Science Project: Coffee Taste vs Brewing Method
I have always suspected that the taste of coffee has to do with brewing method aside from the quality and freshness of the coffee beans. My daughter did her school science project to discover which brewing method produces the tastiest coffee.
Rather than simply having human subjects taste the coffee and give their subjective opinions regarding the taste of the coffee, she chose a more objective and scientific approach. She used a pH meter to measure the pH level of the coffee brewed by different methods.
A quick review of pH: The pH scale is from zero to 14. Zero is the most acidic, like battery acid, and 14 is the most basic, like liquid plumber. 7 is neutral, like pure water.
She decided to brew coffee in three different ways using the following methods:
1. Standard Coffee Maker
2. Percolator
3. Boiled water poured over grounded beans.
Materials and ingredients used are shown in the picture.
I have always suspected that the taste of coffee has to do with brewing method aside from the quality and freshness of the coffee beans. My daughter did her school science project to discover which brewing method produces the tastiest coffee.
Rather than simply having human subjects taste the coffee and give their subjective opinions regarding the taste of the coffee, she chose a more objective and scientific approach. She used a pH meter to measure the pH level of the coffee brewed by different methods.
A quick review of pH: The pH scale is from zero to 14. Zero is the most acidic, like battery acid, and 14 is the most basic, like liquid plumber. 7 is neutral, like pure water.
She decided to brew coffee in three different ways using the following methods:
1. Standard Coffee Maker
2. Percolator
3. Boiled water poured over grounded beans.
Materials and ingredients used are shown in the picture.
Procedure:
Samples of three solutions with varying pH levels were tested for pH with the pH Meter. This is a sanity check just to make sure that the equipment works as expected.
Solutions were: vinegar, Gaviscon, and water. The vinegar pH level was 2.3, the Gaviscon had 8.0 pH, and filtered tap water was at 6.5 pH.
The same amount of coffee and water was used for each of the three brewing methods.
Coffee was brewed and the same amount was poured into a cup and allowed to cool down and then measured for pH. In the next picture the pH Meter used is shown measuring the pH level of coffee.
Results: The pH level of the standard Coffee Maker coffee was 5.53, the pH reading of the boiled and poured method was 5.45, and the Percolated coffee was at 5.35 pH.
Tasting each of the coffees brewed was done by family members and the consensus was that the percolated coffee tasted the best, followed by the Coffee Maker coffee, and the least tasty was the coffee produced by the boiled/poured method.
I was surprised that the best tasting coffee, which was percolated, had the highest acidity level.
Also, I was surprised that the worst tasting coffee was not the one with the lowest pH level.
Perhaps because boiled water poured over ground coffee did not saturate the beans as much as the percolator or the coffeemaker and thus extracted less flavor.
This experiment shows that of the three brewing methods used, the best tasting coffee has higher acid content. Could this be a coincidence? I suspect that coffee that is brewed slowly at a higher temperature tastes better because it forces more acid and flavor out of the beans. What would be interesting to do next is to see if the coffee kept warm on a heater plate after brewing gets more acidic as time goes by.
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