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Effect of water temperature and time on caffeine extraction from coffee

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Nhan Pham Phuoc at Can Tho University
Nhan Pham Phuoc
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Abstract

The stimulating effect of coffee is mainly depended on caffeine availability in products. Caffeine levels in grains of two coffee species, Coffea arabica and Coffea robusta, have been quantified via the maximal absorbance of standard caffeine at 288 nm. Three popular coffee brands in Vietnam were selected for quality assessment based on the qualitative information printed on their labels. Caffeine level in C. robusta is always higher than that of C. arabica at any time durations and temperatures of extraction. Best combination between time and temperature for caffeine extraction is 15 min and 90°C or 100°C. About 90% of caffeine has been removed from coffee powder by routine percolated. The extracted caffeine is tightly correlated with extracting sequence by the equation of y = 1.7647x with R = 0.9963. The chosen coffee -1.5023 2 products have higher caffeine contents, at least 2.5 times than those appeared on their labels.
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... Caffeine, catechins and L-theanine levels remained the same for 45ºC to 75ºC but reduced greatly when the temperature increased to 90ºC (Figure 3, Table 1). The varying amounts of compounds in the tea when brewed with different water temperatures might be due to the fact that there are certain ranges of temperatures that are best for the compounds to be released [20][21][22]. ...
... However, the literature suggests that the optimum conditions to extract L-theanine is 80ºC, 85ºC for catechins, and 90ºC or 100ºC for caffeine [20][21][22]. This difference might be due to different measuring methods. ...
... Various types of compounds and their correlation with brewing water temperature, types of tea, brewing time could also be investigated. For example, specific types of catechins such as EGCG and ECG, various kinds of sugar, or flavanols such as kaempferol and quercetin glycoside [21], could all be future research topics. ...
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