Browsing by Author "Bahri, Hamdi"
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- Assessing Serra da Estrela PDO cheeses’ origin-production date using fatty acids profilesPublication . Lima, M.J. Reis; Bahri, Hamdi; Morais, Jorge Sá; Veloso, Ana C.A.; Fontes, Luísa; Lemos, Edite Teixeira de; Peres, António M.Serra da Estrela is a Portuguese traditional cheese produced with raw ewe’s milk from “Churra Mondegueira” and “Bordaleira” autochthonous breeds and the wild thistle flower (Cynara cardunculus L.), which benefits from the status of Protected Designation of Origin. Cheese chemical composition, namely the fatty acids profile, depends on milk composition and on manufacturing practices. Thus, the identification of possible chemical biomarkers capable of classifying Serra da Estrela cheeses according to the dairy manufacturing plant, geographical origin or production date would be of utmost relevance for producers and consumers. A typical fatty acids profile, including 23 saturated and unsaturated fatty acids, was identified for the studied cheeses, being butyric, caproic, caprilic, capric, lauric, miristic, palmitic, stearic, oleic, linoleic and its trans-isomer and α-linolenic acids the most abundant ones (relative mean abundances ranging from 1.4% ± 0.5% to 23.9% ± 1.9%). Linear discriminant models were established based on the most discriminative fatty acids (namely, caproic, caprilic, undecanoic, lauric, pentadecanoic, palmitic, palmitoleic, heptadecanoic, oleic, linoleic trans-isomer, heneicosanoic and arachidonic acids) that included less abundant fatty acids, which were selected using the simulated annealing algorithm. The established models enabled assessing cheeses’ origin (models based on 10–12 fatty acids) and/or production date (model based on 20 fatty acids) with predictive sensitivities of 71–88%. Therefore, fatty acids profiles coupled with chemometric techniques, could be foreseen as a fingerprint of cheese’s genuineness, enhancing the consumers’ confidence when purchasing this high-value cheese.
- Characterization of leaf-associated fungi from olive cultivars with different levels of resistance to anthracnosePublication . Bahri, Hamdi; Baptista, Paula; Ramos, Vítor Manuel CapelaOlive anthracnose, caused by Colletotrichum spp., is one of the most damaging fruit diseases in olive crops worldwide. Their control is very difficult and relies mostly on the use of copper-based fungicides. The plant-associate fungal community has been increasingly recognized for playing an important role in plant health. Thus, in this work, the leaf-associated fungi of olive cultivars with different levels of resistance to anthracnose were characterized to identify potential fungi implicated in host resistance. A culture-dependent approach was used to assess both epiphytic and endophytic fungal communities of leaves of olive cultivars Madural (susceptible to anthracnose) and Cobrançosa (moderately tolerant), and the isolates obtained were identified by rRNA sequencing. Overall, Ascomycota phylum and Aureobasidium genus were the most dominant, being epiphytes significantly more diverse and abundant than endophytes. Among the genera identified in the most-resistant cultivar, Aspergillus and Pseudocercospora were the most frequently isolated within epiphytic and endophytic communities, respectively; whereas in the susceptible cultivar, Aureobasidium and Didymocyrtis, were the most frequently isolated within epiphytic and endophytic communities, respectively. The host plant (at cultivar level) had a structuring effect on the composition of fungal communities of leaves, being this effect greater on epiphytes than on endophytes. Thus, it is likely that each cultivar selects specific fungal taxa, which may lead to specific feedbacks on fitness of plant genotypes. In total, 20 fungal taxa (15 endophytes and 5 epiphytes) were responsible for more than 50% of the dissimilarity found on fungal community between cultivars. Among these, three taxa from the Phaeomoniellaceae family and one unidentified fungus, were the most discriminant. Their functional role needs to be studied in the future, because they might be important in conferring host plant resistance towards anthracnose.
