Introduction of Curdlan Optimizes the Comprehensive Properties of Methyl Cellulose Films

Storage stability of konjac glucomannan/curdlan films at low temperature and its coating for the preservation of cucumbers

Fruits and vegetables suffer severe moisture loss during cold storage. To explore the mechanism of water transfer, this study investigated the properties of konjac glucomannan (KGM)/curdlan (KC) composite films after cold storage treatment, the preservation of KC-coated cucumbers, and the water transfer. The results showed that the weight, thickness, free water content, and enthalpy (ΔH) of endothermic peak of the film increased after cold storage, mainly because of the water adsorption and diffusion. K6C4 (the KGM/curdlan mass ratio in 6:4) maintained uniform and dense and showed the lowest dissolution loss of 21.92%. Moreover, the water content of K6C4 film changed by 1.1% on day 15, and K6C4 exhibited excellent gas barrier and mechanical properties. These were attributed to the optimal matrix formed by the assembly of KGM and curdlan in K6C4, contributing to the stability of structure and performance. K6C4 coating significantly maintained the quality of cucumbers. At the end of storage, the firmness and weight loss of the coating group were 19.3% and 24.4% higher than the control group, respectively. The color, total solid content, acid, and VC were maintained for coating group. The low-field nuclear magnetic resonance revealed that K6C4 coating inhibited the water transfer from the center to the epidermis of cucumbers by blocking the water produced by respiration and the free water in the tissues. The storage stability and water transfer analysis will contribute to the understanding of the mechanism of coating inhibiting moisture loss of fruits and vegetables.

Pickering emulsion gels with curdlan as both the emulsifier and the gelling agent: Emulsifying mechanism, gelling performance and gel properties

For the first time, curdlan (CL) was reported to have emulsifying property. Based on its emulsifying property and gelling property, the CL-based simple-structured emulsion gels were prepared. Among different CLs, CL-4 showed relatively good emulsifying property and its based emulsion showed the best stability, which might be mainly due to its highest hydrophobic property. The initial CL-4 gel formation temperature of the emulsion increased with oil volume fraction, which might be due to the oil droplets' interfering effect. Many non-spherical oil droplets appeared in the emulsion gel, which was mainly due to the squeezing effect of CL-4 gelation. The hardness, chewiness, springiness and cohesiveness of CL-4 based emulsion gels increased with CL-4 content. The texture parameters of emulsion gels with oil ratio ranging from 20 % to 40 % did not change significantly, which might benefit for increasing functional components' transportation efficiency of the emulsion gel without weakening its gel property significantly.

Effects of Different Plasticizers on the Structure, Physical Properties and Film Forming Performance of Curdlan Edible Films

This study successfully developed edible films with excellent mechanical strength and notable water resistance, utilizing curdlan (CL) as the primary matrix and incorporating various plasticizers, including glycerol (GLY), ethylene glycol (EG), propylene glycol (PRO), xylitol (XY), sorbitol (SOR), and polyethylene glycol (PEG). A comprehensive suite of analytical techniques, including Fourier transform infrared spectroscopy (FTIR), wide-angle X-ray diffraction (XRD), scanning electron microscopy (SEM), dynamic mechanical analysis (DMA), and tensile testing, were employed to evaluate the films' structural and mechanical properties. After incorporating PEG, the water sensitivity increased slightly, with a contact angle (CA) of 97.6°, and a water solubility (WS) of 18.75%. The inclusion of plasticizers altered the crystalline structure of the CL matrix, smoothing and flattening the film surface while reducing hydrogen-bonding interactions. These structural changes led to a more uniform distribution of amorphous chain segments and a decrease in glass transition temperatures. Among the tested plasticizers, GLY exhibited the highest compatibility with CL, resulting in the smoothest surface morphology and delivering the most effective plasticizing effect. The CL-GLY film showed a dramatic improvement in flexibility, with an elongation at break that was 5.2 times higher than that of the unplasticized film (increasing from 5.39% to 33.14%), indicating significant enhancement in extensibility. Overall, these findings highlight the potential of CL-GLY films as sustainable and effective materials for food packaging applications.

Recovery and characterization of cellulose microfibers from fallen leaves and evaluation of their potential as reinforcement agents for production of new biodegradable packaging materials

