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COCOTEA / 16 – CHEMICAL AND SENSORY PERSPECTIVE ON BREWED COFFEE FLAVOUR AS AFFECTED BY STORAGE CONDITIONS OF GREEN COFFEE BEANS

Daan van Beek1, Wender Bredie2, Mads Høgsted3, Rikke V. Hedegaard1 1Food Chemistry, Department of Food Scienc , University of Copenhagen.

2Sensory Science, Department of Food Science, University of Copenhagen.

3Estate Coffe, Copenhagen Roaster a/s, Gl. Koegelandevej 22, 2500 Valby ù

E-mail: rvh@life.ku.dk

The influence packaging of green coffee beans in either traditional Burlap sacks or vacuumed plastic bags on the chemical and sensory profile of freshly brewed coffee were determined during storage at five different temperature and relative humidity conditions over a period of four months.

The relative concentration of 23 volatile compounds were determined in the roasted coffee beans by dynamic headspace of freshly brewed coffee after collection on a Tenax TA trap followed by detection by GC- MS and the fresh brewed coffees were assessed over 10 sensory attributes, by a trained consumer panel.

An increase in water content of more than 258 % were observed after three months storage at a low temperature and a high humidity, when stored in Burlap sacks, whereas four months at a low humidity and a high temperature resulted in 45 % dehydration.

A positive correlation was found for 17 volatiles with storage of green beans in burlap sacks at a medium to high temperature over a storage period of four months.

The aroma compounds 2,6-dimethyl-pyrazine and ethyl-pyrazine were found to be characteristic for storage of green beans at a high temperature and a low humidity. Whereas 3- dihydro-6-methylthieno[2,3]furan and 2,2-bifuran were related to storage at medium temperature and medium humidity.

A correlation between water content and water activity was found only for the aroma compound 1-(2-Furanylmethyl)-1H-Pyrrole. Storage in burlap sacks was strongly correlated to spicy, smoky, tarry and bitter flavours, whereas storage under vacuum developed a sweet flavour over time, whereas low temperature storage resulted in sour and flowery characteristics.

It can be concluded, that storage in burlap sacks or vacuum packed plastic bags results in different chemical and sensory profile of the coffee.