Antimicrobial activity of Carum copticum and Satureja khuzestanica essential oils and acetic acid in vapor phase at different relative humidities and temperatures in peanuts

The impact of relative humidity (RH) and temperature on the effectiveness of acetic acid (AC) and essential oils of Carum copticum and Satureja khuzestanica in the vapor phase against pathogens was investigated. Inoculated peanuts were exposed to antimicrobial vapors at three humidity levels (63 ± 1, 75 ± 0, and 84 ± 1%) and three temperatures (25, 37, and 50°C) for 0, 1, and 2 hr. Results showed that increasing the RH, temperature, and fumigation time significantly affected the inhibition rate of the mentioned vapors. The highest inhibitory effect was observed under vaporizing condition including 84 ± 1% RH and 50°C, which reduced the initial population of Bacillus cereus, Staphylococcus aureus, Shigella dysenteriae, and Salmonella Typhi (8.1–8.3 log CFU/g) to 1.1, 0.5, 2.7, and 1.0 log CFU/g after 2 hr exposure to AC vapors, respectively. The results provide a promising approach to increase the inhibition rate of antimicrobial compounds in the vapor phase. Novelty impact statement Increasing the RH significantly enhanced the inhibition rate. The microbial inactivation level is enhanced with the increase of temperature. Vapors of AC exhibited higher antimicrobial activity than the two studied essential oils.