Objective: To analyse the distribution of caffeine doses obtainable from espresso coffee sold by a sample of commercial coffee vendors located on the Gold Coast, Qld, Australia.
Design: A cross section of "Espresso/short black" coffee samples were purchased and analysed for their caffeine content using micellar electrokinetic capillary chromatography (MEKC). Coffees were collected using systematic cluster sampling across five major retail centres.
Results: Ninety-seven espresso samples were analysed. The mean (+/-SD) quantity of caffeine was 106+/-38 mg/serve with a concentration of 2473+/-1092 mg/l. There was considerable variation in caffeine content. The range per serve was 25-214 mg whilst the concentration range was 580-7000 mg/l. Twenty-four samples (24.7%) contained 120 mg of caffeine or higher and 12 samples (12.3%) exceeded 167 mg per serve.
Conclusions and implications: The number of heavily caffeinated samples differentiates these findings from frequently cited caffeine values and supports similar data recently collected throughout the United Kingdom. As a result, the accuracy of any previous intake modelling regarding caffeine use in the Australian population is in doubt. The present data suggests that the probability of consumer exposure to high caffeine doses is greater than previously anticipated. Greater sample numbers from a broader selection of venues is required to confirm the extent of caffeine content variance within retail ground coffees.