Análise sensorial química e perfil de voláteisde cafés especiais das quatro regiões cafeeiras do estado de Minas Gerais

Abstract

The significant increase in the demand for specialty coffees, both in the domestic and international market, together with the potential of different producing regions in the state of Minas Gerais for the production of specialty coffees, justifies studies aimed at understanding the relationship between chemical constitution and volatile profile of roasted coffee and the sensory quality of the drink from these regions. As a result, this study was conducted with the following objectives: i) evaluate how the interaction between processing and regions affects coffee quality, as well as relate the chemical composition (titratable acidity, pH, ash, soluble solids, total sugars, trigonelline, caffeine, 5-caffeoylquinic acid (5-CQA), tridecanoic acid, pentadecanoic acid, palmitic acid, stearic acid, oleic acid, linoleic acid, α-linolenic acid, eicosanoic acid and heneicosanoic acid) with their sensory quality and ii) characterize volatile and sensory profiles of specialty coffees produced in the four regions of Minas Gerais and correlate volatile compounds with the results of the sensory analysis. Coffee samples from the regions Southern Minas Gerais, Matas de Minas, Cerrado Mineiro and Chapada das Minas, as well as dry (natural) and wet (parchment) pre-processing procedures, were evaluated. For each region, two samples of different processes were obtained, totaling eight samples. The design was completely randomized (CRD). It was concluded that: i) specialty coffee samples showed significant differences for all analyzed variables, except for the sensory attributes of regions in southern Minas Gerais, Matas de Minas and Cerrado Mineiro. Coffees from the region Chapada das Minas had the lowest sensory scores for all attributes, including final sensory score. The type of processing significantly influenced the majority content of the analyzed variables. The ash content allowed coffee discrimination with higher and lower sensory scores. The variables caffeine and sweetness influenced the discrimination of coffees from Chapadas de Minas, regardless of the type of processing, with higher and lower intensity, respectively. The highest concentrations of eicosanoic and heneicosanoic acids were related to coffees with higher sensory scores and contributed to their discrimination in relation to coffees with lower sensory scores; ii) the classes of chemical compounds with the most likely identifications and larger areas were furans, pyrazines and ketones. The samples natural Sul de Minas (SM_NAT); parchment Cerrado Mineiro (CER_CD); natural Cerrado Mineiro (CER_NAT); parchment Sul de Minas (SM_CD) and natural Chapadas de Minas (CHA_NAT) were mainly related to 2-furanmethanol acetate. Other compounds, such as 3 pentanone, 2- methyl-; 2.3-dimethylpyrazine; 3-ethyl-2,5-dimethylpyrazine and 5- methylfurfural also contributed to the discrimination of these coffees. The sample CHA_CD was mainly related to 2,3-dimethylpyrazine. However, pyridine and acetic acid were also related to this coffee, which may have contributed to its smaller score in the sensory analysis. The coffees in the region Matas de Minas were discriminated by the compound 2,6-dimethylpyrazine, which can be considered an indicator of the quality of these coffees.