Preparation and characterization of β-glucan/polyvinyl alcohol/clove essential oil film and its application in the preservation of fresh broad bean pods

In this study, an active film was developed based on β-glucan (BG)/polyvinyl alcohol (PVA)/clove essential oil (CEO) and its preservation effects on fresh broad bean pods were examined. The impact of different BG:PVA ratios (50:50, 40:60 and 30:70) and CEO concentrations (0.25%, 0.50% and 1.00%) on the capacities of film were investigated. A BG:PVA ratio of 40:60 and CEO content of 0.5% (w/w) were adopted following the optimization of the physical, mechanical and barrier capacities of the blended film. Subsequent characterization of the film via Fourier transform infrared spectroscopy, X-ray diffraction and scanning electron microscopy suggested that the BG hydroxyl groups interacted well with the PVA and CEO, and the good heat stability of the BG/PVA-CEO film was confirmed via thermal gravimetric analysis-differential scanning calorimetry. Importantly, the BG/PVA-CEO film also showed good antimicrobial activity. Moreover, the BG/PVA-0.5% CEO film effectively preserved fresh broad bean pods over a 30-day storage period, based on assessments of appearance, firmness, weight loss and the enzyme activities. These results indicate the promising applicability of the novel BG/PVA-CEO films as active coating materials for the preservation of fresh produce and food products.