Edible films based on aqueous emulsions of low-methoxyl pectin with recovered and purified sunflower waxes

Development of phage-containing hydrogel for treating Enterococcus faecalis-infected wounds

BACKGROUND

Chronic wound infections caused by Enterococcus faecalis pose formidable challenges in clinical management, exacerbated by the emergence of vancomycin-resistant strains. Phage therapy offers a targeted approach but encounters delivery hurdles. Due to their biocompatibility and controlled release properties, hydrogels hold promise as carriers.

OBJECTIVE

This study aimed to fabricate phage-containing hydrogels using sodium alginate (SA), carboxymethyl cellulose (CMC), and hyaluronic acid (HA) to treat E. faecalis-infected wounds. We assessed the efficacy of these hydrogels both in vitro and in vivo.

METHODS

The hydrogel was prepared using SA-CMC-HA polymers. Phage SAM-E.f 12 was incorporated into the SA-CMC-HA hydrogel. The hydrogel's swelling index was measured after 24 h, and degradation was assessed over seven days. Surface morphology and composition were analyzed using Scanning Electron Microscopy (SEM) and Fourier-transform infrared spectroscopy (FTIR). Antibacterial activity was tested via optical density (OD) and disk diffusion assays. Phage release and stability were evaluated over a month. In vivo efficacy was tested in mice through wound healing and bacterial count assays, with histopathological analysis.

RESULTS

Hydrogels exhibited a swelling index of 0.43, a water absorption rate of %30, and 23% degradation over seven days. FTIR confirmed successful polymer incorporation. In vitro studies demonstrated that phage-containing hydrogels significantly inhibited bacterial growth, with an OD of 0.3 compared to 1.1 for the controls. Hydrogels remained stable for four weeks. In vivo, phage-containing hydrogels reduced bacterial load and enhanced wound healing, as shown by improved epithelialization and tissue restoration.

CONCLUSION

Phage-containing hydrogels effectively treat wounds infected with E. faecalis-infected wounds, promoting wound healing through controlled phage release. These hydrogels can improve clinical outcomes in the treatment of infected wounds.

Study of the Physical, Chemical, and Structural Properties of Low- and High-Methoxyl Pectin-Based Film Matrices Including Sunflower Waxes

The development of bio-based materials remains one of the most important alternatives to plastic materials. Although research in this field is growing, reporting various materials and methodologies, it is still necessary to increase exploration. The aim of this work was to expand and complement previous research on the preparation and characterization of high- and low-methoxyl pectin films obtained by casting, with the addition of commercial and recovered sunflower waxes. The results showed that the addition of sunflower waxes to the pectin matrix generated some discontinuity in the aggregate, increasing the thickness and roughness of the film. However, due to their hydrophobic nature, the waxes contributed to lower vapor transmission rate values of the films. On the other hand, the low-methoxyl pectin films had a more crystalline structure, which could help to diminish water vapor permeability values, mechanical resistance and rigidity, and improve their elongation. Regarding chemical characteristics, most of the raw materials' chemical groups were found in the resulting films, and the presence of C-H bending due to pectin gelation was observed. Finally, the compatibility and contribution of pectin and sunflower waxes to the production of the films were demonstrated, as well as the possibility of using materials from industrial waste in food packaging applications.

Current Advancements in Pectin: Extraction, Properties and Multifunctional Applications

Pectin is a heterogeneous hydrocolloid present in the primary cell wall and middle lamella in all dicotyledonous plants, more commonly in the outer fruit coat or peel as compared to the inner matrix. Presently, citrus fruits and apple fruits are the main sources for commercial extraction of pectin, but ongoing research on pectin extraction from alternate fruit sources and fruit wastes from processing industries will be of great help in waste product reduction and enhancing the production of pectin. Pectin shows multifunctional applications including in the food industry, the health and pharmaceutical sector, and in packaging regimes. Pectin is commonly utilized in the food industry as an additive in foods such as jams, jellies, low calorie foods, stabilizing acidified milk products, thickener and emulsifier. Pectin is widely used in the pharmaceutical industry for the preparation of medicines that reduce blood cholesterol level and cure gastrointestinal disorders, as well as in cancer treatment. Pectin also finds use in numerous other industries, such as in the preparation of edible films and coatings, paper substitutes and foams. Due to these varied uses of pectin in different applications, there is a great necessity to explore other non-conventional sources or modify existing sources to obtain pectin with desired quality attributes to some extent by rational modifications of pectin with chemical and enzymatic treatments.

Pectin Films with Recovered Sunflower Waxes Produced by Electrospraying

Valorization of by-products obtained from food processing has achieved an important environmental impact. In this research, sunflower wax recovered from oil refining process was incorporated to low and high-methoxyl pectin films produced by electrospraying. Film-forming solutions and wax-added electrosprayed films were physical and structurally evaluated. The addition of sunflower wax to the film-forming solutions reduces conductivity while raising surface tension and density, whereas the type of pectin had a larger impact on viscosity, with the low-methoxyl solution having the highest value. These changes in physical solution properties influenced the film characteristics, observing thicker films with lower water vapor transmission rate (WVTR) when adding wax. Micrographs obtained by scanning electron microscopy (SEM) revealed the presence of wax particles as small spherical shapes, having a good distribution through the sectional area of films. According to X-ray diffraction (XRD), atomic force microscopy (AFM) and mechanical properties analyses, the presence of wax had an impact on the degree of crystallinity, producing a more amorphous and rougher film’s structure, without affecting the elongation percentage and the tensile stress (p>0.05). These results showed that wax addition improves the physical properties of films, while the suitability of using both pectins and the electrospraying technique was demonstrated.

Physical characterization of high methoxyl pectin and sunflower oil wax emulsions: A low-field 1 H NMR relaxometry study

Pectin-wax-based emulsion systems could be used to form edible films and coatings with desired water permeability characteristics. Pectin is often used in food industry due to its gelling and viscosity increasing properties. Physical properties of pectin are highly dependent on its esterification degree. Waxes are commonly used as edible coatings to enhance the water barrier properties of food products. This study focuses on preparing emulsions with sunflower oil wax (SFW) and high methoxyl pectin (HMP) at different concentrations for any possible edible film or coating formulations. Sunflower oil (SFO) was added as the dispersed oil phase to these emulsions. Characterization of the emulsions was performed by using particle size, rheology, and time domain nuclear magnetic resonance (NMR) relaxometry measurements. Effects of HMP concentration and the presence of SFO in the emulsion formulations were explored. Mean particle size values were recorded between 1 and 3 µm. Rheology measurements showed that increasing HMP concentrations and presence of SFO in emulsions resulted in more pseudoplastic behavior. NMR transverse relaxation times (T₂ ) were measured to detect the differences between the emulsions. Relaxation spectrum analysis was also conducted for a detailed understanding of the transverse relaxations. Addition of SFO and higher HMP concentrations decreased the T ₂ values of the emulsion systems (P < 0.05). However, T₂ decreasing effect of SFO was compensated at 10% (w/w) HMP concentration showing that SFO was well dispersed in this particular emulsion formulation. Changes in the rheological behavior and relaxation times provided insight on the formation and stability of the emulsions. PRACTICAL APPLICATION: Findings of this study can be utilized and integrated to produce edible films and coatings with different water permeability characteristics. This study showed that NMR relaxometry parameters were also effective in monitoring and determining the physical characteristics of the pectin-wax-based emulsion systems as other conventional techniques including rheology and particle size measurements. Our NMR relaxometry findings were in correlation with the flow behavior and particle size results of the investigated emulsion systems.