Publicação
Technological processes for reduction of fungal and mycotoxin contamination of nuts
| Resumo: | Almond and hazelnut production in Portugal are 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 security. Mycotoxins are secondary metabolites produced by filamentous fungi that frequently contaminate these commodities. This work intended to evaluate the influence of storage conditions on the microbial and mycotoxin stability and safety of nuts throughout long-term storage. For that, almond and hazelnut samples were stored under different relative humidity (RH) conditions (60, 70 and 80%) at 25°C for up to 6 months. The storage of two almond varieties – Lauranne and Guara - under 60% and 70% RH at 25°C were further compared with storage at 4 ºC for 9 months. Microbial loads (aerobic mesophiles and yeasts and molds) were determined at post-harvest stage and after being submitted to preservation, and molds were identified morphologically and molecularly. Nuts were also subjected to multi- mycotoxin analysis by LC-MS/MS to determine their mycotoxin contamination level and profile. For hazelnuts, five fungal species were identified belonging to four fungal genera commonly associated with mycotoxin production: Alternaria, Aspergillus, Fusarium, and Penicillium. For hazelnuts, an important range of mycotoxin was detected after 6 months of storage with a remarkable cumulative amount in 80% RH at 25°C, when compared to 60% and 70% RH at 25°C. For almonds, 26 species were identified belonging to seven genera: Alternaria, Aspergillus, Cladosporium, Fusarium, Penicillium, Paecilomyces, Talaromyces. For the variety Guara, mycotoxins related to Aspergillus sect. Flavi such as Aflatoxin B1, B2, G1, G2, Averufin, Versicolorin C, Norsolorinic acid were detected only after nine months of storage at 70 and 60% RH at 25°C. Penicillium sp. mycotoxins as Quinolactacin A, Roquefortine C and Flavoglaucin were also detected. Flavoglaucin was present in all time-points and conditions of storage in important amounts. For the variety Lauranne, Penicillium sp. mycotoxins were detected such as Citrinin, Quinolactacins A and B, Roquefortines Cand D, Cyclopenin, Cyclopenol, Penitrem A, Viridicatin and Viridicatol. Mycotoxins related to Aspergillus sp. such as Aspulvinone E, Flavoglaucin, Paspalin, Asperglaucide, Asperphenamate, cyclo(L-Pro-L-Tyr) and cyclo(L-Pro-L-Val) were also detected. |
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| Autores principais: | Jelassi, Arij |
| Assunto: | Almonds Hazelnuts Mycotoxins Aspergillus Penicillium Fungi Storage conditions |
| Ano: | 2021 |
| País: | Portugal |
| Tipo de documento: | dissertação de mestrado |
| Tipo de acesso: | acesso restrito |
| Instituição associada: | Instituto Politécnico de Bragança |
| Idioma: | inglês |
| Origem: | Biblioteca Digital do IPB |
| Resumo: | Almond and hazelnut production in Portugal are 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 security. Mycotoxins are secondary metabolites produced by filamentous fungi that frequently contaminate these commodities. This work intended to evaluate the influence of storage conditions on the microbial and mycotoxin stability and safety of nuts throughout long-term storage. For that, almond and hazelnut samples were stored under different relative humidity (RH) conditions (60, 70 and 80%) at 25°C for up to 6 months. The storage of two almond varieties – Lauranne and Guara - under 60% and 70% RH at 25°C were further compared with storage at 4 ºC for 9 months. Microbial loads (aerobic mesophiles and yeasts and molds) were determined at post-harvest stage and after being submitted to preservation, and molds were identified morphologically and molecularly. Nuts were also subjected to multi- mycotoxin analysis by LC-MS/MS to determine their mycotoxin contamination level and profile. For hazelnuts, five fungal species were identified belonging to four fungal genera commonly associated with mycotoxin production: Alternaria, Aspergillus, Fusarium, and Penicillium. For hazelnuts, an important range of mycotoxin was detected after 6 months of storage with a remarkable cumulative amount in 80% RH at 25°C, when compared to 60% and 70% RH at 25°C. For almonds, 26 species were identified belonging to seven genera: Alternaria, Aspergillus, Cladosporium, Fusarium, Penicillium, Paecilomyces, Talaromyces. For the variety Guara, mycotoxins related to Aspergillus sect. Flavi such as Aflatoxin B1, B2, G1, G2, Averufin, Versicolorin C, Norsolorinic acid were detected only after nine months of storage at 70 and 60% RH at 25°C. Penicillium sp. mycotoxins as Quinolactacin A, Roquefortine C and Flavoglaucin were also detected. Flavoglaucin was present in all time-points and conditions of storage in important amounts. For the variety Lauranne, Penicillium sp. mycotoxins were detected such as Citrinin, Quinolactacins A and B, Roquefortines Cand D, Cyclopenin, Cyclopenol, Penitrem A, Viridicatin and Viridicatol. Mycotoxins related to Aspergillus sp. such as Aspulvinone E, Flavoglaucin, Paspalin, Asperglaucide, Asperphenamate, cyclo(L-Pro-L-Tyr) and cyclo(L-Pro-L-Val) were also detected. |
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