What we did in class this term

Another term of delicious food chemistry – some of our activities…

Today’s molecule – furan

I don’t need ANY bad news about my espresso coffee!

From FECYT – Spanish Foundation for Science and Technology, via “Eurekalert

Here is their press release…

“Coffee in capsules contains more furan than the rest”

Coffee in capsules contains more furan than the rest, although the levels are still within safe health limits.

“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.

“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 μg/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.”


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.

Awesome ! Coffee week in our class too.

from SciencePunk

Work on sensor arrays has great potential in food quality control.

The original work seems to have been for detection of toxic gases and has been around for while, but aren’t aromas just fragrant volatiles?

Work has been published in Nature and very recently in Chemical Communications.

A colorimetric sensor array for identification of toxic gases below permissible exposure limits
Liang Feng, Christopher J. Musto, Jonathan W. Kemling, Sung H. Lim and Kenneth S. Suslick,  Chem. Commun., 2010
DOI: 10.1039/b926848k

So, author Suslick’s son has published this little interesting missive in “Analytical Chemistry”

Discrimination of Complex Mixtures by a Colorimetric Sensor Array: Coffee Aromas; Benjamin A. Suslick, Liang Feng, Kenneth S. Suslick;  Analytical Chemistry Article ASAP

In this work the sensors are able to discriminate without ambiguity 10 different commercial coffees and coffees at various stages of roasting, as the excerpted figure shows.

Just fabulous!

roasted sensors

Real natural Decaf

A species of coffee from Cameroon is caffeine free.

Read about it here http://species.asu.edu/2009_species09 where it was named one of the top 10 new species of 2009 (named in 2008) by the

International Institute for Species Exploration at Arizona State University.

Coffee and Conservation report that the plant was was “first collected in 1983, but remained unstudied and not described to science until 2008” in their post.

Stoffelen, P., M. Noirot, E. Couturon & F. Anthony. 2008. A new caffeine-free coffee from Cameroon. Botanical Journal of the Linnean Society 158: 67-72.

OSU campus-based folks can see the full text of the paper via this link http://www3.interscience.wiley.com/journal/121394905/abstract


“A new Coffea species from Cameroon is described and compared with the other species of Central Africa. Coffea charrieriana Stoff. & F. Anthony can be recognized easily using morphological characters of leaves, flowers and fruits. Moreover, it is the first record of a caffeine-free Coffea species for Central Africa and only the second report for the African continent. Cameroon is one of the three centres of diversity for the genus Coffea, showing a similar number of species to that of Tanzania. © 2008 The Linnean Society of London, Botanical Journal of the Linnean Society, 2008, 158, 67–72″.

It seems that caffeine free coffee species are rare. I don’t know how long it takes to breed new coffee varieties, but i am sure someone is working on getting the caffeine-free trait into a cultivatable form. Stay tuned.

As a dedicated caffeine devotee I vote that the new variety should be called “What’s the point?” in honor of the no-fat decaf latte.


What flavor would you like with your coffee ? Cockroach ?

From Food Media blog at Chow a story about a story that aired on NPR’s Fresh Air about the work of entomologist Doug Emlen from the University of Montana-Missoula.


The main story is about dung beetles http://www.npr.org/templates/story/story.php?storyId=103775784 This page has a link to the broadcast so you can listen yourself.

According to Chow the cockroach story begins at about 34m 50s into the audio.

At about 32:14 Terry Gross, the NPR host, asks Emlen how tolerant he is of insect pests. Part of his reply is that even most entomologists he knows don’t like cockroaches and that many people are allergic to components of cockroach cuticles and faeces. He then goes on to the story related by Food Media about pre-ground coffee – but it worth listening to the original delivery.

Mind you – it appears that “untrained cockroaches showed a clear preference for vanilla” according to Susan Decker, Shannon McConnaughey, and Terry L. Page, (pardon me for quoting the authors out of context) in the paper “Circadian regulation of insect olfactory learning”  Proceedings of the National Academy of Sciences vol. 104 no. 40: 15905-15910. Thanks to Bug Girl’s Blog for the citation.  —

— So if you like vanilla flavored coffee, watch out for untrained cockraoches !!!

Coffee acidity resource

On the Coffee Research dot org site a well referenced discussion of coffee acidity

( http://www.coffeeresearch.org/science/sourmain.htm )

Note the discussion in the body of the text “Excessive quinic acid has been associated with unfavorable sourness when coffees are roasted too dark or brewed coffee is left on a heater plate.  This sourness, however, is contradictory to the rise in pH and reduced perceived acidity at darker roasts and is likely operating under a different mechanism“.

Our roast degree series near the end of the foam stability observations.

Starbucks goes instant

The Starbucks claim.

Starbucks VIA™ Ready Brew is rich, full-bodied Starbucks® coffee in an instant. Unlike traditional instant coffee, which lacks the essential oils that give coffee its flavor and aroma, ours is made with the highest-quality arabica beans, finely ground to release their fullest flavor. Try these samples and discover a whole new way to make great coffee at home or on the go”.

You be the judge.

What do they do differently ?

Well this is their take on it “using their “super secret” technology” http://www.youtube.com/watch?v=c1YU5kRmDUo

Here is the abstract from the only patent application with Starbucks as assignee that relates to a coffee beverage

United States Patent Application 20080317924

Inventor:Yang; Angel

December 25, 2008

Beverage and Method of Making Same


The present embodiments are directed to beverages such as ready-to-drink coffee and tea beverages. A beverage in accordance with the embodiments described herein includes at least two discrete, preprepared and packaged components. In some embodiments, one of the components is a coffee or tea base, and another component is a dairy or soy base. During final processing, the two or more discrete bases are combined together with water and packaged for sale as a ready-to-drink beverage.


It is interesting to go to the U.S. Patent Office website and read the detailed description especially paragraphs 0036, 0039, and 0040 in the detailed description. All this is freely available in the public domain.

A foam wrapped in an emulsion covering a colloidal suspension

Getting prepared for our new lab experience – starting to work out the kinks – have a 60 kg balance to use to judge the 30 lbs (14 kg) of force needed to pack the ground coffee into the portafilter, and a stopwatch to time the shot.

Logging my grind fineness against shot time

About  5min after pulling 17 sec double shot

Getting the machine working – plenty of coffee this p.m.

Click on thumbnail images to see larger images…