Encapsulation of Rosmarinus officinalis essential oils in chitosan-benzoic acid nanogel with enhanced antibacterial activity in beef cutlet against Salmonella typhimurium during refrigerated storage

In the present study, encapsulation by chitosan (CS)-benzoic acid (BA) nanogel was used to improve antioxidant and antimicrobial activity as well as stability of the Rosmarinus officinalis essential oils (REOs). The mean diameter of the gel nanoparticles produced was below 100 nm with a uniform size distribution and spherical shape. Subsequently, the antibacterial activity of the coatings including free REOs and CS-BA nanogel-encapsulated REOs against Salmonella typhimurium was evaluated on inoculated beef cutlet samples. The results obtained showed that the CS-BA nanogel-encapsulated REOs coating was more effective compared with the free REOs in reducing Salmonella population on beef cutlets under refrigerated storage. Nano-encapsulation at 2 mg/g beef cutlet had the most promising effect on reducing the pathogens population. Moreover, nano-encapsulation led to least impact on increasing pH of the beef cutlet samples. CS-BA nanogel-encapsulated REOs at 0.5 mg/g beef cutlet had minimum effects on the color values during storage. Overall, the results obtained revealed that due to the volatility and instability of the EOs when exposed to environmental factors, their encapsulation considerably improved their performance. In conclusion, REOs in form of nanogel can be used as an effective tool to reduce foodborne pathogens like S. typhimurium and in extending meat shelf life. (C) 2017 Elsevier Ltd. All rights reserved.