Characterization of flavors and off-flavors in water and beverages

© Ursula Deja-Schnieder

Flavors in beverages

Food and drink products, from the moment of manufacture to the moment of consumption, are subjected to various conditions which can cause changes in their sensory properties. Desired flavor changes arise, for example, as a result of preserving agents/measures or due to the manufacturing process. Aging processes, for example during the manufacture of alcoholic drinks, are responsible for flavor development and give the drinks their characteristic taste.

Off-flavors in beverages

Interactions involving the packaging or microbes can, however, lead to undesired changes to the flavor (leading to so-called off-flavors), such as a medicinal off-flavor in mineral water. In addition, external factors can cause the development of undesired flavors in beverages, for example storage of beverages in sunlight.

Analysis of flavors and off-flavors in beverages

Compounds which cause off-flavors are usually present in the ultra-trace range and can cause off-odors via an enormous number of mechanisms and precursors. The development of strategies to prevent off-flavors requires unambiguous characterization and identification of the off-flavors using established and advanced analytical techniques. The characterization of the relevant odorants is being undertaken using high resolution gas chromatography - olfactometry (HRGC-O) couped with mass spectrometry (MS).

We are measuring the migration of undesired odorants from packaging materials to beverages and identifying the relevant reaction pathways. With regard to off-flavors, we are determining whether they lead to flavor changes due to undesirable substances from external sources (e. g. from the packaging material or from contamination) or via new generation (e. g. via thermal, chemical, or microbial processes). Our evaluation is completed using sensory tests carried by a trained panel of experts. Based on the findings, rapid methods for detecting flavors, off-flavors, and their precursor molecules will be developed along with customized strategies for optimizing product flavor.