Potencial aplicação do extrato de resíduo de seriguela (Spondias purpurea L.)/nanoZnO em filmes ativos à base de resíduo de mandioca

Abstract

Synthetic plastic food packaging is largely responsible for the generation and accumulation of waste disposed of in nature. In addition, significant quantities of agroindustrial waste rich in relevant substances are wasted. Therefore, a biodegradable packaging based on natural polymers from renewable sources, such as the starch present in the cassava residue, is an alternative as biomaterial. And, additives such as nanoZnO and agroindustrial residues of seriguela may improve the barrier and mechanical properties of these films, as well as confer a bioactive characteristic due to antimicrobial and antioxidant activities. Thus, the aim of this work was to produce and characterize films based on flour of residues from the industrial processing of cassava (FRM), incorporated with nanoZnO and extract from the seriguela residues, for application as active packaging. In the first step, the extract obtained from seriguela residues and nanoZnO were evaluated for the inhibitory activity against bacterial pathogenicity and virulence systems TTSS (Type Three Secretion System) and QS (Quorum Sensing) for Pseudomonas savastanoi, in which 60% extract and 3% nanoZnO presented the best results; to the antibacterial action in which the extract inhibited the growth of Clavibacter michiganensis pv michiganensis and Xanthomonas phaseoli, the latter being also inhibited by nanoZnO; and to the antifungal action against Botrytis cinerea, confirmed for both. In the second step, the films were produced under three conditions: control (5% FRM and 2% glycerol), A (5% FRM, 10% extract, 0.5% nanoZnO and 2% glycerol) and B (5% FRM, 20% extract, 0.5% nanoZnO and 2% glycerol); and their characterization. The additivated films had a low phenolic retention (< 3%). Solubility and thickness did not have significant changes, but all conditions presented an efficient barrier to water vapor (values from 0.0004 to 0.004 g.mm/m2.h.kPa). Additivated films obtained higher % of swelling (A: 112.02% and B: 129.61%) than control (101.36%), and became darker and more opaque, reddish-yellow in color. The use of the additives led to reductions that reached up to 99% for light transmission in the visible region, and in the UV region low percentages were found (0.095 to 0.176%), showing potential for protection of susceptible food to oxidative degradation. The scanning electron microscopy indicated good film uniformity under additivated conditions. Concerning the antimicrobial action, the films were able to cause inhibition against S. aureus and E. coli, being more effective against S. aureus. Thus, the results indicated the potential use of starch as biomaterial, and seriguela residue extract and nanoZnO as bioactive additives.