Aluminium and Aroma Compound Concentration in Beer During Storage at Different Temperatures

Franjo Ivušić¹*, Marija Soldo Gjeldum², Zvonimir Nemet³, Leo Gracin¹ and Vladimir Marić¹

¹Faculty of Food Technology and Biotechnology, Pierottijeva 6, HR-10 000 Zagreb, Croatia
²Pliva, Prilaz Baruna Filipovića 25, HR-10 000 Zagreb, Croatia
³Karlovačka pivovara d.d., Dubovac 22, HR-47 000 Karlovac, Croatia

Article history:
Received January 23, 2006
Accepted May 18, 2006

Key words:
aluminium, beer, aroma compounds (esters and higher alcohols), storage

Summary:
Problem of aluminium in beer has been elaborated in several papers over the last decade. However, the effect of aluminium on organoleptic properties of beer has been observed in few papers where it has been stated that aluminium gives beer a »metallic« and bitter flavour without any observations on particular aroma compound changes. Also, the number of reports on precise changes of aroma components throughout different storage conditions is surprisingly scarce. In order to investigate the changes of aluminium concentration along with aroma compound changes, graphite furnace-atomic absorption spectrophotometry (GF-AAS) with Zeeman background correction and gas chromatography with static headspace sampler (GC-HSS) were used in this work. Analyses were conducted periodically throughout seven months of storage on three different brands of beer from name breweries. Samples were taken before and after filling in aluminium cans. One part of samples was stored in a refrigerator (4 °C) and the other in a thermostatic chamber (22 °C). The effects of beer brand and storage conditions on aluminium concentration and level of aroma compounds were measured. To prove the effect of aluminium concentration on the changes of aroma compounds, the adequate level of aluminium sulphate was added to bottled beer samples stored at 28 °C. Although different beer types showed significantly different aluminium concentration, it could be the result of other factors (different batches of identical beer type showed significantly different aluminium concentration as well). Samples that were stored in the refrigerator were protected from aluminium migration from the can to the beer and showed increased aroma stability. Level of aroma constituents of analyzed beer brands was significantly different. Elevated aluminium concentration did not have any noticeable effect on the level of aroma compounds in beer samples stored at 28 °C.

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