ABSTRACT
Lipids in food are conventionally analyzed in two stages: extraction with organic solvent and fat esterification reaction, in this case, the type of fat of each food influences the choice of extraction and esterification reagents. In the direct method, such procedures are performed in one step. This work compared the conventional extraction method and quantification of lipids and fatty acids, with a direct method in infant formula. A reference sample of infant formula conteining certified lipids and fatty acids values from the National Institute of Standards and Technology was used. The conventional method for lipid analysis used the acid hydrolysis method; for the determination of fatty acids, the fats were extracted with a mixture of ethyl ether and petroleum ether. The direct method consisted of direct trans esterification with sodium methoxide. In the analysis of fatty acids, the majority of the results showed statistically equal values (α < 0.05) for both methods. The direct method proved suitable, mainly because of reduction in analytical time and quantity of solvents (AU).
Os lipídios em alimentos são analisados, de forma convencional, em duas etapas: extração com solvente orgânico e reação de esterificação da gordura, neste caso o tipo de gordura de cada alimento influencia na escolha dos reagentes da extração e esterificação. No método direto, estes procedimentos são realizados em uma etapa única. Este trabalho comparou a metodologia convencional de extração e quantificação de lipídios e ácidos graxos, com um método direto em fórmula infantil. Foi utilizada uma amostra de referência de fórmula infantil com valores certificados para lipídios e ácidos graxos da Nacional Institute of Standards and Technology. A metodologia convencional para a análise de lipídios empregou método com hidrólise ácida; para a determinação dos ácidos graxos, a gordura foi extraída com uma mistura de éter etílico e éter de petróleo. O método direto fundamentou-se na transesterificação direta com metóxido de sódio. Na análise dos ácidos graxos, a maioria dos resultados demonstrou valores estatisticamente iguais (α < 0,05) para os dois métodos. O método direto demonstrou ser apropriado, principalmente pela diminuição do tempo de análise e quantidade de solventes (AU).
Subject(s)
Chromatography, Gas , Fats , Fatty AcidsABSTRACT
Classical method of sample preparation for fatty acid analysis is a complicated, rigorous, multiple-step process that is often time-consuming. However, innovation has made it possible to obtain fatty acids esters in a single step without compromise of the quality and quantity of the products obtained. Fatty acid methyl esters (FAMEs) were obtained from Sabal causiarum seed using direct trans-esterification method. The reaction was performed in a one necked glass reactor equipped with a reflux condenser. The composition of the FAMEs obtained was analyzed using GC-FID/GC-MS. The FAMEs was also evaluated for its antioxidant potential using DPPH assay while α- tocopherol served as a standard. From the Total ion chromatogram, a total of twelve fatty acids were identified with the dominant being linoleic acid (29.83%), an essential polyunsaturated omega-6 fatty acid. Other compounds obtained in significant yield include palmitic acid (20.75 %), dodecanoic acid (12.15 %), oleic acid, an omega-9 monounsaturated fatty acid (11.51%), 11-Octadecenoic acid (5.89 %), Ceric acid (4.97) and lignoceric acid (4.56 %). The oil had higher antioxidant potential (with IC50 value 0.19 ± 0.31 mg/mL) than the standard, alpha-tocopherol (with IC50 of 0.25 ± 0.4 (mg/mL). The direct trans-esterification method enables the quick determination of the fatty acid profile of Sabal causiarum seed. It is a viable method that saves time, limit use of solvents and reduce the possibility of contaminations that is associated with classical multistage procedure. The chemical composition and high antioxidant value of the oil is a strong indication of the future economical and biological relevance of the Sabal causiarum seed oil.