AROMA ANALYSIS OF APPLE JUICE - INFLUENCE OF SALT ADDITION ON HEADSPACE VOLATILE COMPOSITION AS MEASURED BY GAS-CHROMATOGRAPHY AND CORRESPONDING SENSORY EVALUATIONS

Sensory response to the aroma of a food depends on the composition and concentrations of the volatiles of the headspace. When analyzing the headspace composition by gas chromatography, salts are often added to the sample as a means of increasing the concentration of the aroma compounds in the vapor phase (e.g., enrichment of the vapor phase). This will only give a correct impression of the original aroma when all volatile components are affected equally. In this study on apple juice aroma, it is demonstrated that the degree of headspace enrichment resulting from salt addition is different for esters, aldehydes and alcohols. In the collection system, the average degree of enrichment at 40.degree. C was greater than 4 for alcohols, between 1.75-3.50 for aldehydes and < 1.75 for esters. How these differences can be useful when trying to identify gas chromatography peaks is also discussed. Sensory evaluations showed that aroma response is changed when salt is added to the juice, resulting in an increased aroma intensity and off-aroma. Fruit aroma was not affected. A comparison of the sensory responses with headspace gas chromatographic measurements indicates that increase in off-aroma can be related to the increase in alcohol percentage in the headspace. When attempting to correlate sensory scores with aroma component concentrations as measured by headspace gas chromatography, it is most important that the test conditions utilized for each analysis correspond as closely as possible with each other.