Avaliação da estabilidade oxidativa de compostos bioativos em óleos especiais extraídos por prensagem a frio
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Data
2019-10-18
Autores
Pazzoti, Geisa Simplício de Oliveira
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Editor
Universidade Estadual Paulista (Unesp)
Resumo
A procura por óleos especiais com elevada estabilidade oxidativa, ricos em compostos bioativos e, portanto, benéficos à saúde, cresce a cada ano. Objetivou-se com o presente trabalho caracterizar quimicamente as sementes, bem como avaliar as propriedades físico-químicas, os teores de compostos bioativos e a capacidade antioxidante dos óleos extraídos por prensagem a frio de chia (Salvia hispanica L.), gergelim (Sesamum indicum L.) e linhaça (Linum usitassimum L.) quando submetidos a diferentes temperaturas (60, 90 e 120°C/5 h) e estocados à temperatura ambiente (25,5°C) por 0, 6 e 12 meses. As sementes apresentaram altos teores de lipídios (31,3 a 46,7%) e proteínas (16,6 a 25,5%), com destaque para as de gergelim. Os óleos submetidos ao aquecimento e estocados à temperatura ambiente apresentaram comportamentos bastante semelhantes: boa qualidade, devido aos baixos índices de ácidez, peróxidos e ρ-anisidina. Por outro lado, o óleo de chia recém extraído, já apresentou na condição inicial, apresentou degradação hidrolítica, enquanto que os de gergelim se destacaram pela maior estabilidade oxidativa. Os ácidos graxos palmítico (17%), oleico (48%) e linoleico (27%) se sobressaíram nos óleos de gergelim e o α-linolênico (58%) no de chia. As concentrações de carotenoides e fenólicos totais decresceram com o aumento da temperatura e do tempo de estocagem, mas a maior retenção de carotenoides foi obtida no óleo de gergelim branco, ao longo dos dois processos. Nos óleos de chia e gergelim submetidos a elevação de temperatura, foram encontrados quatro diferentes fitosteróis, com destaque para o β-sitosterol. Tanto nos óleos submetidos ao aquecimento, quanto nos estocados à temperatura ambiente, o γ-tocoferol se sobressaiu, sobretudo, nos de gergelim. Os resultados da capacidade antioxidante apresentaram oscilações durante nos dois processos avaliados, porém os óleos mostraram expressiva capacidade antioxidante. Pode-se verificar grande potencial para o uso das sementes de chia, gergelim e linhaça, bem como dos seus óleos afim de enriquecer os alimentos industrializados e agregar valor na gastronomia brasileira.
The search for special oils with high oxidative stability, which are rich in bioactive compounds and, thus, beneficial to health, grows every year. Therefore, the present study aimed to chemically characterize the seeds, as well as evaluate the physicochemical properties, the content of bioactive compounds, and the antioxidant capacity of chia (Salvia hispanica L.), sesame (Sesamum indicum L.), and linseed (Linum usitassimum L.) oils extracted by cold pressing, when subjected to different temperatures (60, 90, and 120ºC/5 h) and stored at room temperature (25.5°C) for 0, 6, and 12 months. The seeds presented high lipid (from 31.3 to 46.7%) and protein (from 16.6 to 25.5%) content, especially sesame. The oils subjected to heating and stored at room temperature presented similar behavior: good quality due to low acidity levels and low peroxide and ρ-anisidine values. On the other hand, chia oil, at its initial state, presented hydrolytic degradation, while sesame oils stood out for their high oxidative stability. Palmitic (17%), oleic (48%), and linoleic (27%) fatty acids stood out in sesame oils, while α-linolenic acid stood out in chia oil (58%). The content of total carotenoids and phenolic compounds decreased as the temperature and storage time increased. However, the highest retention of carotenoids was obtained in white sesame oil, during both processes. In chia and sesame oils subjected to increase of temperature, four different phytosterols were found, especially β-sitosterol. In the oils subjected to heating, as well as in those stored at room temperature, γ-tocopherol stood out, especially in sesame oils. The results regarding antioxidant capacity presented oscillations during both evaluated processes. However, the oils showed significant antioxidant capacity. It is possible to observe great potential for the use of chia, sesame, and linseed, as well as their oils, in order to enrich industrialized foods and add value to Brazilian gastronomy.
The search for special oils with high oxidative stability, which are rich in bioactive compounds and, thus, beneficial to health, grows every year. Therefore, the present study aimed to chemically characterize the seeds, as well as evaluate the physicochemical properties, the content of bioactive compounds, and the antioxidant capacity of chia (Salvia hispanica L.), sesame (Sesamum indicum L.), and linseed (Linum usitassimum L.) oils extracted by cold pressing, when subjected to different temperatures (60, 90, and 120ºC/5 h) and stored at room temperature (25.5°C) for 0, 6, and 12 months. The seeds presented high lipid (from 31.3 to 46.7%) and protein (from 16.6 to 25.5%) content, especially sesame. The oils subjected to heating and stored at room temperature presented similar behavior: good quality due to low acidity levels and low peroxide and ρ-anisidine values. On the other hand, chia oil, at its initial state, presented hydrolytic degradation, while sesame oils stood out for their high oxidative stability. Palmitic (17%), oleic (48%), and linoleic (27%) fatty acids stood out in sesame oils, while α-linolenic acid stood out in chia oil (58%). The content of total carotenoids and phenolic compounds decreased as the temperature and storage time increased. However, the highest retention of carotenoids was obtained in white sesame oil, during both processes. In chia and sesame oils subjected to increase of temperature, four different phytosterols were found, especially β-sitosterol. In the oils subjected to heating, as well as in those stored at room temperature, γ-tocopherol stood out, especially in sesame oils. The results regarding antioxidant capacity presented oscillations during both evaluated processes. However, the oils showed significant antioxidant capacity. It is possible to observe great potential for the use of chia, sesame, and linseed, as well as their oils, in order to enrich industrialized foods and add value to Brazilian gastronomy.
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Palavras-chave
Chia, Gergelim., Linhaça, Ácidos graxos, Controle de qualidade, Compostos bioativos, Sesame, Linseed, Fatty acids, Quality control, Bioactive compounds