Optimization of Coffee Liqueur Manufacturing Process using Caffeine Content

Coffee liqueur is an alcoholic beverage made by soaking coffee in spirit. Though coffee liqueur is one of the well- known liqueur, few research was made so far. In this research, coffee liqueur was prepared by using different recipes involving liquors with different ethanol concentrations (20, 40, or 80%), and the soaking periods (14, 21, or 30 days) of the coffee liqueur ingredients (roasted coffee beans, coffee bean powder and other ingredients). Volatile and semi-volatile compounds are important for the organoleptic quality of roasted coffee beans. However, the amounts of these compounds in roasted coffee beans are more dependent on roasting conditions than those of non-volatiles. Furthermore, volatiles are more easily lost during storage. On the other hand, caffeine, a well-known compound of coffee is an intrinsic non-volatile chemical, and the caffeine is present in larger than other potential indicator components in coffee beans, ensuring the quantitative consistency of the coffee extracts in the liqueur. Caffeine was quantified from the prepared coffee liqueurs by HPLC after method validation. The average caffeine content of all 54 analyses (6 analyses per sample) was 2081.2 μg/mL. The highest caffeine concentration 2793 μg/mL was acquired in the sample prepared by 80% ethanol liquor. A soaking period of 14 days, was considered inadequate for sufficient caffeine extraction regardless of liquor alcohol content. Caffeine concentration peaked after soaking coffees and other ingredients for 21 days at 80% ethanol concentration. On the other hand, the most consistent caffeine concentrations in liqueurs were obtained by soaking for 21 days in 40% ethanol (RSD 7.8%), thus it could be the optimum coffee liqueur recipe. The consistency of coffee liqueur quality was assured using caffeine content.