Combined effects of oregano essential oil and salt on the growth of Escherichia coli in salad dressing

Abstract

There is a broad research interest in the search for alternatives to chemical additives for use as natural food preservatives. Although many natural compounds have biological in vitro properties evidenced, in situ studies are still scarce. This study evaluated the effect of oregano essential oil (OEO) and salt (NaCl) concentrations against Escherichia coli (ATCC 8739), in salad dressing, using the response surface methodology. The experiment included a 2 central composite rotatable design (CCRD) in a total of 11 formulations of salad dressings. Oregano essential oil was characterized by gas chromatography and salad dressings by ash, lipids, proteins and moisture. OEO was composed mainly by carvacrol (65.1%) and p-cymene (12.0%). Salad dressings showed similar chemical profiles. A mathematical model for the prediction of the antibacterial activity in salad dressing was obtained. The results revealed that the interaction between OEO and salt showed effect on the bacterial count. However, the effect of salt was negative suggesting that the highest NaCl concentrations decreases the bacterial count. Therefore, within the parameters studied, the use of OEO to control E. coli in salad dressing can be considered promising and allows reduction in the levels of salt to be incorporated in food.

Multivariate approach in voltammetric identification and simultaneous determination of eugenol, carvacrol, and thymol on boron-doped diamond electrode

“…Carvacrol [2-methyl-5-(propan-2-yl)phenol, cymophenol, isothymol, CAS number: 499-75-2] is a phenolic terpenoid, geometric isomer of thymol, present in the form of yellowish liquid ( Fig. 1) obtained from essential oils of dictamnus (Origanum dictamnus), oregano (Origanum vulgare), and thyme (Thymus vulgaris): the oil contains 42.9-82.3%, 8.6-65.1%, and 2.2-81.5% of carvacrol, respectively [5,[16][17][18][19][20][21][22][23][24][25][26][27]. Other oils rich in carvacrol are obtained from marjoram (Origanum majorana), lemon thyme (Thymus pulegioides), and summer savory (Satureja hortensis); its content in oil is: 2.2-48.7%, 32.8-62.6%, and 34.4-50.6%, respectively [5,22,23,[28][29][30][31].…”

The impact of Qodume Shirazi seed mucilage‐based edible coating containing lavender essential oil on the quality enhancement and shelf life improvement of fresh ostrich meat: An experimental and modeling study

“…In addition, the excessive use of chemical preservatives leads to the development of bacterial resistance against antibiotics. Therefore, the study of natural antimicrobials has also received medical attention (Gonçalves Cattelan et al, 2018).…”

Modeling the Combined Effect of pH, Protein Content, and Mexican Oregano Essential Oil Against Food Spoilage Molds

“…When different essential oils (oregano and thyme) were combined, an additive antimicrobial effect on the bacteria was observed. When NaCl (5 g/100 mL) was added to the media added with starch, water activity decreased, and microbial counts were also reduced (Perricone et al, 2015;Cattelan et al, 2018). When OEO (carvacrol 65.1%) and NaCl were evaluated separately on the growth of Escherichia coli, the effect observed suggested the use of the essential oil with salt reduction in the food products, considering the health problem caused by a high salt intake (Witkowska et al, 2014).…”