Optimizing Tea Extraction Through Physical Agitation

Abstract

Tea is the second most consumed beverage in the world, yet its brewing methods have seen little technological innovation compared to other popular beverages like coffee. Our research investigates whether agitation methods can shorten brew time while maintaining or improving sensory quality. We performed a blind tasting experiment (n=11) using green tea to compare ultrasonic agitation (UA) and mechanical agitation (MA) to static steeping for 1, 3, and 5 minutes. The outcome of this experiment informed our next steps, indicating that mechanical agitation for a total steep time of 3 minutes was the preferred time and agitation method. A three-step mathematical model was developed, which explains how compounds first move outside the tea cell walls, then into the water in the tea bag, and finally across the mesh into the cup. This model also predicted a faster time to reach a 95% concentration of extracted compounds through an increase in dipping frequency, further supporting the hypothesis that agitation can shorten brew time while maintaining or improving quality. Finally, a prototype tea machine was designed and fabricated, which can consecutively brew 2-3 cups of tea. The machine can be controlled via Bluetooth and features fully customizable parameters including water temperature, dispense volume, dipping frequency, agitation steep time, and static steep time. This analysis has both theoretical and commercial implications. Mechanical agitation has been realized into a physical product, which can increase the speed of quality tea making and adapt to consumer preference.