Evaluation of chemically characterised essential oils of Coleus aromaticus,Hyptis suaveolens and Ageratum conyzoides against storage fungi and aflatoxin contamination of food commodities

The result of the present investigation explores the efficacy of chemically characterised essential oils (EOs) of Coleus aromaticus, Hyptis suaveolens and Ageratum conyzoides as antifungal and antiaflatoxigenic agent against some storage fungi and the toxigenic strain of Aspergillus flavus (Saktiman 3NSt). Minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) of these EOs were also determined against the toxigenic strain of A. flavus (Saktiman 3NSt). The EO from C. aromaticus was found to be most effective exhibiting MIC and MFC at 0.1μL mL^?1. The EOs also completely checked aflatoxin B₁ synthesis in concentration‐dependent manner. In addition, fumigation of stored wheat samples with EOs exhibited remarkable protection (>80%) from fungal infestation showing their efficacy during in vivo storage conditions. Based on the results of the present investigation, the EOs of C. aromaticus, H. suaveolens and A. conyzoides may be recommended as novel plant‐based antifungal and aflatoxin B₁ suppressor over the synthetic preservatives.     

Efficacy of Acorus calamus L. essential oil as a safe plant‐based antioxidant,Aflatoxin B1 suppressor and broad spectrum antimicrobial against food‐infesting fungi

The study explores the efficacy of Acorus calamus L. essential oil (EO) as a safe plant‐based broad spectrum antifungal, antiaflatoxin, antioxidant food additive. The oil completely inhibited the growth and toxin production of the toxigenic strain of Aspergillus flavus at 0.4 and 0.25 μL mL^?1, respectively. EO exhibited pronounced antifungal activity against sixteen food‐infesting fungal species at 0.5 μL mL^?1. The EO showed strong antioxidant efficacy (IC₅₀ 1.06 μL mL^?1) and nonphytotoxic nature on germination of chickpea seeds. The EO was found nonmammalian toxic showing high LD₅₀ (4877.4 μL kg^?1) for mice (oral, acute). The chemical profile of EO was determined through GC and GC–MS analysis. The findings strengthen the possibility of A. calamus EO as a plant‐based food additive in view of its favourable safety profile, antioxidant and antiaflatoxigenic efficacy and broad spectrum antimicrobial activity against food‐infesting fungi.     

Impact of volatile compounds generated by essential oils on Aspergillus section Flavi growth parameters and aflatoxin accumulation

BACKGROUND: The advantage of essential oils is their bioactivity in the vapour phase, a characteristic that makes them attractive as possible fumigants for stored grain protection. In this study the antifungal and antiaflatoxigenic effects of the volatile fractions of five essential oils (EOs) were evaluated by vapour contact on Aspergillus section Flavi isolates. RESULTS: In maize meal extract agar the volatile fractions of Pimpinella anisum L. (anise), Pëumus boldus Mol. (boldus), Hedeoma multiflora Benth. (mountain thyme), Lippia turbinata var. integrifolia (Griseb.) (poleo) and Syzygium aromaticum L. (clove) were able to decrease the growth rate and lag phase of aflatoxigenic isolates. Boldus EO showed the best antifungal effect on Aspergillus section Flavi growth rate. In sterilised maize grains, boldus and poleo EOs showed antifungal effects on growth rate and aflatoxin accumulation. The volatile fraction of boldus EO completely inhibited the growth of isolates at water activity (a_w) levels of 0.955, 0.930 and 0.900, while poleo EO showed this effect only at the lower a_w levels (0.930 and 0.900). All aflatoxigenic isolates showed reduced total aflatoxin accumulation in the presence of boldus EO under all a_w conditions. CONCLUSION: These findings clearly indicate that the volatile fraction of boldus EO could be used to control aflatoxigenic fungi in stored maize. Copyright © 2009 Society of Chemical Industry     

Chemical composition of Ocimum basilicum L. essential oil and its efficacy as a preservative against fungal and aflatoxin contamination of dry fruits

