Poboljšanje kvaliteta napitka kafe izborom optimalnih uslova prženja i odnosa različitih vrsta kafe / Improvement of coffee beverage quality by selecting optimal roasting conditions and optimal ratio of different coffee species

Consumption of black coffee prepared in a traditional way is very popular in our region. By selecting the optimum parameters of roasting in industrial conditions and defining ratio of the individual species of coffee, it aims to achieve the appropriate quality, and the most acceptable sensory properties of a coffee beverage. In order to fulfill consumers expectations, it is necessary to define the parameters of quality coffee for the needs of each target market. Using descriptive sensory analysis it is possible to give a precise description of the aroma, taste and color of coffee beverage, as the most important sensory characteristics, with significant impact on the quality and acceptability of quality. The aim of this PhD thesis was to achieve optimal sensory quality black coffee beverage, by defining the parameters of the coffee roasting within the industrial conditions and defining the optimal ratio of coffee Arabica and Robusta species, as well as defining a sensory profile and the system of sensory analysis black coffee beverage which was prepared on traditional way. In order to define the parameters of the roasting process, it is necessary to determine the optimum temperature of roasting, which will enable the development and formation of pleasant sensory properties of coffee beans. For the preparation of coffee beverage in the traditional way, usually used two species of coffee, Arabica and Robusta in different ratio. Based on the results of chemical and physical analysis of coffee samples (different species and blends) at different roasting temperatures and results of sensory analysis of a coffee beverage prepared from coffee samples in the traditional way, with the aim of improving the coffee beverage quality, by determining optimal conditions of roasting and ratio of different species of coffee, it could be concluded that the samples of coffee beverage prepared from samples produced according to the production specification do not had the expected quality of coffee beverage. It also could be concluded that by production of individual species of coffee samples roasted at 167 and 175° C, and their blends was not reached optimal quality of coffee beverage. It was also concluded that the coffee beverage of sample roasted at 171C, N1 was rated as the sample of the best sensory properties (82.35%). The ratio of coffee Arabica Class II, Arabica Class I and Robusta was 34.28%: 51.42%: 14.30%. Value of titratable acidity was 128.86, chlorogenic acid content was 3.77%, caffeine content was 2.29%, protein content was 13.79%, the content of free fat was 14.37%, total content of saturated fatty acids was 42.65%, and total content of unsaturated fatty acids was 57.36%, pH value was 5.35 and aw value was 0.102. The antioxidant activity was amounted 235.57 μmol TE/g sample (DPPH) and 217.62 μmol TE/g sample (ABTS). Coffee beverage prepared in the traditional way from a sample U1 roasted at 171 °C, finely ground, was characterized as very pleasant, with the most harmonious aromatic profile, pleasant bitterness and acidity, pleasant and moderate body and gentle and harmonious impression in the mouth. The ratio of coffee Arabica Class II, Arabica Class I and Robusta in this sample was 34.28%: 51.42%: 14.30%.