Evaluation of volatile and thermal properties of boza, a traditional fermented beverage

Abstract

Although boza is widely preferred and consumed, there is no detailed study on volatile and thermal characteristics. A liquid–liquidextraction (LLE) method has been proposed for the volatile extraction of boza using GC-MS. DB-Wax column from 50 °C to 250 °C at a rate of 4 °C/min with a final hold at 250 °C for 10 min. A helium gas was selected as a carrier gas with a 3.2 ml/min linear velocity. The retention time of the internal standard (4-nonanol) used in our study, was detected in the middle of the chromatogram, and the peak response was relatively stable. The odor activity values (OAVs) were utilized to elucidate the aroma and key odorant substances. Based on OAVs, the most important aroma compounds identified in boza were hexanoic acid [25.1, cheesy goat], 4-vinyl phenol [12.1, phenolic/burnt], acetoin [9.1, buttery/creamy], acetic acid [6.7, vinegary/irritant] and octan-2-ol [3.5, coconut]. The high-performance liquid chromatography (HPLC) system was used to determine the organic acids in boza. The quality parameters of the method were established in terms of the linearity of the calibration, the limit of quantification, the limit of detection, and recovery experiments. The proposed method showed a good recovery from 79.47 to 109.96%. The proposed method was found to be specific as no interference peaks were observed for blank samples. Regarding thermal properties, onset temperature (To), peak temperature (Tp), and end set temperature (Te) increase with the heating rate. In contrast, with increasing temperature, there was a slight decrease in the endothermic peak width (EPW) and peak height index (PHI) values. The level of alcohol was 0.06% below the criteria of the Turkish Boza Standard (TSE 9778).