Search

The questionable safety of food spoiled by microorganisms is and should be the subject of attention and investigation. Pathogens such as Penicillium expansum are more difficult to control due to their resistance and ubiquity. Awareness of plant essential oils (EOs) as alternative natural preservatives is increasing because of their significant antimicrobial activity. The aim of this research work was therefore to contribute to this topic with new results. The antifungal activity of twelve EOs was tested in vitro against five strains of Penicillium expansum, using the vapour-phase diffusion method. Three EOs, from bergamot, star anise and rosaline, inhibited colony growth during two-week cultivation with a partial efficacy, all other EOs showed complete (100%) inhibitory activity at a concentration of 625 μL.L-1. These (EOs from clove, cinnamon, cinnamon bark, laurel, lemongrass, peppermint, Mitcham mint, spearmint, and lavender) were included in the second part of the trial, the aim of which was to determine their minimum inhibitory doses (MIDs). In the case of peppermint, Mitcham mint, spearmint and lavender EOs, some strains of P. expansum grew already at a concentration of 500 μL.L-1. Clove EO stopped the fungal growth of two strains at 250 μL.L-1. Laurel EO was 100% effective at MID 250 μL.L-1 throughout the cultivation period. EOs from lemongrass and cinnamon bark had similar efficacy on the strains. Both EOs were able to inhibit one strain at a MID of 125 μL.L-1, cinnamon bark EO inhibited the remaining strains at 250 μL.L-1, lemongrass EO inhibited three strains at 250 μL.L-1 and one at 500 μL.L-1. The lowest MID was recorded for cinnamon EO, which effectively inhibited two strains at 125 μL.L-1, two strains at 62.5 μL.L-1 and one strain even at 31.25 μL.L-1. The sensitivity of the strains used in this study varied according to the EOs used. [ABSTRACT FROM AUTHOR]

Essential oils (EOs) are a suitable alternative for extending the shelf life of foods. The aim of this research was to test the effect of fifteen EOs extracted from plants of the Lamiaceae family on five strains of Cladosporium cladosporioides. Cladosporium cladosporioides is frequently found on fruit and may be involved in fruit spoilage. The strains used in the study were isolated directly from lesions on berries. The growth of the fungi on the fruit was the reason for its rejection from sale. The antifungal activity of EOs against Cladosporium cladosporioides strains was determined by the microatmospheric method (625 μl EO/L air) during 14 days of cultivation. Thirteen EOs: thyme and red thyme (from Thymus vulgaris L.), mitcham mint (Mentha x piperita L. var. Mitcham), peppermint (Mentha x piperita L.), savory (Satureja hortensis L.), sage (Salvia officinalis L.), spearmint (Mentha spicata L. var. crispa), lavender (Lavandula angustifolia Mill.), marjoram (Origanum majorana L.), bergamot-mint (Mentha citrata Erh.), wild thyme (Thymus serpyllum L.), hyssop (Hyssopus officinalis L.), and oregano (Origanum vulgare L.) were shown to inhibit growth of all strains to 100%. Basil (Ocinum basilicum L.) and rosemary (Rosmarinus officinalis L.) EOs did not have a 100% inhibitory effect on all strains throughout the cultivation period. Subsequently, minimum inhibitory concentrations (MIDs) were determined using the microatmospheric method. LD90 and LD50 values were estimated by probit analysis. Based on the MID, LD90, and LD50 results, the essential oils can be divided into three groups. The first group (most effective): thyme, red thyme, spearmint, wild thyme, and oregano EO; the second group: peppermint, lavender, mitcham mint and savory EO; the third group: sage, marjoram, bergamot-mint and hyssop EO. The most effective EOs can be used to suppress the growth of Cladosporium cladosporioides in the vapour phase. [ABSTRACT FROM AUTHOR]

