The effect of roasting degree on the caffeine content in coffee

Kava je, zbog atraktivne arome i punoće okusa, jedan od najčešćih konzumiranih napitaka u svijetu. Njezino konzumiranje je zapocelo u 6. stoljeću u Etiopiji, a danas se konzumira u cijelom svijetu. Najznačajniji bioaktivni sastojak kave je kafein. Svrha ovog rada je odrediti udjel kafeina u cetiri uzorka kave: Minas i Cioccolatato (Coffea arabica) te Cherry i Vijetnam (Coffea canephora), prženih u tri stupnja. Udjeli kafeina određeni su primjenom tri različite metode: ekstrakcija kloroformom, mikro-metoda te metoda s olovnim acetatom. Antioksidacijski kapacitet kave određen je primjenom dvije metode: reakcijom s željezo(III) tripiridiltriazin (Fe3+-TPTZ) kompleksom (FRAP metoda), te reakcijom s 1,1- difenil-2-pikrilhidrazil radikalom (DPPH metoda). Provedeno je i senzorsko ocjenjivanje svih uzoraka kave. Najveći udjel kafeina u svim uzorcima kave određen je primjenom mikrometode. Ovisno o primjenjenoj metodi svijetlo i srednje prženje kave rezultiralo je najvećim udjelom kafeina.Due to its full taste and aroma, coffee is one of the most consumed drinks in the world. The consumption of coffee began in the 6th century in Ethiopia and continues to be consumed throughout the world. The most important bioactive component of coffee is caffeine. The objective of this work is to determine the caffeine content in four samples of coffee; Minas and Cioccolatato (Coffee arabica type), and Cherry and Vietnam (Coffea canephora type), roasted in three stages. The caffeine content was determined using three different methods: extraction with chloroform, micro-method and method with lead acetate. Two methods are used to determine the antioxidant capacity of coffee: reaction with iron (III) - ferric-tripiridyltriazine (Fe3+ - TPTZ) complex (FRAP method), and with the 1,1-diphenyl-2- picrylhydrazyl (DPPH method). Also, all samples have gone through a sensory evaluation. Among these three methods, the greatest caffeine content in coffee samples was determined with the micro method. Depending on the method used the caffeine content was the highest in light and midium roasted coffee