Main content area

Nanoemulsions of Mentha piperita L. essential oil in combination with mild heat, pulsed electric fields (PEF) and high hydrostatic pressure (HHP) as an alternative to inactivate Escherichia coli O157: H7 in fruit juices

de Carvalho, Rayssa Julliane, de Souza, Geany Targino, Pagán, Elisa, García-Gonzalo, Diego, Magnani, Marciane, Pagán, Rafael
Innovative food science & emerging technologies 2018 v.48 pp. 219-227
Escherichia coli O157, Mentha piperita, adverse effects, anti-infective agents, antimicrobial properties, droplets, electric field, essential oils, food preservation, food safety, guavas, heat, high pressure treatment, juice quality, mango juice, nanoemulsions, synergism
This study was performed in order to obtain and characterize nanoemulsions of Mentha piperita L. essential oil (n-MPEO) to assess its efficacy in combination with mild heat (MHT) (50, 52, 54 °C; 10 min), pulsed electric fields (PEF) (20, 25, 30 kV/cm; 150 μs), and high hydrostatic pressure (HHP) (150, 200, 300 MPa; 15 min) treatments in causing a 5- log10 reduction in survival counts (from 7 to <2 log10 CFU/mL) of Escherichia coli O157:H7 in guava and mango juices. The droplets of n-MPEO were < 200 nm and showed good stability for 4 months at 4 °C. The n-MPEO at 5.0 μL/mL displayed a more efficacious long-term antimicrobial activity than suspensions of MPEO (s-MPEO). Combined treatments of s-MPEO or n-MPEO and MHT, PEF, or HHP acted synergistically against E. coli. Nevertheless, combined treatments with n-MPEO showed the same or even higher efficacy than those with s-MPEO (up to 1- additional log10 reduction). Thus, by using nanoemulsions, lower doses of antimicrobial compounds (up to 4 times) or milder MHT (up to 4 °C), PEF (up to 5 kV/cm) and HHP (up to 100 MPa) treatments can be applied, while still guaranteeing the microbial safety of tropical fruit juices.The exploration of a series of different delivery systems of antimicrobial compounds in food products improves their antimicrobial efficacy and aids in the establishment of successful combined treatments for food preservation. The preparation of nanoemulsions of MPEO not only enhances the compound's stability, but also its antimicrobial efficacy (20% reduction in treatment time as compared with non-emulsified MPEO). Valuable synergistic effects that can be observed when combining n-MPEO with MHT, PEF, or HHP (up to 2.5- additional log10 reductions) reveal alternatives to traditional treatments that are successful because they help reduce treatment intensity, thereby helping to avoid adverse effects on juice quality without compromising food safety.