Caracterização e estabilidade oxidativa de misturas de óleo de linhaça e óleo de abacate
Arquivos
Data
2022-12-15
Autores
Moura, Milena da Silva 
Orientadores
Braga, Matheus Boeira
Tipo
Trabalho de conclusão de curso
Título da Revista
ISSN da Revista
Título de Volume
Resumo
O óleo de linhaça (OL) é rico em ácidos αlinolênico e linoleico, ácidos graxos essenciais dos
grupos ômega3 e ômega6, respectivamente. No entanto, sua composição química o torna
suscetível à degradação oxidativa, o que pode reduzir suas possibilidades de utilização em
matrizes alimentares. A mistura de óleos vegetais de diferentes composições pode originar
produtos alimentícios com propriedades específicas e maior estabilidade oxidativa. O óleo de
abacate (OA) destaca-se por sua composição (rico em ácido graxo oleico, ácido graxo
essencial monoinsaturado do grupo ômega9, e tocoferóis, compostos com alta capacidade
antioxidante), apresentando um potencial para compor misturas com o óleo de linhaça. Assim,
esse trabalho teve como objetivo geral estudar diferentes misturas entre o OL e o OA, com o
intuito de aumentar a estabilidade oxidativa, alterando-se a concentração dos ácidos graxos
mono e poli-insaturados. Os óleos de linhaça e de abacate e suas misturas (25%75% OA:OL,
50%50% OA:OL, 75%25% OA:OL) foram caracterizados quanto as propriedades físicas e
físico-químicas: densidade; pH; reologia; índice de peróxido (IP); coeficientes de extinção
exclusiva (K232 e K268); acidez; porcentagem de ácidos graxos livres expresso em ácido oleico
(FFA). Posteriormente, analisou-se a estabilidade oxidativa acelerada dos óleos e misturas a
partir das análises de IP, K232 e K268, a uma temperatura fixa de 45 oC. Óleos puros
apresentaram composições semelhantes às encontradas na literatura: 69,22% de ácidos graxos
poli-insaturados, 21,11% de ácidos graxos monoinsaturados e 9,63% de ácidos graxos
saturados para o óleo de linhaça; 14,75% de ácidos graxos poli-insaturados, 61,92% de ácidos
graxos monoinsaturados e 23,36% de ácidos graxos saturados para o óleo de abacate. O óleo
de linhaça apresentou IP de 0,33 mEq/kg, FFA de 0,29%, K232 de 1,90 e K268 de 0,16,
indicando uma boa qualidade. O óleo de abacate apresentou FFA de 0,89%, K232 de 3,08, K268
de 0,13 e IP de 14,96 mEq/kg, indicando um estado de considerável oxidação lipídica. A
partir dos resultados das análises de estabilidade, observou-se um fator de aumento de 1,22
para o IP da mistura 25%75% OA:OL e de 9,0 para o óleo de linhaça puro após 14 dias. Os
fatores de aumento obtidos após 28 dias para ambos os coeficientes de extinção foram
menores para todas as misturas quando comparados ao óleo de linhaça puro. As formulações
50%50% e 75%25% OA:OL apresentaram os melhores resultados em relação aos
coeficientes K232 e K268 (menores valores de fator de aumento). A partir da análise dos
resultados de estabilidade, constatou-se um maior avanço da oxidação lipídica do óleo de
linhaça e o efeito positivo da adição de óleo de abacate na estabilidade oxidativa das misturas.
