Filme biodegradável à base de quitosana e amido de resíduo agroindustrial para conservação de fruta minimamente processada

Abstract

The development of biodegradable films has been the subject of several studies in order to replace conventional polymers of petrochemical origin, especially for use as packaging in the food industry. In view of the above, this research aimed to develop and characterize a film, through various formulations, composed of a blend of starch from the pit of the avocado fruit (Persea americana, Mill.) with chitosan, with and without hydroalcoholic extract from the flour of the seed of the jatoba fruit (Hymenaea courbaril, L) at concentrations of 5, 10 and 15%, as bioactive packaging for application in the preservation of minimally processed melon. The films obtained were evaluated for their thermal and physicochemical properties of water solubility, humidity, thickness, visual parameters (color and opacity), water vapor permeability, antioxidant activity (in vitro) and antibacterial activity (in vitro), as well as their biodegradability. Melon slices containing or not containing selected films were evaluated for soluble solids content, mass loss, titratable acidity, pH, color and total counts of aerobic mesophilic bacteria and molds and yeasts during 14 days of storage at 5 ºC. Analysis of the bioactive compounds in the jatoba seed extract showed contents of 8,833.33 (mg EAG/100g) and 36.43 (mg QCE/100g) for total phenolic compounds and total flavonoids, respectively. Analysis of the antibacterial activity of the extract showed the largest inhibition halos (<10 mm) against B. cereus, P. aeruginosa and E. faecalis. The characterization analyses carried out showed that the thermal stability of the films was influenced by the addition of the extract, in which the greatest resistance to heat was seen in the films added with the extract. The moisture content and solubility were lower for the film with extract (8% and 33%, respectively) than for the film without extract (21% and 43%, respectively). On the other hand, the antioxidant activity was higher for the film with the highest concentration of extract (inhibition rate of 58% and 81% by the ABTS and DPPH methods, respectively) compared to the film without extract (44% and 32%, respectively). The antibacterial activity of films with an increased extract concentration was also higher against nine bacteria. The vapor permeability analysis showed no significant differences between the films tested. The biodegradability analysis showed that the films with extract required a longer biodegradation period when compared to the film without added extract. The vapor permeability analysis showed no significant differences between the films tested. The biodegradability analysis showed that the films with extract required a longer biodegradation period when compared to the film without added extract. Regarding the shelf life of the minimally processed melon, it was observed that the films with extract reduced the counts of mesophilic aerobic bacteria by up to 2 Log CFU/g compared to the fruit with film without extract, however, they did not influence the count of molds and yeasts (maintaining between 3.0 and 4.0 Log CFU/g), the soluble solids content (6.0-6.9 ºBrix) and the pH (4-6) during storage. The acidity (0.1-0.2%) of the melons increased slightly during storage and weight loss increased when the extract film was used. The films synthesized showed potential for use as bioactive food packaging, particularly in reducing bacterial growth during storage of minimally processed melons at 5ºC for 14 days.