Next Article in Journal
Characterization of Fungal FAD-Dependent AA3_2 Glucose Oxidoreductases from Hitherto Unexplored Phylogenetic Clades
Next Article in Special Issue
Agronomic Factors Influencing the Scale of Fusarium Mycotoxin Contamination of Oats
Previous Article in Journal
Bioinformatics and Transcriptome Analysis of CFEM Proteins in Fusarium graminearum
Previous Article in Special Issue
Current Perspectives of Biocontrol Agents for Management of Fusarium verticillioides and Its Fumonisin in Cereals—A Review
 
 
Search for Articles:
Title / Keyword
Author / Affiliation / Email
Journal
Article Type
 
 
Advanced Search
 
Section
Special Issue
Volume
Issue
Number
Page
 
Journals
JoF
Volume 7
Issue 10
10.3390/jof7100872
jof-logo
Submit to this Journal Review for this Journal Propose a Special Issue
► Article Menu

Article Menu

share Share announcement Help format_quote Cite question_answer Discuss in SciProfiles thumb_up
...
Endorse textsms
...
Comment
first_page
settings
Order Article Reprints
Font Type:
Arial Georgia Verdana
Font Size:
Aa Aa Aa
Line Spacing:
Column Width:
Background:
Article

Antimycotic Effects of 11 Essential Oil Components and Their Combinations on 13 Food Spoilage Yeasts and Molds

by
Laura Nißl
,
Florian Westhaeuser
and
Matthias Noll
*
Department of Applied Sciences, Institute for Bioanalysis, Coburg University of Applied Sciences and Arts, 96450 Coburg, Germany
*
Author to whom correspondence should be addressed.
J. Fungi 2021, 7(10), 872; https://doi.org/10.3390/jof7100872
Submission received: 12 September 2021 / Revised: 8 October 2021 / Accepted: 12 October 2021 / Published: 16 October 2021
(This article belongs to the Special Issue Different Antimycotoxin Strategies)
Browse Figures
Review Reports Versions Notes

Abstract

:
Food safety is important to reduce food spoilage microorganisms and foodborne pathogens. However, food safety is challenging, as customers’ demand for natural preservatives is increasing. Essential oils (EOs) and their components (EOCs) are alternative antibacterial and antimycotic food additives. In this study, the minimal inhibitory concentrations (MIC) of 11 different EOCs against 13 food spoilage molds and yeasts were investigated via the microdilution method. Cinnamaldehyde (CA) revealed the lowest MIC for all tested strains and all EOCs (32.81–328.1 µg ml−1). However, CA is organoleptic and was therefore combined with other EOCs via the checkerboard method. Overall, 27 out of 91 combinations showed a synergistic effect, and both respective EOC concentrations could be reduced by maintaining MIC. Thereby, the combination with citral or citronellal showed promising results. The concentration-dependent effect of CA was studied in further detail on Saccharomyces cerevisiae, with CA causing delayed growth-kinetics and reduced total cell numbers. In addition, flow cytometric measurements combined with live–dead staining indicate the fungicidal effect of CA, due to decreasing total cell numbers and increasing relative amount of propidium iodide-positive cells. In this study, we demonstrated that CA is a potent candidate for the use as a natural preservative against food-relevant mold and yeasts showing fungistatic and fungicidal effects. Therefore, CA and EOC combinations with respective lower EOC concentrations reduce organoleptic reservations, which ease their application in the food industry.

1. Introduction

In food manufacturing and storage, the fungal spoilage of products causes severe economic losses, impairment of food quality, reduction in nutrient availability and also impacts food safety, due to the potential presence of mycotoxins [1,2,3]. To increase the shelf-life of food, manifold antifungal, mainly chemical, preservatives are in use. Due to the development of resistances to such additives, and increasing consumer interest in both minimally processed food and reduction in chemical preservatives, the need for naturally derived additives to combat fungal decay is emerging [4,5]. Essential oils (EOs) and their components (EOCs) meet these criteria, which are aromatic and volatile liquids extracted from natural raw material of plants. EOs are complex mixtures containing various individual constituents (ICs), such as terpenes, terpenoids, and aromatic compounds [6]. Often, two or three ICs are major components (20–70%), whereas others are present in trace amounts [7]. EOs have shown to act against food spoilage, due to their antiviral [8], antitoxigenic [9,10], antiparasitic [11,12], insecticidal [13,14], antibacterial [15,16,17] and also antifungal [5,18,19] characteristics. The antimicrobial activities of EOs are predominantly linked to their main components, whereas minor components are attributed to synergistically supporting the activities [17,19,20,21,22]. The classification of a range of essential oils and their EOCs as generally being recognized as safe by the United States Food and Drug Administration ensures their application in food. Approximately 3000 EOs are known so far, and 300 of them are commercially important mainly for the flavors and fragrances market, due to their organoleptic activity [23]. For usage as preservative for food products, this intense aroma is undesired and exceeds consumers’ acceptability [24].
Individual EOCs have some significant advantages over EOs. Due to their chemical stability, and the fact that the majority of pure EOCs do not alter their biological properties. In contrast, the composition and antimicrobial effects of EOs vary, due to the geographical origin of plants, plant components, harvest season and extraction method [25,26,27].
The use of combinations of EOCs cause synergistic, commutative, indifferent or antagonistic effects on the MIC of each employed EOC [28]. Synergistic interactions can be found if the combined effect of EOCs are greater in reducing the MIC than the sum of the individual EOCs. A commutative effect is observed when the combination does not change the effect neither negatively nor positively. Indifference indicates that the effect of the combination of two EOCs is the same as the most potent one used alone. Finally, antagonism is observed when the effect of one or both EOCs is less when they are applied together than when individually applied [29,30]. To differentiate between fungistatic and fungicidal effects, MIC analyses can be combined with flow cytometric analyses [31]. Such flow cytometric analyses are linked with two fluorescent agents SYTO9 or N’,N’-dimethyl-N-[4-[(E)-(3-methyl-1,3-benzothiazol-2-ylidene)methyl]-1-phenylquinolin-1-ium-2-yl]-N-propylpropane-1,3-diamine (SYBR) and propidium iodide (PI), which are capable of differentiating the viability of bacteria [32] and fungi [33].
To date, many studies have investigated the MICs of EOCs against spoilage bacteria [34,35,36], but publicly available datasets for yeasts and molds are sparse. However, these eukaryotic microorganisms can cause severe diseases [2] and are frequently found in food products [1,3]. In this study, a variety of food industry relevant EOCs from the group of terpenes (such as citral, citronellal, citronellol, limonene, and linalool) and of aromatic compounds (such as carvacrol, cinnamaldehyde (CA), eugenol, geraniol, and isoeugenol) were employed as a survey of their antimicrobial activities against 13 known food spoilage yeasts and mold strains. Some of these strains have so far not been assessed and the information of the antimycotic efficiency of EOCs can be compared to strains with reported information. On the one hand, this study provides an overview of MICs of EOCs, and FIC indices of EOC combinations with CA. On the other hand, we examine the effect of CA via growth curves and live–dead staining of S. cerevisiae via flow cytometric analysis to elucidate its antimycotic effect on a single-cell level. Such high-resolution analyses are needed to investigate the fungistatic effects of sub-lethal EOC concentrations on the growth of S. cerevisiae.

