Title and Abstract

Coffee contains a tremendous number of chemicals, with over 1000 aroma compounds (Davies, 2011). One of the most prominent chemicals in coffee is Caffeine (C8H10N4O2). Caffeine is a bitter, white chrystaline purine. It acts as a central nervous system stimulant. When it reaches one’s brain, the most noticeable effect is alertness. One will feel more awake, so it’s a common ingredient in medications to treat or manage drowsiness, headaches, and migraines. (Pietrangelo, Cherney, 2017) Coffee brewing is the simple extraction of solutes (coffee solids) with a solvent (water) from a matrix (coffee grounds) to produce a solution (coffee beverage) (Steiman, 2016). Our experiment is on finding out what it takes to brew the perfect cup of coffee in relation to the time taken. We brewed six different types of grounded coffee beans that vary in brand, type and strength to find out the varying caffeine peaks of each type. To measure the caffeine peaks, we used a digital refractometer, which works by measuring the degree to which the light changes direction, called the angle of refraction. The refraction angles are correlated to refractive index (nD) values. Using these values, we can determine the concentration of the caffeine in the coffee. During the course of experiment, the temperature of the coffee was kept constant and readings were taken at regular time intervals. Our experimental results indicated that the caffeine peaks across most of the 6 types occur from the 25th to the 40th minute. We can thus conclude that the caffeine concentration of coffee is dependant on the time taken. For coffee drinkers who want the most caffeine out of their morning fix and have time to spare, it will be best for them to leave their coffee for around half an hour in the coffee maker before drinking it.