Composition, Diffusion, and Antifungal Activity of Black Mustard (Brassica nigra) Essential Oil When Applied by Direct Addition or Vapor Phase Contact

Abstract

In this study, we characterized the essential oil (EO) of black mustard (Brassica nigra) and quantified its antimicrobial activity, when applied by direct contact into the liquid medium or by exposure in the vapor phase (in laboratory media or in a bread-type product), against the growth of Aspergillus niger, Aspergillus ochraceus, or Penicillium citrinum. Allyl-isothiocyanate (AITC) was identified as the major component of B. nigra EO with a concentration of 378.35 mg/ml. When B. nigra EO was applied by direct contact into the liquid medium, it inhibited the growth of A. ochraceus and P. citrinum when the concentration was 2 μl/ml of liquid medium (MIC), while for A. niger, a MIC of B. nigra EO was 4 μl/ml of liquid medium. Exposure of molds to B. nigra EO in vapor phase showed that 41.1 μl of B. nigra EO per liter of air delayed the growth of P. citrinum and A. niger by 10 days, while A. ochraceus growth was delayed for 20 days. Exposure to concentrations ≥ 47 μl of B. nigra EO per liter of air (MIC) inhibited the growth of tested molds by 30 days, and they were not able to recover after further incubation into an environment free of EO (fungicidal effect). Adsorbed AITC was quantified by exposing potato dextrose agar to B. nigra EO in a vapor phase, exhibiting that AITC was retained at least 5 days when testing EO at its MIC or with higher concentrations. Mustard EO MIC was also effective against the evaluated molds inhibiting their growth for 30 days in a bread-type product when exposed to EO by vapor contact, demonstrating its antifungal activity.

Essential oils used in aromatherapy: A systemic review

“…Many plants like M. piperita, black mustard (Brassica nigra), Angelica archangelica, Cymbopogon nardus, Skimmia laureola, Artemisia sieberi and Cuminum cyminum have been tested positive for their antifungal activity. They are in the initial phase of clinical trials and if the results are as per the expectation, they will be a very good alternative for existing antifungal drugs which are not frequently used for their toxic systemic effects [86][87][88][89][90][91].…”

Effect of chitosan and alginate beads incorporated with lavender, clove essential oils, and vanillin against Botrytis cinerea and their application in fresh table grapes packaging system

“…Lavender EO could also effectively inhibit B cinerea , and its antifungal effect was synergized by vanillin . Rosemary is very effective EO in reducing the severity of grey mould . However, the main components in EOs are volatile compounds, which easily evaporate and decompose during handling, owing to direct exposure to pressure, heat, light, or oxygen.…”

“…These severe environments induce the loss of activity of the active components. In addition, the application of EOs in the vapour phase was reported to provide higher efficiency in inhibiting fungal growth than in the liquid phase and required significantly lower amounts to achieve the same antifungal effect compared with the use in the liquid phase …”

“…4 Rosemary is very effective EO in reducing the severity of grey mould. 5 However, the main components in EOs are volatile compounds, which easily evaporate and decompose during handling, owing to direct exposure to pressure, heat, light, or oxygen. These severe environments induce the loss of activity of the active components.…”

“…In addition, the application of EOs in the vapour phase was reported to provide higher efficiency in inhibiting fungal growth than in the liquid phase and required significantly lower amounts to achieve the same antifungal effect compared with the use in the liquid phase. 5,6 Encapsulation is an alternative way to retain the functional properties of EOs by protecting these active compounds from degradation, oxidation, or evaporation. In encapsulant materials, normally, the polymer matrix plays an important role as a carrier for the delivery or controlled release of the active molecules under specific conditions.…”