2. Materials and Methods

2.1. Strains, Chemicals and Cultivation

All strains (Aspergillus niger, DSM 12634; Fusarium solani, DSM 1164; Penicillium funiculosum, DSM 10640; Candida parapsilosis, DSM 5784; Debaryomyces hansenii, DSM 70590; Dekkera bruxellensis, DSM 70001; Hansenula anomala, DSM 70263; Issatchenkia orientalis, DSM 6128; Kluyveromyces marxianus, DSM 70073; Pichia membranifaciens, DSM 70633; Saccharomyces cerevisiae, DSM 70499; Schizosaccharomyces octosporus, DSM 70573; Schizosaccharomyces pombe, DSM 70576) were obtained from the German Culture Collection (DSMZ, Braunschweig, Germany). Strains were kept in Roti®-Store cryo vials (Carl Roth GmbH + Co. KG, Karlsruhe, Germany) for conservation. Each strain was cultivated on yeast plates (YM agar; DSMZ medium 186: 3 g L−1 yeast extract, 3 g L−1 malt extract, 5 g L−1, peptone from soybeans, 10 g L−1 glucose, agar 1.5% (w/v)) or potato dextrose plates for molds (PD agar; 6.5 g L−1 potato infusion, 20 g L−1 glucose, agar 1.5% (w/v)). After 3 to 5 days of incubation, strains were transferred onto new plates for subsequent experiments. EOCs carvacrol (CAR, ≥98.00%), cinnamaldehyde (CA, ≥98.00%), citral (CI, ≥96.00%), citronellal (CLA, ≥85.00%), citronellol (CLO, ≥95.00%), eugenol (EU, ≥98.00%), geraniol (GE, ≥97.00%), isoeugenol (IEU, ≥98.50%), limonene (LM), linalool (LN, ≥97.00%) and vanillin (VA, ≥97.00%) were purchased from Sigma-Aldrich Inc. (St. Louis, MO, USA).

2.2. Antifungal Susceptibility Tests

The antifungal assays were performed as described previously by the European Committee on antimicrobial susceptibility testing [37,38] with minor modifications. Fourfold concentrated stock solutions and serial twofold dilutions of sterile-filtered (0.2 µm PTFE, Rotilabo®, Carl Roth GmbH + Co. KG) EOCs were prepared in 20% Tween 20 (v/v) (Carl Roth GmbH + Co. KG) and tested in a concentration range of 0.004 to 8 µg µL−1 (w/v or v/v). For comparison with previously reported MIC values, concentrations were converted into µg mL−1, using the following density values: CAR 0.976 g mL−1; CA 1.05 g mL−1; CI 0.888 g mL−1; CLA 0.857 g mL−1; CLO 0.855 g mL−1; EU 1.067 g mL−1; GA 0.879 g mL−1; IEU 1.082 g mL−1; LM 0.86 g mL−1; and LN 0.87 g mL−1. The antifungal drug Amphotericin B (Carl Roth GmbH + Co. KG) was diluted in 20% dimethyl sulfoxide (DMSO, Carl Roth GmbH + Co. KG), sterile-filtered (0.2 µm PTFE, Rotilabo®, Carl Roth GmbH + Co. KG) and used as a reference in a concentration range from 0.0157 to 16 µg mL−1.
The in vitro MIC values were determined via the broth microdilution method in triplicate in a 96-well microtiter plate. Yeast inoculum suspensions were prepared as described previously [37] and were adjusted to an optical density (OD) of 0.12 to 0.15 at a wavelength of 620 nm (OD620) by a spectrophotometer (ScanDrop 250, Analytik Jena AG, Jena, Germany), while mold inoculum was adjusted to a cell number of 1.0 × 106 spores mL−1 as described earlier [38]. Each well contained 50 µL EOC dilution, 100 µL of twofold concentrated medium (PD or YM bouillon) and 50 µL yeast or mold inoculum. Microtiter plates for yeast susceptibility tests were incubated at 25 °C for 48 h. As growth of D. bruxellensis and the mold strains were slow, those were incubated at 25 °C for 72 h. After incubation, OD620 was measured with a microtiter plate reader (FLUOstar Omega, BMG Labtech GmbH, Ortenberg, Germany). Growth was defined by a ΔOD620 ≥ 0.2, which was the difference between inoculated EOC and corresponding non-inoculated EOC blank value. Therefore, MIC was defined as the lowest concentration, with a ΔOD620 < 0.2.

2.3. Synergy Tests via Checkerboard Method

To evaluate the synergistic, commutative, indifferent or antagonistic effect of two EOCs, the checkerboard microdilution method was used as introduced by [39] in three biological replicates (see microplate setup in Supplementary Figure S1). Each well contained 25 µL of each EOC of respective eightfold concentration, 100 µL of twofold concentrated medium (PD or YM bouillon) and 50 µL yeast or mold inoculum and were incubated as described above. In addition, each EOC combination was prepared with 50 µL water instead of 50 µL inoculum as reference to calculate the respective ΔOD620 (see Supplementary Figure S1). Wells without EOCs but with inoculum were used as positive growth controls, whereas wells without EOCs and inoculum were used as negative controls. The ΔOD620 was measured after incubation as described above. Due to the improved checkerboard technique with simultaneous determination of MIC and fractional inhibitory concentration (FIC), we used the calculation and classification of the above described effects and calculation of FICs as described previously [28]. Briefly, for calculations, the lowest FICs of wells with ΔOD620 < 0.2 along the turbidity/non-turbidity interface were used [40]. The average of the mean FICs of three biological replicates were used to categorize combinations as synergistic (FIC < 1), commutative (FIC = 1), indifferent (1 < FIC ≤ 2) or antagonistic effect (FIC > 2) [28].

2.4. Growth Kinetics

The growth kinetics of S. cerevisiae with and without CA was evaluated in a 96-well microtiter plate setup over time with three independent replicates. Each well contained 100 µL of twofold concentrated YM medium, 50 µL of S. cerevisiae inoculum (see above) and 50 µL of different CA concentrations (0.125 MIC to 2 MIC). In addition, blanks, positive and negative controls were set as described above. The ΔOD620 was calculated each 60 min for a period of 48 h as described above.

