Effect of sodium alginate/phosphate-stabilized amorphous calcium carbonate nanoparticles on chitosan membranes

Sustainable seedling pots: Development and characterisation of banana waste and natural fibre-reinforced composites for horticultural applications

Plastic pots used in horticultural nurseries generate substantial waste, causing environmental pollution. This study aimed to develop biodegradable composites from banana pseudo-stem reinforced with agricultural residues like pineapple leaves, taro and water hyacinth as eco-friendly substitutes. The aim of this study is to develop optimised banana biocomposite formulations with suitable reinforcements that balance mechanical durability, biodegradation, and seedling growth promotion properties to serve as viable eco-friendly alternatives to plastic seedling pots. This study was carried out by fabricating banana fibre mats through pulping, drying and hot pressing. Composite sheets were reinforced with 50 % pineapple, taro or water hyacinth fibres. The mechanical properties (tensile, yield strength, elongation, bursting strength), hydrophilicity (contact angle, water absorption), biodegradability (soil burial test), and seedling growth promotion were evaluated through appropriate testing methods. The results show that banana-taro composites exhibited suitable tensile strength (25 MPa), elongation (27 %), water uptake (41 %) and 82 % biodegradation in 60 days. It was observed that biodegradable seedling trays fabricated from banana-taro composite showed 95 % tomato seed germination and a 125 cm plant height increase in 30 days, superior to plastic trays. The finding shows that the study demonstrates the potential of banana-taro biocomposites as alternatives to plastic nursery pots, enabling healthy seedling growth while eliminating plastic waste pollution through biodegradation.

Preparation and sustained-release of chitosan-alginate bilayer microcapsules containing aromatic compounds with different functional groups

This study investigated the release of aromatic compounds with distinct functional groups within bilayer microcapsules. Bilayer microcapsules of four distinctive core materials (benzyl alcohol, eugenol, cinnamaldehyde, and benzoic acid) were synthesized via freeze-drying. Chitosan (CS) and sodium alginate (ALG) were used as wall materials. CS concentration, using orthogonal experiments with the loading ratio as a metric. Under optimal conditions, three other types of microcapsules (cinnamic aldehyde, benzoic acid, and benzyl alcohol) were obtained. The four types of microcapsules were characterized using Fourier-transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), transmission electron microscope (TEM), and thermogravimetric analysis (TGA), and their sustained release characteristics were evaluated. The optimal conditions were: CS dosage, 1.2 %; CS-to-eugenol mass ratio, 1:2; and CS-to-ALG mass ratio, 1:1. By comparing the IR spectra of the four types of microcapsules, wall material, and core material, the core materials were revealed to be encapsulated within the wall material. SEM results revealed that the granular protuberances on the surface of the microcapsules were closely aligned and persistent when magnified 2000×. The TEM results indicated that all four microcapsules had a spherical and bilayer structure. The thermal stability and sustained release results showed that the four microcapsules were more resilient and less volatile than the four core materials. The release conformed to first-order kinetics, and the release ratios of the four microcapsules were as follows: benzyl alcohol microcapsules ˃ eugenol microcapsules ˃ cinnamaldehyde microcapsules ˃ benzoic acid microcapsules. The prepared bilayer microcapsules encapsulated four different core materials with good sustained release properties.

Chitosan coating enriched with biosynthetic CuO NPs: Effects on postharvest decay and quality of mango fruit

A chitosan-based nanocomposite film (CSC) was developed by mixing chitosan (CS, 2 %, v/v) and copper oxide nanoparticles (CuO NPs, 500 μg∙mL-1) synthesized using Alpinia officinarum extract for the safe storage of mango fruit. The effects of CuO NPs on the morphological, mechanical, thermal, physical and antifungal properties of the CS films and postharvest quality of mango fruit were determined. Scanning electron microscopy (SEM) analysis confirmed that CuO NPs were uniformly dispersed into the CS matrix. X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) profiles showed that intermolecular H-bondings occurred between CS and CuO NPs, accompanied by decreased crystallinity and increased amorphous structure. In comparison to the pure CS film, addition of CuO NPs obviously improved the morphological, mechanical, thermal, physical and antifungal properties of CSC film. CSC coating treatment obviously delayed the fruit decay and yellowing, as well as reduced losses of weight and firmness of mango (Mangifera indica L.) fruit during the storage, when compared with the control and CS coating treatment. Meanwhile, it significantly decreased the respiration rate and ethylene generation and maintained high level of ascorbic acid (AsA), titratable acid (TA) and soluble sugar content (SSC) of the fruit during the storage. Notably, Cu presented in the CSC film was restrained to the peel, indicating that the CSC coated mango fruit had good edible safety. Principal component analysis (PCA) confirmed that CSC coating played a positive role in mango preservation. Therefore, CSC coating can be considered a potential application for successfully controlling of postharvest disease and prolonging the shelf life for mango fruit.

