Percorrer por autor "Sulyok, Michael"
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- Effect of different storage conditions on the stability and safety of almondsPublication . Rodrigues, Paula; Jelassi, Arij; Kanoun, Elifa; Sulyok, Michael; Correia, Paula; Ramalhosa, Elsa; Pereira, ErmelindaAlmond production in Portugal is of great importance for the economy of their main producing areas. However, the contamination of these nut fruits with fungi and mycotoxins poses a significant risk to food safety and security. This work intended to evaluate the influence of storage conditions on the microbial andmycotoxin stability and safety of almonds throughout long-term storage. Two almond varieties—Lauranne and Guara—were submitted to three different storage conditions, namely, 4◦C with noncontrolled relative humidity (RH), 60% RH at 25◦C, and 70% RH at 25◦C, for a storage period of 9 months. Samples were collected after 0, 3, 6, and 9 months of storage and analyzed for microbial loads (aerobicmesophiles, yeasts, and molds),mold incidence and diversity, and mycotoxin contamination. In total, 26 species were identified belonging to 6 genera: Aspergillus, Cladosporium, Fusarium, Penicillium, Paecilomyces, and Talaromyces. For the variety Guara, mycotoxins related to Aspergillus sect. Flavi, such as aflatoxins, averufin, versicolorin C, and norsolorinic acid, were detected only after 9 months of storage at 70% and 60% RH. Penicillium mycotoxins, such as quinolactacin A and roquefortine C, were also detected. For the variety Lauranne, Penicillium mycotoxins were detected, such as citrinin, quinolactacins A and B, roquefortines C and D, cyclopenin, cyclopenol, penitrem A, viridicatin, and viridicatol. Mycotoxins related to Aspergillus, such as aspulvinone E, flavoglaucin, paspalin, asperglaucide, asperphenamate, cyclo(L-Pro-L-Tyr), and cyclo(L-Pro-L-Val), were also detected.
- Effect of different storage conditions on the stability and safety of almondsPublication . Rodrigues, Paula; Jelassi, Arij; Kanoun, Elifa; Sulyok, Michael; Correia, Paula; Ramalhosa, Elsa; Pereira, ErmelindaAlmond production in Portugal is of great importance for the economy of their main producing areas. However, the contamination of these nut fruits with fungi and mycotoxins poses a significant risk to food safety and security. This work intended to evaluate the influence of storage conditions on the microbial and mycotoxin stability and safety of almonds throughout long-term storage. Two almond varieties-Lauranne and Guara-were submitted to three different storage conditions, namely, 4 degrees C with noncontrolled relative humidity (RH), 60% RH at 25 degrees C, and 70% RH at 25 degrees C, for a storage period of 9 months. Samples were collected after 0, 3, 6, and 9 months of storage and analyzed for microbial loads (aerobic mesophiles, yeasts, and molds), mold incidence and diversity, and mycotoxin contamination. In total, 26 species were identified belonging to 6 genera: Aspergillus, Cladosporium, Fusarium, Penicillium, Paecilomyces, and Talaromyces. For the variety Guara, mycotoxins related to Aspergillus sect. Flavi, such as aflatoxins, averufin, versicolorin C, and norsolorinic acid, were detected only after 9 months of storage at 70% and 60% RH. Penicillium mycotoxins, such as quinolactacin A and roquefortine C, were also detected. For the variety Lauranne, Penicillium mycotoxins were detected, such as citrinin, quinolactacins A and B, roquefortines C and D, cyclopenin, cyclopenol, penitrem A, viridicatin, and viridicatol. Mycotoxins related to Aspergillus, such as aspulvinone E, flavoglaucin, paspalin, asperglaucide, asperphenamate, cyclo(L-Pro-L-Tyr), and cyclo(L-Pro-L-Val), were also detected. Practical Application(Optional, for JFS Research Articles ONLY) The quality of almonds depends on the storage period and the RH and temperature at which they are stored. Storage of almonds at 60% RH at 25 degrees C is a good storage condition to maintain the stability and safety of nuts in terms of microbial and mycotoxin contaminations.
