Unit 4: Understanding Data (Designing Coffee)
Lesson 2: Designing Coffee
U04_L02_05-R1-Original_Unit_Design_Report
ThisreportwassubmittedbytheteamofChemicalEngineeringstudentswhoseworkservesasthe
foundationforthisunit.Itisprovidedasbackgroundmaterialforteachers,butmanyofthevaluesand
proceduresusedinthisreportdifferfromthoseusedintheclassroomlabactivity.Sostudentsshould
notcopythesevalues,butreviewthisreportasamodelfortheformattouseinreportingontheir
actuallabresults.
Purpose of Experiment
This experiment is meant to help us design a coffee brewing process to obtain a
coffee with a specific total dissolved solids (TDS) reading. We want to find a
process that is safe, easy to reproduce, faster, and cheaper. This experiment will
result in data that will help us choose the best brewing process.
Design of Experiment
Vary three variables (factors), with at least two values (levels) for each variable,
as listed below. Eight different tests are needed. Measure total dissolved solids
(TDS) over time for each test. Repeat tests at least two times to measure
repeatability. (The values indicated below differ from those in the final design.)
Label
A
B
C
D
Variable
Temperature
(°C)
Grain Size
Coffee/water
ratio
Time
Test
1
2
3
4
5
6
7
8
•
+ (high)
80
- (low)
20
750-1000µm
Whole
bean
0.017 g/mL
0.033 g/mL
A
+
+
+
+
-
B
+
+
+
+
-
C
+
+
+
+
-
Use 300 mL of water in each test sample, to maximize sample size. This
means:
o “high” coffee/water ratios correspond to 10.0 g coffee
o “low” coffee/water ratios correspond to 5.0 g coffee
Copyright 2017-18, The Board of Regents of the University of Texas System. All Rights Reserved.
Requests to reproduce any part of this material may be made to Engineer Your World.
Page 1 of 3
Unit 4: Understanding Data (Designing Coffee)
Lesson 2: Designing Coffee
U04_L02_05-R1-Original_Unit_Design_Report
•
Experience tells us that the “hot” (80°C) tests will probably reach steady
state (meaning the will level out) total dissolved solids (TDS) readings more
quickly than the “cold” (20°) or room temperature tests. So measure the
cold tests for a longer period of time.
Materials List for Tests
•
•
•
•
•
•
•
•
•
•
•
TDS/Conductivity meter
o HM Digital, AP-2 AquaPro
Coffee Beans
o San Francisco Bay Premium Gourmet French Roast Arabica Coffee
Beans, 3 lb bag; 1/2 of bag ground at grocery store
Mass scale, 0-100g range
Graduated cylinder, to measure 300 mL
Tap water, 5L (or distilled water if available)
Paper coffee filters
Twist-ties
Water heating device (hot plate, water boiler, microwave)
Thermometer
Mason jars, at least 8
Timer or stopwatch
Test Procedure
1. Label all mason jars with the sample
number. Prepare data collection sheet.
Measure TDS of tap water for reference.
2. For a single test, make coffee packet with
coffee filter and coffee bean sample (9.69
or 5.1 g coffee). Close packet with twist-
tie.
Copyright 2017-18, The Board of Regents of the University of Texas System. All Rights Reserved.
Requests to reproduce any part of this material may be made to Engineer Your World.
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Unit 4: Understanding Data (Designing Coffee)
Lesson 2: Designing Coffee
U04_L02_05-R1-Original_Unit_Design_Report
3. Heat 300 mL of water as necessary and confirm temperature with
thermometer.
4. Add packet and water to the mason jar. Start timer.
5. Measure TDS of sample at 1 min, 5 min, 10 min, and 15 min after start of
brewing, and additional times as needed. For “cold” tests, measure 24
hours after start.
6. Plot data and determine which processes lead to target ppm readings.
Copyright 2017-18, The Board of Regents of the University of Texas System. All Rights Reserved.
Requests to reproduce any part of this material may be made to Engineer Your World.
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