The study presents fungal and aflatoxin contamination of some dry fruits and Ocimum basilicum essential oil (EO) as a plant‐based preservative. During mycoflora analysis, 2045 fungal isolates were recorded from dry fruits and 40% isolates of Aspergillus flavus were toxigenic in nature. The EO of O. basilicum exhibited strong fungitoxicity against toxigenic strain of A. flavus. Its minimum inhibitory concentration (MIC) was recorded at 1.0 μL ml^?1, and it completely inhibited aflatoxin B₁ production at 0.5 μL ml^?1. The oil exhibited broad fungitoxic spectrum and considerably reduced A. flavus isolates from dry fruits when used as fumigant in closed storage containers at 1.0 μL ml^?1. The chemical profile of the EO was standardised through GC–MS analysis. Based on antifungal potency, antiaflatoxigenicity and efficacy as fumigant during storage conditions, O. basilicum EO may be recommended as a botanical preservative for enhancing the shelf life of dry fruits and edible products during storage.     

Use of essential oil from Mentha arvensis L. to control storage moulds and insects in stored chickpea

BACKGROUND: Fungal contamination and Callosobruchus infestation results in qualitative and quantitative losses of chickpea seeds during storage. Most of the synthetic chemicals used as preservatives have adverse effects. Therefore, the antifungal and insecticidal potential of Mentha arvensis essential oil was evaluated to determine whether this could be an eco‐friendly substitute of synthetic preservatives. RESULTS: The stored chickpea seeds were dominated by Aspergillus flavus (46.1%) and 30% isolates among them were found toxigenic. The MIC of Mentha oil against A. flavus was recorded at 400 µL L^?1 and it exhibited broad fungitoxic activity against 14 storage fungi. The oil was found superior to some prevalent synthetic fungicides. Mentha oil showed potent insecticidal activity against Callosobruchus chinensis at different concentrations and exposure times. The oviposition by C. chinensis was completely checked at 10 µL L^?1 while F₁ emergence was completely inhibited at 200 µL L^?1. During in situ experiments, 94.05% protection of the chickpea from C. chinensis by Mentha oil showed superiority over the organophosphate insecticide malathion, where 90.75% protection was recorded. CONCLUSION: The Mentha EO showing potent fungitoxic and insecticidal efficacy and may be recommended as a plant‐based preservative in the management of fungal and insect infestation of chickpea and other pulses during storage. Copyright © 2009 Society of Chemical Industry     

Effects of Onion (Allium cepa L.) and Garlic (Allium sativum L.) Essential Oils on the Aspergillus versicolor Growth and Sterigmatocystin Production

Abstract: In the present study the effects of individual and combined essential oils (EOs) extracted from onion (Allium
cepa L.) bulb and garlic (Allium sativum L.) clove on the growth of Aspergillus versicolor and sterigmatocystin (STC) production were investigated. The EOs obtained by hydrodistillation were analyzed by GC/MS. Twenty one compounds were identified in onion EO. The major components were: dimethyl‐trisulfide (16.64%), methyl‐propyl‐trisulfide (14.21%), dietil‐1,2,4‐tritiolan (3R,5S‐, 3S,5S‐ and 3R,5R‐ isomers) (13.71%), methyl‐(1‐propenyl)‐disulfide (13.14%), and methyl‐(1‐propenyl)‐trisulfide (13.02%). The major components of garlic EO were diallyl‐trisulfide (33.55%), and diallyl‐disulfide (28.05%). The mycelial growth and the STC production were recorded after 7, 14, and 21 d of the A. versicolor growth in Yeast extract sucrose (YES) broth containing different EOs concentrations. Compared to the garlic EO, the onion EO showed a stronger inhibitory effect on the A. versicolor mycelial growth and STC production. After a 21‐d incubation of fungi 0.05 and 0.11 μg/mL of onion EO and 0.11 μg/mL of garlic EO completely inhibited the A. versicolor mycelial growth and mycotoxins biosynthesis. The combination of EOs of onion (75%) and garlic (25%) had a synergistic effect on growth inhibition of A. versicolor and STC production. Practical Application: A substitution of synthetic preservatives with natural antimicrobial compounds in food safety to control fungal contamination and mycotoxin production.     

