Odorants activity values, OAV

Reliable quantitative data are a prerequisite for evaluating the contribution of a single odorant to a positive aroma or off-flavor. They are needed to calculate odor activity values (OAV) that are defined as the ratio of the concentration to the sensory threshold of a given compound in a matrix (Rothe and Thomas, 1963 Acree et al., 1984). These values give guidance in the evaluation of the impact of an odorant to the overall aroma profile. 

Grosch, W. 1994. Determination of potent odorants in foods by aroma extract dilution analysis (AEDA) and calculation of odor activity values (OAVs). Flavour Fragrance J. 9 147-158. 

A first step to approach the situation in the food is a calculation of odor activity values (OAV)... 

Concentrations (pg/kg) and odor activity values (OAV) of selected key odorants in roasted... 

One way to quantify the odor impact of a compound is to determine the aroma value or odor activity value (OAV). This is calculated by dividing the concentration of the compound by its perception threshold. Therefore, the odor impact of a compound increases in proportion to its OAV when this value is >1. Thus, compounds exhibiting higher OAV values are more likely to contribute to the aroma of wine and have an important influence on its sensory characteristics. 

To establish exactly the flavor differences between Scheurebe and Gewurztraminer wines, it is therefore necessary to quantify the levels of recognized odorants and to calculate the odor activity values (OAV s). According to Rothe and Thomas (75) the OAV is defined as ratio of concentration to odor threshold value of the compound. 

Table II. Concentrations and Odor Activity Values (OAV s > 10) of Potent Odorants of Scheurebe and Gewurztraminer Wines...

Table VII. Influence of barrel aging on the concentrations and odor activity values (OAV"s) of potent odorants in Gewiirztraminer wine...

ODOR ACTIVITY VALUE (OAV) OR ODOR UNIT OR AROMA VALUE OR FLAVOR UNIT... 

On the basis of the odor activity value (OAV) concept, only a limited number of volatile components are sensorially relevant in a given foodstuff (Grosch, 1994). Teranishi et al. (1996) also presented a computer-assisted correlation of chromatographic and sensory data in food aromas. In a bar graph were shown the logarithms of the concentrations and of the odor units of the individual constituents of the aroma. The representation shows clearly the constituents present above the threshold values and therefore the most useful for the aroma. 

Fig. 5. Odorant Activity Values (OAVs) for the fruity series versus those of the spicy series in sheny-type wines during their biological ageing.

To evaluate the contribution of a chemical compwimd to the aroma of a wine the odor activity value (OAV) was determined. OAV is a measure of importance of a specific compound to the odor of a sample. It was calculated as the ratio between the concentration of an individual compound and the perception threshold found in literatures (Francis Newton, 2005 Vilanova, et al., 2008). 

Odor activity value (OAV) is defined as the ratio of concentration to odor threshold. Hence, to be able to calculate odor activity values, it is first necessary to exactly quantify the compounds that are deemed to be of interest in a food. 

In summary, we can state that isotope dilution analysis permits exact quantitative determination of fragrance and flavor compounds, even in matrices of complicated composition. The quantitative data for key flavor compounds obtained by flavor compound analysis including SIDA enable their odor activity values (OAV) to be calculated. This provides a reliable basis for producing flavor compositions that are very similar to their natural counterparts. Due to its accuracy and precision, it might be expected that SIDA will become more widely used and progressively more applied in flavor and fragrance science in future. 

The ratio of the concentration of an odorant to its odor threshold gives the odor activity value (OAV). This is often used to rank the olfactory importance of aroma constituents. However, the OAV concept has been criticized (18,19) because it assumes that a linear relationship exists between the odor intensity and the odorant concentration. This is in conflict with most accepted psychophysical laws based on logarithmic or exponential relationships (20). A recent article by Reineccius and coworkers confirms that OAVs do not represent the contribution of odorants in the overall aroma and that using OAVs to rank their contributions could result in a misinterpretation (21). 

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