2.5. Flow Cytometric Analyses

S. cerevisiae cells with and without CA together with controls (see above) were additionally investigated in six biological replicates by using SYBR Green I (SYBR; 10,000× concentrated in DMSO; Lonza Group AG, Basel, Switzerland) and propidium iodide (PI; 1 mg mL−1; Biotium, Inc., Fremont, CA, USA) staining with subsequent flow cytometric analyses, using a NovoCyte Flow Cytometer (Acea Biosciences Inc., San Diego, CA, USA) as described previously [41]. The analysis and gating of data, displayed in logarithmic scale, were performed using the Novo Express software 1.2 (Acea Biosciences Inc. San Diego, CA, USA).

2.6. Statistical Analysis

All FICs were expressed as mean ± SE (n = 3). Statistical analyses were performed to evaluate significant differences from flow cytometric cell counts of stained cells and growth kinetics (see Section 3.3) using one-way analysis of variance (ANOVA) and Tukey post-hoc test using OriginPro 2019 (OriginLab Corporation, Northampton, MA, USA). The significance level was set to p ≤ 0.05.

3. Results

3.1. Cinnamaldehyde Showed Highest MIC

All EOCs were emulsified in 5% Tween 20 (v/v), which had no negative effect on viability and growth kinetics of each strain. CA caused the lowest MIC, ranging from 32.8 to 262.5 µg mL−1, followed by CI (111.0–1776 µg mL−1) and CLA (107.1–1714 µg mL−1) while the other tested EOCs showed higher MIC values (Table 1).
P. funiculosum, D. hansenii and P. membranifaciens were most sensitive to EOCs compared to the other tested strains. In contrast, I. orientalis, K. marxianus and S. cerevisiae showed higher MICs, compared to other strains (Table 1).

3.2. Synergistic Effects of Cinnamaldehyde with EOCs

To test the synergistic, commutative, indifferent or antagonistic effects, CA was combined via the checkerboard method with each of the seven selected EOCs, which also caused low MIC values (see Table 1). CI and CA as well as CLA and CA showed the lowest FICs in combination for the majority of mold and yeast strains (Table 2). Other EOC combinations revealed less synergistic effects, and the combination CLO and CA showed mainly indifferent effects. Yeast strains P. membranifaciens, S. cerevisiae and both Schizosaccharomyces strains were the most sensitive strains with EOC combinations with CA, while H. anomala was the most resistant strain (Table 2).

3.3. Growth Kinetics of S. cerevisiae were Impaired by CA

The low MIC of CA prompted us to examine the effect of sub-lethal EOC concentrations on the growth kinetics of S. cerevisiae. Increasing concentrations of CA revealed a drastically impaired growth rate of S. cerevisiae, even at low concentrations (Figure 1). Cells treated with 0.125 and 0.25 MIC of CA showed a significantly delayed growth curve compared to respective positive control without CA treatment (Figure 1, Table 3). Moreover, this delay in growth kinetics was enhanced with increasing CA concentrations (e.g., 0.5 MIC). In addition, MIC and double MIC of CA inhibited growth, fully confirming a fungistatic effect (see Table 1).

3.4. Cinnamaldehyde Showed Fungicidal Effects

To gain more information, the same S. cerevisiae cultivations were used for flow cytometric analyses in combination with SYBR and PI staining. While the OD620 measurements revealed fungistatic effects on growth kinetics (Figure 1), the flow cytometric analyses discovered additionally a fungicidal effect of CA (Figure 2). The total cell number of S. cerevisiae (SYBR positive) decreased with increasing CA (Figure 2a), which is in line with OD620 measurements (Figure 1). In turn, the relative number of PI-positive cells was significantly higher with MIC and double MIC of CA (Figure 2b), with a reduced cell number compared to inoculum concentration (Figure 2a), indicating a fungicidal effect of CA.

