orabase and citral

The extensive use of chemical pesticides in agricultural production has caused great damage to the soil and ecological environment. Citral, a monoterpene aldehyde, has been shown to inhibit the growth of a variety of pathogenic fungi by affecting mitochondrial structure. However, the high volatility and chemical instability of citral may restrict its applications in the agricultural industries. In this study, a concise and facile method for the preparation of modified copolymer chitosan/carboxymethyl cellulose (CS/CMC) hydrogels microspheres loaded with citral was developed to increase and stabilize the bioavailability of this natural bioactive substance. Polyelectrolyte composite scaffold hydrogel microspheres were synthesized by polycationic chitosan (CS) and polyanionic carboxymethyl (CMC). Citral was embedded into the microspheres by coupling the carbonyl group of citral with the amino group of CS to form a Schiff base structure. The effects of three parameters including CS/CMC weight ratio, concentration of CMC and citral on the loading ratio were investigated and optimal loading of 68% was achieved based on single-factor experiments. X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy and scanning electron microscopy (SEM) were employed to confirm and characterize the structure and surface morphology of the microspheres. Both the XRD and FTIR spectra indicated that the microspheres contain -C=N- covalent bonds between CS and citral. The hydrogel microspheres with incorporated citral exhibited effective and improved in vitro antibacterial effects against E. coli, S. aureus and B. subtilis than non-loaded CS microspheres. Moreover, CS/CMC-citral-MPs showed a good antifungal effect in vivo in reducing disease incidence caused by the plant pathogenic fungus Botrytis cinerea in Solanum lycopersicum. Different from the previous applications of CS and citral in the preservation of picked fruits, citral was embedded into CS/CMC microspheres to achieve improved plant protection against Botrytis cinerea. The microspheres are a promising green antimicrobial agent against plant pathogens in crop protection and other fields.

Topics: Acyclic Monoterpenes; Anti-Bacterial Agents; Botrytis; Carboxymethylcellulose Sodium; Chitosan; Fungicides, Industrial; Hydrogels; Hydrogen-Ion Concentration; Microscopy, Electron, Scanning; Microspheres; Plant Diseases; Solanum lycopersicum; Spectroscopy, Fourier Transform Infrared; X-Ray Diffraction

Emulsification approach is widely employed to deliver beneficial agents to liquid food products, whereas utilizing emulsions with solid food is scarce. In this research, coarse and nano emulsions of citral were prepared and embedded in chitosan or carboxymethyl cellulose (CMC) polysaccharides to form active edible coatings for solid-state delivery. Polysaccharides stabilized the emulsions by electrostatic interactions, while chitosan also prevented coalescence. The nano emulsion based films showed a more organized and dense morphology (E-SEM), higher water vapor barrier, better mechanical features (strength, elasticity and Young modulus) than the coarse ones. When applied on a solid food model, fresh-cut melons, the nanoemulsified edible coatings demonstrated a superior antimicrobial protection (up to a 5-log reduction) and significantly extended product's storability (up to 13 days). The presented approach could be further employed for the delivery of other beneficial agents (nutrients, aroma, antimicrobial, antioxidants) to solid food products, contributing a general progress in this field.

Topics: Acyclic Monoterpenes; Agriculture; Carboxymethylcellulose Sodium; Chitosan; Cucurbitaceae; Emulsions; Food Handling; Food Quality; Monoterpenes; Nanostructures; Static Electricity