Flaxseed oil (FO) is is rich in alphalinolenic and linoleic acids, essential fatty acids part omega3 and omega6 groups, respectively. Nonetheless, its chemical composition makes it highly susceptible to oxidative degradation, which might reduce its possibilities of use in food matrixes. Mixing vegetable oils with different compositions may lead to food products with specific properties and a higher oxidative stability. Avocado oil (AO) stands out among other fruit oils because of its composition (high concentration of oleic acid, essential monounsaturated fatty acid in the omega9 group, and tocopherols, compounds with a high antioxidant capacity), with a high potential of composing mixtures with flaxseed oil. Therefore, this project’s general goal was studying different mixtures between FO and AO, aiming for the enhancement of oxidative stability through a change in the mono and poliunsaturated fatty acids concentration. Flaxseed and avocado oils and the different oil mixtures (25%75% AO:FO, 50%50% AO:FO, 75%25% AO:FO) were studied as to their physical and physicochemical properties: density, pH, rheology, peroxide value (PV), exclusive extinction coefficients (K232 e K268), acidity value and free fatty acids percentage, expressed in oleic acid equivalent (FFA). Subsequently, the oils and mixtures’ accelerated oxidative stability was analyzed through PV, K232 and K268 under a constant temperature of 45 °C. Pure oils had physical and physicochemical properties similar to those found in literature: 69,22% of poliunsaturated fatty acids, 21,11% of monounsaturated fatty acids and 9,63% of saturated fatty acids for flaxseed oil, and 14,75% of poliunsaturated fatty acids, 61,92% monounsaturated fatty acids and 23,36% of saturated fatty acids for avocado oil. Flaxseed oil presented PV of 0,33 mEq/kg, FFA of 0,29%, K232 of 1,90 and K268 of 0,16, being considered a good quality oil. Avocado oil presented FFA of 0,89%, K232 of 3,08, K268 of 0,13 and PV of 14,96 mEq/kg, indicating advanced lipid oxidation. Oxidative stability studies showed an enhancement factor of 1,22 for the 25%75% AO:FO mixture and 9,0 for pure flaxseed oil after 14 days. After 28 days, K232 enhancement factors were lower for the mixtures when compared to pure flaxseed oil, and K268 enhancement factors were higher, but mixture’s results were also lower than the ones obtained for pure flaxseed oil. K232 and K268 showed better results for the 50%50% and 75%25% AO:FO mixtures. The stability results indicated a higher advancement for lipidic degradation reactions in flaxseed oil, which led to the conclusion that adding avocado oil was positive for the mixtures’ oxidative stability.
Flaxseed oil (FO) is is rich in alphalinolenic and linoleic acids, essential fatty acids part omega3 and omega6 groups, respectively. Nonetheless, its chemical composition makes it highly susceptible to oxidative degradation, which might reduce its possibilities of use in food matrixes. Mixing vegetable oils with different compositions may lead to food products with specific properties and a higher oxidative stability. Avocado oil (AO) stands out among other fruit oils because of its composition (high concentration of oleic acid, essential monounsaturated fatty acid in the omega9 group, and tocopherols, compounds with a high antioxidant capacity), with a high potential of composing mixtures with flaxseed oil. Therefore, this project’s general goal was studying different mixtures between FO and AO, aiming for the enhancement of oxidative stability through a change in the mono and poliunsaturated fatty acids concentration. Flaxseed and avocado oils and the different oil mixtures (25%75% AO:FO, 50%50% AO:FO, 75%25% AO:FO) were studied as to their physical and physicochemical properties: density, pH, rheology, peroxide value (PV), exclusive extinction coefficients (K232 e K268), acidity value and free fatty acids percentage, expressed in oleic acid equivalent (FFA). Subsequently, the oils and mixtures’ accelerated oxidative stability was analyzed through PV, K232 and K268 under a constant temperature of 45 °C. Pure oils had physical and physicochemical properties similar to those found in literature: 69,22% of poliunsaturated fatty acids, 21,11% of monounsaturated fatty acids and 9,63% of saturated fatty acids for flaxseed oil, and 14,75% of poliunsaturated fatty acids, 61,92% monounsaturated fatty acids and 23,36% of saturated fatty acids for avocado oil. Flaxseed oil presented PV of 0,33 mEq/kg, FFA of 0,29%, K232 of 1,90 and K268 of 0,16, being considered a good quality oil. Avocado oil presented FFA of 0,89%, K232 of 3,08, K268 of 0,13 and PV of 14,96 mEq/kg, indicating advanced lipid oxidation. Oxidative stability studies showed an enhancement factor of 1,22 for the 25%75% AO:FO mixture and 9,0 for pure flaxseed oil after 14 days. After 28 days, K232 enhancement factors were lower for the mixtures when compared to pure flaxseed oil, and K268 enhancement factors were higher, but mixture’s results were also lower than the ones obtained for pure flaxseed oil. K232 and K268 showed better results for the 50%50% and 75%25% AO:FO mixtures. The stability results indicated a higher advancement for lipidic degradation reactions in flaxseed oil, which led to the conclusion that adding avocado oil was positive for the mixtures’ oxidative stability.