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Abstract(s)
O azeite é o óleo vegetal mais apreciado pelos consumidores, devido às suas características organoléticas e composição química que lhe conferem propriedades únicas. Quer as caraterísticas sensoriais quer as químicas estão muito dependentes da cultivar de oliveira. Por sua vez, na cozinha moderna, cada vez mais os azeites estão sujeitos a processos térmicos que influem nas suas propriedades, tendo os antioxidantes um papel importante na prevenção dessa ação. Assim, o presente trabalho teve por objetivo o estudo de diferentes azeites elementares ao nível da sua qualidade, composição química e atividade antioxidante e o estudo do efeito da adição de extratos de alga Scenedesmus almeriensis na composição quando o azeite é sujeito a aquecimento.
A caraterização dos azeites elementares mostrou que o fator cultivar é determinante para na composição. Para os parâmetros de qualidade, os azeites elementares apresentaram valores dentro dos limites estabelecidos para a classificação de azeite virgem extra. Os azeites obtidos eram diferentes em termos de composição química, caraterísticas sensoriais e atividade antioxidante. A cv. Manzanilla apresentou o maior conteúdo em ácido oleico (83,43%). Em relação as frações dos ácidos gordos PUFA/SFA, as cvs. Arbonosa, Cobrançosa, Cornicabra e Manzanilla apresentaram valores ligeriamente abaixo do limite recomendado.
No que respeita à adição de extrato de alga, observou-se um efeito protetor quando o azeite foi submetido a aquecimento. O azeite aquecido sem adição de alga apresentou valores de índice de peróxido superiores, enquanto que o azeite aquecido com adição de alga, devido ao teor em pigmentos, valores superiores de coeficientes de extinção K232 e K270. A análise da composição química mostrou que os ácidos gordos e os tocoferóis não foram afetados pela adição de extrato de alga. A adição de extrato de alga ao azeite teve um efeito positivo na atividade antioxidante apresentando-se esses azeites mais estáveis. A colorimetria mostrou que os azeites com extratos de alga apresentavam coloração mais laranja o que estará relacionado com o teor superior em pigmentos. Os resultados obtidos permitem afirmar que a adição de extrato de alga não alterou significativamente os parâmetros de qualidade do azeite, podendo favorecer um aumento da sua resistência quando exposta ao aquecimento.
Olive oil is the vegetable oil most appreciated by the consumer due to its organoleptic characteristics and chemical composition that confer unique properties. Whether the sensory and chemical characteristics are highly dependent on olive cultivar. In turn, in modern kitchen, is increasing the use of vegetable oils under thermal process, which influence their properties, having antioxidants an important role in preventing this action. The present study aimed to the study of different varietal oils in terms of their quality, chemical composition and antioxidant activity and the effect of adding algae extracts from Scenedesmus almeriensis in the composition when the oil is subjected to heating. The characterization of the varietal olive oils showed that the cultivar factor is crucial to the composition. For quality parameters, the varietal olive oils showed values within the legal limits established for extra virgin olive oil classification. The oils obtained were different in terms of their chemical composition, sensory characteristics and antioxidant activity. The cv. Manzanilla had the highest content of oleic acid (83.43%). For the PUFA/SFA fraction of fatty acids, cvs. Arbonosa, Cobrançosa, Cornicabra and Manzanilla had values slightly below the recommended range. Regarding the addition of algae extract, we observed a protective effect when the oil was subjected to heating. The heated oil without the addition of algae showed greater peroxide index values, while the heated oil with the addition of algae, due to the pigments content, reported higher values for K232 and K270 extinction coefficients. The chemical composition analysis showed that the fatty acids and tocopherols were not affected by the addition of algae extract. Addition of olive oil algae extract had a positive effect on antioxidant activity presenting these oils higher stability. The colorimetry showed that the oils with algae extracts had more orange color which is related to higher pigment content. The results allow us to state that the addition of algae extract did not significantly alter the oil quality parameters that could favor an increase in their resistance when exposed to heat.
Olive oil is the vegetable oil most appreciated by the consumer due to its organoleptic characteristics and chemical composition that confer unique properties. Whether the sensory and chemical characteristics are highly dependent on olive cultivar. In turn, in modern kitchen, is increasing the use of vegetable oils under thermal process, which influence their properties, having antioxidants an important role in preventing this action. The present study aimed to the study of different varietal oils in terms of their quality, chemical composition and antioxidant activity and the effect of adding algae extracts from Scenedesmus almeriensis in the composition when the oil is subjected to heating. The characterization of the varietal olive oils showed that the cultivar factor is crucial to the composition. For quality parameters, the varietal olive oils showed values within the legal limits established for extra virgin olive oil classification. The oils obtained were different in terms of their chemical composition, sensory characteristics and antioxidant activity. The cv. Manzanilla had the highest content of oleic acid (83.43%). For the PUFA/SFA fraction of fatty acids, cvs. Arbonosa, Cobrançosa, Cornicabra and Manzanilla had values slightly below the recommended range. Regarding the addition of algae extract, we observed a protective effect when the oil was subjected to heating. The heated oil without the addition of algae showed greater peroxide index values, while the heated oil with the addition of algae, due to the pigments content, reported higher values for K232 and K270 extinction coefficients. The chemical composition analysis showed that the fatty acids and tocopherols were not affected by the addition of algae extract. Addition of olive oil algae extract had a positive effect on antioxidant activity presenting these oils higher stability. The colorimetry showed that the oils with algae extracts had more orange color which is related to higher pigment content. The results allow us to state that the addition of algae extract did not significantly alter the oil quality parameters that could favor an increase in their resistance when exposed to heat.
Description
Mestrado com dupla diplomação com a Universidade Tecnológica Federal do Paraná
Keywords
Azeites elementares Caraterização Antioxidantes Extrato de alga Scenedesmus almeriensis Aquecimento