Microbial inactivation of paprika using oregano essential oil combined with high-pressure CO2

•Oregano essential oil (OEO) was evaluated against the spores of paprika.•OEO sporicidal activity could not be established up to 3% w w−1.•A combined treatment of high-pressure CO2 with 2.6% OEO at 80 °C was tested.•At 35% humidity and 30 min time, microbial reduction was 99.5%.•Extra HPCD flow removed the excess OEO to produce an acceptable sensory effect.

This work evaluated the use of oregano essential oil (OEO) in isolation and in combination with high-pressure carbon dioxide (HPCD) to reduce the microbial count of paprika. When applied in isolation, the OEO treatment did not inactivate paprika’s natural spore population to a satisfactory level. A combination of OEO and HPCD was then tested. CO2 at 100 bar and 80 °C was mixed with the OEO before being continuously passed through the paprika for 30 min. To facilitate the germination of the bacterial spores, the test was repeated with paprika samples of varying humidity. Combining OEO with HPCD increased the microbial inactivation of paprika by 99.5%. But according to a sensory evaluation, the maximum acceptable OEO level in paprika was 200 ppm (0.02%). To remove excess OEO and water, HPCD was passed in isolation for an additional 20 min. This was sufficient to make the odor of OEO imperceptible in the paprika.

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