2ND CONGRESS ON FOOD STRUCTURE DESIGN, Antalya, Turkey, 26 - 28 October 2016, vol.1, no.1, pp.136
Salep is a food additive which is not cultivated on a commercial scale and is obtained by collecting tubers of the Orchidaceae plants from the wild. Following various processes, the tubers are available for consumption as a highly valued food ingredient. Salep is mainly composed of mucilaginous and starchy material of polyholoside structure and can easily be adulterated by readily available, cheap ingredients that form similar textural structure. The most common adulterants are starches and gums.
The aim of the study was to identify the similarities and differences in glass transition (Tg) and melting transitions of powder salep and adulteration materials. Tg values and melting transitions of the samples were determined by differential scanning calorimetry (DSC). In the study, 4 salep tuber samples collected from different locations of Turkey (Yozgat, Bartın, Van and Muğla) were used. Tuber saleps were dried and grinded prior to analysis. Starch (potato, rice, wheat and corn) and gum (xantan gum, guar gum, gum arabic, locust bean gum) samples were collected from the market in powder forms. The DSC curves were obtained in the temperature range from 0 to 350°C under the dynamic atmosphere of N2 (30 ml/min) heating rate of ß=10°C/min using an Al capsule containing approximately 30 mg of sample material.
The results showed that, there were no significantly differences among the Tg values of the samples. Similarly, melting temperature values of the samples were of identical. However, melting heat values of the salep samples were found to be in the range from 133.63 to 177.03 J/g, the values of the other analyzed samples (starches and gums) were between 176.08 and 323.62 J/g. Obtained findings clearly indicate that, the salep samples were characterized by significantly different melting heat values than the other adulteration materials.
In conclusion, DSC technique may be applicable for the quantitative detection of salep adulteration, based on the parameters in DSC melting curves.