Relationships of Overall Estery Aroma Character in Lagers with Volatile Headspace Congener Concentrations
Ittipon Techakriengkrai1, Alistair Paterson1,3, Behnam Taidi2 and John R. Piggott1
1 Centre for Food Quality, University of Strathclyde, Department of Bioscience, 204 George Street, Glasgow G1 1XW, Scotland, UK.
2 Scottish Courage Ltd, Technical Centre, Sugarhouse Close, 160Canongate, Edinburgh EH8 8DD, Scotland, UK.
3 Corresponding author. E-mail: alistair.paterson@strath.ac.uk
J. Inst. Brew. 112(1), 41–49, 2006 | VIEW ARTICLE
ABSTRACT
In lager beers the intensity of “estery” aroma character is re-garded as an important component of sensory quality, but its origins are somewhat uncertain. Overall “estery” aroma intensity was predicted from capillary gas chromatographic (GC) data following solid phase micro extraction (SPME) of headspaces. Estery character was scored in 23 commercial lagers using rank-rating, allowing assessors (13) constant access to a range of appropriate standards. From univariate data analysis, all asses-sors behaved similarly and lagers fell into three significantly different groups: low (1), high (1) and intermediate (21). The quantification of 36 flavour volatiles by SPME of headspaces was reproducible and principal component analysis explained 91% total variance. Multiple linear regression could utilise only a restricted (26) set of flavour volatiles, whereas partial least square regression, that considered all flavour components, showed significant differences and improved prediction. How-ever, an artificial neural network that could compensate for non-linearities and interactions in ester perception gave the most robust prediction at R2 = 0.88.
Key words:
Artificial neural network, beer sensory quality, par-tial least square regression, sensory instrumental correlation rank rating.
Publication no. G-2006-0403-403 ©2006 The Institute & Guild of Brewing