Study on the Sustainability Potential of Thyme, Oregano, and Coriander Essential Oils Used as Vapours for Antifungal Protection of Wheat and Wheat Products

Abstract

This study aims to highlight the antifungal, antimicotoxigenic potential and phytotoxic effect of three essential oils (EOs) of Origanum vulgare (OEO), Thymus vulgaris (TEO), and Coriandrum sativum (CEO) on wheat storage, but also the impact of EOs treatment on the sensory properties of bakery products obtained from the wheat seeds. The chemical composition of EOs was determined using GC-MS analysis; the fungal load was evaluated using the direct plating technique, while mycotoxin analyses were conducted using enzyme-linked immunosorbent assay (ELISA). A selective antifungal effect has been highlighted in terms of the action of EOs vapours. OEO and TEO are inhibited Alternaria, Fusarium and Drechslera, while Saccharomyces and Cladosporium have proven to be the most tolerant fungi. Drechslera is the most sensitive, the effect of all EOs being a fungicidal one. However, the fungicidal effect proved present in all EOs applied as vapours with values ranging between 0.2–0.4%. Regarding the phytotoxic effect of EOs vapours on the germination of the seeds, TEO and OEO had an inhibitory effect, especially at 0.4%. The effect is cumulative over time. The EOs inhibited deoxynivalenol (DON) occurrence; the maximum percentage of inhibition was obtained after 21 days of vapours exposure, being more effective in the case of 0.2%. EOs vapours treatment does not affect the quality of bread obtained from treated wheat seeds from a sensory point of view.

Natural Emulsions Based on Essential Oils as Antifungal and Antimycotoxicogenic Agents on Wheat for Bakery Industry

“…The composition of the emulsions is presented in Table 1 . The concentration of the EOs was selected based on an extensive literature search and several experimental tests previously conducted by our group [ 24 , 26 ]. The composition of the emulsions was determined after establishing the minimum concentration with fungistatic effect (CMFs) and the minimum concentration with fungicidal effect (CMFg) of the EOs against Fusarium graminearum , the most important fungal pathogen on wheat for bakery products, as described in Section 2.6 .…”

“…The seed treatment was performed according to a previous study [ 24 ]. The wheat seeds (Antille variety) were washed with 1:9 ( v / v ) sodium hypochlorite solution to remove opportunistic microorganisms, and the seeds were rinsed three times with sterile distilled water and dried at 100 °C until a relative humidity of 14%.…”

“…The method used to detect the fungal growth involved the direct plating technique on dichloran rose bengal chloramphenicol (DRBC) medium (Oxoid, CM0727, Thermo Fisher Scientific Inc., Hemel Hempstead, England) [ 24 ]. After the exposure of wheat seeds to vapours of different EO mixtures and emulsions, the Petri plates were incubated in the dark at 22 °C for 3–4 days, and then the number of colonised seeds was registered at 7, 14, 21, and 28 days.…”

“…Previous studies have shown the antifungal potential of EOs extracted from Origanum sativum (oregano), Coriandrum sativum (coriander), and Thymus vulgaris (thyme) [ 6 , 23 ]. The fungicidal effect of these EOs, their potential to control storage fungi, and the prevention of DON mycotoxins in cereals and cereal products were argued [ 24 ].…”

“…Based on our previous results that demonstrated the antifungal and antimycotoxicogenic potential of coriander, thyme, and oregano EOs [ 24 ], in this study we aimed, on the one hand, to evaluate the synergistic/antagonistic effects of combining previously analysed EOs and, on the other, to obtain natural emulsions based on binary and tertiary mixtures of EOs and to test them in terms of their antifungal and antimycotoxicogenic effects.…”