4. Discussion

EOCs are used as flavoring agents, and their antifungal activity was previously reported [42,43,44]. CA was the most potent antifungal EOC of the 11 tested EOCs, with the lowest MICs for all 13 food spoilage yeasts and molds (Table 1), which is in line for A. niger and F. solani [44] and D. bruxellensis [45]. In addition, close relative species from the genera Aspergillus [42,46], Penicillium [47], Fusarium [48], and Candida [43,49] revealed also low MIC values if CA or cinnamon plant extract were applied. Moreover, many bacterial genera showed low MICs in the presence of CA [35]. The MICs of EOs were species specific (Table 1), which was also reported previously [18,44,45]. Overall, P. funiculosum, D. hansenii and P. membranifaciens were most sensitive to EOCs, whereas I. orientalis, K. marxianus and S. cerevisiae showed generally higher MICs (Table 1).
However, a direct comparison of individual MIC values with published data is complicated, as it is affected by the inoculum size, growth stage, culture medium, emulsifying agent, pH of the medium, incubation time/temperature and different methods for MIC determination [18,23,50]. MIC values can shift between ± one dilution step in independent replicates, but if the MICs are determined in the same experimental setup (dilution of drugs and microorganisms) for FIC analyses, potential errors of individual MICs are extinguished [28]. As CA was the most potent EOC (Table 1), we assessed the antifungal efficacy of CA combined with other subsequent potent EOCs CI, CLA, CLO, GE, IEU and LN on all tested 13 spoilage yeasts and molds (Table 2). Although the majority of studies used FIC analyses to assess antibacterial combinations of EOCs, very few and recent studies also addressed antifungal FIC analyses. The combination of cinnamon and lemongrass showed synergistic effects (FIC = 0.75) for Aspergillus flavus [51], which is lower than our FICs for A. niger (Table 2). Another study showed that the combination of cinnamaldehyde and citral was effective against Penicillium expansum and caused membrane damages, including a loss of membrane integrity and ergosterol content [52]. Therefore, similar membrane damages can be expected in the synergistic interaction of CA and CI in our investigations of P. funiculosum (Table 2). Based on our panel of 13 yeasts and molds, A. niger, F. solani and K. marxianus were the most resistant strains with mainly commutative and indifferent FICs (Table 2). For instance, the presence of EO caused a thinner hyphal diameter and hyphal wall and in higher concentration disruption of plasma membranes and disorganization of mitochondrial structures for A. niger [53]. Similarly, EO caused deformation and loss of integrity of the cell wall and in higher concentration disruption of plasma membranes in F. solani [54]. Although less information is available for other molds and yeasts of this study, the cell wall and its membranes are the first barrier against the presence of EO, and respective modifications can be the reason to survive higher EO concentrations. Besides the primary lesion of cell membrane, the disruption of cell wall integrity, the impairment of ergosterol biosynthesis and CA2+ homeostasis, the accumulation of intracellular reactive oxygen species (ROS), DNA damage and the inhibition of specific enzymes were described as target sites of CA and other EOCs [42,55,56,57]. In turn, Aspergillus ochraceus and Escherichia coli were capable of converting cinnamaldehyde to cinnamic acid, which is indicative of a resistance mechanism against both EOCs [36,46].
P. membranifaciens, S. cerevisiae, and both Schizosaccharomyces strains were more sensitive to EOC combinations (Table 2), indicating that the cell wall and its membrane as well as potential detoxification mechanisms were less effective, compared to other tested strains. Cell wall and detoxification strategies by antioxidant enzymes of S. cerevisiae were also affected by the presence of EO [58,59]. The concentration-dependent effect on the growth of S. cerevisiae was so far rarely studied, and our findings revealed that growth was not only significantly delayed in the presence of sub-lethal CA (CA concentrations below MIC) but also the proliferation was significantly reduced (Figure 1 and Figure 2). Similar results of delayed growth curves and reduced offspring were observed for C. albicans and C. tropicalis with sub-lethal CA concentrations and were linked to plasma membrane ATPase activity and ergosterol biosynthesis [43]. Our results also indicate that the struggle with CA was very resource consuming for S. cerevisiae, as fewer resources were present for a fast and high number of offspring (Figure 1, Table 3). Moreover, sub-lethal CA concentrations were fungistatic, and once the MIC was applied, they were fungicidal, as the inoculum concentration was decreased after incubation (Figure 2). Although the quantity of offspring is reduced at sub-lethal CA concentrations, their cell membrane integrity remains intact. S. cerevisiae was still able to proliferate once CA was removed in fresh media, although it was incubated beforehand for 48 h with up to 0.5 MIC of CA. However, once 1 MIC was applied, the re-growth of S. cerevisiae without CA was not observed, underlining a fungicidal effect. Therefore, already sub-lethal CA concentrations are beneficial to extend the EOC shelter against food spoilage. However, once sub-lethal CA concentrations become low or less bio-available in the food matrix, spoilage microorganisms can use this advantage for growth and potentially mycotoxin production.
The application of CA in films showed low MICs for D. hansenii species and relative species of the genera Candida and Penicillium [60] used in our study, but concentration-dependent effects of EO and EOCs ideally combined with flow cytometric analyses should be carried out to ensure a safe extension of food shelf life.

5. Conclusions

Our survey extended the panel of EOCs on 13 food spoilage yeasts and molds and established a fundament of corresponding FIC analyses, as such analyses are, so far, in their infancy. Our dataset showed that combinations of EOCs with cinnamaldehyde (CA), especially against P. membranifaciens, S. cerevisiae and both Schizosaccharomyces strains, were powerful as potential combinations to extend food shelf life. Furthermore, via flow cytometric analyses, this study demonstrated the fungicidal effect of CA. However, each food matrix should be analyzed in detail, as EOC concentrations below MIC delay their growth but fungicidal effects were only observed ≥ 1 MIC.

Supplementary Materials

The following are available online at https://www.mdpi.com/article/10.3390/jof7100872/s1, Figure S1: Microtiter plate set-up for simultaneous MIC and FIC.

Author Contributions

For M.N. conceived and designed research. L.N. and F.W. conducted experiments and analyzed data. L.N. and M.N. wrote the manuscript. All authors have read and agreed to the published version of the manuscript.

Funding

This research was supported by Adalbert-Raps-Stiftung.

Institutional Review Board Statement

Not applicable.

Informed Consent Statement

Not applicable.

Data Availability Statement

All data are presented in this document and in the supplemental part.

Acknowledgments

We thank Lisa Klein and Anna Rudolph for technical support and laboratory work. We thank Antje Vondran for fruitful discussions to solve technical limitations.

Conflicts of Interest

The authors declare no conflict of interest.

