Influência dos parâmetros de processo na formação do aroma e sabor indesejado de cereal em café aglomerado

Abstract

The agglomerated instant coffee is the product of the powder instant coffee agglomeration. Its production involves stages of processes whose thermal variations change qualitatively and quantitatively the volatile compounds fractions responsible for the aroma and flavor of the finished product. The coffee beverage industry considers the cereal like flavor and aroma as a fault in the production of the agglomerated instant coffee. In this way, this study had as the aim to apply experimental plan to evaluate the parameters of the processes of the agglomerated instant coffee production on an industrial scale. The effects of those parameters in the coffee volatile components and in the intensity of the cereal taste were evaluated through the fractional 24-1 with resolution IV. The independent variables studied were the burner temperature (BT), the process air flow (AF), the temperature of the fluidized bed hot section (LT) and the steam pressure (SP). The results of the experimental plan were made by the use of sensory analysis performed by a trained team for the detection of the undesired aroma and flavor. Additionally, the volatile compounds were extracted by solid-phase microextractiontechniquewithsampling in theheadspace (HS-SPME), identified and quantified by gas chromatography coupled to mass spectrometry (GC-MS). The effect of the factors studied was evaluated by variance analysis (ANOVA) with significance level of 90% and the results showed by Pareto charts. The principal components analysis (PCA) was made with the aim to identify, among several compounds, those that implies on more cereal flavor and aroma, those which major contribution and which ideal process conditions could be used to reduce the cereal flavor and aroma development. According to PCA, it was found that pyridine, 2-metoxi-4-vinylphenol, 2,3-dimethylpyrazine, 2,5-dimetylpyrazine, 2,6-dimethylpyrazine, 4-methyltiazol, pyrazine, 2-methoxyphenol, 4,5-dimethylthiazol contribute to the development of the cereal flavor and aroma. It was also found that the agglomeration must be according to TQ = 215°C, AF=250 rpm, LT=120°C and EPV = 1,2 x 100 KPa.