- Effect of relative humidity on the quality and safety of peeled almond kernels (Prunus dulcis Mill.) during simulated maritime transport/storagePublication . Fernandes, Luana; Graeff, Francieli; Jelassi, Arij; Sulyok, Michael; Garcia, Carolina; Rodrigues, Nuno; Pereira, J.A.; Bento, Albino; Kanoun, Alifa; Rodrigues, Paula; Pereira, Ermelinda; Ramalhosa, ElsaLong-term transport and storage of peeled almonds under unsuitable conditions may cause the product’s rejection. To get knowledge in this topic, peeled almonds were stored at 25◦C and 60, 70, and 80% relative humidity (RH). The maintenance of high RH (80%) caused some visual defects after 4 months. Even though the 60, 70, and 80% RH did not clearly affect the production of primary and secondary products formed in the lipid oxidation during the 6 months of storage, sometimes an increase in the values of the specific extinction at the wavelength of 268 nm (K268) was observed at 80% RH, suggesting the occurrence to some extent of secondary oxidation. Concerning microbial counts, the almonds stored at 60 and 70% RH presented a satisfactory microbial quality until 6 months; however, at 80% RH, the mold counts were higher than the reference values after 2 months. Several mycotoxins were detected at low levels, including aflatoxins B1 and G1, although some showed higher amounts at 80% RH. In general, it is recommended that almond producers and industrials should consider the use of low RH (< 80%) for maritime transport and long-term storage of almond kernels.
- Effect of relative humidity on the quality and safety of peeled almond kernels (Prunus dulcis Mill.) during simulated maritime transport/storagePublication . Fernandes, Luana; Graeff, Francieli; Jelassi, Arij; Sulyok, Michael; Garcia, Carolina; Rodrigues, Nuno; Pereira, J.A.; Bento, Albino; Kanoun, Alifa; Rodrigues, Paula; Pereira, Ermelinda; Ramalhosa, ElsaLong-term transport and storage of peeled almonds under unsuitable conditions may cause the product's rejection. To get knowledge in this topic, peeled almonds were stored at 25 degrees C and 60, 70, and 80% relative humidity (RH). The maintenance of high RH (80%) caused some visual defects after 4 months. Even though the 60, 70, and 80% RH did not clearly affect the production of primary and secondary products formed in the lipid oxidation during the 6 months of storage, sometimes an increase in the values of the specific extinction at the wavelength of 268 nm (K-268) was observed at 80% RH, suggesting the occurrence to some extent of secondary oxidation. Concerning microbial counts, the almonds stored at 60 and 70% RH presented a satisfactory microbial quality until 6 months; however, at 80% RH, the mold counts were higher than the reference values after 2 months. Several mycotoxins were detected at low levels, including aflatoxins B1 and G1, although some showed higher amounts at 80% RH. In general, it is recommended that almond producers and industrials should consider the use of low RH (< 80%) for maritime transport and long-term storage of almond kernels. Practical Application High levels of relative humidity during storage/transport of almond kernels favor fungal growth, mycotoxin production, and secondary oxidation (rancidity). It is recommended to keep the almond kernels under low RH (< 80%) in maritime transport and long storage, especially in tropical countries.
- Enzymes and secondary metabolites profiles of Gnomoniopsis smithogilvyi are affected by chestnut mediumPublication . Sampaio, Ana; Camelo, Verónica; Fraga, Irene; Gomes, A.; Sulyok, Michael; Gomes-Laranjo, José; Dias, Albino A.; Rodrigues, PaulaChestnut tree (Castanea sativa Mill) is a crop with high economic and social importance in Trás-os-Montes Region. The pre and post-harvest quality of its nuts can be affected by many factors, being the lasses dueto fungi very large. During the last decade a new endophyte fungus, Gnomoniopsis smithogilvyi, causing brown rot, has been isolated from both rotten and healthy fruits, and its growth seems to be related with the increase of air temperatura and rainfall during spring. The present study aims to understand the influence of chestnut substrate on G. smithogilvyi biochemistry, in arder to develop strategies to reduce its incidence in the fruit and improve the contrai of brown rot. lnitially, the presence of the enzymes involved in the decomposition of chestnuts, such as amylase, proteases, carboxymethylcellulase (CMCase), ~-glucosidase, xylanase, among others, was investigated. Further, some hydrolase activities were evaluated in two isolates of G. smithogilvyi incubated in potato (PDB) and chestnut media (CM) along an incubation period (3, 7 and 14 days), in arder to study the effects "isolate", "medium" and "incubation period" on enzymes production. Also, the synthesis of secondary metabolites in fungai dry biomass was assessed by Liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS). Ali isolates produced the enzymes screened and, in general, the enzyme production varied between the isolates (P< 0.0000), the media (P< 0.0000) and along the incubation period (P< 0.0000). Amylase activity was positively correlated with xylanase (P< 0.0001), CMCase (P< 0.0001), and Avicelase {P< 0.01), xylanase with CMCase (P< 0.01) and ~-glucosidase with Avicelase (P< 0.0001 ). By contrast, ~-glucosidase was negatively correlated with CMCase {P< 0.01 ). Twenty secondary metabolites were detected along the incubation: eight in both isolates and media, tive and three only in isolates grew in PD o r CM, respectively. Some of these metabolites had been associated with other fungi and have known biological activities.