- Fatty acids profile of Serra da Estrela PDO cheeses and respective atherogenic and thrombogenic indicesPublication . Lima, M.J. Reis; Fontes, Luísa; Bahri, Hamdi; Veloso, Ana C.A.; Lemos, Edite Teixeira de; Peres, António M.This study aims to determine the physicochemical and fatty acids composition of Serra da Estrela cheese (SEC), as well as health-related lipid indices, like the atherogenic and thrombogenic indices, and to evaluate the influence of producer, geographical origin and production date. Design/methodology/approach – All 24 SEC produced between November 2017 and March 2018 were collected at selected certified producers and analyzed by NIR spectrophotometer and by GC. Data were statistically evaluated by chemometric tools. Findings – In all evaluated SEC, 23 fatty acids were quantified. Cheese origin influenced nutritional and health-related lipid indices). The cheeses were characterized by a relative high abundance of saturated fatty acids (67-76%), followed by a medium content of monounsaturated fatty acids (17-25%) and by low level of polyunsaturated fatty acids (5-7%). A putative positive association between cheese consumption and healthy lipid indices could be reached. Practical implications – The contents of some medium and long chain fatty acids as well as of nutritional and health indices were influenced by cheese producer, geographical origin and production date pointing out the need for standardizing production procedures. Social implications – The SEC plays a key role in the local economy, being an endogenous product with unique sensory characteristics and nutritional potential, for which the knowledge of the lipids profile and health indices is of utmost relevance. Originality/value – SEC is an iconic Portuguese cheese with Protected Designation of Origin. Based on the results, like health-related lipid indices, evaluated for the first time, a positive association between cheese consumption and healthy lipid indices could be envisaged.
- Identifying the geographical origin of Serra da Estrela PDO cheeses using fatty acids profilesPublication . Fontes, Luísa; Lima, M.J. Reis; Bahri, Hamdi; Morais, Jorge Sá; Veloso, Ana C.A.; Lemos, Edite Teixeira de; Peres, António M.Serra da Estrela is a traditional Portuguese cheese with a Protected Designation of Origin (PDO) certification. This cheese is produced from raw ewe’s milk from “Churra Mondegueira” and “Bordaleira” Portuguese autochthonous breeds and coagulated using wild thistle flower (Cynara cardunculus L.), and its production is geographically limited. Serra da Estrela is the most known and popular Portuguese cheese and is appreciated worldwide, being preferentially consumed as a soft cheese, with an average maturation of 30-45 days, although some consumers prefer to consume it as a hard cheese after at least 6 months of storage [1]. Due to its social and agroeconomic relevance, Serra da Estrela cheese is prone to geographical origin adulterations. The present work aims to verify if the fatty acids (FA) profile could be used as a geographical origin biomarker. The results showed that, although a similar FA profile (23 individual fatty acids identified, being the most abundant ones: C4:0, C6:0, C8:0, C10:0, C12:0, C14:0, C16:0, C18:0, C18:1n9c, C18:2n6t, C18:2n6c and C18:3n3) could be established for all cheeses, regardless the producer, geographical origin and production date, the overall profile could be used for discriminating the cheeses according to their geographical origin (5 municipalities within the PDO region). A linear discriminant analysis (LDA) with the simulated annealing (SA) algorithm enabled establishing a classification model that was able to correctly classify 96% of the original grouped samples (Fig.1) and had a predictive sensitivity of 88% (leave-one-out cross-validation). So, FA profile could be used as a geographical origin authentication tool, providing the consumer a guarantee regarding this high-value and appreciated food.
- Identifying the geographical origin of Serra da Estrela PDO cheeses using fatty acids profilesPublication . Lima, M.J. Reis; Bahri, Hamdi; Morais, Jorge Sá; Veloso, Ana C.A.; Fontes, Luísa; Lemos, Edite Teixeira de; Peres, António M.Serra da Estrela Cheese (SEC) is a Portuguese traditional cheese that bears a Protected Designation of Origin label, produced in a limited geographical region, using Raw ewe milk from "Churra Mondegueira" and "Bordaleira" autochthonus breeds; Wild thistle flower (Cynara cardunculusL.) and Salt