Effect of bean maturity and roasting temperature on chemical content of robusta coffee

Abstract

This study aims to determine the effect of roasting temperature on chemical content of coffee beans at various fruit maturity. Robusta coffee was obtained from Karawang Regency, West Java. After picking, sortation, and drying in the sun to 10% moisture content, the coffee beans were roasted at 190°C, 200°C, 210°C for 12 minutes. Physical properties observed were weight loss during the roasting. The chemical content observed were water, caffeine, fat, chlorogenic acid and ash before and after roasting. Chemical content analysis was performed using gravimetric methods, soxhlet extraction, and UV-Vis spectrophotometry. The color, aroma and flavor of roasted bean were conducted by organoleptic test. The results obtained, the ripe coffee bean with roasting temperature of 210°C is the best, which gives the lowest yield. The unripe green beans have the highest water content. The roasting temperature did not provide a significant difference in fat, caffeine, chlorogenic acid, and ash content. Organoleptic test results (color and aroma) showed that the mature beans with roasting temperature of 200-210°C were the most preferred, while the coffee brew most preferred was overripe bean with the roasting temperature of 200°C.

The Effect of Freeze Drying and Determination of Heat Transfer on Various Maturity Levels of Robusta Coffee Fruits

“…The smaller the value of aw, the longer the shelf life of food products because spoilage microbes cannot grow. According to Wahyuni et al [15], the value of aw in robusta coffee fruit is ≥ 0.98 because it is included in fresh fruit aw value of robusta coffee beans after the drying process <0.6 with a maximum allowable water content of 7%.…”

“…In general, the term food drying is carried out through sun drying, i.e., the water content of the food is moved to sunlight without the process of controlling the drying temperature and relative humidity. Fruits that will be dried by sun drying are done by blanching first to prevent browning reactions and deactivating enzymes [15]. In addition to using sunlight, drying can be done by freezedrying/lyophilization methods.…”

“…The difference in the duration of the drying process is caused by differences in pressure during the process, causing the pressure values used for each process to be different. Coffee beans' water content affects thermal conductivity, i.e., the higher the water content, the higher the thermal conductivity coefficient value [15]. The value of heat transfer for the drying process of each level of maturity is different, as presented in Table II.…”

“…The water content of foodstuffs is generally reduced to the extent that microbes cannot grow anymore in them. Coffee bean water content tends to decrease when the temperature and roasting time increase because the greater the temperature difference between the heating medium and the material, the faster the heat transfers to the material and the faster the evaporation of water from the material [15].…”

Effect of Fruit Ripening Level and Roasting Temperature on Robusta Coffee Bean Quality

“…This process is very complex, because the amount of heat transferred to the seeds is very important. During coffee roasting, moisture is lost and a chemical reaction occurs [8]. Roasting time varies from 7 to 30 minutes depending on the type of equipment and the quality of the ground coffee [5], [9].…”