Development and Characterization of Biodegradable Composite Films Based on Gelatin Derived from Beef, Pork and Fish Sources

Stretchable and Electroactive Crosslinked Gelatin for Biodevice and Cell Culture Applications

Biomimetic substrates that incorporate functionality such as electroactivity and mechanical flexibility, find utility in a variety of biomedical applications. Toward these uses, nature-derived materials such as gelatin offer inherent biocompatibility and sustainable sourcing. However, issues such as high swelling, poor mechanical properties, and lack of stability at biological temperatures limit their use. The enzymatic crosslinking of gelatin via microbial transglutaminase (mTG) yields flexible and robust large area substrates that are stable under physiological conditions. Here, we demonstrate the fabrication and characterization of strong, stretchable, conductive mTG crosslinked gelatin thin films. Incorporation of the conductive polymer poly(3,4-ethylenedioxythiophene) polystyrene sulfonate in the gel matrix with a bioinspired polydopamine surface coating is used to enable conductivity with enhanced mechanical properties such as extensibility and flexibility, in comparison to plain gelatin or crosslinked gelatin films. The electroconductive substrates are conducive to cell growth, supporting myoblast cell adhesion, viability, and proliferation and could find use in creating active cell culture systems incorporating electrical stimulation. The substrates are responsive to motion such as stretching and bending while being extremely handleable and elastic, making them useful for applications such as electronic skin and flexible bioelectronics. Overall, this work presents facile, yet effective development of bioinspired conductive composites as substrates for bio-integrated devices and functional tissue engineering.

Physical and Mechanical Characteristics of Gelatin-Based Films as a Potential Food Packaging Material: A Review

This review discusses the potential application of gelatin-based film as biodegradable food packaging material from various types of gelatin sources. The exploitation of gelatin as one of the biopolymer packaging in the food industry has rising interest among researchers as the world becomes more concerned about environmental problems caused by petroleum-based packaging and increasing consumer demands on food safety. Single gelatin-based film properties have been characterized in comparison with active and intelligent gelatin-based composite films. The physical properties of gelatin-based film such as thickness, color, and biodegradability were much influenced by total solid contents in each film. While, for mechanical and light barrier properties, poultry-based gelatin films have shown better properties compared to mammalian and marine gelatin films. This paper detailed the information on gelatin-based film characterization in comparison with active and intelligent gelatin-based composite films. The physical properties of gelatin-based film such as color, UV-Vis absorption spectra, water vapor permeability, thermal, and moisture properties are discussed along with their mechanical properties, including tensile strength and elongation at break.

Preparation and physicochemical characterization of films prepared with salmon skin gelatin extracted by a trypsin-aided process

The recovery of gelatins from Atlantic salmon (Salmo salar) skin for film formation and characterization was studied. Fish skins pre-treated with trypsin (250 U/g) produced the highest hydroxyproline content (7.41 ± 0.49 mg hydroxyproline/g treated skin) and yield (53.05 ± 4.38%) of gelatin, as compared to the use of saline solution. Pre-treatment with a lower concentration of trypsin (1 U/g) at a shorter pre-treatment time successfully reduced the degradation of gelatin with co-production of high molecular weight α-chains. Gelatin was further extracted by a trypsin-aided process for film formation and characterization. Films with increasing protein concentration (from 1 to 5%, w/v) exhibited higher thickness, tensile strength, and elongation at break (EAB), but a marked decrease in EAB for films with 6 and 7% (w/v). Films with 5% proteins showed higher thickness, lower tensile strength and higher EAB with increasing concentrations of glycerol (from 10 to 50% of proteins, w/w). All films exhibited high water uptake, decrease in light transmission and an increase in opacity as the protein and glycerol contents increased. Electrophoretic studies showed that the increase in the mechanical properties of the films was correlated with the increase in protein concentration, owing to the increased content of high molecular weight chain fractions. Furthermore, Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) revealed the interaction between the proteins and glycerol for all films. This study demonstrated the viability of the trypsin supplementation process to obtain salmon skin gelatin for film formation.