Antifungal and antimycotoxigenic effects of Zingiber officinale,Cinnamomum zeylanicum and Cymbopogon martinii essential oils against Fusarium verticillioides

ABSTRACT

There is an increasing demand for fungi control in grains, especially toxigenic. Also, there is growing concern on the use of synthetic fungicides; thus alternatives are needed. The aim of this study was to evaluate the antifungal and antimycotoxigenic action of essential oils (EOs) from Zingiber officinale, Cinnamomum zeylanicum and Cymbopogon martinii against Fusarium verticillioides, a spoilage and toxigenic fungus. Essential oils were first chemically characterised by gas chromatography coupled to mass spectrometry, and their antioxidant potential was measured by the DPPH, ABTS and FRAP methods. Minimum inhibitory concentration (MIC) and disc diffusion were used to assess antifungal activity. Scanning electron microscopy was used to evaluate morphological changes in the fungus. Antimycotoxigenic activity of the EOs against the production of fumonisin B₁ and B₂ by F. verticillioides was evaluated using ultra-high-performance liquid chromatography system. Z. officinale, C. zeylanicum and C. martinii EOs were predominantly composed by zingiberene and geranial; eugenol; and geraniol, respectively. All the EOs had high antioxidant power, especially that from C. zeylanicum. The MICs were 250, 500 and 2,000 µg mL^?1 for C. zeylanicum, C. martinii and Z. officinale EOs, respectively. Mycelial reduction of F. verticillioides was observed when EOs were used, and the lowest activity was detected in the Z. officinale EO. Overall, the tested EOs promoted structural damage to the fungal cell wall, decreased conidia size and mycelial reduction. Antimycotoxigenic evaluation of the EOs evidenced a significant reduction (p < .05) in the production of fumonisins B₁ and B₂ with all the EOs evaluated in the study. These results suggest that especially C. zeylanicum and C. martinii EOs are highly useful for controlling F. verticillioides and fumonisins production.     

In vitro antimicrobial effects and mechanism of action of selected plant essential oil combinations against four food-related microorganisms

The aim of this study was to evaluate the antimicrobial efficacy of selected plant essential oil (EO) combinations against four food-related microorganisms. Ten EOs were initially screened against Escherichia coli, Staphylococcus aureus, Bacillus subtilis and Saccharomyces cerevisiae using agar disk diffusion and broth dilution methods. The highest efficacy against all the tested strains was shown when testing the oregano EO. EOs of basil and bergamot were active against the Gram-positive bacteria (S. aureus and B. subtilis), while perilla EO strongly inhibited the growth of yeast (S. cerevisiae). The chemical components of selected EOs were also analyzed by GC/MS. Phenols and terpenes were the major antimicrobial compounds in oregano and basil EOs. The dominant active components of bergamot EO were alcohols, esters and terpenes. For perilla EO, the major active constituents were mainly ketones. The checkerboard method was then used to investigate the antimicrobial efficacy of EO combinations by means of the fractional inhibitory concentration index (FICI). Based on an overall consideration of antimicrobial activity, organoleptic impact and cost, four EO combinations were selected and their MIC values were listed as follows: oregano–basil (0.313–0.313 μl/ml) for E. coli, basil–bergamot (0.313–0.156 μl/ml) for S. aureus, oregano–bergamot (0.313–0.313 μl/ml) for B. subtilis and oregano–perilla (0.313–0.156 μl/ml) for S. cerevisiae. Furthermore, the mechanisms of the antimicrobial action of EO combinations to the tested organisms were studied by the electronic microscopy observations of the cells and the measurement of the release of cell constituents. The electron micrographs of damaged cells and the significant increase of the cell constituents' release demonstrated that all EO combinations affected the cell membrane integrity.     

