Submitted to: Flavour and Fragrance Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/29/2008
Publication Date: 9/30/2008
Citation: Plotto, A., Margaria, C.A., Goodner, K.L., Baldwin, E.A. 2008. Odour and flavour thresholds for key aroma components in an orange juice matrix: esters and miscellaneous compounds. Flavour and Fragrance Journal. 23:398-406. Interpretive Summary: Traditional methods to study aromas and flavors in a food involve gas chromatography to isolate, identify and quantify volatile compounds. Comparison of the amount of volatile compounds isolated from the food with respective odor thresholds is used to calculate an "Odor Activity Value" (OAV) for each compound in a food, and therefore determines which compounds are responsible for the odorous character of the food. The drawback of this method is that most published threshold values use water as the dilutant of the compound. However, volatile compounds interact with non-volatile compounds in a food matrix, such as carbohydrates, lipids and proteins, even in a beverage or fruit, which contain mostly water. This study presents the method and results of threshold values of compounds important for orange juice flavor obtained by using a deodorized orange juice matrix as the dilutant. The OAV of these compounds in two different orange juices are calculated to illustrate the differences of OAVs obtained between the two methods (water or juice). These results show the importance non-soluble compounds on odor and flavor perception. The threshold values provided by this research are directly applicable by the industry in comparison with the current values that are published in water.
Technical Abstract: Thresholds for flavor volatiles have been traditionally calculated in water or air, but they may vary widely in more complex matrices such as milk, gels, or fruit slurries. The data presented is part of a continuing study to provide the industry with threshold guidelines more adequate for the use of flavors in citrus juices. Thresholds of aroma compounds of orange juice (OJ) were determined in reconstituted pump-out (RPO), approaching a deodorized OJ matrix, and served at 10-12 °C, temperature at which OJ is consumed. The Three-Alternative-Forced-Choice (3-AFC) method was used (ASTM: E-679). Sixteen to twenty panelists were presented with RPO samples arranged in five rows of three samples corresponding to five spiking levels, each separated by a factor of 3, with a 3-AFC presentation at each level. For each compound, the test was repeated four times. Compounds tested were verified for purity by GC/MS and GC/O. Orthonasal and retronasal thresholds for esters were twice (methyl butanoate) to thirty times (ethyl propanoate) higher in the orange juice matrix than published values in water. The Odor Activity Values (OAV) of volatile compounds were calculated for two OJs; nine compounds had an orthonasal OAV lower than 1 when using thresholds determined in RPO, when in contrast, these compounds had an OAV greater than 1 when calculated with published thresholds determined in water. The relative OAV of some compounds had changed, indicating a different contribution of these compounds to OJ flavor when their OAV was calculated in RPO. These results show the importance of non-water soluble compounds on odor and flavor perception. The threshold values provided by this research are directly applicable to the industry in comparison with the current values that are published in water.