No abstract

This study aimed to determine the in vitro and in situ antifungal activity of (14) selected essential oils (EOS), namely clove, thyme, red thyme, litsea, eucalyptus, niaouli, fennel, anise, cumin, basil, rosemary, sage, bergamot mint, and marjoram, by vapor contact against the growth of two strains of Penicillium commune (KMi–183 and KMi–402). Furthermore, to exclude the negative effect of EOs on the lactic acid bacteria (LABs) (Streptococcus spp.) on cheeses, their influence was monitored. Next, the sensory evaluation of cheese treated by EOs was evaluated. The results show that litsea and clove EOs were the most effective in the vapor phase against both tested strains. These EOs were characterized by the highest amount of α- (40.00%) and β-Citral (34.35%) in litsea and eugenol (85.23%) in clove. The antitoxicogenic activity of less effective (in growth inhibition) EOs on cyclopiazonic acid (CPA) production by the tested strains was also observed. The growth of Streptococcus spp. (ranging from 8.11 to 9.69 log CFU/g) was not affected by the EOs in treated cheese. Even though the evaluators recognized some EOs in sensory evaluation by the triangle test, they did not have a negative effect on the taste and smell of the treated cheeses and were evaluated as edible. The antifungal activity of EOs against several types of microscopic fungi and their effect on the sensory properties of treated foods needs to be further tested to achieve the most effective protection of foods from their direct contaminants.

Bread is considered an intermediate - moisture food product that is prone to mould spoilage. Growth of spoilage fungi is currently controlled with the addition of chemical preservatives. Consumers demand more natural products and there is a need to reduce the amount of chemical preservatives added to foods. Essential oils (EOs) and their constituents emerged as promising and effective compounds to protect foods from lipid peroxidation and provide microbiological food safety. So the aim of our study was to determinate microscopic fungi involved in contamination of bread target the genus Eurotium and to evaluate the antifungal activity of 5 EOs by vapor contact against the fungal species of this genus. In all samples after three days of cultivation fungi created colonies on the surface of the crust and the pieces of the bread samples stored on DRBC were after three days of cultivation covered with fungi colonies. Altogether 195 isolates were recovered from 8 bread samples and assigned to 10 fungal genera. The most frequently genus of fungi was Penicillium, Aspergillus, Cladosporium, Epicoccum and Eurotium. Based on phylogenetic and morphological studies, five different Eurotium species were identified: E. amstelodami, E. chevalieri, E. herbariorum, E. rubrum and E. repens. In this study, we explored the potential of five essential oils retrieved from some Lamiaceae species, concretely: basil (Ocinum basilicum L.), lavender (Lavandula angustifolia Mill.), oregano (Origanum vulgare L.), mint (Metha piperita L.) and sage (Salvia officinalis L.). Gas chromatography–mass spectrometry (GC-MS) analysis allowed for the identification of 28 compounds as main constituents. Inhibitory activity of EOs was assessed against 5 species of genus Eurotium (2 isolates for each specie). In all studied strains, the essential oils caused significant differences (Pbasil (with the best Mycelial growth Inhibition (MGI) 93.65% to E. herbariorum) and the low effect had sage essential oil (with the best MGI 68.62% to E. repens). The present study demonstrated the potential food preservative ability of essential oils from some Lamiaceae species.

The aim of this study was to evaluate the fungicidal effect of eleven essential oils against six isolates of the genus Rhizopus. Isolates were obtained from various moldy foods (chestnut, bread, strawberry, nectarine, blackberry and cherry tomatoes). The essential oils used in this study were extracts of basil (Oscimum basilicum L.), hyssop (Hyssopus officinalis L.), lavender (Lavandula angustifolia MILLER.), marjoram (Origanum majorana L.), mint (Mentha piperita L.), oregano (Origanum vulgare L.), rosemary (Rosmarinus officinalis L.), sage (Salvia officinalis L.), summer savory (Satureja hortensis L.), thyme (Thymus vulgaris L.) and wild thyme (Thymus serpyllum L.). Semi-quantitative composition of the essential oil samples was determined by gas chromatography coupled with mass spectrometry (GC-MS). The GC-MS analyses of the essential oils led to identification of 139 compounds, of which 49 were presented in ≥1% amount in at least one essential oil. The antifungal activity of essential oils against the Rhizopus spp. was determined, using microatmosphere method (0.625 μL.ml -1 of air), during 7 days. Seven essential oils: thyme, mint, summer savory, lavender, marjoram, oregano and wild thyme completely inhibited the growth of all isolates. Other essential oils have different effects on the growth of isolates. Basil essential oil stimulated growth of two isolates on the second day of cultivation. The growth of other isolates was, by contrast, inhibited by this essential oil in the same time of cultivation. Hyssop essential oil completely inhibited growth of two isolates, other 4 isolates were inhibited to fourth day of cultivation. In conclusion, certain essential oils are highly effective in vapour phase and can be used in another test of their antifungal activity and could be used in control of Rhizopus spp. or other fungal pathogens.

This paper was focused on the determination of the inhibitory effect of selected essential oils on growth of ten isolates of Aspergillus flavus and their potential ability to produce mycotoxins in vitro by TLC method. The isolates were obtained from moldy bread of domestic origin. We followed the impact of five essential oils at 100% concentrationlemon, eucalyptus, oregano, sage and thyme. The effect of the essential oils we tested the gaseous diffusion method. We isolates grown on CYA (Czapek yeast extract agar), in the dark at 25 1 °C, 14 days. The diameter of colonies grown we continuously measured on the 3 rd , 7 th, 11 th , and 14 th day of cultivation. The results of the paper suggest that oregano and thyme essential oil had 100% inhibited the growth of all tested isolates of Aspergillus flavus. Lemon, eucalyptus and sage essential oil had not significant inhibitory effects on tested isolates Aspergillus flavus, but affected the growth of colonies throughout the cultivation. In addition to the inhibitory effect we witnessed the stimulative effect of lemon, eucalyptus and sage essential oil to some isolates. Together with the antifungal effect of essential oils, we monitored the ability of Aspergillus flavus isolates to produce mycotoxinsaflatoxin B 1 (AFB 1 ) and cyclopiazonic acid (CPA) in the presence of essential oils. Production mycotoxins we have seen in the last (14 th ) day of cultivation. Lemon and eucalyptus essential oil did not affect the production of mycotoxins. In the case of sage essential oil we were recorded cyclopiazonic acid production in three of the ten isolates from the all three repetitions, while neither isolate did not produced aflatoxin B 1 . The production of secondary metabolites was detected in all control samples. From the results we can say that oregano and thyme essential oil could be used as a natural preservative useful in the food industry.