Tunisian Salvia officinalis L. and Schinus molle L. essential oils: their chemical compositions and their preservative effects against Salmonella inoculated in minced beef meat

The essential oils (EOs) extracted from the aerial parts of cultivated Salvia officinalis L. and the berries of Schinus molle L. were analysed by gas chromatography–mass spectrometry (GC–MS) and 68 and 67 constituents were identified, respectively. The major constituents were 1,8-cineole (33.27%), β-thujone (18.40%), α-thujone (13.45%), borneol (7.39%) in S. officinalis oil and α-phellandrene (35.86%), β-phellandrene (29.3%), β-pinene (15.68%), p-cymene (5.43%) and α-pinene (5.22%) in S. molle oil.In its second part, the present study was conducted to evaluate the in vitro antimicrobial activity of both studied EOs. For this purpose, paper disc-diffusion method and broth microdilution test were used. The disc-diffusion method showed significant zone of lysis against all the pathogens studied (gram-negative and gram-positive bacteria, yeast). These activities remained stable after six months, and decreased approximately by 20% after one year of storage of the EOs at 4 to 7 °C. On comparing the efficiency of both EOs, S. officinalis EO exhibited higher antibacterial activity against the majority of strains and especially against Candida albicans (two fold more active according to the inhibition zones values). The minimal inhibitory concentrations (MICs) were reported between 4.5 mg/ml and 72 mg/ml on nutrient broth. The particular chemotype of each EO may be involved in its specific antimicrobial behaviour.Furthermore, the inhibitory effect of these EOs were evaluated against two foodborne pathogens belonging to Salmonella genus, experimentally inoculated (10³ CFU/g) in minced beef meat, which was mixed with different concentrations of the EO and stored at 4 to 7 °C for 15 days. Although the antibacterial activities of both EOs in minced beef meat were clearly evident, their addition had notable effects on the flavour and taste of the meat at concentrations more than 2% for S. molle and 1.5% for S. officinalis. One solution to the above-mentioned problem may be the use of combinations of different food preservation systems. In this context, each of the EOs has been used along with low water activity (addition of NaCl) in addition to low refrigeration temperatures. Results on the Salmonella growth showed that some combinations could be recommended to eliminate germs from minced raw beef. By using this method, a stable and, from a microbiological point of view, safe meat can be produced without substantial loss in sensory quality.Results obtained herein, may suggest that the EOs of S. officinalis and S. molle possess antimicrobial activity, and therefore, they can be used in biotechnological fields as natural preservative ingredients in food and/or pharmaceutical industry.     

Evaluation of Cinnamomum tamala Oil and Its Phenylpropanoid Eugenol for Their Antifungal and Antiaflatoxigenic Activity

During screening of 20 plant extracts against toxigenic strain of Aspergillus flavus (SK 3NSt), the extract of Cinnamomum tamala was found to exhibit absolute fungitoxic activity (100% growth inhibition). Hence, essential oil of C. tamala was extracted and selected for further investigations. The selected oil was subsequently standardised through physico-chemical and fungitoxic properties. Minimum inhibitory concentration (MIC) of the oil for absolute inhibition of growth of the toxigenic strain of A. flavus (SK 3NSt) was found to be 150 μl/l and oil showed fungicidal nature at its respective MIC. The oil had a broad fungitoxic spectrum. It was found to be absolutely inhibitory to almost all the 11 fungi tested when its fungitoxic spectrum was assayed. The antifungal potency of oil was found to be greater in comparison to some prevalent synthetic fungicides. The oils had the potency to withstand high inoculum density. The oil remained active up to 2 years and was thermostable. In addition, the oil showed significant efficacy in arresting aflatoxin B₁ secretion by the toxigenic strain (SK 3NSt) of A. flavus at 750 μl/l. GC-MS analysis of the oil led to the identification of main components of oil viz. eugenol (45.58%), β-pinene (10.03%), β-myrcene (9.73%), β-ocimene (4.51%), β-costol (3.88%) and thujyl alcohol isomer (2.51%). The efficacy of C. tamala oil as aflatoxin B₁ suppressor is being reported for the first time. Eugenol, the major component of oil showed absolute antiaflatoxigenic efficacy even at 250 μl/l. The high LD₅₀ value (16.94 ml/kg body weight) of oil recorded on mice indicates its non-mammalian toxicity and suggests the recommendation of the oil as a novel and safe post-harvest biological preservative of food commodities for their preservation from contaminating fungi.     

