Addition of montmorillonite to improve the barrier and wetting properties of chitosan-based coatings and the application on the preservation of Shatang mandarin

Influence of Corn Flour-Based Coating Functionalized with Muña Essential Oil for Prolong Storability of Strawberries at Refrigeration

Andean crops are highlighted for their bioactive compounds with diverse functional properties. These properties can be exploited to produce functional coatings that conserve fresh fruits. This study aimed to evaluate the purple corn flour coating by adding muña essential oil and montmorillonite to the shelf life of strawberries. The components of muña essential oil were characterized. The treatments evaluated were T1-control, without coating, T2 (2.5% w/v), T3 (3% w/v), and T4 (4% w/v) of purple corn flour, 0.2% w/v montmorillonite, and 0.2% v/v muña essential oil. The strawberries were stored at 4 °C ± 1ºC for 12 days. Weight loss, total soluble solids, pH, acidity, color, firmness, and microbial activity were evaluated. The results show that the main compounds of muña essential oil were pulegone (49.4%), iso-menthone (18.5%), and menthone (17.7%). The coated strawberries showed less weight loss than the control, and their acidity decreased slightly. The coating conserved the color and appearance of the strawberries. The concentration of purple corn flour did not significantly influence the color of coated strawberries. T3 and T4 maintain the firmness of strawberries during storage. The mold and yeast count of the coated treatments was 1.24 log CFU g-1 smaller than the control. In conclusion, the antimicrobial activity of the coating reduced the development of molds and yeasts and helped preserve the physicochemical characteristics of strawberries during 12 days of refrigeration.

Study on the barrier properties of carboxymethyl cellulose/montmorillonite mulch films regulated by magnetic field

To enhance the barrier performance of biomass films, carboxymethyl cellulose (CMC) was combined with montmorillonite (MMT) modified by stearyltrimethylammonium bromide (STAB) and loaded with Fe₃O₄ particles as a nano-filler, and a CMC/m-OMMT mulch film was fabricated using magnetic field orientation. The characterization of m-OMMT was conducted through Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and vibrating sample magnetometry (VSM), which confirmed the successful intercalation of STAB into the MMT structure, along with the effective loading of Fe₃O4 particles onto the MMT matrix. A comprehensive investigation into the mechanical properties of CMC/m-OMMT films revealed that, in the dry state, the films exhibited a tensile strength of 29 MPa and an elongation at break of 64 %. A series of barrier performance tests were conducted on the films. The findings demonstrated that the incorporation of MMT and the application of a magnetic field substantially enhanced the water contact angle, increasing it from 86° to 112°. Additionally, water vapor permeability increased by approximately 30 %, soil erosion was reduced by about 22 %, and UV resistance was notably improved by 94 %. Moreover, scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and biodegradation tests on the CMC/m-OMMT/40mT films revealed that the magnetic field effectively oriented the MMT nanosheets within the composite matrix. This study presents a novel approach for enhancing the barrier properties of biomass-based mulch films.

Effect of Surfactant Formula on the Film Forming Capacity, Wettability, and Preservation Properties of Electrically Sprayed Sodium Alginate Coats

Surfactants are always added to coating formulations to ensure good adhesion of edible coatings to a product's surface and to maintain freshness. In this study, the effects of the mix surfactants Tween 20 and Span 80 with different hydrophile-lipophile balance (HLB) values on the film-forming ability, wettability, and preservation capacity of blueberry sodium alginate coating were investigated. The results indicated that Tween 20 obviously ensured favorable wettability and improved the uniformity and mechanical properties of the resulting film. While the addition of Span 80 reduced the mean particle size of the coating, enhanced the water resistance of the film, and helped to reduce blueberry weight loss. A sodium alginate coating with low viscosity and medium HLB could better inhibit the galactose, sucrose, and linoleic acid metabolism of blueberries, reduce the consumption of phenols, promote the accumulation of flavonoids, and thus display superior coating performance. In summary, sodium alginate coating with medium HLB had comprehensive advantages in film-forming ability and wettability and was conducive to the fresh-keeping role.