In this study, contamination by microscopic fungi (focused on Penicillium and Aspergillus species) of 75 fruit samples (strawberries, blackberries, blueberries, raspberries, grapes) and 29 tomato samples, which were obtained from Slovak stores was investigated. Totally 93.3% of fruit samples were contaminated with micromycetes (70.6% Botrytis spp., 52.0% Cladosporium spp., 42.7% Penicillium spp., 13.3% Rhizopus spp., 8.0% Alternaria spp., 6.7% Mucor spp., 5.3% Aspergillus spp., 4.0% Fusarium spp., and 1.3% Epicoccum spp.) and 6.7% of samples were contaminated with yeasts. The presence of 15 species of the genus Penicillium in fruits, namely P. atramentosum, P. aurantiogriseum, P. brevicompactum, P. bialowiezense, P. citrinum, P. crustosum, P. digitatum, P. expansum, P. fellutanum, P. glabrum, P. hordei, P. italicum, P. kiamense, P. olsonii, and P. purpurescens was found. With the highest frequency, P. brevicompactum (12.0%) and P. expansum (10.7%) were isolated from fruits. Four isolates of the genus Aspergillus were isolated from fruit samples (A. section Clavati, A. section Flavi, and two isolates of A. section Nigri). Thin layer chromatography (TLC) was used for testing of mycotoxin production by selected fungal isolates. Overall, 93.3% of tested Penicillium isolates and one tested Aspergillus of section Clavati proved the ability to produce at least one of the tested mycotoxins. As for tomato samples, 93.1% were contaminated with microscopic filamentous fungi (79.3% Penicillium spp., 24.1% Botrytis spp. and Alternaria spp., 10.3% Cladosporium spp., Mucor spp. and Rhizopus spp., 6.9% Aspergillus spp. and 3.4% Fusarium spp.) and 6.9% samples were contaminated with yeasts. In 65.5% of tomato samples, the occurrence of 8 species of the genus Penicillium (P. brevicompactum, P. crustosum, P. expansum, P. griseofulvum, P. italicum, P. olsonii, P. sublectaticum, P. thomii), and two species of the genus Aspergillus (from section Circumdati and Flavi) was recorded. P. olsonii (58.6%) and P. griseofulvum (10.3%) were isolated with the highest frequency. All 7 tested Penicillium isolates (100.0%) and 1 isolate of the genus Aspergillus (section Flavi), which were obtained from tomatoes, had the ability to produce at least one of the tested mycotoxins. Aspergillus section Flavi isolate (from tomatoes of Slovak origin) produced 5.5 μg.mL-1 of aflatoxin B1, 4.2 μg.mL-1 of aflatoxin B2, 154.4 μg.mL-1 of aflatoxin G1, and 5.6 μg.mL-1 of aflatoxin G2 on 14th day of cultivation on liquid YES medium at 25±1 °C in darkness, and detected by high pressure liquid chromatography (HPLC). [ABSTRACT FROM AUTHOR]

Vegetables represent a very important part of the diet. However, one of the problems of the vegetable market is its shelf life and related safety. A significant reason for vegetable losses in the retail network is the development of microorganisms, mainly micromycetes. They can significantly affect the quality of products, and due to the production of toxic metabolites, they also carry a toxicological risk. The aim of our study was to detect fungi that cause damage to selected types of vegetables in the food retail chains in Slovakia and are therefore directly responsible for product losses. Totally 44 samples of root, cabbage, and fruiting vegetables were mycologically analysed. Micromycetes, causing visible damage to the analysed vegetable samples, were inoculated to M137, M096, or M696 media from HiMedia and cultivated for 7 days at 25±1 °C. Important isolates were subjected to toxicological analysis by the thin-layer chromatography. The results show that the most common cause of carrot spoilage is the genus Berkeleyomyces. In the case of parsley, it was yeast Geotrichum candidum. Alternaria spp. occurred most often in the case of broccoli and cauliflower. Tomatoes were the most frequently spoiled by representatives of the genus Penicillium, or Botrytis cinerea and Cladosporium, cucumbers by Cladosporium and Alternaria species, similar to peppers, and the main spoiler of eggplants was Botrytis cinerea. Alternaria spp. showed a relatively high ability to produce altenuene, alternariol, and alternariol monomethyl ether. Penicillium expansum from carrots produced roquefortine C, patulin, and citrinin, and Penicillium paneum from tomatoes synthesized roquefortine C. [ABSTRACT FROM AUTHOR]