Antibacterial activity of Thymus capitatus and Thymus algeriensis essential oils against four food‐borne pathogens inoculated in minced beef meat

The antibacterial activity of the essential oils extracted from Thymus capitatus and Thymus algeriensis was studied against Escherichia coli, Salmonella typhimurium, Staphylococcus aureus, and Pseudomonas aeruginosa. In this study, the disk method showed that T. capitatus EO has a strong antibacterial effect, whereas T. algeriensis EO showed a moderate activity. In addition, the inhibitory effect of both EOs was evaluated against four pathogenic strains inoculated experimentally (10⁸ CFU/g) in the minced beef meat, mixed with different concentrations of EOs, and stored for 15 days. Both EOs at low concentrations (0.01 and 0.05% [vol/wt]) exerted a bacteriostatic effect (p < .001), only against E. coli and S. typhimurium. However, at higher concentrations (1 and 3% [vol/wt]), the bactericidal activity was pronounced (p < .0001), in particular in the case of T. capitatus EO against all strains, except P. aeruginosa. The latter was still present after 15 days of storage, which explains its resistance.

Practical applications

Results from this study were confirmed that both thyme EOs could be considered as a very promising natural preservatives for foods from microbial spoilage in the food industries, also they can serve to inhibit or prevent the growth of food‐borne pathogens.     

Antimicrobial activity of eucalyptus essential oil against Pseudomonas in vitro and potential application in refrigerated storage of pork meat

The objective of this study was to investigate the influence of eucalyptus essential oil (EO) on the Pseudomonas in vitro and application in the pork meat. Eucalyptus oil showed the greatest antimicrobial activity to Pseudomonas among five EOs (tea tree oil, eucalyptus oil, clove oil, mentha oil and garlic oil) in vitro. Eucalyptus oil treatment caused the increasing of membrane permeability and the modifications of ultrastructure and morphology of Pseudomonas spp. and P. aeruginosa. Treatment of refrigerated pork with eucalyptus oil led to a significant decrease P. spp. count, pH, total volatile basic nitrogen and 2‐thiobarbituric acid values, as well as higher sensory scores of custom acceptance than those in control at the end of cold storage. It was conclude that eucalyptus EO is a potential alternative to chemical treatment to control the spoilage and extend the shelf life of refrigerated pork meat.     

Selected plant essential oils and their main active components,a promising approach to inhibit aflatoxigenic fungi and aflatoxin production in food

Recent research has showed that Aspergillus flavus and Aspergillus parasiticus are aflatoxigenic species that can become very competitive in the framework of climate change. Aflatoxins show carcinogenic, mutagenic, immunotoxic and teratogenic effects on human and animals. Effective and sustainable measures to inhibit these species and aflatoxins in food are required. Origanum vulgare and Cinnamomum zeylanicum essential oils (EOs) and their major active constituents, carvacrol and cinnamaldehyde, respectively, were assayed for inhibiting these species and aflatoxin production in maize extract medium under different environmental conditions. Doses of 10–1000 mg l^?1 were assayed and the effective doses for 50 (ED₅₀) and 90% (ED₉₀) growth inhibition were determined. The ED₅₀ of cinnamaldehyde, carvacrol, oregano EO, and cinnamon EO against A. flavus were in the ranges 49–52.6, 98–145, 152–505, 295–560 mg l^?1 and against A. parasiticus in the ranges 46–55.5, 101–175, 260–425 and 490–675 mg l^?1, respectively, depending on environmental conditions. In A. flavus treatments ED₉₀ were in the ranges 89.7–90.5, 770–860 and 820–>1000 mg l^?1 for cinnamaldehyde, carvacrol and cinnamon EO, and in A. parasiticus treatments in the ranges 89–91, 855–>1000 and 900–>1000 mg l^?1, respectively. ED₉₀ values for oregano EO against both species were >1000 mg l^?1. Growth rates of both species were higher at 37 than at 25°C and at 0.99 than at 0.96 a_w. Aflatoxin production was higher at 25 than at 37°C. Stimulation of aflatoxin production was observed at low doses except for cinnamaldehyde treatments. The effectiveness of EOs and their main constituents to inhibit fungal growth and aflatoxin production in contact assays was lower than in vapour phase assays using bioactive EVOH-EO films previously reported.     

