Plant Essential Oils as Active Antimicrobial Agents

Abstract

Essential oils derived from plants have been recognized for decades to exhibit biological activities, including antioxidant, anticancer, and antimicrobial attributes. Antimicrobial activities of these natural plant materials have been intensively explored in recent years, mainly in response to the overwhelming concern of consumers over the safety of synthetic food additives. Gram-negative organisms are believed to be slightly less sensitive to essential oils than Gram-positive bacteria. Generally, a higher concentration is required to obtain the same efficacy in foods than in synthetic media. The combinations of different types of essential oils or with other food additives have been found to potentially exhibit synergistic if not additive effects. This suggests a cost-efficient and wholesome alternative to both food industry and consumers, at the same time adhering to the hurdle technology in inhibiting proliferation of foodborne pathogens. This review aims to examine the conventional methods commonly used for assessment of antimicrobial activities of essential oils and phytochemicals, the use of these substances as antimicrobials in food products, factors that affect their efficacy, synergism between components or with available food preservatives as well as the challenges and future directions of using essential oils and phytochemicals as natural food preservatives.

Antifungal activity of essential oils extracted from Agastache mexicana ssp. xolocotziana and Porophyllum linaria against post-harvest pathogens

“…Essential oils are volatile secondary metabolites produced in plants that confer protection to the plants from pathogens, insects, and environmental insults such as excessive solar radiation. Extracted essential oils from plants, such as Allium, Cinamomum, Mentha, Origanum and Rosmarinus, have antimicrobial and antiviral activities (Seow et al, 2014); whereas others such as Thymus and Syzigium, have been also used to preserve food (Tongnuanchan and Benjakul, 2014).…”

Essential oils-oriented chiral esters as potential pesticides: Asymmetric syntheses, characterization and bio-evaluation

“…Most essential oils are consisting of a lot of chemical components, and mainly include some terpenes, phenolics and alcohols. In recent years, essential oils have attracted much attention owning to their diverse biological activities (Isman, 2006;Kordali et al, 2008;Bakkali et al, 2008;Regnault-Roger et al, 2012) such as insecticidal (Kumar et al, 2011;Machial et al, 2010;Maciel et al, 2010;Liu et al, 2010), repellent (Gu et al, 2009;Zhang et al, 2011;Mann et al, 2012;Ukeh and Umoetok, 2011), lure (Dev et al, 2010;Kendra et al, 2014), antifeedant (Kumar et al, 2009;Baskar and Ignacimuthu, 2012) activities and growth-reducing effect on a variety of insects (Regnault-Roger and Hamraoui, 1994;Ketoh et al, 2005), as well as excellent antimicrobial activity (Smith-Palmer et al, 1998;Seow et al, 2014;Dhara and Tripathi, 2013). However, most of essential oils are volatile, unstable to light and heat, easy to decompose, et c, and so which are mainly used together with chemical pesticide to reduce the dosage of chemical pesticide nowadays (Abbassy et al, 2009;Wen et al, 2013;Tong and Bloomquist, 2013).…”

Activity of selected essential oils on spoiling fungi cultured from Marzolino cheese

“…Essential oils (EOs) are mixtures of aromatic oily liquids extracted from different parts of plants, usually by steam distillation [3]. Several of them are characterized by antimicrobial activities, mainly due to their content in terpenes and phenylpropanoids [4,5], and have been used both in therapy [6] and to control spoilage flora of foodstuff [7].…”