Page optimization of the foam-mat drying process to soluble coffee production

Abstract The expansion of the soluble coffee production is an alternative to the traditional coffee consumption, which is necessary to meet the new demands of consumers looking for convenience and practicality. Thus, this study of techniques that simplify and reduce costs to obtain soluble coffee become even more pertinent. Therefore, the objective of this work was to optimize the drying process of coffee extract in the foam bed by adjusting the Page Model by non-linear regression. Two methods for the concentration of the extract were evaluated: (A) in rotary evaporator and (B) in open stainless-steel container. The kinetics of drying the coffee extract in a foam bed under the temperatures of 40, 50, 60, 70 and 80 °C were described by the model. Besides that, a multivariate equation was proposed for drying by detecting influence of temperature on the k parameter, of the Page Model and later validation of the results. The time to obtain the concentrated extract was close to the two concentration methods (A- 2 hours and 30 minutes and B- 2 hours and 40 minutes). The Page model presented a good fit with values of determination coefficients above 99%. The results confirmed that the temperature is a determinant factor in the product moisture loss speed, presenting shorter drying times with the temperature increase. The correlation between experimental and predicted data was satisfactory for the validation of the results. The mathematical model can also assist in the correlation of drying parameters with physicochemical and sensory changes of soluble coffee in order to improve technological parameters.摘要 速溶咖啡产能扩张是传统咖啡消费的可行替代路径，可有效满足消费者对便捷性与实用性的新兴需求。因此，针对简化流程、降低成本以制备速溶咖啡的技术研究，其必要性与重要性愈发凸显。据此，本研究的目标为通过非线性回归修正Page模型（Page Model），优化泡沫床干燥咖啡提取物的工艺过程。本研究评估了两种咖啡提取物浓缩方法：（A）旋转蒸发仪法，（B）不锈钢敞口容器法。该模型可有效描述40℃、50℃、60℃、70℃及80℃条件下，泡沫床干燥咖啡提取物的干燥动力学过程。此外，本研究通过探究温度对Page模型中k参数的影响，构建了用于干燥过程的多元方程，并对所得结果进行了验证。两种浓缩方法的提取物制备时长相近：方法A耗时2小时30分钟，方法B耗时2小时40分钟。Page模型拟合效果优异，决定系数均高于99%。研究结果证实，温度是影响产品水分流失速率的决定性因素：随着温度升高，干燥时长显著缩短。实验数据与预测数据的相关性良好，结果验证效果令人满意。该数学模型还可用于关联干燥参数与速溶咖啡的理化及感官变化，进而优化工艺参数。