4. Discussion

4.1 Key findings & Analysis of results

The data we have collected have shown that the caffeine peak of 5 out of the 6 types of coffee we have experimented on occurs between the 25th and 40th minuter. Specifically, for the Boncafe All Day coffee and Suzuki Royal Blend coffee, it occurs at the 30th minute. For the cafedirect and Boncafe Night coffee, it occurs at the 40th minute. For the Suzuki Italiano Espresso, it occurs at the 35th minute. However, an anomaly is that for the Cafedirect Machu Picchu coffee, it occurs at the 50th minute, at 3.33% instead of the common trend of being between the 25th minute and the 40th minute. We felt that the anomaly might have been because the Cafedirect Machu Picchu coffee is the weakest compared to the rest in terms of concentration, as observed in the data collected. Thus the caffeine peak is not as evident compared to the rest. The key finding of this experiment is that the caffeine peak of coffee we experimented on most commonly occurs between the 25th to 40th minute, with 83%, or 5 out of 6 samples fulfilling this criteria. 

4.2 Explanation of key findings

The experimental results in section 3 leads to the key finding that the caffeine concentration of most of the 6 types of coffee we experimented on is highest between the 25th and 40th minute. There was an anomaly, as previously mentioned. We also discovered that the last reading at the one hour mark usually fluctuates higher, but that should be because of the regular fluctuations as previously mentioned. 

4.3 Evaluation of Hypothesis

Our hypothesis is that the caffeine concentration will increase as time passes. However, through our experiment, we discovered that there is a peak where the caffeine concentration is the highest. After the peak, the concentration will drop and remain constant with occasional fluctuations. Although the concentration did increase as time passes, it was only up to a certain point, otherwise known as the peak. The increase did not continue after the peak. Thus, our hypothesis was not entirely accurate. 

4.4 Limitations and Areas for improvement 

Limitations 

    1. We could not keep the temperature constant at 90 degrees which is the optimum temperature to brew coffee as using the water bath would not allow us to take regular measurements, the hotplate would not keep the temperature constant and the coffee machine will keep the temperature constant, however, not at 90 degrees.

    2. It was difficult for us to find many types of coffee beans. In the supermarkets, there were only certain brands that could be grounded. We could not obtain enough types of coffee beans. We eventually settled for the packaged grounded coffee beans, as we could not find 6 different types of coffee beans that could be grounded in store.

    3. We were unable to ensure that the grind size of the coffee we used is the same. Thus, we made use of a sieve that has relatively small holes. That allowed us to sieve out the finer grains, and thus ensuring the grind size is the same across all our 6 types of coffee, to prevent inconsistency.

Areas for improvement

    1. We could have done more research before the experiment. Our experimental procedure had serious flaws which we only discovered some time into our experimental phase. Thus, we had to change our experiment by a lot and we had to rush to finish our experiment to meet the deadline. In order to prevent this in future projects, we should have done more research before we even start our experiment in order to ensure that our experiment is done correctly.

    2. Had we planned our time more wisely, it would be possible for us to test for more variables such as the organic oils and the acidity of the coffee instead of just caffeine. Those variables also contribute to the concentration of the coffee as a whole. If we had more time, we would have also repeated our experiment to ensure the results collected are more accurate.

    3. We could have conducted the experiment using more types of coffee. Due to budget and availability constraints, we were only able to test using 6 types of grounded coffee beans. If we had more time to source for the coffee samples and more time to conduct the experiments, we could have gone up to 10 types, to improve the accuracy and the consistency of our experiment. We could also have tested for how different grind sizes of the same type of coffee affect the caffeine peak.