Determining caffeine and 3-caffeoylquinic acid content in artisanal processed specialty coffee varieties with different roasting grades, origins, and brewing methods

Abstract: Coffee is one of the most consumed beverages in the world, with about 10 million tons of coffee consumed in 2021. There are a lot of steps between the coffee tree and served beverage, as there are several processing methods each contributing to differences in fragrance, aroma, and acidity. Coffee intake has shown to have health promoting effects and has been linked to lower mortality rate. The most well-known component of coffee is caffeine, a stimulant which has an awakening effect, but there are a lot more compounds which are less well known, like the chlorogenic acids. This is a family of related compounds which have antioxidative capacity and demonstrated anti-carcinogen, anti-obesity, and anti-diabetic effects in some studies. Specialty coffee is a category of coffee which has gone through a rigorous process where flavour, aroma, acidity, and a few other factors are taken into account before being graded. This poses as an extra income for some farmers, as it is more expensive than regular coffee. If climate keeps changing, this might lead to lesser opportunities for coffee farmers to grow and sell all kinds of coffee and working with higher quality, rather than higher quantity, might be a better option for the individual, as well as for the climate. RP-HPLC is a commonly used analysis method and will be used to conduct the analyses of this study. The aim of the study was to quantitatively determine the caffeine and 3-caffeoylquinic acid (3-CQA) content in artisanal processed specialty coffee in varieties with different origins and roasting grades. The coffee varieties were ground, and brewed using three methods, filter-funnel, French press and cold brew and thereafter analysed using RP-HPLC, developed from another study and configured to acquire quicker analyses. The development of the method yielded a standard curve which was used to calculate the caffeine and 3-CQA concentration in coffee samples. The results indicated that cold brews yielded higher concentrations of caffeine and 3-CQA in most cases. The least differences when comparing brewing methods within coffee varieties were seen between filter-funnel and French press coffee. The most notable difference was seen with the light roasted Ayla variety, which yielded much higher 3-CQA concentrations compared the other two varieties (Velo collective and Ureña). It can be concluded through other studies that the higher 3-CQA content could be explained by roasting grade, and that further analyses on raw coffee samples would be needed to test differences when accounting for origin, as different roasts affect the caffeine and 3-CQA content.