Optimization of the roasting conditions of arabica coffee cultivated in the cerrado area of Brazil

Abstract The aim of this work was to optimize, by way of a rotational central composite design (RCCD), the roasting temperature and time conditions of beans from three Coffea arabica L. genotypes cultivated in the Cerrado, Brazil under controlled water stress conditions, to maintain a high soluble solids content and a roasting colour acceptable by consumers. In this way it will be possible to know the potential use of these genotypes in the instant coffee industry. The RCCD design was carried out with 2 factors (time and temperature) and 11 experiments for each of the three genotypes. The soluble solids contents were determined using a digital refractometer and the roasted bean colour evaluated using the Agtron system. The software R was used in both the variance analysis and in the multiple linear regression to define the prediction mathematical models and the statistical parameters. The Excel SOLVER tool version 2010 was used to select the best colour-soluble solids binomial to provide a colour from 65# to 45# (medium light to moderately dark) on the Agtron system and the highest soluble solids value. The roasting temperature and time conditions that maintained high soluble solids contents and produced roasted beans with an appropriate colour for consumption were 204.8 °C and 10.9 minutes for the cultivar MG 1177; 214.2 °C and 8.8 minutes for MG 0188; and 240 °C and 7 minutes for Icatu 2944, showing the potential for traditional consumption and the production of instant coffee.

摘要 本研究旨在通过旋转中心复合设计（rotational central composite design, RCCD），优化巴西塞拉多地区在受控水分胁迫下种植的3个阿拉伯咖啡（Coffea arabica L.）基因型的咖啡豆烘焙温度与时间参数，以维持较高的可溶性固形物含量，并获得消费者可接受的烘焙色泽，进而明确这些基因型在速溶咖啡产业中的应用潜力。本研究针对3个基因型各设置2个考察因素（烘焙时间与烘焙温度），每个基因型开展11组实验。采用数字折射仪测定咖啡豆的可溶性固形物含量，借助Agtron系统评估烘焙豆色泽。使用R软件完成方差分析与多元线性回归分析，以构建预测数学模型并计算相关统计参数。采用2010版Excel SOLVER工具筛选最优的色泽-可溶性固形物组合，要求Agtron系统读数处于65#至45#区间（对应中浅至中深烘焙色泽），且可溶性固形物含量达到最高水平。最终得到各基因型的最优烘焙条件：品种MG 1177为204.8℃、10.9分钟；MG 0188为214.2℃、8.8分钟；Icatu 2944为240℃、7分钟，结果表明这些基因型具备传统饮用及速溶咖啡生产的应用潜力。