Flavor chemistry and odor thresholds

Determination of odor thresholds of components in water solution was an ear ly method adopted by many researchers for evaluating the relative contribut ion of food aroma/flavor components. Some more recent methods determine odo r thresholds in air added to GC effluent from flavor volatile separation. R elatively simple methods are available for calculating thresholds in air fr om thresholds determined in water. Similar methods can be used for calculat ing oil and oil-water mixture thresholds from water threshold data. The rat io of a component's concentration in the food to its water odor threshold v alue has been useful in determining relative aroma/flavor importance for mo stly aqueous foods. Small variations in chemical nature and structure can l ead to large changes in threshold values. Water threshold values are compar ed for various acetyl nitrogen heterocyclic compounds, alkylhydroxyfuranone s and 4-alkoxyfuranone derivatives. Even the most careful studies can lead to errors in threshold measurements. Some examples are given where threshol d determination errors were caused by minor amounts of very low threshold i mpurities.