CAFFEINE ANALYSIS BY THIN-LAYER CHROMATOGRAPHY RELATED TO THE PHYSICAL-CHEMICAL PROPERTIES OF DIFFERENT VARIETIES OF COFFEE AND SURROGATES

The aim of this study was to evaluate the physical-chemical characteristics of different types of coffee, decaffeinated and of two types of coffee substitutes based on barley and chicory. The following physical-chemical characteristics were performed: moisture, pH, content of polyphenols and qualitatively determination of caffeine, by thin-layer chromatography. The moisture of the investigated coffee and substitutes of coffee was in the range 1,5 and 3,6%. By analyzing the moisture of the coffee substitutes, we observed that coffee based on barley has the highest moisture and chicory has the lowest value. The caffeine was qualitatively determined by thin-layer chromatography. It was found that all types of the investigated samples contain caffeine excepting decaffeinated coffee. Polyphenols content of the analysed coffee samples varied in the range of 2.8-3.2 mg/g.