References

  1. Bueno, D.J.; Silva, J.O.; Oliver, G. Fungal isolation and enumeration in foods. Met. Mol. Biol. 2004, 268, 127–131. [Google Scholar] [CrossRef]
  2. Fung, F.; Clark, R.F. Health effects of mycotoxins: A toxicological overview. J. Toxicol. Clin. Toxicol. 2004, 42, 217–234. [Google Scholar] [CrossRef] [PubMed]
  3. Valle Garcia, M.; Sonnenstrahl Bregão, A.; Parussolo, G.; Olivier Bernardi, A.; Stefanello, A.; Venturini Copetti, M. Incidence of spoilage fungi in the air of bakeries with different hygienic status. Int. J. Food Microbiol. 2019, 290, 254–261. [Google Scholar] [CrossRef]
  4. Tian, J.; Wang, Y.; Zeng, H.; Li, Z.; Zhang, P.; Tessema, A.; Peng, X. Efficacy and possible mechanisms of perillaldehyde in control of Aspergillus niger causing grape decay. Int. J. Food Microbiol. 2015, 202, 27–34. [Google Scholar] [CrossRef] [PubMed]
  5. Omidbeygi, M.; Barzegar, M.; Hamidi, Z.; Naghdibadi, H. Antifungal activity of thyme, summer savory and clove essential oils against Aspergillus flavus in liquid medium and tomato paste. Food Control 2007, 18, 1518–1523. [Google Scholar] [CrossRef]
  6. de Souza, E.L.; da Cruz Almeida, E.T.; de Sousa Guedes, J.P. The potential of the incorporation of essential oils and their individual constituents to improve microbial safety in juices: A review. Compr. Rev. Food Sci. Food Saf. 2016, 15, 753–772. [Google Scholar] [CrossRef] [Green Version]
  7. Bakkali, F.; Averbeck, S.; Averbeck, D.; Idaomar, M. Biological effects of essential oils--a review. Food Chem. Toxicol. 2008, 46, 446–475. [Google Scholar] [CrossRef]
  8. Bishop, C.D. Antiviral activity of the essential oil of Melaleuca alternifolia (Maiden amp; Betche) cheel (tea tree) against tobacco mosaic virus. J. Essent. Oil Res. 1995, 7, 641–644. [Google Scholar] [CrossRef]
  9. Juglal, S.; Govinden, R.; Odhav, B. Spice oils for the control of co-occurring mycotoxin-producing fungi. J. Food Prot. 2002, 65, 683–687. [Google Scholar] [CrossRef] [PubMed]
  10. Ultee, A.; Smid, E.J. Influence of carvacrol on growth and toxin production by Bacillus cereus. Int. J. Food Microbiol. 2001, 64, 373–378. [Google Scholar] [CrossRef]
  11. Pessoa, L.M.; Morais, S.M.; Bevilaqua, C.M.L.; Luciano, J.H.S. Anthelmintic activity of essential oil of Ocimum gratissimum Linn. and eugenol against Haemonchus contortus. Vet. Parasitol. 2002, 109, 59–63. [Google Scholar] [CrossRef]
  12. Pandey, R.; Kalra, A.; Tandon, S.; Mehrotra, N.; Singh, H.N.; Kumar, S. Essential oils as potent source of nematicidal compounds. J. Phytopathol. 2000, 148, 501–502. [Google Scholar] [CrossRef]
  13. Karpouhtsis, I.; Pardali, E.; Feggou, E.; Kokkini, S.; Scouras, Z.G.; Mavragani-Tsipidou, P. Insecticidal and genotoxic activities of oregano essential oils. J. Agric. Food Chem. 1998, 46, 1111–1115. [Google Scholar] [CrossRef]
  14. Konstantopoulou, I.; Vassilopoulou, L.; Mavragani-Tsipidou, P.; Scouras, Z.G. Insecticidal effects of essential oils. A study of the effects of essential oils extracted from eleven Greek aromatic plants on Drosophila auraria. Experientia 1992, 48, 616–619. [Google Scholar] [CrossRef]
  15. Valero, M.; Giner, M.J. Effects of antimicrobial components of essential oils on growth of Bacillus cereus INRA L2104 in and the sensory qualities of carrot broth. Int. J. Food Microbiol. 2006, 106, 90–94. [Google Scholar] [CrossRef]
  16. Oussalah, M.; Caillet, S.; Lacroix, M. Mechanism of action of Spanish oregano, Chinese cinnamon, and savory essential oils against cell membranes and walls of Escherichia coli O157:H7 and Listeria monocytogenes. J. Food Prot. 2006, 69, 1046–1055. [Google Scholar] [CrossRef]
  17. Utchariyakiat, I.; Surassmo, S.; Jaturanpinyo, M.; Khuntayaporn, P.; Chomnawang, M.T. Efficacy of cinnamon bark oil and cinnamaldehyde on anti-multidrug resistant Pseudomonas aeruginosa and the synergistic effects in combination with other antimicrobial agents. BMC Complement. Altern. Med. 2016, 16, 158. [Google Scholar] [CrossRef] [Green Version]
  18. Pinto, E.; Vale-Silva, L.; Cavaleiro, C.; Salgueiro, L. Antifungal activity of the clove essential oil from Syzygium aromaticum on Candida, Aspergillus and dermatophyte species. J. Med. Microbiol. 2009, 58, 1454–1462. [Google Scholar] [CrossRef]
  19. Jantan, I.b.; Karim Moharam, B.A.; Santhanam, J.; Jamal, J.A. Correlation between chemical composition and antifungal activity of the essential oils of eight Cinnamomum species. Pharmaceut. Biol. 2008, 46, 406–412. [Google Scholar] [CrossRef] [Green Version]
  20. Paster, N.; Menasherov, M.; Ravid, U.; Juven, B. Antifungal activity of oregano and thyme essential oils applied as fumigants against fungi attacking stored grain. J. Food Prot. 1995, 58, 81–85. [Google Scholar] [CrossRef]
  21. Marino, M.; Bersani, C.; Comi, G. Impedance measurements to study the antimicrobial activity of essential oils from Lamiaceae and Compositae. Int. J. Food Microbiol. 2001, 67, 187–195. [Google Scholar] [CrossRef]
  22. Marino, M.; Bersani, C.; Comi, G. Antimicrobial activity of the essential oils of Thymus vulgaris L. measured using a bioimpedometric method. J. Food Prot. 1999, 62, 1017–1023. [Google Scholar] [CrossRef]
  23. Burt, S. Essential oils: Their antibacterial properties and potential applications in foods--a review. Int. J. Food Microbiol. 2004, 94, 223–253. [Google Scholar] [CrossRef]
  24. Lv, F.; Liang, H.; Yuan, Q.; Li, C. In vitro antimicrobial effects and mechanism of action of selected plant essential oil combinations against four food-related microorganisms. Food Res. Int. 2011, 44, 3057–3064. [Google Scholar] [CrossRef]
