Week 4: Would You Like to Upgrade Your Meal to a Large?

You might be might wondering what order is mentioned in the title, your favorite french fries, your favorite ice cream, or maybe even your entire meal as you are in the drive-thru line at Chick-Fil-A (the best place to buy french fries). COVID-19 has changed our lives in regards to how we eat out, but the most important question remains, "would you like to upgrade your meal to a large," you could ask yourself the same question when it comes to coffee particle size, the focus of week four.

Lecture

It is crazy to think that the term is 45% done, but when the talk of exams and presentations begins, the reality of time hits. This realization hit me during lecture when we began discussing our midterm presentation, how is it possible that it is already midterm time! Besides midterm presentation, during lecture we discussed the pros and cons of creating our own procedure. The process of trial and error is a great learning tool which was evident during week three when the procedure for solid-liquid extraction and the impact of temperature was changed midweek, but the results were far better in showing which temperature would result in the greatest extraction. Lecture this week emphasized that it is okay if things do not work out as long as there is a change that will make the experiment better and provide valuable results.

Redesigning procedures after trial and error is just as important as creating significant experimental questions and goals. The purpose of performing an experiment is highlighted through the questions that are asked and the goals that need to be accomplished. The information we learn with coffee about temperature, particle size, and other various independent variables answer the experimental questions and can be applied to other materials and extraction process designs.

Procedure

Following the steps of a recipe ensures the optimal dinner or most delicious dessert, the same goes for solid-liquid extractions, coffee particle size, and the resulting concentration. The procedure for temperature required boiling water, weighing coffee beans, carefully pouring, and repeatedly measuring various aspects of the experiment. The same procedure steps apply for particle size only this week the water temperature remains 68°C for all three trials based on the results from last week. The reason for this choice in temperature is for the ability to be able to apply the procedure experimented with coffee to the extraction of curcumin from turmeric with the use of ethanol, where boiling point must be greatly considered.

This week, the independent variable being tested is particle size. Questions such as what the optimal particle size, how much coffee can be extracted in optimal conditions, does particle size of coffee directly affect the solubility of coffee, and what is the relationship between particle size and concentration/conductivity will be answered by testing various particles sizes while keeping other variables the same. The three sizes that will be tested is a fine, medium, and coarse grind.

For more details regarding the exact steps of the procedure, please visit the week three blog, but keep in mind the variable is no longer temperature, and instead particle size.

Lab

Boiling water, weighing coffee beans, grinding the beans to various sizes, and setting up in the kitchen are the steps required for a successful day in the at-home kitchen lab. Once the correct amount of coffee beans was weighted, ground to their respective sizes, and placed into filters, the interesting part began, would coffee bean particle size impact concentration, if so how?

Approximately 60 grams of ground coffee beans are required to complete the particle size experiment. Once the coffee is ground to the required size (fine, medium, or coarse), the water is heated to 68°C, the cups are set up, and the timer is ready to go, the process of filtration can begin.

After four minutes of filtering, and cooling to the temperature of a calibration curve, the conductivity measured in μS can be taken three times per cup with probe rinsing and drying between each reading. The average conductivity value is then plugged into the x-value of the calibration curve equation and the concentration for each cup is calculated.

Even with different kitchens, different materials, different coffee, and different days, the calibration curves created with instant coffee allow for data analysis across various experiments.

Ultimately, experimenting with various particle sizes, collecting data, and graphing the results, proved that a smaller particle size for coffee beans results in a better solid-liquid extraction which is proved by a higher concentration versus time ratio.

So far, a water temperature of 68°C and a smaller particle size for coffee beans has been proved to provide the best results. Come back in a week to find out the next independent variable tested in the quest of creating an extraction process that can be applied to various materials, not just beloved coffee.