Improvement of Hydrophobicity and Gas Permeability of the Polyvinyl Alcohol Film Utilizing Monoglyceride Coating and Diatomaceous Earth Filling and Its Application to Fresh-Cut Mango

Abstract

The widespread utilization of the polyvinyl alcohol (PVA) film is significantly hindered by two prominent limitations: water sensitivity and low gas permeability. In this work, a novel PVA film coated with monoglyceride (MG) and filled with diatomaceous earth (DS) was fabricated to address these issues. Scanning electron microscopy and 3D morphology revealed that the R a value improved from 3.72 to 7.21 μm. Also, the successful coating of MG was confirmed by X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy. Pull-off adhesion tests proved that the film containing 0.5 g of MG exhibited the highest adhesive properties. The PVA/MG/DS film had the highest contact angle of 122.32°, the lowest water vapor permeability of 7.19 g/m2/day, and the lowest oxygen permeability of 55.35 (cm3 × cm × cm2 × s × Pa)−1. Moreover, this type of film exhibited higher light transmittance, better thermal stability, and greater mechanical properties than pure PVA film. Consequently, the PVA/MG/DS film displayed superior performance in preserving the freshness and quality of fresh-cut mango, with a lowest weight loss of 4.48%, a lowest total soluble solids of 7.98%, a greatest titratable acidity of 0.88%, a highest ascorbic acid of 76.67 mg/100 g, and best sensory quality.

How APTMS Acts as a Bridge to Enhance the Compatibility of the Interface between the Hydrophilic Poly(vinyl alcohol) Film and the Hydrophobic Stearic Acid Coating

“…The sensory evaluation panel consisted of five male and five female sensory evaluation professionals, all aged between 25 and 35. 34 The sensory test encompassed aspects such as appearance, texture, taste, odor, and overall acceptability to assess the quality of fresh-cut apples. A nine-point hedonic scale was employed, with ratings ranging from 1 (very poor) to 9 (very good).…”

“…Following APTMS washing, the PVA-APTMS-SA film exhibited a relatively rough yet uniform structure, indicating that APTMS acts as a bridging agent, enhancing the compatibility between the hydrophilic PVA film and the hydrophobic SA coating. 31,34 The EDS spectra of the PVA-based films are presented in Figure 1c. It was evident that only C and O elements were detected in the pure PVA film.…”

“…However, the cross section of the SA-coated film displayed rough structures and a notable phase separation. Following APTMS washing, the PVA-APTMS-SA film exhibited a relatively rough yet uniform structure, indicating that APTMS acts as a bridging agent, enhancing the compatibility between the hydrophilic PVA film and the hydrophobic SA coating. , …”

“…To further evaluate the overall freshness of the stored apples, the sensory qualities of appearance, texture, taste, odor, and overall acceptability were also measured, as shown in Figure . The results revealed that the PVA-APTMS-SA film exhibited the highest sensory quality, which aligned with the findings from WL, pH, firmness, and TSS measurements, indicating a significant improvement in the freshness of the fresh-cut apples . In conclusion, the PVA-APTMS-SA composite film displayed great potential in extending the freshness of fresh-cut apples compared to the pure PVA film, with a higher WL of 8.36%, a higher firmness of 1.52 N, a higher TSS of 8.36%, and a comparatively better sensory freshness.…”

“…During the storage period, images of the fresh-cut apple preservation process were systematically collected at 2-day intervals. The sensory evaluation panel consisted of five male and five female sensory evaluation professionals, all aged between 25 and 35 . The sensory test encompassed aspects such as appearance, texture, taste, odor, and overall acceptability to assess the quality of fresh-cut apples.…”