In the present work, cellulose microfibers (CMFs) isolated from fallen autumn leaves of cherry plum (Prunus cerasifera pissardii nigra), white mulberry (Morus alba) and plane (Platanus orientalis) trees were characterized and used as reinforcement agents in sodium alginate-based biodegradable films. Fourier transform infrared spectroscopy (FT-IR) characterization showed that the CMFs were successfully isolated from the leaves with high purity. The extracted CMFs had a particle size ranging from 321.20 nm to 632.26 nm and negative zeta potential values (-27.33 to -21.40). The extraction yield of CMFs ranged from 19.53% to 26.00%. Incorporation of the leaf-derived CMFs into sodium alginate based films (1%, w:w) increased their tensile strength (from 153.73 to 187.78 MPa) and elongation at break values (from 105.97% to 89.90%) and significantly decreased oxygen (from 121.46 to 75.56 meq kg-1) and water vapor permeabilities (from 2.36 to 1.60 g mm h-1 m-2 kPa-1)(p < 0.05). Furthermore, the supplementation of CMFs into the biopolymer matrix had no significant effect on the color (L*: 85.35-85.67; a*: -0.75-0.71; b*: 4.23-4.94) and moisture content (44.64-48.42%) of the film samples, although the thickness increased (40.33-94.66 μm). Scanning electron microscopy (SEM) images showed that CMFs were homogeneously dispersed in the film matrix. Overall, this study confirms that fallen cherry plum, white mulberry, and plane leaves are valuable sources of CMFs which could be used in the manufacturing of biodegradable nanocomposite films as reinforcement agents.

A novel curdlan/methyl cellulose/walnut green husk polyphenol edible composite film for walnut packaging

In this study, polyphenols were extracted from walnut green husk, an agricultural waste, and were incorporated into curdlan (CD) and methyl cellulose (MC) to create a novel edible composite film. For structural character, the film matrix was tightly bound primarily by non-covalent bonds and the addition of walnut green husk polyphenols (WGHP) significantly reduced the surface roughness of the composite film. For mechanical properties, the addition of WGHP improve the flexibility of films, and it significantly improved the barrier ability of ultraviolet rays and water-vapor. Furthermore, the incorporation of WGHP to the CD-MC film resulted in enhanced antioxidant and antibacterial effects, which effectively retards lipid oxidation in fried walnuts. Consequently, the fabricated CD-MC-WGHP composite film bears immense potential for use in food preservation applications, particularly in extending the shelf life of fried walnuts.

Preparation, Characterization, and Application of pH-Response Color-Changeable Films Based on Pullulan, Cooked Amaranth (Amaranthus tricolor L.) Juice, and Bergamot Essential Oil

Pullulan-based smart packaging films were prepared by mixing cooked amaranth juice and bergamot essential oil. The impact of cooked amaranth juice and bergamot essential oil on the color-changeability, structural characterization, and barrier, antioxidant, mechanical and thermal properties of pullulan-based films was determined. Results showed the cooked amaranth juice contained pH-response color-changing betacyanins. The pullulan films containing cooked amaranth juice were color-changeable in pH 9-12 buffers and in ammonia vapor. The color-changeable property of betacyanins in cooked amaranth juice was unaffected by bergamot essential oils. The inner structure of pullulan films was greatly affected by cooked amaranth juice, forming big and ordered humps in film cross-sections. The crystallinity of pullulan films was improved by the combined addition of cooked amaranth juice and bergamot essential oil. Among the films, the pullulan film containing cooked amaranth juice and 6% bergamot essential oil showed the highest UV-vis light barrier property, antioxidant activity, and tensile strength; while the pullulan film containing cooked amaranth juice and 4% bergamot essential oil showed the highest oxygen barrier property and thermal stability. Moreover, the pullulan films containing cooked amaranth juice were able to monitor the freshness of shrimp by presenting color changes from reddish purple to dark red.

Do Curdlan Hydrogels Improved with Bioactive Compounds from Hop Exhibit Beneficial Properties for Skin Wound Healing?

Chronic wounds, among others, are mainly characterized by prolonged inflammation associated with the overproduction of reactive oxygen species and pro-inflammatory cytokines by immune cells. As a consequence, this phenomenon hinders or even precludes the regeneration process. It is known that biomaterials composed of biopolymers can significantly promote the process of wound healing and regeneration. The aim of this study was to establish whether curdlan-based biomaterials modified with hop compounds can be considered as promising candidates for the promotion of skin wound healing. The resultant biomaterials were subjected to an evaluation of their structural, physicochemical, and biological in vitro and in vivo properties. The conducted physicochemical analyses confirmed the incorporation of bioactive compounds (crude extract or xanthohumol) into the curdlan matrix. It was found that the curdlan-based biomaterials improved with low concentrations of hop compounds possessing satisfactory hydrophilicity, wettability, porosity, and absorption capacities. In vitro, tests showed that these biomaterials were non-cytotoxic, did not inhibit the proliferation of skin fibroblasts, and had the ability to inhibit the production of pro-inflammatory interleukin-6 by human macrophages stimulated with lipopolysaccharide. Moreover, in vivo studies showed that these biomaterials were biocompatible and could promote the regeneration process after injury (study on Danio rerio larvae model). Thus, it is worth emphasizing that this is the first paper demonstrating that a biomaterial based on a natural biopolymer (curdlan) improved with hop compounds may have biomedical potential, especially in the context of skin wound healing and regeneration.