Belgium
Dr Bart van der Bruggen and a team from the Department of Chemical Engineering, KU Leuven and PerkinElmer, Belgium, employed static headspace gas chromatography coupled to mass spectrometry (SHGC–MS) to identify aroma compounds in coffee pad powder.

“Coffee is one of the most consumed beverages in the world. It contains a wide range of aroma compounds, which makes it a complex food product. Coffee may contain over 800 volatiles that belong to different chemical families including acids, alcohols, aldehydes, anisoles, esters, furans, ketones, pyrazines, pyridines, pyrroles, thiazoles and thiophenes, as well as phenolic and sulphur compounds. Understanding the composition of coffee with respect to aroma profiles is extremely important when maintaining and improving product quality,” explained Dr van der Bruggen.

In this case, his team studied aroma profiles in coffee pads, which are increasingly used in standard packaging and consumption methods for coffee. “We compared aroma profiles in freshly purchased coffee pads to the same coffee pads after different storage methods, i.e., individually packed and hermetically sealed, enclosed together in an open package, stored in closed plastic bottles at room temperature and at refrigerator temperature,” he said.

Two different types of coffee pads (‘strong’ and ‘Kachalu’) from the same brand were obtained from a local store in Leuven, Belgium. An essential part of the study, which was documented in Food Chemistry [116 (2) 480-483 (2009)] was the development of analytical techniques. An AutoSystem XL Gas Chromatograph coupled to a TurboMass Gold Mass Spectrometer was equipped with a TurboMatrix 16 Headspace Sampler. All analytical equipment was obtained from PerkinElmer, Waltham, MA, USA. According to van der Bruggen, chromatograms with about 30 peaks were obtained and 12 of these were identified as aroma compounds. The aroma compounds identified include four aldehydes, one carboxylic acid, two furans, two ketones, two pyrazines and one sulphur compound.

“The individually packed and hermetically sealed coffee pads showed a decrease in the concentration of a limited number of aroma compounds, whereas the packages that were enclosed together showed a more overall decrease. Furthermore, it was observed that more aroma compounds were lost when storing the pads at room temperature than at 4°C,” he continued. 

“It is evident that there is a need to develop better analytical techniques for identification of aroma compounds. This would allow a better follow-up and optimization of production and storage conditions leading to maintaining the product’s aroma. Coffee is an important product for this, but other food products should be looked at as well. Beverages in particular are largely defined by their aroma content,” he said.

Further research by the team will concentrate on a comparison between static headspace and headspace trap methods for determination of aroma compounds, in coffee and other beverages, so that a larger number of compounds can be identified at lower detection limits.

For more information, contact the author Bart.VanderBruggen@cit.kuleuven.be