Hept-cis-4-enal:: analysis and flavour contribution to fresh milk

To determine the concentration of hept-cis-4-enal in fresh milk, D-7-hept-cis-4-enal was synthesised and used for a stable isotope dilution assay. Hept-cis-4-enal concentrations were found at the low to medium picogram per gram range, and increased during refrigerated storage. The flavour of fresh homogenised/pasteurised milk, spiked with additional hept-cis-4-enal at several different concentrations, was measured by a trained sensory panel using quantitative descriptive analysis. Additional hept-cis-4-enal, at a concentration similar to that of unadulterated milk, was sufficient to influence the flavour of the milk. There are many other aroma compounds, naturally present in fresh milk, which also contribute towards milk flavour. It is a considerable challenge for a single aroma compound to influence flavour, at such low concentrations, when in the presence of these other compounds. Therefore, the contribution that hept-cis-4-enal makes towards the flavour of fresh homogenised/pasteurised milk is considered to be extremely important. (C) 2002 Elsevier Science Ltd. All rights reserved.