A high performance liquid chromatography coupled with fluorescence detection (HPLC-FLD) was evaluated for the monitoring of aflatoxin B1 (AFB1) production by Aspergillus section Flavi isolates, which were found in the commodities of Slovak origin (barley and tomatoes). Rapid validation of the method was performed and the method was applied for the determination of the mycotoxin. Based on the calculated validation characteristics, the method showed high sensitivity and reproducibility. The LOD and LOQ determined were 0.03 and 0.10 μg.mL-1 which is fully acceptable for the determination of the AFB1 in isolates from plant commodities. The calibration graph was linear in the concentration range of 0.01-10.0 μg.mL-1. The optimized method was used for the analysis of the mycotoxin in three Aspergillus section Flavi isolates. The submerse cultivation was performed at 25±1°C in yeast extract sucrose liquid medium and material was collected on the 7th, 14th and 21st day of cultivation. Simple sample extraction was carried out with use of ethyl acetate, and measurement was done with use of the mobile phase consisting of water and methanol by HPLC-FLD. Production of the AFB1 by isolates was ranging from

Species of the Rhizopus genus are often involved in the moulding of bread and bakery products. Essential oils (EOs) are a suitable alternative to extend the shelf life of food. This research was focused on testing the effect of selected EOs on the growth of Rhizopus species. Tested strains were isolated from mouldy breads. The antifungal activity of EOs against R. stolonifer and R. oryzae strains was determined by micro-atmospheric method (625 μL EO/L air) during 7 days of cultivation. Eight EOs, thyme, red thyme, savory, caraway, marjoram, wild thyme, and oregano 100% inhibited the growth of all strains. Basil, sage, and anise EOs only partially inhibited the growth of strains. Subsequently, the minimum inhibitory doses were determined using micro-atmospheric method. Minimal inhibition doses were 250 μL/L for thyme and red thyme EO, 250 and 500 μL/L for savory EO, 250 and 500 μL/L for oregano EO, 500 and ˃500 μL/L for wild thyme EO, ˃500 μL/L for caraway and marjoram EOs. Strains of the genus Rhizopus reacted differently to the presence of EOs. Thyme and red thyme were evaluated as the most effective EOs in this study. [ABSTRACT FROM AUTHOR]

Nowadays, it is very important to find out the protection of plant products as an alternative to synthetic fungicides. The promising alternative is the use of the essential oils (EOs). The aim of our research was to evaluate the antifungal effect of angelica (Angelica archangelica L.), anise (Pimpinella anisum L.), fennel (Foeniculum vulgare Miller.), camphore (Cinnamonum camphorum Nees & Eberm), litsea (Litsea deccanensis L.), cumin (Carum carvi L.), dill (Anethum graveolens L.), thyme (Thymus vulgaris L.), mint (citrate) (Mentha citrata L.), mint (piperita) (Mentha piperita L.), laurel (Laurus nobilis L.), cinnamon (Cinnamomum zeylanicum L.) EOs against three isolates of the genus Rhizopus obtained from moldy plants source the chemical composition of selected EOs was determined by gas chromatography coupled with mass spectrometry (GC – MS) and by gas chromatography with flame ionization detector (GC – FID). The antifungal activity of EOs against the growth of Rhizopus spp. was investigated by gas diffusion method (625 μL/L of air). The mycelium growth inhibition was measured on the 2nd, 4th, and 7th days of cultivation. Six EOs: litsea, mint (citrata), mint (piperita), cumin, thyme and cinnamon completely inhibited the growth of all tested fungi. For these EOs the minimum inhibitory doses were determined. According to probit analyses, the most effective tested EO was thyme and the least effective was cumin. Our results indicated that EOs are effective in the vapor phase and had a potential antifungal activity against Rhizopus stolonifer strains. So, they could be utilized in novel biological fungicide development. [ABSTRACT FROM AUTHOR]