Capability of thyme natural antimicrobials (NAs) to reduce the intensity of high pressure processing (HPP) and
enhance the inactivation of Listeria monocytogenes in fresh cheese was investigated. Thyme extracts were obtained
by supercritical fluid extraction at 30 MPa and 40 MPa and their concentration was estimated in units of carvacrol
(190.44–609.57 μg/mL). The acceptable sensorial threshold of thyme extract in cheese was 0.2% (v/w), a
value lower than the MIC for L. monocytogenes. Detailed kinetic studies of L. monocytogenes inactivation in cheese
were performed following HPP (200–300 MPa) treatments. A maximum 1.68-log10 CFU/g supplementary reduction
was achieved for L. monocytogenes in cheese with HPP & NAs than without NAs. The kinetic parameter zp indicated
an accelerated inactivation of L. monocytogenes when HPP was combined with thyme NAs, as hurdle
applied to fresh cheese (55.99 MPa for HPP and 33.29 MPa for HPP with thyme NAs).
Industrial relevance: Applied as a post-processing treatment high pressure processing (HPP) is considered an effective
listericidal tool that produces limited quality changes in foods compared to other preservative methods. In
order to overcome the main drawback related to HPP effect on cheese structure, a combination of pressure with
natural antimicrobials (NAs) is proposed for reducing the intensity of processing while improving microbiological
safety of food. The efficacy of L. monocytogenes inactivation in cheese by HPP and HPP with NAs from thyme
was kinetically evaluated and modeled in the present work. The current results provide support for the industrial
development of more effective combined HPP with NAs treatment, able to minimize the risk of Listeria presence
in cheese.