Fungal contamination presents several problems: in humans, health issues arise from infections with opportunistic filamentous fungi and yeast, while in food, fungi cause spoilage and, in particular, ...in the case of mycotoxigenic fungi, can cause serious health issues. Several types of fatty acids and their derivatives, oxylipins, have been found to have inhibitory effect towards fungal growth and the production of mycotoxins. The use of fatty acids as antifungals could fulfil consumer's requests of more natural and environmentally friendly compounds, while being less likely to promote fungal resistance. In addition, due to their nature, fatty acids are easily used as food additives. In this work, we review the most relevant and recent studies on the antifungal ability of fatty acids. We focused on saturated fatty acids, unsaturated fatty acids, and oxylipins, their different impact on fungal inhibition, their proposed modes of action, and their ability to impair mycotoxin production. Applications of fatty acids as antifungals and their limitations are also addressed.
The control of fungal contamination is particularly important to avoid both spoilage of food and feed products and the occurrence of toxic compounds, known as mycotoxins. Some lactic acid bacteria ...(LAB) strains have shown the capacity to inhibit fungal growth and the production of mycotoxins. In this work, cell-free supernatants (CFS) of Lactobacillus plantarum UM55 and Lactobacillus buchneri UTAD104 were tested against Penicillium nordicum radial growth and OTA production. When CFS of these strains were used, the radial growth of the fungus was inhibited by less than 20%, but the production of OTA was reduced by approx. 60%. These antifungal effects resulted from organic acids produced by LAB. The CFS of L. plantarum UM55 contained lactic acid, phenyllactic acid (PLA), hydroxyphenyllactic acid (OH-PLA) and indole lactic acid (ILA), while L. buchneri UTAD104 CFS contained acetic acid, lactic acid and PLA. These organic acids were further tested individually for their inhibitory capacity. Calculation of the inhibitory concentrations (ICs) showed that acetic acid, ILA and PLA were the most effective in inhibiting P. nordicum growth and OTA production. When the inhibitory activity of LAB cells incorporated into the culture medium was tested, L. buchneri UTAD104 inhibited the production of OTA entirely in all conditions tested, but fungal growth was only inhibited completely by the highest concentrations of cells. Acetic acid production was primarily responsible for this effect. In conclusion, the ability of LAB to inhibit mycotoxigenic fungi depends on strain capability to produce specific organic acids, and those acids may differ from strain to strain. Also, the use of LAB cells, especially from L. buchneri, in food products prone to contamination with P. nordicum (e.g. dry-cured meats and cheeses) may be an alternative solution to control fungal growth and OTA production.
Irradiation for Mold and Mycotoxin Control: A Review Calado, Thalita; Venâncio, Armando; Abrunhosa, Luís
Comprehensive reviews in food science and food safety,
September 2014, Letnik:
13, Številka:
5
Journal Article
Recenzirano
Odprti dostop
The mycotoxin issue requires constant vigilance from economic, regulatory, and scientific agents to minimize its toxicological effects on human and animals. The implementation of good practices to ...avoid fungal growth and mycotoxin production on agricultural commodities is essential to achieve most restrictive safety standards; however, the contribution of novel technologies that may act on postharvesting and poststorage situations may be equally important. Several methodologies, more or less technologically advanced, may be used for this purpose. In this work, we review the role, contribution, and impact of irradiation technology to control the presence of fungi and mycotoxins in food and in feed. The effect of this technology on the viability of mold spores and on the elimination of mycotoxins is reviewed. A critical evaluation of the advantages and disadvantages of irradiation in this context is presented.
