AROMA MODIFICATIONS DURING DRYING OF APPL E PUREE

During the drum drying apple flakes (cv. Golden Delicious) preparation , important modifications of aroma compounds isolated from these produ cts were observed. The results obtained by gas liquid chromatography a nd coupled gas chromatography-mass spectrometry or by combined hedonic response measurement (CHARM) analysis show that two categories of mod ifications occur during the treatment. Some compounds responsible for apple aroma: C6 alcohols and aldehydes, esters, alpha-farnesene are lo st. On the other hand an increase of the concentration of several comp ounds including 6-methyl-5-hepten-2-one, 2-(E)-heptenal, octanol, nona nal in the apple flakes aromatic extract was observed. New compounds: furane derivatives, pyrazines, pyridine, saturated aldehydes such as o ctanal or unsaturated aldehydes such as (2E)-nonenal, (2E, 4E) - decad ienal..., beta-damascenone or beta-ionone were produced during the pro cess. Some of these compounds, furfural and 2-amyl furane have been co rrelated with the development of cooked apple odours. Variations of so me compounds concentration according to the treatment temperature, bet ween 120 and 140-degrees-C, or to concentration of aroma precursor i.e . polyunsaturated fatty acids or amino acids, give information on the mechanisms involved in aroma modifications during apple flakes process ing. The optimal drying temperature, for preservation of the organolep tic properties of apple puree, has been determined.