Innovative, eco-friendly packaging based on persimmon (Diospyros kaki L. cv. Rama Forte): film properties and influence on the quality of minimally processed vegetables

The objective of this work is to develop an edible and biodegradable film based on persimmon puree (Diospyros kaki L. cv. Rama Forte) with plasticizer (glycerol and pectin) by casting technique. The film was then characterized and applied on minimally processed carrot (Daucus carota), beetroot (Beta vulgaris) and cucumber (Cucumis sativus). The film showed high carbohydrate content (87.66 g.100g-1) as well as high values of water solubility (80.86%) and vapor permeability [5.77 g.mm.(hm²kPa)-1]. Regarding its mechanical properties, the film presented 1.35MPa, 18.68% and 8.20MPa of tensile strength at rupture, elongation at rupture and Young's modulus, respectively. Scanning electron microscopy showed smooth surfaces with no pores or cracks and good plasticizer dispersion. Films presented orange-ish color and sufficiently translucent. Fourier-transform infrared spectroscopy confirmed the results of the chemical composition. Thermogravimetric analysis showed two important steps of degradation: 203 and 339ºC. The film exhibited antimicrobial activity, especially against Staphylococcus aureus. Vegetables coated with persimmon film or polyvinyl chloride (PVC) (positive control) were similar regarding microbial population evolution after storage for nine days at 4°C. Salmonella sp. was absent in 25g; thermotolerant coliform estimations ranged from <3 and 160 MPN.g-1; psychrophiles and fungi count presented an average ranging from <4 of 8.7 log CFU.g-1. This similarity was also evidenced by pH value and colorimetric (L* and ∆E*) parameters after a storage period. However, PVC proved to be 2.7 times more efficient to reduce vegetable weight loss than persimmon film. It is noteworthy that the film, unlike synthetic PVC, is biodegradable and edible, being a trend for the area of food packaging, since there is growing environmental concern and greater demand for technology in the context of the circular economy. Further studies has been done to improve the film´s mechanical and barrier properties, as well as to evaluate its potential as active packaging.