•

Fish skins pre-treated with trypsin produced a high hydroxyproline content.

•

Fish skins pre-treated with trypsin produced a gelatin yield of 53.05%.

•

Increasing protein concentration increased the mechanical properties of the films.

•

Films have potential for use in food packaging applications.

Design of Bioinspired Emulsified Composite European Eel Gelatin and Protein Isolate-Based Food Packaging Film: Thermal, Microstructural, Mechanical, and Biological Features

The study focused on the elaboration and the characterization of blend biofilms based on European eel skin gelatin (ESG) and protein isolate (EPI) and the assessment of European oil (EO) incorporation effect on their properties. Data displayed that the incorporation of EPI and EO to the gelatin formulation decreased the lightness and yellowness of composite and emulsified films, respectively, compared to ESG film. Moreover, ESG films exhibited improved mechanical properties than EPI films. FTIR analysis, all incorporated films with EO at the ratio 1:4 (oil/polymer) revealed similar characteristic bands as in free-oil films. Further, the SEM images of 100% ESG and 100% EPI films showed a smooth and homogenous structure, whereas the cross-section of blend film (at a ratio 50:50) displayed a rougher microstructure. In addition, emulsified film ESG100 revealed a smooth and homogeneous microstructure compared to that prepared using EPI/ESG 50/50 ratio. Furthermore, EPI or EO addition into the ESG matrix enhanced the blend films antioxidant activities.

Biopolymeric Films of Amphiphilic Derivatives of Chitosan: A Physicochemical Characterization and Antifungal Study

The chemical modification of chitosan has been an active subject of research in order to improve the physicochemical and antifungal properties of chitosan-based films. The aim of this study was to evaluate the physiochemical and antifungal properties of films prepared with chitosan and its derivatives containing diethylaminoethyl (DEAE) and dodecyl groups (Dod). Chitosans and selected derivatives were synthesized and characterized, and their films blended with glycerol and sorbitol (5%, 10%, and 20%). They were studied by means of the evaluation of their mechanical, thermal, barrier, and antifungal properties. The collected data showed that molecular weight (Mw), degree of acetylation, and grafting with DEAE and Dod groups greatly affected the mechanical, thickness, color, and barrier properties, all of which could be tailored by the plasticizer percentage. The antifungal study against Aspergillus flavus, Alternaria alternata, Alternaria solani, and Penicillium expansum showed that the films containing DEAE and Dod groups exhibited higher antifungal activity than the non-modified chitosans. The mechanical properties of highly soluble films were improved by the plasticizers at percentages of 5% and 10%, indicating these derivatives as potential candidates for the coating of seeds, nuts and fruits of various crops.

Development and characterization of cuttlefish (Sepia officinalis) skin gelatin-protein isolate blend films

In the present study, cuttlefish skin gelatin (CSG) and protein isolate (CSPI) blend films were prepared and their physicochemical and antioxidant properties were characterized. CSG (4%, w/v) was blended with CSPI (3%, w/v) at different ratios and 15% of glycerol (w/w, plasticizer/polymer dry matter). Results showed that increasing of CSPI content induced lower lightness but higher redness, yellowness and color difference values compared to CSG film. In addition, CSPI film had the lowest tensile strength (TS) and elongation at break (EAB) values. The FTIR spectra of blend films showed a shift in the position of peaks related to the amide-I group, suggesting that they were involved in the interaction between the biopolymers. The structural properties evaluated by DSC showed a total miscibility between both polymers. This result was also confirmed by the SEM study, revealing a compact and homogenous structure in the blend films. Moreover, the water contact angle decreased in blend films, especially for those having higher proportion of CSPI. The antioxidant activity of films was markedly favored by the CSPI incorporation. Therefore, CSPI addition into gelatin matrix allowed to improve the blend films properties, mainly governed by the CSG/CSPI ratio.