  25. Braga, M.E.M.; Leal, P.F.; Carvalho, J.E.; Meireles, M.A.A. Comparison of yield, composition, and antioxidant activity of turmeric (Curcuma longa L.) extracts obtained using various techniques. J. Agric. Food Chem. 2003, 51, 6604–6611. [Google Scholar] [CrossRef]
  26. Prakash, B.; Singh, P.; Mishra, P.K.; Dubey, N.K. Safety assessment of Zanthoxylum alatum Roxb. essential oil, its antifungal, antiaflatoxin, antioxidant activity and efficacy as antimicrobial in preservation of Piper nigrum L. fruits. Int. J. Food Microbiol. 2012, 153, 183–191. [Google Scholar] [CrossRef] [PubMed]
  27. Jordán, M.J.; Martínez, R.M.; Goodner, K.L.; Baldwin, E.A.; Sotomayor, J.A. Seasonal variation of Thymus hyemalis Lange and Spanish Thymus vulgaris L. essential oils composition. Ind. Crop. Prod. 2006, 24, 253–263. [Google Scholar] [CrossRef]
  28. Fratini, F.; Mancini, S.; Turchi, B.; Friscia, E.; Pistelli, L.; Giusti, G.; Cerri, D. A novel interpretation of the Fractional Inhibitory Concentration Index: The case Origanum vulgare L. and Leptospermum scoparium J. R. et G. Forst essential oils against Staphylococcus aureus strains. Microbiol. Res. 2017, 195, 11–17. [Google Scholar] [CrossRef]
  29. Renneberg, J. Definitions of antibacterial interactions in animal infection models. J. Antimicrob. Chemother. 1993, 31 (Suppl. D), 167–175. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  30. Davidson, P.M.; Parish, M.E. Methods for testing the efficacy of food antimicrobials. Food Technol. 1989, 43, 148–155. [Google Scholar]
  31. Jiang, Y.; Wu, N.; Fu, Y.-J.; Wang, W.; Luo, M.; Zhao, C.-J.; Zu, Y.-G.; Liu, X.-L. Chemical composition and antimicrobial activity of the essential oil of Rosemary. Environ. Toxicol. Pharmacol. 2011, 32, 63–68. [Google Scholar] [CrossRef]
  32. Noll, M.; Trunzer, K.; Vondran, A.; Vincze, S.; Dieckmann, R.; Al Dahouk, S.; Gold, C. Benzalkonium chloride induces a VBNC state in Listeria monocytogenes. Microorganisms 2020, 8, 184. [Google Scholar] [CrossRef] [Green Version]
  33. Vanhauteghem, D.; Demeyere, K.; Callaert, N.; Boelaert, A.; Haesaert, G.; Audenaert, K.; Meyer, E. Flow cytometry is a powerful tool for assessment of the viability of fungal conidia in metalworking fluids. Appl. Environ. Microbiol. 2017, 83, e00938-17. [Google Scholar] [CrossRef] [Green Version]
  34. Hyldgaard, M.; Mygind, T.; Meyer, R.L. Essential oils in food preservation: Mode of action, synergies, and interactions with food matrix components. Front. Microbiol. 2012, 3, 12. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  35. Moleyar, V.; Narasimham, P. Antibacterial activity of essential oil components. Int. J. Food Microbiol. 1992, 16, 337–342. [Google Scholar] [CrossRef]
  36. Visvalingam, J.; Hernandez-Doria, J.D.; Holley, R.A. Examination of the genome-wide transcriptional response of Escherichia coli O157:H7 to cinnamaldehyde exposure. Appl. Environ. Microbiol. 2013, 79, 942–950. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  37. Arendrup, M.C.; Guinea, J.; Cuenca-Estrella, M.; Meletiadis, J.; Mouton, J.W.; Lagrou, K.; Howard, S.J. EUCAST Definitive Document E.DEF 9.3. Method for the Determination of Broth Dilution Minimum Inhibitory Concentrations of Antifungal Agents for Conidia Forming Moulds. 2015. Available online: https://www.aspergillus.org.uk/wp-content/uploads/2016/03/EUCAST_E_Def_9_3_Mould_testing_definitive_0.pdf (accessed on 7 October 2021).
  38. Arendrup, M.C.; Guinea, J.; Cuenca-Estrella, M.; Meletiadis, J.; Mouton, J.W.; Lagrou, K.; Howard, S.J. EUCAST DEFINITIVE DOCUMENT E.DEF 7.3.1 Method for the Determination of Broth Dilution Minimum Inhibitory Concentrations of Antifungal Agents for Yeasts. 2015. Available online: https://www.eucast.org/fileadmin/src/media/PDFs/EUCAST_files/AFST/Files/EUCAST_E_Def_7_3_1_Yeast_testing__definitive.pdf (accessed on 7 October 2021).
  39. Bonapace, C.R.; White, R.L.; Friedrich, L.V.; Bosso, J.A. Evaluation of antibiotic synergy against Acinetobacter baumannii: A comparison with Etest, time-kill, and checkerboard methods. Diagn. Microbiol. Infect. Dis. 2000, 38, 43–50. [Google Scholar] [CrossRef]
  40. Bonapace, C.R.; Bosso, J.A.; Friedrich, L.V.; White, R.L. Comparison of methods of interpretation of checkerboard synergy testing. Diagn. Microbiol. Infect. Dis. 2002, 44, 363–366. [Google Scholar] [CrossRef]
  41. Heymich, M.-L.; Nißl, L.; Hahn, D.; Noll, M.; Pischetsrieder, M. Antioxidative, antifungal and additive activity of the antimicrobial peptides Leg1 and Leg2 from chickpea. Foods 2021, 10, 585. [Google Scholar] [CrossRef]
  42. Qu, S.; Yang, K.; Chen, L.; Liu, M.; Geng, Q.; He, X.; Li, Y.; Liu, Y.; Tian, J. Cinnamaldehyde, a promising natural preservative against Aspergillus flavus. Front. Microbiol. 2019, 10, 2895. [Google Scholar] [CrossRef] [Green Version]
  43. Shreaz, S.; Sheikh, R.A.; Rimple, B.; Hashmi, A.A.; Nikhat, M.; Khan, L.A. Anticandidal activity of cinnamaldehyde, its ligand and Ni(II) complex: Effect of increase in ring and side chain. Microb. Pathog. 2010, 49, 75–82. [Google Scholar] [CrossRef]
  44. Gehan, I. Kh, M.; Samir, A.M., A. Antifungal potential and biochemical effects of monoterpenes and phenylpropenes on plant. Plant Protect. Sci. 2017, 54, 9–16. [Google Scholar] [CrossRef] [Green Version]
  45. Mitropoulou, G.; Nikolaou, A.; Santarmaki, V.; Sgouros, G.; Kourkoutas, Y. Citrus medica and Cinnamomum zeylanicum essential oils as potential biopreservatives against spoilage in low alcohol wine products. Foods 2020, 9, 577. [Google Scholar] [CrossRef] [PubMed]
  46. Hua, H.; Xing, F.; Selvaraj, J.N.; Wang, Y.; Zhao, Y.; Zhou, L.; Liu, X.; Liu, Y. Inhibitory effect of essential oils on Aspergillus ochraceus growth and ochratoxin A production. PLoS ONE 2014, 9, e108285. [Google Scholar] [CrossRef] [Green Version]
