Viscoelastic and Functional Properties of Cod-Bone Gelatin in the Presence of Xylitol and Stevioside

Rheological Properties of Fish and Mammalian Gelatin Hydrogels as Bases for Potential Practical Formulations

Hydrogels have the ability to retain large amounts of water within their three-dimensional polymer matrices. These attractive materials are used in medicine and the food industry; they can serve as the basis for structured food products, additives, and various ingredients. Gelatin is one of widely used biopolymers to create hydrogels that exhibit biocompatibility and tunable rheological properties. In this study, we offer a comparative analysis of rheological properties of gelatin-based hydrogels (C = 6.67%), including mammalian gelatins from bovine and porcine skins and fish gelatins from commercial samples and samples extracted from Atlantic cod skin. Mammalian gelatins provide high strength and elasticity to hydrogels. Their melting point lies in the range from 22 to 34 °C. Fish gelatin from cod skin also provides a high strength to hydrogels. Commercial fish gelatin forms weak gels exhibiting low viscoelastic properties and strength, as well as low thermal stability with a melting point of 7 °C. Gelatins were characterized basing on the analysis of amino acid composition, molecular weight distribution, and biopolymer secondary structure in gels. Our research provides a unique rheological comparison of mammalian and fish gelatin hydrogels as a tool for the re-evaluation of fish skin gelatin produced through circular processes.

Gelatin-Based Antimicrobial Films Incorporating Pomegranate (Punica granatum L.) Seed Juice by-Product

Pomegranate (Punica granatum L.) seed juice by-product (PSP) was added as reinforcing and antimicrobial agent to fish gelatin (FG) films as a promising eco-friendly active material for food packaging applications. A complete linkage analysis of polysaccharides in PSP showed xylan and cellulose as main components. This residue showed also high total phenolic content and antioxidant activity. Three formulations were processed by adding PSP to FG (0, 10, 30 wt. %) by the casting technique, showing films with 10 wt. % of PSP the best performance. The addition of PSP decreased elongation at break and increased stiffness in the FG films, particularly for 30 wt. % loading. A good compatibility between FG and PSP was observed by SEM. No significant (p < 0.05) differences were obtained for barrier properties to oxygen and water vapour permeability compared to the control with the incorporation of PSP, whereas water resistance considerably increased and transparency values decreased (p < 0.05). High thermal stability of films and inhibition against S. aureus were observed. The addition of PSP at 10 wt. % into FG was shown as a potential strategy to maintain the integrity of the material and protect food against lipid oxidation, reducing huge amounts of pomegranate and fish wastes.

Facile Fabrication of Sandwich Structural Membrane With a Hydrogel Nanofibrous Mat as Inner Layer for Wound Dressing Application

A common problem existing in wound dressing is to integrate the properties of against water erosion while maintaining a high water-uptake capacity. To tackle this issue, we imbedded one layer of hydrogel nanofibrous mat into two hydrophobic nanofibrous mats, thereafter, the sandwich structural membrane (SSM) was obtained. Particularly, SSM is composed of three individual nanofibrous layers which were fabricated through sequential electrospinning technology, including two polyurethane/antibacterial agent layers, and one middle gelatin/rutin layer. The obtained SSM is characterized in terms of morphology, component, mechanical, and functional performance. In addition to the satisfactory antibacterial activity against Staphylococcus aureus and Escherichia coli, and antioxidant property upon scavenging DPPH free radicals, the obtained SSM also shows a desirable thermally regulated water vapor transmission rate. More importantly, such SSM can be mechanically stable and keep its intact morphology without appearance damage while showing a high water-absorption ratio. Therefore, the prepared sandwich structural membrane with hydrogel nanofibrous mat as inner layer can be expected as a novel wound dressing.