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Chemical Engineering Laboratory II
“ Study of the influence of several operating parameters
on coffee leaching .”
Laboratory Work 5
Group - 03
Deep Bhattarai (a40902)
Professor
Ramiro Martins
Date of experiment: 20 /0 4 /
Summary
The main goal of this experimental work is to statistically analyze the influence of certain
parameters during the coffee leaching process. To analyze the parameters the caffeine content
is studied using the 2K^ factorial method. The effects of the parameter on the extraction of the
caffeine concentration were also explored using different techniques.
Material required:
- Watch glass
- Spatula
- Heat plate
- Coffee maker
- Coffee mill
- Beakers
- Tina
- Graduated cylinder
- Funnel
- Filter paper
- Scissors
- Volumetric pipettes
- Pompete
Procedure:
- At first, we should weight the coffee.
- Then we need to carry out extraction experiments (leaching process).
- We need to cool the extracts by inserting them in a vat with water and ice.
- We need to perform filtration.
- After we should adjust the volume of all extracts to constant value.
- At last, analyse the sample using a UV-spectrophotometer at 274 nm.
Results and discussion Calibration curve For the quantitative analysis of the caffeine concentration in samples we need to establish the relationship between concentration of caffeine and adsorption. So, to establish this relationship calibration curve was built using the data provided in the Table 1. The absorbance for the caffeine content to build calibration curve was read under UV-spectrophotometer at the wavelength of 274nm. Table 1: Data of the absorbance of caffeine for calibration curve. S.N Concentration(mg/L) Absorbance(AU) 1 5 0. 2 10 0. 3 15 0. 4 20 1. 5 25 1.
The equation for the relation between caffeine content and absorbance is shown below:
Absorbance = 0.0494 * Concentration + 0.0114 Equation 1
R^2 = 0.99 97
Experimental data analysis
In this experiment 2 factors were studied with 2 level giving the possible combination of the
experiment to be 4 in total. So, to have the precise results this 4 combination was replicated
total the 8 experiments.
Table 2: Parameters use for designing the experiment Number of experiments Parameters Type of coffee Normal 1 Pressurized 2 physical state of coffee Grinded 3 Entire grains 4
Therefore, considering the dilution factor for each experiment following results were
calculated.
Thus, we can say that the caffeine content depends more on the physical state of the coffee
(grinded / entire grain) than on the type.
The Analysis of Variance (ANOVA) was also done using the excel and the results obtained is
displayed by the Table 4.
Table 4: ANOVA analysis using experimental data Source of Variation SS df MS F P-value F crit Sample 1.37846374 1 1.378464 292.4159 6.86E- 05 7. Columns 2.12706794 1 2.127068 451.2186 2.9E- 05 7. Interaction 1.6149119 1 1.614912 342.574 5.01E- 05 7. Within 0.01885621 4 0. Total 5.13929979 7
Conclusion
We can conclude that the caffeine concentration mostly depends more on the physical state of
the coffee rather than the type of coffee. We can also conclude that there is certainly a
interaction between the parameter since F critical is less than the calculated F value which
means rejection of null hypothesis (null hypothesis H 0 : There is no interaction between
parameters).
As it was possible to observe during this work, many parameters come into play during the
leaching process. These interact on the caffeine content but also on other parameters since
coffee contains more than 100 components. It would then be interesting to study the influence
that the type of coffee, for example, has on these compounds.
References
➢ Martins, R. (2020). Adsorption study of acetic acid in an activated carbon packed
column.
https://virtual.ipb.pt/portal/site/ecbe68f0-752a-11eb-8f3d-fa163e43b405.
➢ https://www.fox.temple.edu.
➢ https://www.stat.purdue.edu/
➢ Design of Experiments for Engineers and Scientists, by Jiju Antony.
➢ https://www.fox.temple.edu/wp-content/uploads/2016/05/The-2k-Factorial-
Design.pdf.
Appendix
Effect (state) = 𝑅𝑒𝑠𝑢𝑙𝑡𝑠(𝐺𝑟𝑖𝑛𝑑𝑒𝑑 𝑁𝑜𝑟𝑚𝑎𝑙 )+𝑅𝑒𝑠𝑢𝑙𝑡𝑠 ( (^) 𝑃𝑟𝑒𝑠𝑠𝑢𝑟𝑖𝑧𝑒𝑑𝐺𝑟𝑖𝑛𝑑𝑒𝑑 ) 2
𝑅𝑒𝑠𝑢𝑙𝑡𝑠( (^) 𝑁𝑜𝑟𝑚𝑎𝑙𝐺𝑟𝑎𝑖𝑛)+𝑅𝑒𝑠𝑢𝑙𝑡𝑠 ( (^) 𝑃𝑟𝑒𝑠𝑠𝑢𝑟𝑖𝑧𝑒𝑑𝐺𝑟𝑎𝑖𝑛 ) 2 Equation 2 Effect (type) = 𝑅𝑒𝑠𝑢𝑙𝑡𝑠(𝐺𝑟𝑖𝑛𝑑𝑒𝑑 𝑁𝑜𝑟𝑚𝑎𝑙 )+𝑅𝑒𝑠𝑢𝑙𝑡𝑠 ( (^) 𝑁𝑟𝑜𝑚𝑎𝑙𝐺𝑟𝑎𝑖𝑛) 2
𝑅𝑒𝑠𝑢𝑙𝑡𝑠( (^) 𝑃𝑟𝑒𝑠𝑠𝑢𝑟𝑖𝑧𝑒𝐺𝑟𝑖𝑛𝑑𝑒𝑑𝑑)+𝑅𝑒𝑠𝑢𝑙𝑡𝑠 ( (^) 𝑃𝑟𝑒𝑠𝑠𝑢𝑟𝑖𝑧𝑒𝑑𝐺𝑟𝑎𝑖𝑛 ) 2
Equation 3
Effect ( 𝑡𝑦𝑝𝑒 𝑠𝑡𝑎𝑡𝑒) =^ 𝑅𝑒𝑠𝑢𝑙𝑡𝑠(𝐺𝑟𝑖𝑛𝑑𝑒𝑑 𝑁𝑜𝑟𝑚𝑎𝑙 ) − 𝑅𝑒𝑠𝑢𝑙𝑡𝑠 ( (^) 𝑁𝑟𝑜𝑚𝑎𝑙𝐺𝑟𝑎𝑖𝑛) 2 -^ 𝑅𝑒𝑠𝑢𝑙𝑡𝑠( (^) 𝑃𝑟𝑒𝑠𝑠𝑢𝑟𝑖𝑧𝑒𝐺𝑟𝑖𝑛𝑑𝑒𝑑𝑑) − 𝑅𝑒𝑠𝑢𝑙𝑡𝑠 ( (^) 𝑃𝑟𝑒𝑠𝑠𝑢𝑟𝑖𝑧𝑒𝑑𝐺𝑟𝑎𝑖𝑛 )
2 Equation 4
The through calculation is done in Excel file which is attached with this report. Thankyou.