  47. Huang, F.; Kong, J.; Ju, J.; Zhang, Y.; Guo, Y.; Cheng, Y.; Qian, H.; Xie, Y.; Yao, W. Membrane damage mechanism contributes to inhibition of trans-cinnamaldehyde on Penicillium italicum using Surface-Enhanced Raman Spectroscopy (SERS). Sci. Rep. 2019, 9, 490. [Google Scholar] [CrossRef]
  48. Wei, J.; Bi, Y.; Xue, H.; Wang, Y.; Zong, Y.; Prusky, D. Antifungal activity of cinnamaldehyde against Fusarium sambucinum involves inhibition of ergosterol biosynthesis. J. Appl. Microbiol. 2020, 129, 256–265. [Google Scholar] [CrossRef]
  49. Bakhtiari, S.; Jafari, S.; Taheri, J.B.; Kashi, T.S.J.; Namazi, Z.; Iman, M.; Poorberafeyi, M. The effects of cinnamaldehyde (cinnamon derivatives) and nystatin on Candida albicans and Candida glabrata. Open Access Maced. J. Med. Sci. 2019, 7, 1067–1070. [Google Scholar] [CrossRef] [PubMed]
  50. Ciani, M.; Menghini, L.; Mariani, F.; Pagiotti, R.; Menghini, A.; Fatichenti, F. Antimicrobial properties of essential oil of Satureja montana L. on pathogenic and spoilage yeasts. Biotechnol. Lett. 2000, 22, 1007–1010. [Google Scholar] [CrossRef]
  51. Xiang, F.; Zhao, Q.; Zhao, K.; Pei, H.; Tao, F. The efficacy of composite essential oils against aflatoxigenic fungus Aspergillus flavus in maize. Toxins 2020, 12, 562. [Google Scholar] [CrossRef]
  52. Wang, Y.; Feng, K.; Yang, H.; Yuan, Y.; Yue, T. Antifungal mechanism of cinnamaldehyde and citral combination against Penicillium expansum based on FT-IR fingerprint, plasma membrane, oxidative stress and volatile profile. RSC Adv. 2018, 8, 5806–5815. [Google Scholar] [CrossRef] [Green Version]
  53. Helal, G.A.; Sarhan, M.M.; Abu Shahla, A.N.K.; Abou El-Khair, E.K. Effects of Cymbopogon citratus L. essential oil on the growth, lipid content and morphogenesis of Aspergillus niger ML2-strain. J. Basic Microbiol. 2006, 46, 456–469. [Google Scholar] [CrossRef]
  54. Wang, S.; Zheng, Y.; Xiang, F.; Li, S.; Yang, G. Antifungal activity of Momordica charantia seed extracts toward the pathogenic fungus Fusarium solani L. J. Food Drug Anal. 2016, 24, 881–887. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  55. OuYang, Q.; Duan, X.; Li, L.; Tao, N. Cinnamaldehyde exerts its antifungal activity by disrupting the cell wall integrity of Geotrichum citri-aurantii. Front. Microbiol. 2019, 10, 55. [Google Scholar] [CrossRef]
  56. Bang, K.H.; Lee, D.W.; Park, H.M.; Rhee, Y.H. Inhibition of fungal cell wall synthesizing enzymes by trans-cinnamaldehyde. Biosci. Biotechnol. Biochem. 2000, 64, 1061–1063. [Google Scholar] [CrossRef] [PubMed]
  57. Hu, L.; Wang, D.; Liu, L.; Chen, J.; Xue, Y.; Shi, Z. Ca(2+) efflux is involved in cinnamaldehyde-induced growth inhibition of Phytophthora capsici. PLoS ONE 2013, 8, e76264. [Google Scholar] [CrossRef] [Green Version]
  58. Chami, F.; Chami, N.; Bennis, S.; Bouchikhi, T.; Remmal, A. Oregano and clove essential oils induce surface alteration of Saccharomyces cerevisiae. Phytother. Res. 2005, 19, 405–408. [Google Scholar] [CrossRef] [PubMed]
  59. Höferl, M.; Stoilova, I.; Schmidt, E.; Wanner, J.; Jirovetz, L.; Trifonova, D.; Krastev, L.; Krastanov, A. Chemical composition and antioxidant properties of Juniper Berry (Juniperus communis L.) essential oil. Action of the essential oil on the antioxidant protection of Saccharomyces cerevisiae model organism. Antioxidants 2014, 3, 81–98. [Google Scholar] [CrossRef] [Green Version]
  60. López, P.; Sánchez, C.; Batlle, R.; Nerín, C. Development of flexible antimicrobial films using essential oils as active agents. J. Agric. Food Chem. 2007, 55, 8814–8824. [Google Scholar] [CrossRef]
Jof 07 00872 g001 550
Figure 1. Effect of 0.125 minimal inhibitory concentration (MIC; 0.02 µL mL−1) of cinnamaldehyde (CA); 0.25 MIC CA (0.03 µL mL−1); 0.5 MIC CA (0.06 µL mL−1); 1 MIC CA (0.125 µL mL−1); or 2 MIC CA (0.25 µL mL−1) compared to negative control without cells and positive control without treatment with CA on the growth of S. cerevisiae over time. Error bars (only negative error bars are shown) indicate standard error of independent biological triplicate measurements (n = 3). Different letters beside curves indicate significant differences (p < 0.05) between different treatments according to one-way analysis of variance.
Figure 1. Effect of 0.125 minimal inhibitory concentration (MIC; 0.02 µL mL−1) of cinnamaldehyde (CA); 0.25 MIC CA (0.03 µL mL−1); 0.5 MIC CA (0.06 µL mL−1); 1 MIC CA (0.125 µL mL−1); or 2 MIC CA (0.25 µL mL−1) compared to negative control without cells and positive control without treatment with CA on the growth of S. cerevisiae over time. Error bars (only negative error bars are shown) indicate standard error of independent biological triplicate measurements (n = 3). Different letters beside curves indicate significant differences (p < 0.05) between different treatments according to one-way analysis of variance.
Jof 07 00872 g001
Jof 07 00872 g002 550
Figure 2. Total cell number (a) and relative amount of PI positive of S. cerevisiae cells (b) after 48 h of growth with cinnamaldehyde (CA). Positive control treated without CA; 0.125 minimal inhibitory concentration (MIC) CA (0.02 µL mL−1); 0.25 MIC CA (0.03 µL mL−1); 0.5 MIC (0.06 µL mL−1) CA; 1 MIC CA (0.125 µL mL−1); or 2 MIC CA (0.25 µL mL−1). Dashed line (a) denotes inoculum concentration. Error bars indicate standard error of six independent replicates (n = 6). Different letters above bars indicate significant differences (p < 0.05), according to one-way analysis of variance.
Figure 2. Total cell number (a) and relative amount of PI positive of S. cerevisiae cells (b) after 48 h of growth with cinnamaldehyde (CA). Positive control treated without CA; 0.125 minimal inhibitory concentration (MIC) CA (0.02 µL mL−1); 0.25 MIC CA (0.03 µL mL−1); 0.5 MIC (0.06 µL mL−1) CA; 1 MIC CA (0.125 µL mL−1); or 2 MIC CA (0.25 µL mL−1). Dashed line (a) denotes inoculum concentration. Error bars indicate standard error of six independent replicates (n = 6). Different letters above bars indicate significant differences (p < 0.05), according to one-way analysis of variance.