Antifungal,antiaflatoxin and antioxidant potential of chemically characterized Boswellia carterii Birdw essential oil and its in vivo practical applicability in preservation of Piper nigrum L. fruits

The study explores the chemical profile, antimicrobial and antioxidant activity of Boswellia carterii essential oil (EO). The EO significantly inhibited growth and aflatoxin production by the food borne toxigenic strain of Aspergillus flavus at 1.75 μl/ml and 1.25 μl/ml respectively. It exhibited broad fungitoxic spectrum against 12 food borne moulds and also showed strong antioxidant activity, IC₅₀ value and % inhibition of linoleic acid peroxidation being 0.64 μl/ml and 51.68% respectively. The antifungal action of EO was observed in terms of reduction in ergosterol content of plasma membrane of A. flavus. As fumigant in food system in storage containers, the EO provided 65.38% protection against fungal deterioration of Piper nigrum. GC–MS results revealed 31 components of EO. The chemically characterized B. carterii EO may thus be recommended as plant based preservative in view of its antifungal, antiaflatoxigenic, antioxidant activity and efficacy in food system.     

Original article: Antifungal activities of cinnamon oil against Rhizopus nigricans,Aspergillus flavus and Penicillium expansum in vitro and in vivo fruit test

The postharvest pathogens such as R. nigricans, A. flavas and P. expansum are the causal agents of jujube or orange fruit, therefore, in vitro and in vivo antifungal activities of cinnamon oil to inactivate these fungi were investigated. Cinnamaldehyde is the main constituent of cinnamon oil. The minimum inhibitory concentrations of cinnamon oil against Rhizopus nigricans, Aspergillus flavus and Penicillium expansum were 0.64% (v/v), 0.16% (v/v) and 0.16% (v/v), respectively. The antifungal activity of cinnamon oil against A. flavus and P. expansum was stronger than that against R. nigricans and the activity was improved with increasing its concentration. In an in vivo study, cinnamon oil with concentrations of 2.0% (v/v) and 3.0% (v/v) showed complete control the growth of fungi in wound‐inoculated Lingwu Long Jujube and Sand Sugar Orange fruits. These results revealed that cinnamon oil has a good potential to be as a natural antifungal agent for fruit applications.     

Chemical composition and antimicrobial activity of essential oils of Thymus algeriensis,Eucalyptus globulus and Rosmarinus officinalis from Morocco

BACKGROUND: The present study reports on the antimicrobial activity and chemical composition of the essential oils (EOs) of Thymus algeriensis, Eucalyptus globulus and Rosmarinus officinalis from Morocco. RESULTS: The composition of these species was analysed by GC‐MS, and 65 components were identified. Eucalyptus globulus EO showed a great similarity with EOs from other regions, with 1,8‐cineole (79.85%) the major component. Also rich in this constituent was Rosmarinus officinalis (43.99%). However, the chemical profile of Thymus algeriensis was rather different, and for the first time such a high content of borneol (23.48%) has been described in this EO. The antimicrobial activity of these species has also been studied against seven pathogenic and spoiling bacteria of significant importance. According to the results, Thymus algeriensis showed the best bacteriostatic and bactericidal effect, followed by Eucalyptus globulus and Rosmarinus officinalis. CONCLUSIONS: As far as we know this is the first time that minimum inhibitory and bactericidal concentration values have been reported for Eucalyptus globulus EO. Our data support the possible use of this EO as well as Thymus algeriensis EO, as potential natural agents in preservatives for food and pharmaceutical products. Copyright © 2011 Society of Chemical Industry     

Evaluation of the chemical composition and antimicrobial activity of Mentha pulegium,Juniperus phoenicea,and Cyperus longus essential oils from Morocco

The present study evaluates the chemical composition and antimicrobial activity of the essential oils (EOs) of Mentha pulegium L., Juniperus phoenicea L. and Cyperus longus L. from Morocco. The composition of these species was analyzed by GC/MS and 84 components were identified. M. pulegium EO showed a great similarity with EOs coming from other regions, as pulegone, the major component, accounted for about 70% of the EO. The EO of J. phoenicea had as main components α-pinene (24.9%), β-phellandrene (24.4%) and α-terpinyl acetate (12.9%). The EO extracted from C. longus was remarkably rich in sesquiterpene hydrocarbons (83.2%), which included β-himachalene (46.6%), α-humulene (16.9%), and γ-himachalene (10.1%). The antimicrobial activity of these EOs has been evaluated against seven bacteria of significant importance for food hygiene. According to the results, M. pulegium showed the best bacteriostatic and bactericidal effect, followed by J. phoenicea and C. longus. So far as we know, this is the first report on the quantitative composition and biological activity of the essential oil from C. longus. The tested EOs showed a variable degree of antimicrobial activity being M. pulegium the most effective one.     

