Effect of dehydration by sun or by oven on volatiles and aroma compounds of Trachanas

Abstract

Trachanas is one of the most important traditional food products of Cyprus. It is made from fermented sheep or goat’s milk or a mixture of both. The fermented milk is heated and crushed wheat is added to produce a porridge mixture. The mixture is then dried and stored in the form of “biscuits”. Dehydration is performed either by sun, at a domestic level, or industrially using an oven. The objective of this study was to detect differences in aroma compounds of sun-dried or oven-dried Trachanas samples. Six samples (three sun-dried batches and three oven-dried batches) were prepared to make a porridge mixture according to the Cypriot tradition. Dried Trachanas samples were chemically analysed by the electronic nose SMart Nose system, by gas chromatography-mass spectrometry (GC/MS) and by gas chromatography-mass spectrometry-olfactometry (GC/MS/O). Triangle tests were also performed by a panel of 30 people from the CoRFiLaC staff in Ragusa, Italy. Principal component analysis applied to SMart Nose results showed a good separation between sun and oven-dried samples: Sun-dried samples showed a higher variability explained by the traditional process, in comparison to the oven-dried samples. GC/MS and GC/MS/O analysis showed higher numbers of compounds for the sun-dried Trachanas samples. In particular, double the number of odour active compounds were detected by GC/MS/O in the sun-dried samples, revealing that the use of the oven in the dehydration process generally resulted in a lower intensity of aroma. Triangle test confirmed instrumental results and clearly indicated detectable differences by consumers between sun- and oven-dried Trachanas.