Method for producing coffee

Abstract: Coffee extracts having excellent taste and flavor can be produced by roasting coffee beans after being stored for 7 to 21 days at a temperature in the range of from the freezing point of the raw beans to 3 °C.

Description: The invention relates to a method for producing coffee having excellent taste and flavor. The consumption of coffee has been steadily increasing year by year, and the taste of consumers for coffee is becoming increasingly diversified and refined. With these changes, techniques for blending and roasting raw beans and for storing roasted beans have also been improved. However, no consideration has so far been given on the storage and ripening of raw coffee beans, and hence raw beans are preserved under insufficient temperature and packaging management. The publication by R.J. Clarke et al. "Coffee" vol. 2: Technology, 1987, pages 49 to 52 (Elsevier Applied Science, London GB and New York USA) reports about a series of technical ideas and considerations in conjunction with coffee and around the starting raw beans and different green coffee types, e.g. Kenya, Brazils, Arabica etc., i.e. storage, drying, use of bags, isotherm mode, stability, cleaning etc. A selection of technical parameters to improve raw coffee is given in DE 464 107-C where the raw coffee is cooled down to a temperature below 0°C and particularly during more than 24 hours or 48 hours or more down to a temperature of -8°C to -10°C. Thus it is the object of the present invention to provide a method for making coffee extract with highest quality taste and flavor. According to the invention this object is solved by the process of claim 1, i.e. a process for making coffee extract from raw coffee beans available in the market place by the steps of (1) roasting said beans; (2) grinding the roasted beans; and (3) exposing the ground beans to hot water to form a coffee extract solution, which consists of pretreating said raw coffee beans before said roasting step to thereby improve the flavor properties of said coffee extract wherein said pretreatment consists essentially of (a) placing the raw coffee beans in a freezer maintained at temperature in a range from -4°C to no more than 3°C wherein the beans remain in an unfrozen condition while in said freezer; (b) keeping said beans in said freezer in said temperataure range for at least 7 days and for not more than 21 days; (c) removing said beans from said freezer; and (d) starting the roasting of the beans within 24 hours after the removal from said freezer. Preferably the temperature at step (a) is in a range from -4°C to 0°C, i.e. in the "HYO-ON" range. Generally tie "HYO-ON" range means a temperature range from the freezing point of a substance to 0°C. In a particular embodiment the beans are charged into a bag before they are placed in the freezer. It can be preferable to store the raw coffee beans in a gas-permeable bag like a polyethylene bag or a jute bag. Also an aluminum bag can be used. Coffee extract obtained from coffee beans roasted in accordance with the method of the invention is excellent in flavor and taste. In practicing the present invention, raw coffee beans are stored for 7 to 21 days under unfrozen conditions at a temperature in the range from -4°C (freezing point of the raw beans) to 3°C, preferably in the "HYO-ON" range. Raw coffee beans are little fruits of coffee trees and are prepared by removing skin and sarcocarp from the fruits and then drying the fruits. The present invention can be applied to any raw coffee beans available on the market. When beans are stored at a temperature lower than their freezing point or at a temperature higher than 3°C, there can be attained no substantial improvements in the taste and flavor of resultant coffee extract. Freezing point of raw coffee beans varies depending on the moisture content in the beans, amount of of water-soluble components contained therein, and the like. Raw coffee beans are stored for a period of from 7 to 21 days, preferably from 12 to 17 days. When beans are stored for a period shorter than 7 days, the taste and flavor of coffee extract prepared therefrom will be improved only insufficiently, whereas when beans are stored for a period longer than 21 days, there will be attained no substantial improvements in the taste and flavor of coffee extract prepared therefrom. Raw coffee beans stored under conditions mentioned above are then roasted preferably within 24 hours after the storage. The roasting can be effected by any of the conventional methods, using, e.g., a roaster. In accordance with the method of the present invention, high quality roasted coffee beans can be obtained by a simple treatment, and coffee extract having excellent taste and flavor can be prepared therefrom. Example 1 Into a polyethylene resin bag was charged 500 g of raw coffee beans (Columbia), and the bag was stored for 14 days in a freezer (manufactured by Nippon Light Metal Co., Ltd.) maintained at a temperature of from -1.5 to -0.5 °C. Thereafter, the beans were roasted by a coffee roaster, ground and then extracted with hot water to give 6 liters of coffee extract. For comparison, raw coffee beans stored at room temperature were roasted, ground and extracted with hot water in the same manner as above to give a control sample. The taste and flavor of these coffee extracts were examined by a panel of 50 members. Their taste and flavor, when judged to be excellent, were rated as 3; when judged good, 2; and when judged poor, 1. The sum total of the points so rated are shown in Table 1. Taste Flavor Control 77 66 Present Invention 123 134 Example 2 Into a polyethylene resin bag was charged 300 g of raw coffee beans (Jamaica), and the bag was stored for 12 to 17 days in a freezer maintained at a temperature of -1.5 to -0.5 °C. Thereafter, the beans were roasted, ground and extracted to give coffee extract. To this extract (835 g) were added 100 g of milk and 65 g of sugar to make the total weight 1,000 g, and the mixture was then canned. For comparison, a sample of canned coffee was prepared in the same manner as above, using raw coffee beans stored at room temperature. The taste and flavor of these canned coffees were examined by a panel of 30 members. Their taste and flavor, when judged to be excellent, were rated as 3; when judged good, 2; and when judged poor, 1. The sum total of points so rated are shown in Table 2. Points Control 50 Present Invention 80 Example 3 Three hundred grams (300 g) each of coffee beans were charged into a polyethylene resin bag, a jute bag and an aluminum bag, and these packaged raw coffee beans and non-packed raw coffee beans (300 g) were stored in a freezer at a temperature of -1.5 to -0.5 °C for 14 days. Thereafter, the beans were roasted, ground and extracted with hot water to give 3.6 liters each of coffee extracts. For comparison, raw coffee beans stored at room temperature were roasted, ground and extracted in the same manner as above to give a control sample. These coffee extracts were rated by a panel of 20 members in the same manner as in Example 2. Results obtained are shown in Table 3. It would be understood from the results that polyethylene resin and jute bags are preferable as a package for containing raw coffee beans. Points Control 33 Polyethylene resin bag 53 Jute bag 50 Aluminum bag 40 Not packed 37 Example 4 Into polyethylene resin bags was charged 300 g each of raw coffee beans (robusta), and the bags were stored in a freezer at a temperature of -1.5 to -0.5 °C for a period of 9 days, 14 days, 16 days or 20 days. Thereafter, the beans were roasted, ground and extracted under the same conditions to give coffee extracts. For comparison, a control sample of coffee extract was prepared in the same manner as above, using raw coffee beans stored at room temperature. These coffee extracts were evaluated by a panel of 20 members in accordance with the same rating as in Example 2. The contents of chlorogenic acid and caffeine contained in the roasted coffee beans were determined by liquid chromatography. Results obtained are shown in Table 4. It would be understood from the results that the taste and flavor of coffee extract can be markedly improved when raw coffee beans are stored before roasting at -1.5 to -0.5 °C for a period of from 14 to 16 days. It would also been understood that roasted beans stored for 14 to 16 days contain increased quantities of chlorogenic acid. In general, chlorogenic acid is regarded to be an ingredient useful as an indicator for the degree of roasting of coffee beans. It is, however, highly probable that the above difference in the taste and flavor of coffee extract is based on the difference in the content of chlorogenic acid because there is little difference in the content of caffeine, an important ingredient which decides the taste of coffee extract. In Food Chemistry, 15 , 219-227 (1984) is reported that robusta beans contain chlorogenic acid in quantities higher than in arabica beans, which are generally regarded to be inferior in quality to robusta. This report seems to support the presumption that the improvement in the quality of coffee beans according to the present invention is associated with chlorogenic acid. Example 5 Into polyethylene resin bags was charged 300 g each of raw coffee beans (Colombia), and the bags were stored for 14 days in a refrigerator (4 to 6 °C), a freezer (-1.5 to 0.5 °C) or a deep freezer (-22 to -17 °C). Thereafter, the beans were roasted, ground or extracted under the same conditions to give coffee extracts. For comparison, a control sample was prepared in the same manner as above, using raw coffee beans stored at room temperature. These coffee extracts were evaluated by a panel of 20 members in accordance with the same rating as in Example 2. The content of ingredients contained in the roasted coffee beans was determined as in Example 4. Results obtained are shown in Table 5.

