Desenvolvimento de embalagens ativas a partir de mantas poliméricas nanoestruturadas e aplicação na pós-colheita de frutas

Abstract

Fruits are susceptible to various post-harvest losses and active packaging systems, in addition to being physical barriers, also act to extend the shelf life of these foods. These systems feature active compounds that can act in various ways, either in the food or in the packaging headspace, maintaining the quality of the packaged product for a longer time. Based on the above and taking into account the scarcity of studies on the interaction and application of nanostructured polymeric mats in food, the present study aimed to develop through the solution blow spinning (SBS) technique and characterize nanofibers of poly (vinyl alcohol) in water (FWater) and those enriched with aqueous extracts of açaí pulp (FAP), cocoa shell (FCS), jabuticaba peels (FJP) and carrot residues (FCR) and poly (lactic acid) (PLA) control (FControl) and with encapsulated 1-MCP/α-CD complex (F1-MCP). As well as, to evaluate the technological feasibility of applying these nanofibers in active packaging systems intended for maintaining the post-harvest quality of strawberries and bananas, respectively. In the first study, it was observed that the nanofibers FAP, FCS, FJP and FCR presented greater similarities among themselves and great differences, mainly in relation to the contents of phenolic compounds (TPC), antioxidant activity and photostability, when compared with FWater. PVA nanofibers had mean diameters below 600 nm and uniform morphology. The FJP and FWater nanofibers were tested as an edible active coating in the refrigerated storage of intact strawberries. There was a deceleration in events related to senescence, such as changes in surface color, degradation of TPC and antioxidant activity, and the occurrence of unsuitable fruits, especially those fruits coated with FJP, when compared to uncoated strawberries. In the second study, using scanning electron microscopy (SEM), it was found that the mean diameters of the PLA nanofibers were less than 200 nm. The presence of the 1-MCP/α-CD complex altered the thermal properties and reduced the hydrophobicity of the nanofibers. Thus, through the characterization analyzes of the nanofibers, it was possible to infer that the crystals of the 1-MCP/α-CD complex were encapsulated and are found on the surface of the F1-MCP nanofibers. Both PLA nanofibers were tested as nano-sachets in the refrigerated storage of whole 'Prata' bananas, in the green stage of maturation. Thus, it was confirmed that the nano-sachet containing encapsulated 1-MCP/α-CD complex released the ethylene-blocking gas in the headspace of the packaging, delaying the increase in respiration rate, soluble solids content and titratable acidity, as well as loss of mass and firmness and changes in the color of the fruit peels during storage, when compared to bananas in packages with the control nanofiber sachet and without sachet. Both studies confirmed the feasibility of obtaining PVA and PLA nanofibers by SBS, as well as the applicability of these nanomaterials in active packaging systems used to increase shelf life and maintain post-harvest fruit quality.