Preparation, characterization and release kinetics of a multilayer encapsulated Perilla frutescens L. essential oil hydrogel bead

Encapsulation has been widely used as the protection of essential oils, which gives the possibility of their implementation as food preservatives. In this study, Perilla frutescens L. essential oil (PLEO) microcapsule powders were prepared firstly by spray drying method using octenyl succinic anhydride starch (OSAs) as wall material, and then they were further encapsulated by sodium alginate and chitosan via polyelectrolyte complex coacervates method. The best results were obtained by using 4 % of OSAs-PLEO microcapsule powders, 2 % of sodium alginate and 1.5 % of chitosan producing PLEO hydrogel beads with encapsulation efficiency of 61.29 % and loading degree of 41.11 %. Morphology observation showed PLEO hydrogel beads was a millimeter scale spherical particle. FTIR assay confirmed the physical embedding of OSAs on PLEO and the formation of complex coacervates between sodium alginate and chitosan. TG and DSC assay showed the chitosan/alginate/OSAs complex coacervates as wall materials substantially improved the thermal stability of PLEO. Besides, PLEO hydrogel beads had a better stability in aqueous and acidic food formulations, which achieved a complete and prolonged release of PLEO. The Peppas-Sahlin model was the best approach for PLEO release profile, and release phenomenon was mainly governed by Fickian diffusion.

Preparation of Chitosan/β-Cyclodextrin Composite Membrane and Its Adsorption Mechanism for Proteins

A significant portion of the protein in food waste will contaminate the water. The chitosan/modified β-cyclodextrin (CS/β-CDP) composite membranes were prepared for the adsorption of bovine serum albumin (BSA) in this work to solve the problem of poor adsorption protein performance and easy disintegration by a pure chitosan membrane. A thorough investigation was conducted into the effects of the preparation conditions (the mass ratio of CS and β-CDP, preparation temperature, and glutaraldehyde addition) and adsorption conditions (temperature and pH) on the created CS/β-CDP composite membrane. The physical and chemical properties of pure CS membrane and CS/β-CDP composite membrane were investigated. The results showed that CS/β-CDP composite membrane has better tensile strength, elongation at break, Young's modulus, contact angle properties, and lower swelling degree. The physicochemical and morphological attributes of composite membranes before and after the adsorption of BSA were characterized by SEM, FT-IR, and XRD. The results showed that the CS/β-CDP composite membrane adsorbed BSA by both physical and chemical mechanisms, and the adsorption isotherm, kinetics, and thermodynamic experiments further confirmed its adsorption mechanism. As a result, the CS/β-CDP composite membrane of absorbing BSA was successfully fabricated, demonstrating the potential application prospect in environmental protection.

Preparation and Properties of Blended Composite Film Manufactured Using Walnut-Peptide-Chitosan-Sodium Alginate

In this study, layer-by-layer assembly was performed to prepare sodium alginate (SA) layer and walnut-peptide-chitosan (CS) bilayer composite films. Genipin was adopted to crosslink CS and walnut peptide. The properties of walnut peptide-CS-SA composite film were determined, and the influence of material ratio on the performance of composite film was explored. According to the results, the mechanical tensile property, oil absorption property, and water vapor barrier property of the composite film were improved with the presence of genipin. Moreover, the proportion of CS and walnut peptide had significant effects on color, transmittance, mechanical properties, barrier properties, and antioxidant properties of the composite films. Among them, the composite film containing 1% (w/v) CS, 1% (w/v) walnut peptide, and 0.01% (w/v) genipin showed the best performance, with a tensile strength of 3.65 MPa, elongation at break of 30.82%, water vapor permeability of 0.60 g·mm·m-2·h-1·kPa-1, oil absorption of 0.85%, and the three-phase electrochemistry of 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging rate of 25.59%. Under this condition, the tensile property, barrier property, and oxidation resistance of the composite film are good, which can provide a good preservation effect for food, and has great application potential.