Laser-Induced Breakdown Spectroscopy (LIBS) for Spectral Characterization of Regular Coffee Beans and Luwak Coffee Beans

摘要

Luwak (civet) coffee refers to a type of coffee, where the cherries have been priorly digested and then defecated by a civet (Paradoxurus Hermaphroditus), a catlike animals typically habited in Indonesia. Luwak will only selectively select ripe cherries, and digesting them by enzymatic fermentation in its digestive system. The defecated beans is then removed and cleaned from the feces. It is regarded as the world's most expensive coffee, Traditionally the quality of the coffee is subjectively determined by a tester. This research is motivated by the needs to study and develop a method to determining the quality of coffee products. LIBS technique was used to identify the elemental contents of coffee beans based on its spectral characteristics in the range 200-980 nm. Samples of green beans from variant of arabica and robusta, either regular and luwak, were collected from 5 plantations in East Java. From the recorded spectra, intensity ratio of nitrogen (N), hydrogen (H), and oxygen (O) as essential elements in coffee is applied. In general, values extracted from luwak coffee bean is higher with increases 0.03% - 79.93%. A Discriminant Function Analysis (DFA) also applied to identify marker elements that characterize the regular and luwak beans. Elements of Ca, W, Sr, Mg, and H are the ones used to differentiate the regular and luwak beans from arabica variant, while Ca and W are the ones used to differentiate the regular and luwak beans of robusta variant.