Evaluation of the Impact of Varied Carvacrol Concentrations on Salmonella Recovery in Oregano and How Corn Oil Can Minimize the Effect of Carvacrol during Preenrichment

Abstract

Phenolic compounds, like carvacrol, in oregano interfere with the detection of foodborne pathogens such as Salmonella enterica. Carvacrol concentration varies based on plant cultivars and growth region. Six oregano cultivars were used to compare the impact of carvacrol concentration on Salmonella and to evaluate the effectiveness of corn oil to help increase Salmonella survival for detection. The results of Agilent 1200 series high-performance liquid chromatography analysis showed that carvacrol concentration in the six oregano cultivars ranged from 64 to 11,200 ppm. Oregano samples were artificially contaminated with S. enterica and were preenriched in Trypticase soy broth with or without 2% (v/v) corn oil. After 18 to 24 h at 37°C, aliquots were transferred to selective enrichment broths. Salmonella was recovered onto xylose lysine Tergitol 4 agar. Six Salmonella serovars were compared, and recovery varied based on carvacrol concentration and serovar. Samples with higher concentrations of carvacrol showed Salmonella recovery only when they were preenriched with corn oil. Based on metagenomic analysis, the microflora associated with the oregano also varied per cultivar. The results show that, as carvacrol levels increased, Salmonella survival decreased. However, the addition of corn oil to the preenrichment broth can minimize the antimicrobial effects of the phenolic compounds, thus allowing for increased detection of Salmonella from oregano cultivars.

Carvacrol ameliorates acute campylobacteriosis in a clinical murine infection model

“…The antimicrobial properties of carvacrol directed against food-borne pathogens such as C. jejuni [26,29,30,37] Salmonella spp. [37,[43][44][45], Escherichia coli O157:H7 [46] and Bacillus cereus [47,48] have been shown in vitro recently. Synthetic carvacrol was, however, more effective against Gram-negative bacteria than against Gram-positive species [49].…”

Therapeutic application of carvacrol: A comprehensive review

“…The synergic effects of carvacrol with thymol have the higher antibacterial and efflux pump inhibiting capacities in the case of foodborne pathogens (Miladi et al, 2016 ). Beaubrun et al ( 2018 ) showed that carvacrol exhibited antimicrobial activity against S. enterica pre‐enriched with or without 2% (v/v) corn oil.…”