Consumers' acceptance and quality stability of olive oil flavoured with essential oils of different oregano species

The objective of this study was to evaluate chemical and physical stability and consumers' acceptance of olive oil flavoured with oregano essential oils (EOs; Compacto, Cordobes, Criollo and Mendocino). Samples of olive oil were added with 0.05% EO and stored in dark (D) and light (L) conditions for 126 days. Samples with oregano EO had lower lipid oxidation indicator values [K232, K269, peroxide value (PV) and anisidine value], especially in darkness. Olive oil with Cordobes EO in D had the lowest PV (18.71 meqO₂ kg^?1). Using prediction equations, 20 meqO₂ kg^?1 PV in olive oil should be reached in 34 days in L control sample and in 126 days in the Cordobes EO sample in darkness. Samples with Cordobes and Criollo EOs in darkness had the highest chlorophyll content after 126 days (2.91 and 2.88 mg kg^?1, respectively). Sensory analysis showed that oregano EO addition in olive oil was detected by panellists in discriminative test and affected consumer acceptance.     

Impact of Essential Oils on the Taste Acceptance of Tomato Juice,Vegetable Soup,or Poultry Burgers

Despite the vast body of available literature on the possibilities of essential oils (EOs) as food preservatives or functional ingredients, the sensory impact of their addition to foods has barely been approached. This work focuses on the hedonic taste acceptance of 3 food products (tomato juice, vegetable soup, and poultry burgers) when they are incorporated with potentially antimicrobial concentrations (20 to 200 μL/L) of 6 selected EOs (lemon, pennyroyal mint, thyme, and rosemary) and individual compounds (carvacrol, p‐cymene). Although addition of 20 μL/L of pennyroyal mint or lemon EO did not change the taste acceptance of tomato juice, higher concentrations of these compounds or any concentration of the other 4 compounds did. In vegetable soup, the tolerance limit for rosemary EO, thyme EO, carvacrol, or p‐cymene was 20 μL/L, while the addition of 200 μL/L of lemon EO was accepted. Tolerance limits in poultry burgers were established in 20 μL/L for carvacrol and thyme EOs, 100 μL/L for pennyroyal mint EO and p‐cymene, and 200 μL/L for lemon and rosemary EOs. Moreover, incorporation of pennyroyal mint EO to tomato juice or poultry burgers, and enrichment of vegetable soup with lemon EO, could contribute to the development of food products with an improved sensory appeal.     

Application of essential oils in maize grain: impact on Aspergillus section Flavi growth parameters and aflatoxin accumulation

The antifungal activity of Pimpinella anisum L. (anise), Pëumus boldus Mol (boldus), Hedeoma multiflora Benth (mountain thyme), Syzygium aromaticum L. (clove), and Lippia turbinate var. integrifolia (griseb) (poleo) essential oils (EOs) against Aspergillus section Flavi was evaluated in sterile maize grain under different water activity (a_w) condition (0.982, 0.955, and 0.90). The effect of EOs added to maize grains on growth rate, lag phase, and aflatoxin B₁ (AFB₁) accumulation of Aspergillus section Flavi were evaluated at different water activity conditions. The five EOs analyzed have been shown to influence lag phase and growth rate. Their efficacy depended mainly on the essential oil concentrations and substrate water activity conditions. All EOs showed significant impact on AFB₁ accumulation. This effect was closely dependent on the water activity, concentration, and incubation periods. Important reduction of AFB₁ accumulation was observed in the majority of EO treatments at 11 days of incubation. Boldus, poleo, and mountain thyme EO completely inhibited AFB₁ at 2000 and 3000 μg g⁻¹. Inhibition of AFB₁ accumulation was also observed when aflatoxigenic isolates grew with different concentration of EOs during 35 days.