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Problem Statement
Problem Statement
In the Coffee Community, there is an ongoing discussion of whether or not shots of espresso coffee goes bad, or "dies", after a certain period of time of the espresso being pulled. Despite some people thinking that espresso doesn't die, many other people in the coffee community believe that you can only use espresso in drinks for a certain amount of time before the quality of that espresso shot dies. This debate has caused a divide in the community. Conducting an experiment to study certain characteristics of espresso shots can help prove or disprove this myth, I could potentially improve the quality of espresso drinks overall.
Definitions:
Definitions:
Espresso: A small and highly caffeinated sample of coffee that originates in Italy. It is brewed by pushing hot water through finely ground coffee with high pressure. It had three parts; crema, body, and heart.
Dead Espresso: A sample of espresso that doesn't have body
TDS [total dissolved solids] : the coffee-to-water ratio of a sample of espresso (in terms of this study)
Refractometer: The tool used to measure TDS, that records the amount of solids in a liquid sample by the amount of light rays that pass through a specific sample.
Implications / Importance:
Implications / Importance:
Coffee, and caffeine in general, is relied on by many people around the world. Taking a step to potentially help improve the quality of espresso will be very beneficial to the people that love coffee. Dead espresso isn’t considered high-quality coffee, so if my experiment helps prove or disprove dead espresso’s existence, then I might be able to improve the quality of espresso drinks for many coffee drinkers around the world.
The Myth of Dead Espresso Shots
The Myth of Dead Espresso Shots
Does the ratio of water-to-coffee in varying espresso shots change over time?
Researcher
Researcher
Significance and Value of Study
Significance and Value of Study
When an espresso shot "dies", some people claim that the taste changes and becomes bitter. However, some people don't believe this and use "dead" espresso shots in their drinks. Whether the myth is true or not, finding an answer will help improve the quality of drinks, therefore improving the coffee experience.
^ photo edited and taken by researcher
Hypothesis and Assumptions:
Hypothesis and Assumptions:
I hypothesized that I will find the TDS of espresso will differ over time. Whether it increases or decreases, I do believe that scientific characteristics of espresso changes over time, as espresso is very prone to change. I didn't have enough information to guess whether or not the TDS will increase, decrease, or stay the same.
Proposed Method of Study / Definitions and Variables
Proposed Method of Study / Definitions and Variables
Pre-Experiment:
Before beginning my experiment, I rinsed my machine and cleaned out the grouphead, or the part that connects the portafilter to the machine, so that there was absolutely no residue left from previous espresso shots. I also calibrated my refractometer to ensure the most accurate results. I cleaned out and completely dried my portafilter and shot glasses. For reference, the portafilter is the part of the machine that the espresso grounds are placed into and where the brewing process happens. If there was any other liquid than the espresso shot I was going to measure in my shot glass or portafilter, it would have thrown off my data. I wanted to ensure the most accurate results from what I could control. One thing to note is that I repeated this process after every trial (or every three espresso shots). I also cleaned off my refractometer after every shot of espresso so that I was only measuring the current shot I was at.
Step One:
Put espresso-ground coffee in the clean portafilter (enough for a two-shot pull). I used a 100% lighter roast arabica coffee for my espresso, as it was readily available for me to use. Evenly spread out the espresso and tamp down. Note that I did not use a WDT tool, an instrument that helps break up clumps in the espresso ground, or any type of paper filter for any of my espresso shots.
Step Two:
Connect the portafilter and the grouphead in order to start extraction. Start the brewing process and pull the espresso shot. As the shot is pulling, turn on or reset your refractometer so that it will be ready to use for measuring once your espresso is done being brewed.
Step Three:
Take one TBSP of the espresso shot and put it onto the refractometer (or TDS meter). Record the TDS for that specific espresso shot in the data table. For trial two, do this step after waiting five seconds between the end of the brewing process and putting the espresso on the meter. For trial three, do this step after waiting 15 seconds. For trial four, do this step after waiting one minute.
Results -->
Results -->
As displayed, you can see that the TDS of espresso taken in the first trial, with an average of 1.84%, was significantly higher than the TDS of the espresso in the fourth trial, with an average of 1.25%. The second trial had an average TDS of 1.48%, while my third trial had an average of 1.58%. The second and third trials proved to be similar to each other but follows the trend of the TDS decreasing over time.
Conclusion:
Conclusion:
Hypothesis: Based on these trends, this proves my hypothesis to be correct. Before beginning this experiment, I hypothesized that I would find some sort of change, which I did find after I had collected all the data from my experiment. I did not know if that change would be an increase or a decrease as time progressed, but I did predict that I would find change. My data does prove that the TDS changes over time.
Next Steps:
Next Steps:
The next steps I want to take are very clear. Using a high-quality espresso machine in future experiments is something that I hope to do, as it could yield more accurate results. This exact experiment replicated with a different espresso machine could have different results, so seeing what those could be will help answer my question more accurately.
Key Sources:
Key Sources:
BEC-Admin. (2022, November 4). What is a dead espresso shot and how does it taste? Brew Espresso Coffee. Retrieved January 21, 2023 https://brewespressocoffee.com/dead-espresso-shot/#1-what-does-dead-espresso-mean
Várady, M., Tauchen, J., Klouček, P., Popelka, P., (2022, August). Effects of Total Dissolved Solids, Extraction Yield, Grinding and Method of Preparation on Antioxidant Activity in Fermented Specialty Coffee. Fermentation 2022, 8(8), 375. https://doi.org/10.3390/fermentation8080375
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