Distribuição de isômeros de ácido clorogênico e teores de cafeína e trigonelina em cafés solúveis brasileiros

Abstract

Nine Brazilian instant coffee samples were analysed for chlorogenic acids, caffeine and trigonelline using HPLC. Different isomers of chlorogenic acid (CGA) in the groups of caffeoylquinic acids (CQA), dicaffeoylquinic acids (DICQA) and feruloylquinic acids (FQA) were determined. The isomers of the CQA group were predominant in all samples with 5-CQA being the most abundant. Total CGA levels varied from 0.6 to 5.9g%. The samples with lowest CGA content were probably the ones obtained from dark roasted coffee beans. The trigonelline levels varied between 0.3 to 1.0g% reflecting the different conditions used by the manufacturers. The decaffeinated coffee retained about 0.065g% of caffeine and the majority of the other samples showed levels around 2.7g%. The small variability of caffeine within the samples was due to its resistance to the heat treatment. The knowledge of instant coffee composition is relevant to evaluate the real contribution of coffee to the biological effects of the diet.