During week four, we studied the process of mass transfer and flux during the brewing process. One of the goals we have set forth for our design is to gain maximum extraction while maintaining a low acidity brew. While only 30% of coffee is soluble (the other 70% is cellulose which is not soluble), a good-tasting cup of coffee holds 19%-21% of dissolved solids. In order to achieve this, the variable we decided to manipulate was extraction time, given that is easily controlled in the siphon brewer. Our two testing times were one minute and ten minutes, in which calculated the conductivity at each minute. To relate conductivity to the amount of total dissolved solids, we created a calibration curve using instant coffee, coffee comprised solely of dissolved solids. By matching the amount of instant coffee to conductivity values, we were able to match our found conductivity values to the curve to find the corresponding concentration. Then, using the mass of the brew at each time, we found the percent of TDS and corresponding extraction yield. Unfortunately, we were unable to achieve a 20% extraction yield because the brew time was limited by the Mr. Coffee. Our next research goal after designing the experiment is to measure the concentration vs. time of our siphon brewer and the pH vs. time of our siphon brewer. Through graph analysis, we will find the time at which the extraction yield is around 20 and the pH is most neutral. This will give us the ideal brewing time for our final deliverable.
(Pictured Above: Ethan checks the conductivity of the instant coffee)
(Pictured to the Right: Angie helps create the calibration curve using different measurements of dissolved solids.)
(Pictured below: Ben, Alex, and Angie are excited to find our brew time!)
