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Advisor(s)
Abstract(s)
A ocorrência de oxidação lipídica é um processo espontâneo em gorduras, e consequentemente em produtos com teor de gordura significativo. Cosméticos inseremse nesta categoria, apresentando uma intrínseca relação entre a qualidade do produto e o seu valor de mercado com a capacidade de oxidação. Os efeitos secundários da oxidação levam à deterioração e alteração das características organoléticas do produto, como mudança de odor, textura, cor, separação de distintas fases, o que leva a depreciação do produto por parte do consumidor. Perante isto, a indústria verifica a necessidade real de controlar e avaliar a ocorrência de oxidação nos seus produtos contendo gorduras e óleos, de forma a controlar o período de prateleira adequado. Com este trabalho pretendeu-se avaliar o envelhecimento de cosméticos, no caso particular de dez loções corporais e correlacionar a oxidação lipídica com a composição das loções selecionadas. Para além da análise qualitativa das loções corporais em estudo, estas foram ainda submetidas a análises realizadas recorrendo a diversos métodos, de forma a quantificar os produtos de oxidação primários e secundários. Inicialmente, as amostras foram submetidas a um processo de envelhecimento acelerado (através do seu armazenamento a cerca de 45 ºC) sendo que o estudo teve um total de seis meses. Recorrendo a métodos como a quantificação dos Dienos Conjugados (DC) expresso em percentagem e o Índice de Peróxidos (IP) expresso em meqO2/Kg de amostra seca, foi possível a quantificação dos produtos primários de oxidação. Já métodos como o Índice de p-Anidisina (ipA) e a reação do ácido tiobarbitúrico com o malonaldéido (TBARS) expresso em concentração de malonaldeído (mg/g de amostra seca) proporcionaram a quantificação dos produtos secundários de oxidação. Pela análise dos resultados obtidos e correlação com as avaliações organoléticas para cada mês do estudo, foi possível delinear um perfil de oxidação lipídico para cada amostra. Conclui-se que a loção corporal com maior extensão da oxidação lipídica foi a amostra J, uma vez que esta apresenta um valor total de oxidação (TOTOX) superior, de 3,75. Por outro lado, as loções com menor oxidação lipídica no final do estudo foram as amostras B e C com valores de TOTOX de 0,130 e 0,120, respetivamente.
The occurrence of lipid oxidation is a spontaneous process in fats and, consequently, in products with significant fat content. Cosmetics fall into this category, presenting an intrinsic relationship between the product's quality and its oxidation capacity and market value. The secondary effects of oxidation lead to deterioration and alteration of the product's organoleptic characteristics, such as a change in odour, texture, colour, and separation of different phases, which leads to a product's depreciation towards the consumer. Given this, the industry sees the real need to control and assess the occurrence of oxidation in its products containing fats and oils to control the appropriate shelf life. This work aimed to evaluate the ageing of cosmetics, in the particular case of ten body lotions and to correlate lipid oxidation with the composition of the selected lotions. In addition to the qualitative analysis of the body lotions under study, they were also subjected to analysis carried out by different methods to quantify the primary and secondary oxidation products. Initially, the samples were subjected to an accelerated ageing process (through their storage at about 45 ºC), and the study lasted six months. Using methods such as the quantification of Conjugated Dienes (DC) expressed in percentage and the Peroxide Index (PI) method expressed in meqO2/Kg of dry sample, it was possible to quantify the primary oxidation products. On the other hand, methods such as the p-Anidisine Index (ipA) and the reaction of thiobarbituric acid with malonaldehyde (TBARS) expressed as malonaldehyde concentration (mg/g of dry sample) provided the quantification of secondary oxidation products. By analyzing the results obtained and their correlation with the organoleptic evaluations for each month of the study, it was possible to delineate a lipid oxidation profile for each sample. It is concluded that the body lotion with the greatest extent of lipid oxidation was sample J since it has a higher total oxidation value (TOTOX) of 3.75. On the other hand, the lotions with the lowest extent of lipid oxidation at the end of the study were samples B and C, with TOTOX values of 0.130 and 0.120, respectively.
The occurrence of lipid oxidation is a spontaneous process in fats and, consequently, in products with significant fat content. Cosmetics fall into this category, presenting an intrinsic relationship between the product's quality and its oxidation capacity and market value. The secondary effects of oxidation lead to deterioration and alteration of the product's organoleptic characteristics, such as a change in odour, texture, colour, and separation of different phases, which leads to a product's depreciation towards the consumer. Given this, the industry sees the real need to control and assess the occurrence of oxidation in its products containing fats and oils to control the appropriate shelf life. This work aimed to evaluate the ageing of cosmetics, in the particular case of ten body lotions and to correlate lipid oxidation with the composition of the selected lotions. In addition to the qualitative analysis of the body lotions under study, they were also subjected to analysis carried out by different methods to quantify the primary and secondary oxidation products. Initially, the samples were subjected to an accelerated ageing process (through their storage at about 45 ºC), and the study lasted six months. Using methods such as the quantification of Conjugated Dienes (DC) expressed in percentage and the Peroxide Index (PI) method expressed in meqO2/Kg of dry sample, it was possible to quantify the primary oxidation products. On the other hand, methods such as the p-Anidisine Index (ipA) and the reaction of thiobarbituric acid with malonaldehyde (TBARS) expressed as malonaldehyde concentration (mg/g of dry sample) provided the quantification of secondary oxidation products. By analyzing the results obtained and their correlation with the organoleptic evaluations for each month of the study, it was possible to delineate a lipid oxidation profile for each sample. It is concluded that the body lotion with the greatest extent of lipid oxidation was sample J since it has a higher total oxidation value (TOTOX) of 3.75. On the other hand, the lotions with the lowest extent of lipid oxidation at the end of the study were samples B and C, with TOTOX values of 0.130 and 0.120, respectively.
Description
Keywords
Oxidação em cosméticos Oxidação lipídica Dienos Conjugados Índice de Peróxidos Índice de p-Anidisina Reação do ácido tiobarbitúrico com o malonaldéido Oxidation in cosmetics Lipid oxidation Conjugated Dienes Peroxide Index pAnidisine Index Reaction of thiobarbituric acid with malonaldehyde