Lactic acid bacteria (LAB), which are commonly used in the production of fermented foods, have been gaining attention for their antifungal and antimycotoxin properties. In this work, the strain ...Lactobacillus plantarum UM55 was selected among other LAB for inhibiting the growth of Aspergillus flavus. Further, it is shown that cell-free supernatant (CFS) of this strain inhibits the production of aflatoxins (AFLs) by 91%. This inhibition was dependent on CFS pH, increased with increasing concentrations of CFS, and was independent of fungal growth, which was inhibited only by 32%. CFS was also effective in inhibiting the growth and AFLs production in A. parasiticus, A. arachidicola, A. nomius and A. minisclerotigenes. Further, L. plantarum UM55 CFS was analysed for the presence of organic acids and the main differences compared to controls were found in the levels of lactic acid, phenyllactic acid (PLA), hydroxyphenyllactic acid (OH-PLA), and indole lactic acid (ILA). These compounds were individually tested against A. flavus, with all of the compounds showing an inhibiting effect on fungal growth and AFLs production. PLA showed the stronger effects, and the obtained IC90 for the inhibition of growth and AFLs was of 11.9 and 0.87mg/mL, respectively. AFLs IC90 for ILA, OH-PLA and lactic acid were of 1.47, 1.80, and 3.92mg/mL, respectively. The antiaflatoxigenic properties of LAB depend on strain's capability to produce lactic acid, PLA, OH-PLA and ILA.
•The CFS of L. plantarum UM55 inhibited the growth of aflatoxigenic species and their aflatoxin production.•Different aflatoxigenic species showed different susceptibilities.•The inhibition of AFLs production is not due merely to fungal growth reduction.•Those effects were lost when the CFS pH was neutralized.•Lactic, phenyllactic, hydroxyphenyllactic and indole lactic acids are mostly responsible for these effects.
A polyphasic approach consisting of morphological, chemical and molecular characterization was applied to 31 isolates of
Aspergillus Section
Flavi originating from Portuguese almonds, with the aim of ...characterizing and identifying aflatoxigenic and non-aflatoxigenic strains. On the basis of morphological characters (mainly colony color on Czapek-Dox agar and conidia morphology), we found two distinct groups among the population under study: 18 isolates (58%) had dark-green colonies and rough conidia, and were classified as
Aspergillus parasiticus; the remaining 13 isolates (42%) had yellow-green colonies and smooth to finely rough globose conidia, and were classified as
Aspergillus flavus. Chemical characterization involved the screening of the isolates for aflatoxins B (AFB) and G (AFG), and also for cyclopiazonic acid (CPA), by HPLC with fluorescence and UV detection, respectively. All
A. parasiticus isolates were strong AFB and AFG producers, but no CPA production was detected, showing a consistent mycotoxigenic pattern. The
A. flavus isolates showed to be more diversified, with 77% being atoxigenic, whereas 15% produced CPA and low levels of AFB and 8% produced the 3 groups of mycotoxins. Aflatoxin production was also screened on Coconut Agar Medium (CAM), and the results were consistent with the HPLC analysis. Sclerotia production showed no correlation to aflatoxigenicity.
Molecularly, two genes of the aflatoxin biosynthetic pathway,
aflD (=
nor1) and
aflQ (=
ord1
=
ordA) were tested for presence and expression (by PCR and RT-PCR, respectively). The presence of both genes did not correlate with aflatoxigenicity.
aflD expression was not considered a good marker for differentiating aflatoxigenic from non-aflatoxigenic isolates, but
aflQ showed a good correlation between expression and aflatoxin-production ability.
•Ochratoxin A (OTA) was easily degraded by gamma radiation when dissolved in water.•Dry OTA was extremely resistant to gamma radiation.•In wheat flour, a radiation dose of 30.5kGy eliminated 24% of ...the OTA.•In grape juice, a radiation dose of 30.5kGy eliminated 12% of the OTA.•In wine, a radiation dose of 30.5kGy eliminated 23% of the OTA.
Ochratoxin A (OTA) is one of the main mycotoxins that can be found in food. The use of gamma radiation is a technique for preserving food that may exert some effects on mycotoxins. OTA was irradiated in its dry form, in aqueous and in methanolic solutions, and in wheat flour, grape juice and wine. Additionally, the toxicity of OTA irradiated in water was tested. In aqueous solutions, more than 90% of the OTA was degraded by γ-radiation doses ≥2.5kGy, and a 2-fold reduction in OTA cytotoxicity was observed. In food matrices, the elimination of OTA by γ-radiation was found more difficult, as radiation doses of 30kGy eliminate at most 24% of the OTA. Higher moisture content of food matrices did not substantially increase OTA elimination. It is concluded that OTA is very sensitive to irradiation in water solutions but resistant in its dry form and in food matrices.
