The Loss of Aroma Components of the Fruit of Vangueria infausta L. (African Medlar) After Convective Drying

The loss of aroma components after drying the fruit of Vangueria infausta L. was studied by means of convective air drying and gas chromatography techniques. The samples were dried at 80 degrees C, with an air flow of 3m/s at different drying times in the range of 60 up to 420min. Aroma composition, dry matter, and water activity were measured for each sample throughout the drying time. The study shows that the targeted aroma components present in the fresh fruit sample identified in our previous work (hexanoic acid, methyl hexanoate, methyl octanoate, octanoic acid, ethyl hexanoate, and ethyl octanoate) are retained in the matrix for at least 240min of drying. Samples dried for 300min showed decreased amounts of volatiles and practically no aromas were found after 420min. It is hypothesized that the results are explained as a consequence of the crystallization of sugars during the drying process. The suggested explanation is supported by a prediction of the water activity that is critical for obtaining crystallization of a mixture of sugars corresponding to the fruit.