论文标题
在咖啡冲泡中提取不均匀
Uneven Extraction in Coffee Brewing
论文作者
论文摘要
最近的一个实验表明，与理论预测相反，超出造成咖啡的截止点会导致提取较低。对此的一种潜在解释是，精细的研磨促进了咖啡床中的不均匀提取。我们研究了由于溶解与促进不均匀提取的流动之间相互作用而发生的可能性。一个低维模型，其中有两种可能的流动途径得出和分析。该模型表明，在临界磨削尺寸以下，提取的缩小随着磨削尺寸的降低而降低，如实验中所见。在模型中，这是由于孔隙率的初始不平衡与两种途径的渗透率之间的复杂相互作用所致，这会随着流量和提取而增加，从而使所有可溶性咖啡完全从一个途径中完全提取。
A recent experiment showed that, contrary to theoretical predictions, beyond a cutoff point grinding coffee more finely results in lower extraction. One potential explanation for this is that fine grinding promotes non-uniform extraction in the coffee bed. We investigate the possibility that this could occur due the interaction between dissolution and flow promoting uneven extraction. A low dimensional model in which there are two possible pathways for flow is derived and analysed. This model shows that, below a critical grind size, there is a decreasing extraction with decreasing grind size as is seen experimentally. In the model this is due to a complicated interplay between an initial imbalance in the porosities and permeabilities of the two pathways which is increased by flow and extraction, leading to the complete extraction of all soluble coffee from one pathway.