Claims: Process for making coffee extract from raw coffee beans available in the market place by the steps of (1) roasting said beans; (2) grinding the roasted beans; and (3) exposing the ground beans to hot water to form a coffee extract solution, which consists of pretreating said raw coffee beans before said roasting step to thereby improve the flavor properties of said coffee extract wherein said pretreatment consists essentially of (a) placing the raw coffee beans in a freezer maintained at temperature in a range from -4°C to no more than 3°C wherein the beans remain in an unfrozen condition while in said freezer; (b) keeping said beans in said freezer in said temperataure range for at least 7 days and for not more than 21 days; (c) removing said beans from said freezer; and (d) starting the roasting of the beans within 24 hours after the removal from said freezer. Process according to claim 1, wherein the temperature at step (a) is in a range from -4°C to 0°C. Process according to claim 1, wherein said beans are charged into a bag and the bag is stored in said freezer. Process of claim 3, wherein said bag is gas-permeable. Process of claim 3, wherein said bag is a polyethylene bag or a jute bag. Process of claim 3, wherein said bag is an aluminum bag.

Inventors: SAKAIDA KAZUHIRO, TAMAKI YOHJI, SAKAIDA, KAZUHIRO, TAMAKI, YOHJI
Applicants: POKKA CORP, POKKA CORPORATION
Application year: 1990
Main classification: A23F5
IPC codes: A23F5