RESUMO
For many years, garlic has been used as a condiment in food and traditional medicine. However, the garlic skin, which accounts for 25% of the garlic bulk, is considered agricultural waste. In this study, cellulose nanocrystals (CNCs) and garlic extract (GE) from garlic skin were isolated and used as fillers to manufacture biocomposite films. The films were characterized in terms of UV barrier, thermal, mechanical, biodegradability, and antimicrobial activity. The chitosan-containing films and CNCs have significantly improved the films' tensile strength, Young's modulus, and elongation but decreased the film transparency compared to chitosan films. The combination of the CNCs and GE, on the other hand, slightly reduced the mechanical properties. The addition of CNCs slightly decreased the film transparency, while the addition of GE significantly improved the UV barrier properties. Thermal studies revealed that the incorporation of CNC and GE had minimal effect on the thermal stability of the chitosan films. The degradability rate of the chitosan composite films was found to be higher than that of the neat chitosan films. The antimicrobial properties of films were studied against Escherichia coli, Streptomyces griseorubens, Streptomyces alboviridis, and Staphylococcus aureus, observing that their growth was considerably inhibited by the addition of GE in composite films. Films incorporating both CNCs and GE from garlic skin hold more promise for active food packaging applications due to a combination of enhanced physical characteristics and antibacterial activity.
Assuntos
Anti-Infecciosos , Quitosana , Alho , Nanopartículas , Antibacterianos/química , Antibacterianos/farmacologia , Anti-Infecciosos/química , Anti-Infecciosos/farmacologia , Antioxidantes/química , Celulose/química , Quitosana/química , Escherichia coli , Embalagem de Alimentos , Nanopartículas/químicaRESUMO
Phytopathogenic bacteria affect a wide variety of crops, causing significant economic losses. Natural biocides are the alternative to chemical methods of phytopathogens control. The goal of the present study is the evaluation of the biocidal activity of the following: 1) the extract of orange wax (EOW); 2) zinc ferrite nanoparticles (ZF-NPs); 3) the EOW adsorbed on the ZF-NPs; and 4) the EOW/ZF-NPs washed with 40% ethanol. For the biocidal activity, three phytopathogenic bacteria were used, namely, Xanthomonas axonopodis pv. Vesicatoria (Xav) Erwinia amylovora (Ew), and Pseudomonas syringae pv. Phaseolicola (Psph). For the ZF-NPs, an inhibitory effect higher than 50% ( ) was observed for Xav respect to the antibiotic used as positive control. On the other hand, the ZF-NPs did not show inhibitory effects on both Ew and Psph. In addition, the EOW in dimethyl sulfoxide (DMSO) at 100% caused growth inhibition on Xav, bacteriostatic activity on Ew, and had not biological activity on Psph. To the best of our knowledge, the control of Xav by zinc ferrites and orange wax, and the bacteriostatic effect produced by orange wax extract on Ew have not been reported elsewhere. Orange wax and zinc ferrite nanoparticles show potential in control of phytopathogenic bacteria. However, the bactericidal effect depends on the bacterium, the concentration of treatments, and the method of preparation.