Jof 07 00872 g002
Table
Table 1. Minimal inhibitory concentration (MIC) of tested EOCs against yeast and mold strains as mean of independent biological triplicate measurements (n = 3).
Table 1. Minimal inhibitory concentration (MIC) of tested EOCs against yeast and mold strains as mean of independent biological triplicate measurements (n = 3).
EOCs and ControlAmphotericin B CARCACICLACLOEUGEIEULMLNVanillin
A. niger43904262.588817141710213417581082>344017401000
F. solani83904262.5177617143420213417582164>344034802000
P. funiculosum>163904131.3444428.5855106787910821720870500
C. parapsilosis23904262.588817143420426817584328>344069602000
D. hansenii>41952131.3444857855213487921648608701000
D. bruxellensis0.25195232.81222107.13420213417582164344034802000
H. anomala0.5390432.81222428.53420426817584328172034801000
I. orientalis2>3904262.588817146840426835164328344069604000
K. marxianus23904262.54448573420426817584328344034804000
P. membranifaciens41952131.3222428.517102134439.52164172017401000
S. cerevisiae43904131.3222428.53420426817584328344034804000
S. octosporus1390465.63111428.51710213417584328344034802000
S. pombe13904328.1111.5428.53420213417584328344034802000
Concentration of EOCs were shown as µg mL−1. Abbreviations of EOCs are carvacrol (CAR), cinnamaldehyde (CA), citral (CI), citronellal (CLA), citronellol (CLO), eugenol (EU), geraniol (GE), isoeugenol (IEU), limonene (LM), linalool (LN) and vanillin (VA).
Table
Table 2. FIC indices (dark grey = synergistic; medium grey = commutative; light grey = indifferent) of cinnamaldehyde (CA) in combination with selected EOCs as means ± standard error of independent biological triplicate measurements (n = 3).
Table 2. FIC indices (dark grey = synergistic; medium grey = commutative; light grey = indifferent) of cinnamaldehyde (CA) in combination with selected EOCs as means ± standard error of independent biological triplicate measurements (n = 3).
Mold and Yeast StrainsCA + CICA + CLACA + CLOCA + EUCA + GECA+ IEUCA + LN
A. niger1.0 ± 0.11.0 ± 0.11.5 ± 0.21.3 ± 0.11.1 ± 0.11.2 ± 0.01.1 ± 0.1
F. solani1.0 ± 0.11.0 ± 0.01.1 ± 0.11.1 ± 0.11.1 ± 0.11.1 ± 0.11.0 ± 0.1
P. funiculosum0.9 ± 0.21.0 ± 0.11.1 ± 0.11.1 ± 0.01.2 ± 0.21.0 ± 0.11.1 ± 0.3
C. parapsilosis0.9 ± 0.11.0 ± 0.11.0 ± 0.01.0 ± 0.11.1 ± 0.01.2 ± 0.10.9 ± 0.1
D. hansenii1.1 ± 0.11.0 ± 0.11.1 ± 0.11.2 ± 0.11.0 ± 0.11.2 ± 0.11.2 ± 0.1
D. bruxellensis0.8 ± 0.10.9 ± 0.11.1 ± 0.01.0 ± 0.10.9 ± 0.11.1 ± 0.10.9 ± 0.0
H. anomala1.3 ± 0.11.1 ± 0.11.5 ± 0.11.3 ± 0.21.5 ± 0.11.5 ± 0.31.4 ± 0.3
I. orientalis0.9 ± 0.10.8 ± 0.11.1 ± 0.11.2 ± 0.11.0 ± 0.01.1 ± 0.11.0 ± 0.1
K. marxianus1.0 ± 0.11.1 ± 0.11.1 ± 0.11.1 ± 0.11.0 ± 0.11.3 ± 0.11.1 ± 0.0
P. membranifaciens0.9 ± 0.10.6 ± 0.11.1 ± 0.10.8 ± 0.01.1 ± 0.10.8 ± 0.00.9 ± 0.2
S. cerevisiae1.0 ± 0.10.6 ± 0.11.1 ± 0.10.9 ± 0.11.1 ± 0.01.0 ± 0.11.1 ± 0.0
S. octosporus1.0 ± 0.10.9 ± 0.10.9 ± 0.10.7 ± 0.10.7 ± 0.10.7 ± 0.11.0 ± 0.1
S. pombe0.9 ± 0.10.5 ± 0.11.0 ± 0.10.8 ± 0.10.9 ± 0.00.9 ± 0.10.9 ± 0.1
Abbreviations of EOCs are citral (CI), citronellal (CLA), citronellol (CLO), eugenol (EU), geraniol (GE), isoeugenol (IEU), and linalool (LN).
Table
Table 3. Significant growth delay of S. cerevisiae over time of 0.125 minimal inhibitory concentration (MIC; 0.02 µL mL−1) of cinnamaldehyde (CA); 0.25 MIC CA (0.03 µL mL−1); 0.5 MIC (0.06 µL mL−1) CA; 1 MIC CA (0.125 µL mL−1); or 2 MIC CA (0.25 µL mL−1) compared to negative control without cells and positive control without treatment with CA in triplicates (n = 3). OD620 measurements over time (in hours) were carried out and significant differences (p < 0.05) between different treatments according to one-way analysis of variance (n.s. = not significantly different after 48 h) denoted.
Table 3. Significant growth delay of S. cerevisiae over time of 0.125 minimal inhibitory concentration (MIC; 0.02 µL mL−1) of cinnamaldehyde (CA); 0.25 MIC CA (0.03 µL mL−1); 0.5 MIC (0.06 µL mL−1) CA; 1 MIC CA (0.125 µL mL−1); or 2 MIC CA (0.25 µL mL−1) compared to negative control without cells and positive control without treatment with CA in triplicates (n = 3). OD620 measurements over time (in hours) were carried out and significant differences (p < 0.05) between different treatments according to one-way analysis of variance (n.s. = not significantly different after 48 h) denoted.
TreatmentNC2 MIC1 MIC0.5 MIC0.25 MIC0.125 MICPC
PC16 h17 h17 h17 hn.s.n.s.
0.125 MIC13 h14 h14 h19 hn.s.
0.25 MIC19 h19 h19 hn.s.
0.5 MIC25 h25 h25 h
1 MICn.s.n.s.
2 MICn.s.
NC
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Share and Cite

MDPI and ACS Style

Nißl, L.; Westhaeuser, F.; Noll, M. Antimycotic Effects of 11 Essential Oil Components and Their Combinations on 13 Food Spoilage Yeasts and Molds. J. Fungi 2021, 7, 872. https://doi.org/10.3390/jof7100872

AMA Style

Nißl L, Westhaeuser F, Noll M. Antimycotic Effects of 11 Essential Oil Components and Their Combinations on 13 Food Spoilage Yeasts and Molds. Journal of Fungi. 2021; 7(10):872. https://doi.org/10.3390/jof7100872

Chicago/Turabian Style

Nißl, Laura, Florian Westhaeuser, and Matthias Noll. 2021. "Antimycotic Effects of 11 Essential Oil Components and Their Combinations on 13 Food Spoilage Yeasts and Molds" Journal of Fungi 7, no. 10: 872. https://doi.org/10.3390/jof7100872

Note that from the first issue of 2016, this journal uses article numbers instead of page numbers. See further details here.

Article Metrics

Back to TopTop