EFFECT OF HOT-AIR DRYING ON FLAVOR COMPOUNDS OF BELL PEPPERS (CAPSICUM-ANNUUM)

The influence of hot-air drying on the composition of both volatile an d non-volatile flavour compounds of different Dutch bell pepper cultiv ars was investigated. Contents of glucose, fructose, ascorbic, citric, and oxalic acid decreased significantly after drying, while the level s of sucrose, malic, fumaric, and cis-aconitic acid increased. Glucose , fructose and ascorbic acid probably participate in Maillard reaction s during heating. Different effects of drying could be distinguished o n the composition of volatile compounds. The majority of these compoun ds evaporated during drying. Some compounds were partly retained in th e dried bell peppers, whereas others disappeared completely. Gas chrom atography-sniffing port analysis revealed that compounds with mainly ' fresh' odour notes like lettuce/grassy/green bell pepper ((Z)-3-hexena l), fruity/almond ((E)-2-hexenal), fruity (octanal), lettuce/green bel l pepper ((Z)-3-hexenol), and grassy/green bell pepper ((Z)-2-hexenal) decreased or disappeared after drying. Another group of compounds inc reased or were formed during drying, like 4-octen-3-one, (E)-2-heptena l, (E)-2-octenal, (E,Z)- and (E,E)-2,4-heptadienal, decanal, and (E)-2 -nonenal; most are known as autoxidation products of unsaturated fatty acids. The increased levels of 2-methylpropionic and 2- and 3-methylb utyric acid, 2-methylpropanal, and 2- and 3-methylbutanal seemed to be due to Strecker degradation. Gas chromatography-sniffing port analysi s showed that the latter three compounds had distinct cacao, sweaty, a nd spicy odour characteristics.