethane) conjugates (CONJ1 and CONJ2) and lysozyme. Fluorescence spectroscopy in a combination with thermodynamic analysis exhibited that the binding between the conjugates and lysozyme occurred through static quenching and the binding interactions in the complexes were mainly van der Waals forces and hydrogen bonds. The binding constants (KA) determined at 300, 308 and 318K of CONJ1 to lysozyme were 7.96×10(4), 6.45×10(4) and 3.20×10(4)M(-1), respectively and those of CONJ2 to lysozyme were 2.63×10(4), 2.53×10(4) and 1.19×10(4)M(-1), respectively. FTIR analysis showed that the complexes between the conjugates and lysozyme demonstrated sufficiently small deviation in the conformational structures from the native lysozyme. In addition, the morphology revealed by TEM and AFM imaging portrayed the behavior of complex formation in such a way that the conjugates, before complex formation, displayed the core-shell structures. After the complex formation, a number of lysozyme particles were noticeably entrapped as if they penetrated into the preformed core-shell conjugates.