FACTORS AFFECTING CAFFEINE CONTENT AND ACIDITY OF COFFE DURING ROASTING, GRINDING AND BREWING: A REVIEW

Coffees are one of most consumable beverage in the world. Coffee commonly consumed for its caffeine. Caffeine and acidity will determine the quality of a cup of coffee. Therefore, it is important to know the factors that affecting caffeine content and acidity of coffee. By determine these factors, it is easier to controls research variables as well as develop a new coffee extraction method or brewing method. There are three step of post harvesting of green coffee. Starting with roasting, grinding, and brewing. They are both affecting caffeine content and acidity of coffee. During roasting, caffeine content will increase to the highest point then will decline. The increase of internal bean captivities will cause a better caffeine extraction, therefore the caffeine content will increase. On the other hand during extended heat transfers, the increase of internal bean captivities will lead the caffeine content to decline. Grinding process by making beans into smaller particles also affected the caffeine content. The smaller particles and refined coffee will give the higher caffeine content. Espresso method have the highest caffeine content due to the pressure during coffee extraction. The extraction rate during brewing also affected by temperature and time of contact between hot water and coffee ground. Therefore, methods like boiled will also give higher caffeine content. Roasting also give a significant effect to coffee acidity. In the beginning of roasting phase, the acidity will increase due to maillard reaction. These reaction syntheses acetic acid and formic acid. The increase of acidity during roasting occurred because of chlorogenic acid degradation, especially due to extended exposure of heat. Grinding process will affect the acidity of coffee, yet the influence of grinding will strongly influenced by other factors during extraction. The brewing method with the lowest temperature, time of contact between hot water and coffee ground, and pressure will produce a lower acidity. Key Words: review, caffeine, pH, roasting, grinding, brewing, coff