Antimicrobial active edible coating of alginate and chitosan add ZnO nanoparticles applied in guavas (Psidium guajava L.)

Nanostructured coatings made with chitosan (100%Q), alginate (100%A) and blends of 50%Q-50%A; 90% Q-10%A and 90%A-10%Q, were added with (1%v/vgel) of nanoZnO and applied to guavas (Psidium guajava L.). After the coating application, fruits were stored for 15 days at 21 +/- 1 degrees C and 80 +/- 2% RH. To determine the effect on ripening process, fruits were submitted to water loss, texture, color, rot index, and physic-chemical assays. The results showed that coatings are able to prevent rot appearance in every sample, corroborating with the antibacterial action of nanoZnO. Coatings made with alginate and 90%A did not delay the maturation process, however, chitosan matrices (100%Q or 90%Q) protected fruits against excessive mass loss and retarded physic-chemical changes related to maturation. The experiment or study showed that it is possible to extend guava shelf life with ZnO nanostructured coatings with 100%Q or 90%Q-10%A for up to twenty days versus seven days of uncoated fruits.