Tannins are well-known food polyphenols that interact with proteins, namely, salivary proteins. This interaction is an important factor in relation to their bioavailability and is considered the ...basis of several important properties of tannins, namely, the development of astringency. It has been generally accepted that astringency is due to the tannin-induced complexation and/or precipitation of salivary proline-rich proteins (PRPs) in the oral cavity. However, this complexation is thought to provide protection against dietary tannins. Neverthless, there is no concrete evidence and agreement about which PRP families (acidic, basic, and glycosylated) are responsible for the interaction with condensed tannins. In the present work, human saliva was isolated, and the proteins existing in saliva were characterized by chromatographic and proteomic approaches (HPLC-DAD, ESI-MS, sodium dodecyl sulfate−polyacrylamide gel electrophoresis (SDS−PAGE), and MALDI-TOF). These approaches were also adapted to study the affinity of the different families of salivary proteins to condensed tannins by the interaction of saliva with grape seed procyanidins. The results obtained when all the main families of salivary proteins are present in a competitive assay, like in the oral cavity, demonstrate that condensed tannins interact first with acidic PRPs and statherin and thereafter with histatins, glycosylated PRPs, and bPRPs.
The monotypic type genus Bertholletia produces commercially nutritionally harvested edible seeds, Brazil nuts. It is an important product from the Amazon forest in the food production chain, with a ...2008 annual world production of 78,000tonnes, being Brazil responsible for approximately 40% of it. Although there are beneficial nutritional properties, the prevailing mycobiota of Brazil nuts include fungi that are producers of aflatoxins, such as Aspergillus flavus, A. parasiticus and A. nomius. Aflatoxins have deleterious effects in consumption considering the global distribution chain, affecting major exporting countries. The present review is focused on the importance of Brazil nuts for the Amazon rainforest, emphasizing on the social and environmental impact of its production, on the mycobiota contamination of seeds, and on the presence of mycotoxins and related food safety aspects.
Mycotoxins are toxic secondary metabolites produced by filamentous fungi that occur naturally in agricultural commodities worldwide. Aflatoxins, ochratoxin A, patulin, fumonisins, zearalenone, ...trichothecenes, and ergot alkaloids are presently the most important for food and feed safety. These compounds are produced by several species that belong to the Aspergillus, Penicillium, Fusarium, and Claviceps genera and can be carcinogenic, mutagenic, teratogenic, cytotoxic, neurotoxic, nephrotoxic, estrogenic, and immunosuppressant. Human and animal exposure to mycotoxins is generally assessed by taking into account data on the occurrence of mycotoxins in food and feed as well as data on the consumption patterns of the concerned population. This evaluation is crucial to support measures to reduce consumer exposure to mycotoxins. This work reviews the occurrence and levels of mycotoxins in Portuguese food and feed to provide a global overview of this issue in Portugal. With the information collected, the exposure of the Portuguese population to those mycotoxins is assessed, and the estimated dietary intakes are presented.
•Ultrasounds as potential pretreatment for lignocellulosic residues.•Improve cellulase and xylanase production by solid-state fermentation.•Evaluation of wastes from new olive oil extraction ...system.•Physicochemical comparison of olive mill wastes.•Selection of best producers of cellulases and xylanases.
Olive mills generate a large amount of waste that can be revaluated. This work aim to improve the production lignocellulolytic enzymes by solid-state fermentation using ultrasounds pretreated olive mill wastes. The composition of olive mill wastes (crude and exhausted olive pomace) was compared and several physicochemical characteristics were significantly different. The use of both wastes in SSF was evaluated and a screening of fungi for xylanase and cellulase production was carried out. After screening, the use of exhausted olive pomace and Aspergillus niger led to the highest enzyme activities, so that they were used in the study of ultrasounds pre-treatment. The results showed that the sonication led to a 3-fold increase of xylanase activity and a decrease of cellulase activity. Moreover, the liquid fraction obtained from ultrasounds treatment was used to adjust the moisture of solid and a positive effect on xylanase (3.6-fold increase) and cellulase (1.2-fold increase) production was obtained.
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