Coffee in capsules contains more furan than the rest, although the levels are still within safe health limits. Credit: SINC |
“Preparing
a coffee in a drip coffee maker is not the same as making one in an
espresso machine or from capsules, because these give rise to differing
levels of furan”, Javier Santos, a professor at the Department of
Analytical Chemistry at the University of Barcelona and lead author of
the study, tells SINC.
Concern
has risen over recent years about the presence of this compound in
foods, because of its toxic and carcinogenic effects in animals, as well
as the fact that the International Agency for Research on Cancer has
listed it as a possible carcinogen in humans.
Against
this backdrop, the scientists used an automated analytical method to
assess the presence of furan in coffee. The results, published online in
the Journal Food Chemistry, reveal that higher concentrations are found
in espresso (43?146 nanograms/mililitre) than in coffee made in drip
coffee makers, both in the case of normal coffee (20?78 ng/ml) and
decaffeinated coffee (14?65 ng/ml).
The
levels of these toxic products were “slightly lower” (12?35 ng/ml) in
instant coffee, but a great deal higher in those made from the capsules
of a well-known brand, which showed up higher levels (117?244 ng/ml).
“The
reason for these higher levels is due to the fact that
hermetically-sealed capsules prevent furan, which is highly volatile,
from being released, while the coffee makers used to brew this coffee
use hot water at higher pressures, which leads to the compound being
extracted into the drink”, says Javier Santos. The longer that coffee is
exposed to the air in cups or jugs, meanwhile, the more the furan
evaporates.
Different values, but not dangerous
The
researcher stresses that, in all these cases, the levels of the
substances found are within the limits considered to be “safe” to
health. In fact, the team has estimated the amount of furan ingested as a
result of coffee consumption in Barcelona, obtaining values of
0.03?0.38 micrograms/kilogram of body weight, which is less than the
maximum acceptable level (2 ?g/Kg of body weight).
In
order for furan ingestion to exceed the maximum acceptable values, a
person would have to drink at least 20 cups of capsule coffee or 30
espressos per day (for the brands with the highest furan content), or
200 instant coffees. These estimates were made on the basis of 40 ml
cups and an average body weight for coffee drinkers of around 70 Kg.
The
study also shows that furan concentrations are lower if coffee is
roasted at low temperatures over a longer time (140ºC for 20 minutes)
than in coffee roasted under usual conditions (200?220ºC for 10-15
mins).
Furan,
like acrylamide, is one of a group of carcinogenic substances that can
form when foods and drinks are subject to heat treatment. They are the
result of a reaction, known as the Maillard reaction, between
carbohydrates, unsaturated fatty acids and ascorbic acids or its
derivatives.
References:
M.S. Altaki, F.J. Santos and M.T. Galceran. “Occurrence of furan in
coffee from Spanish market: contribution of brewing and roasting”. Food
Chemistry 126 (4) 1527?, June 2011 (Available online December 2010).
Doi: 10.1016/j.foodchem.2010.11.134.
