RESUMEN
Silver nanoparticles have high potential for application in food industry, as they have the ability to inhibit a wide range of bacteria of pathogenic and spoilage origin. They can be obtained from different methods classified in physical and chemical and which are aggressive with the environment since they produce toxic waste. Nowadays, environmentally friendly methods such as green synthesis can be used, through the use of agri-food waste. The use of these wastes is a more sustainable method, because it reduces the environmental pollution, at the same time that silver nanoparticles are obtained. The aim of the present study is the green synthesis of silver nanoparticles using safflower (Carthamus tinctorius L.) aqueous extract from waste and its antibacterial activity on Staphylococcus aureus (Gram positive) and Pseudomonas fluorescens (Gram negative). The analyses by TEM showed that the as-synthesized silver nanoparticles were uniform and spherical particles with an average diameter of 8.67 ± 4.7 nm and confirmed by SEM. The electron diffraction and TEM analyses showed the characteristic crystallinity of silver nanoparticles. FTIR spectroscopy confirmed that various functional groups were responsible for reducing and stabilizing during the biosynthesis process. Nanoparticles inhibited the growth of both types of bacteria from the lowest concentration evaluated (0.9 µg/mL). We conclude that silver nanoparticles synthesized in the present study have potential application as antibacterial agents in food and medicine industry.
RESUMEN
Chitosan was functionalized with epigallocatechin gallate (EGCG) by a free radical-induced grafting procedure, which was carried out by a redox pair (ascorbic acid/hydrogen peroxide) as the radical initiator. The successful preparation of EGCG grafted-chitosan was verified by spectroscopic (UV, FTIR and XPS) and thermal (DSC and TGA) analyses. The degree of grafting of phenolic compounds onto the chitosan was determined by the Folin-Ciocalteu procedure. Additionally, the biological activities (antioxidant and antibacterial) of pure EGCG, blank chitosan and EGCG grafted-chitosan were evaluated. The spectroscopic and thermal results indicate chitosan functionalization with EGCG; the EGCG content was 25.8mg/g of EGCG grafted-chitosan. The antibacterial activity of the EGCG grafted-chitosan was increased compared to pure EGCG or blank chitosan against S. aureus and Pseudomonas sp. (p<0.05). Additionally, EGCG grafted-chitosan showed higher antioxidant activity than blank chitosan. These results indicate that EGCG grafted-chitosan might be useful in active food packaging.
