Aplicação de filmes com nanopartículas de prata na conservação de morangos
Resumo
The consumption of fruits and vegetables has been growing due to the efforts for a
healthier diet. In this context, strawberry can be highlighted for its nutritional value and
for being a tasty and attractive fruit. However, on Brazil conditions, for being harvested
near its physiological maturity, losses in post-harvest quality are high. Polymeric films
containing metal nanoparticles (NPs) have been used in food packaging, once they
present properties that contribute in maintaining the quality of fruits and vegetables. For
instance, silver nanoparticles (AgNPs) stands out for its antimicrobial action. The goal
of this work was to evaluate the post-harvest quality of strawberries packed in
polymeric films containing AgNPs and conventional net polymeric films (without NPs).
For this purpose, commercial low-density polyethylene films (LDPE) containing
AgNPs were characterized by scanning electron microscopy (SEM), Infrared
Spectroscopy Fourier Transform (FTIR), thermogravimetry (TGA), Differential
Scanning Calorimetry (DSC) and X-Ray Diffraction (XRD), antimicrobial activity tests.
For evaluating the films influence on the physical-chemical and microbiological quality
of strawberry, the following experiments were performed: (I) strawberry packaged in
LDPE and LDPE+AgNP films were stored in cold chamber at 5 and 25 °C for nine
days, where physical-chemical and microbiological analyzes were carried out at every
three days; (II) Strawberry packaged by LDPE and LDPE+AgNP films were stored in
cold chamber at 5 and 25 °C for nine days, and were submitted to the same physicalchemical
analysis. To investigate in more details the antimicrobial effects of packaging,
two experiments were carried out with strawberry inoculated by E. coli: (III) firstly,
strawberry inoculated with E. coli with an initial concentration of 108 CFU mL-1 were
stored at 5°C for ten days; subsequently, the physical-chemistry and microbiological
analyses were carried out; and (IV) strawberry inoculated with E. coli with an initial
concentration at 105 CFU mL-1 were stored at 10°C for ten days; subsequently, the
microbiological analyses were carried out at every two days. Adding AgNPs on LDPE
matrix did not influence the thermal and physical-chemical properties of films. Films
containing AgNPs showed antimicrobial activity against Gram-positive and Gramnegative
microrganims. Physical-chemical quality of strawberry was affected mainly by
temperature and storage period. AgNPs contained in LDPE packaging was efficient on
controlling microbial population growth. Antimicrobial activity and post-harvest quality
attained by polyetilene films containing AgNPs may be an indicative for using such
Aplicação de filmes com nanopartículas de prata na conservação de morangos
type of active packing for other fruits and vegetables, which can help decreasing post
harvest losses, and may contribute to improve food safety.