Methanol and Major Volatile Compounds of Turkish Raki and Effect of Distillate Source

摘要

Turkish Raki is the traditional anise flavoured distillate beverage produced mainly from a grape distillate called suma. Two types of Raki are produced in Turkey according to the distillate source. They are Type I - a fresh grape Raki produced only from suma and Type II - a Raki produced from a blended distillate of suma and alcohol of agricultural origin (mainly molasses). In this study the content of ethanol, methanol, distillate based major volatile compounds (aldehydes, esters, higher alcohols), aniseed based anethole and estragole, volatile acid and sugar values in two types of commercial Raki samples (40 samples) was determined and the effect of distillate source on the composition was examined. The distillate and the aniseed based major compounds of the Raki samples were analysed by direct injection with a GC-MS-FID according to the European Commission Reference Method. The results of variance analysis and PCA showed that there was a significant difference between the two types of Raki samples. Total volatiles (esters and higher alcohols), methanol, trans-anethole, estragole and sugar values were higher in the samples made from suma alone. All of the analysed component levels of the Turkish Raki samples were in compliance with Turkish Distilled Beverage Regulations. The methanol levels ranged between 28.00-50.87 g/hL absolute alcohol (AA) in Type I samples and 22.03-41.06 g/hL AA in Type II samples. Distillate based total volatiles levels ranged between 136.12-147.88 g/hL AA, with a mean value of 142.88 g/hL AA, in Type I samples and 102.44-113.45 g/hL, with a mean value of 107.9 g/hL, in the Type II samples. The anise based compound trans-anethole levels were significantly higher in the Type I samples (1,298-1,570 mg/L) than in the Type II samples (1,014-1,199 mg/L). According to distillate based volatiles, the Turkish Raki has a valuable content of volatile substances compared to other anise flavoured spirits.