- Evaluation of the bioactive properties of a secondary metabolite produced by Penicillium nordicumPublication . Wierzbínska, Agata Karolina; Barros, Lillian; Sulyok, Michael; Ferreira, Isabel C.F.R.; Rodrigues, PaulaFungi of the genus Penicillium are promising sources of bioactive substances. Fungal strains isolated from poorly characterized habitais are currently under active investigation as potential producers of biologically active compounds. Penicillium nordicum is mostly known by its ability to produce the mycotoxin ochratoxin A in several protein- and salt-rich food matrices like processed meat and cheese, but it can also produce an array of other secondary metabolites. In a previous study, strains of this species were found to produce, under specific growth conditions, one unidentified compound in apparently big amounts, without producing ochratoxin A. The aim of the present study was to evaluate the bioactive properties of this compound in terms of antioxidant, antimicrobial, cytotoxic and herbicidal properties. For that purpose, the fungus was grown on ham-based médium and the aqueous extract of the compound was used for further tests. The extract showed significant effects on seed germination as well as on root and shoot growth of tomato, lettuce, wheat and oat. The root growth inhibition ranged from 74% to 98%, ana the shoot growth was reduced in 23 to 88%, being tomato the most sensitive plant. The extract did not show any cytotoxic activity in non-tumor porcine liver primary culture cells and human tumor cell lines. The antibacterial effect on human clinicai isolates and antifungal effect on foodbome and environmental isolates was also not significant. Pestalotin was the predominant compound in the fungal extract, with questiomycin and 7- hydroxypestalotin also being found at lower concentrations, as detected by Liquid Chromatography- Mass Spectrometry (HPLC-MS/MS) based multi-metabolite method. The extract was considered as a potential bioherbicide without noticeable negative effects on human and animal cells and also on the environment. Further tests on herbicidal potential are now under development.
- Mycotoxins and other secondary metabolites are produced by Gnomoniopsis smithogilvyi when confronted with biological and chemical control agentsPublication . Álvarez Rubio, Micaela; Agostini, Isadora; Silva, Sofia; Dallemole-Giaretta, Rosangela; Sulyok, Michael; Sampaio, Ana; Rodrigues, PaulaGnomoniopsis smithogilvyi (Gs) is a relevant pathogen of chestnut since it provokes significant losses worldwide. The aim of this study was to screen the effect of a new biocontrol agent (BCA) against Gs isolated from chestnut (CIMO-BCA1) on the mould’s growth as well as on the production of secondary metabolites. The chemical fungicide Horizon® (tebuconazole; HOR) and the commercial biofungicide Serenade® ASO (Bacillus amyloliquefaciens QST 713; ASO) were also tested. Three concentrations of each antifungal (HOR, ASO, and CIMO-BCA1) were faced with Gs in the growth study in a chestnut-based medium. The intermediate concentrations were used for the analyses of metabolites by LC-MS/MS. CIMO-BCA1 was also identified as B. amyloliquefaciens. All agents reduced the mould’s growth, and the CIMO-BCA1 treatment with an intermediate concentration was the most effective. The metabolite analysis revealed, for the first time, the production of two mycotoxins by Gs, including 3-nitropropionic acid and diplodiatoxin. Additionally, HOR stimulated the production of diplodiatoxin. In conclusion, Gs could present a health risk for consumers. B. amyloliquefaciens strains effectively decreased the mould’s growth, but they must be applied at effective concentrations or in combination with other strategies to completely reduce the hazard.