This work provides details regarding the physicochemical, antimicrobial and antioxidant properties of poly(vinyl chloride) (PVC)-based films containing 0.4% quercetin and silver nanoparticles (AgNPs) at various concentrations levels. The incorporation of quercetin and AgNPs into the PVC matrix considerably affected the thermal, mechanical and optical properties of the films. Results obtained from the tensile stresgth test, demonstrated an improvement in the mechanical strength of the films after the incorporation of both quercetin and AgNPs. Moreover, an increase in AgNPs concentration increased the rigidity, as compared to control PVC film. Antimicrobial activity against food pathogens (Escherichia coli, Salmonella Typhimurium and Listeria monocytogenes) was evaluated by an antimicrobial barrier test. Results showed that the PVC-based films with quercetin and AgNPs proved to be highly effective to inhibiting bacterial growth. Therefore, these results indicate promising evidence to possibly aid in the prevention of microbial dissemination in foods. Additionally, films incorporated with quercetin and AgNPs expressed an antioxidant capacity when evaluated via the DPPH method. Among all of the films evaluated, the PVC-based films containing 0.4% quercetin and 1% AgNPs were flexible, exhibiting excellent UV-light barrier properties and for use with fatty foods, with the intent of reducing lipid oxidation and preventing food pathogen dissemination.

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SUMMARYThe performance of oxygen scavengers can be infl uenced by several conditions, such as temperature (T) and relative humidity (RH), which are considered to be the two major factors. Therefore, the development of new scavengers requires the study of their performance, with these conditions varied. In this paper, the response surface methodology (RSM) was used to study the performance of a newly developed oxygen scavenger sachet and to model the infl uences of T and RH and their interaction on the absorption capacity and rate constant of the developed sachet. Commercial oxygen scavenger sachets were used for comparison purposes. The oxygen absorption capacity and rate constant were evaluated with a 2 2 factorial design with a central point. The results showed that each absorber sachet presented a different behaviour and there were signifi cant interactions between T and RH; so, the RSM was the most appropriate for these studies. The developed sachet presented a better performance compared with the commercial ones at 23°C and 53% RH, which represents the condition for commercialization at room temperature of foods of intermediary water activity, while in the extreme conditions (100% RH and 37°C) all sachets present a similar absorption capacity.

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A bi-functionalized molecularly imprinted silica (MIS) was prepared for solid phase extraction of quercetin.