Coffee is the second most widely consumed beverage in France, after water. It has therefore been analysed in the context of the French Total Diet Studies (TDSs).
Over the last several years, a wide range of "expresso"-type machines for domestic use have appeared on the French market, and many homes are now equipped with them. This new way of drinking coffee has brought up questions, especially on possible contamination of the coffee through contact with the capsules or pods it is packaged in. Therefore, ANSES has studied the consequences of these new machines with regard to consumer exposure to certain chemical contaminants. It has also used this study, conducted in the context of a research and development contract (CRD) in partnership with the French National Consumers Institute (INC), to acquire data on the caffeine levels found in these types of coffees.
The main objective of this study was to determine the levels of various chemical compounds in coffee prepared with these machines in order to compare them with the values for traditional drip brew coffee (TDS2 figures).
The tests examined ten brands of capsules, representative of the market offer and compatible with one of the four most popular "expresso" coffee machine technologies sold in France.
The various materials in contact with the ground coffee (capsule body and lid) were characterised (using infra-red spectroscopy by attenuated total reflectance) in order to identify the specific substances to look for. In addition, the chemical substances which coffee may contain - mainly metals - were also analysed.
The levels of the organic and inorganic contaminants which may come from the coffee, the process or the packaging materials ytical techniques (liquid chromatography-tandem mass spectrometry (LC-MS-MS) and inductively coupled plasma mass spectrometry (ICP-MS)).The concentrations measured were then compared to those found in drip brew coffee.
The average levels of all the chemical contaminants screened for except aluminium (cobalt, chrome, tin, nickel, copper, zinc and acrylamide) were slightly higher in the coffee solutions made with capsules than in the control coffee (drip brew coffee), but were of the same order of magnitude. These variations do not significantly modify the contribution of coffee to consumer exposure to these chemical compounds, or to any risk that might be linked to them.
In addition, no organic compounds belonging to the phthalate or bisphenol A groups were detected.
Although the substance furan was detected in all the samples, no conclusions could be made due to the physico-chemical specificities of this compound (in particular its extremely high volatility). ANSES is currently working on methodological developments which will enable more precise characterisation of furan.
With regard to caffeine, coffees prepared using the espresso coffee machines contained higher average concentrations of this substance than drip brew coffee. In addition, the caffeine levels were higher in espresso coffee obtained using a "capsule" technology than in coffee made with pods.
The contaminant levels measured were of the same order of magnitude as those found in the most recent Total Diet Study (TDS2) published by ANSES in 2011. The results of these analyses show that these new techniques do not substantially modify the conclusions of previous risk assessments on coffee-based consumer exposure to chemical contaminants. The new machines could however have repercussions on consumer exposure to caffeine if these coffees are consumed in the same amounts as traditionally-brewed coffee.