Claims
- 1. A method for roasting a high volume of from 5,000 to 12,000 pounds per hour of green coffee in a manner wherein the residence time of the coffee within the roaster is precisely controlled and is less than three minutes comprising the steps of:
- (a) positively feeding green coffee beans into the feed end of a first, longitudinally extended roasting chamber, said roasting chamber comprising a first rotating, cylindrical foraminous container which rotates within said roasting chamber and a first helical screw member attached to and rotatable within said container, said screw member having a diameter equal to that of the container and effective to convey the coffee beans through the roasting chamber at a precise rate upon rotation, the coffee beans being fed into the container at a rate such that the depth of the coffee bed entering is substantially less than 50% of the diameter of the container;
- (b) partially roasting the coffee beans within the first container for from 0.25 to 1.5 minutes while said beans are being subjected to a flow of heated gas which passes upwardly through the first foraminous container at a rate of at least 10 pounds of gas per pound of beans such that the hot gas causes an expansion of the advancing bean bed, the hot gas temperature being less than 630.degree. F. and exceeding 500.degree. F., whereby the beans are partly fluidized, partially dried and partially expanded but do not pop, the coffee beans increasing in their activity as they approach the terminal phase of the partial roast to a point whereat the beans are in a bubbling bed at a temperature exceeding 300.degree. F. but do not exceed 400.degree. F. bean temperature, the bean charge at no time being 100% fluidized, the depth of the partially expanded bed being at all times less than 50% of the diameter of the container;
- (c) passing the partially roasted beans from the discharge end of the first roasting chamber into the feed end of a second longitudinally extending roasting chamber, the first and second roasting chambers being related one to another in a manner which prevent substantial escape of heated gas and beans from the roasting chambers;
- (d) conveying said beans through said second roasting chamber by means of a second roasting, cylindrical foraminous container and a second helical screw member like the first, the coffee beans residing in said second roasting chamber for from 0.25 to 2.0 minutes while said beans are being subjected to a flow of heated gas which passes upwardly through the second foraminous container, said gas having a temperature equal to or less than that of the gas entering the first roasting chamber, said beans being heated to a temperature exceeding 360.degree. F. but less than 480.degree. F. and being more vigorously bubbled in the second roasting chamber than in the first roasting chamber along the length thereof by gas at a mass flow rate of at least about 10 pounds of gas per pound of beans and at least until the beans pop and have the requisite flavor and color developed therein, the bean charge at no time being 100% fluidized, and the temperature of the beans entering the second roaster being no less than 15.degree. F. below the temperature thereof leaving the first roaster;
- (e) passing the roasted coffee beans from the discharge end of the second roasting chamber into a quenching zone; and
- (f) quenching the roasted coffee in said zone with water and/or air to produce a roasted coffee with a whole bean density of from 0.28 to 0.34 g/cc.
- 2. The method of claim 1 wherein the total roasting time is less than 2.0 minutes, and the roasting time within the second roasting chamber is less than 1.5 minutes.
- 3. The method of claim 1 wherein the temperature of gas entering the second roasting chamber is no more than 150.degree. F. less than that entering the first roasting chamber.
- 4. The method of claim 1 wherein the coffee is a single variety.
- 5. The method of claim 1 wherein the coffee is a blend of coffee varieties.
- 6. The method of claim 1 wherein the coffee is principally a Robusta and the gas temperature in said second roasting chamber is 25.degree. to 125.degree. F. less than that in the first chamber.
- 7. The method of claim 1 wherein the coffee is principally a Santos and the gas temperature in said second roasting chamber is 25.degree. to 125.degree. F. less than that in the first chamber.
- 8. The method of claim 1 wherein the coffee is principally Milds and the gas temperature in said second roasting chamber is 0.degree. to 75.degree. F. less than that in the first chamber.
- 9. The method of claim 2 wherein the temperature of gas in the first zone exceeds 525.degree. F.
- 10. The method of claim 9 wherein the temperature of gas in the second zone is 25.degree. F. or more less than that of the first zone and said beans are principally Robusta, Santos and blends thereof.
- 11. The method of claim 9 wherein the temperature of gas in the second zone is 0.degree. to 75.degree. F. less than that of the first zone and said beans are principally Milds.
- 12. The method of claim 1 wherein the coffee in the first and second chambers is subjected to a combined total mass flow rate of 20 to 60 pounds of gas per pound of beans.
- 13. The method of claim 12 wherein the roasted coffee is first charged to a water quench and thereafter is promptly fed to an air quench.
- 14. The method of claim 1 wherein roasted coffee particulate matter including roasted chaff is collected at the discharge end of the second roasting chamber and is recombined with the roasted coffee beans.
- 15. The method of claim 1 wherein the total roasting time from the point of entry to the first roasting chamber to the point of discharge from the second roasting chamber is less than 1.5 minutes and wherein the coffee is fed therealong at a constant rate as determined by the pitches and the rotational speed of the first and second zones' screws.
- 16. The method of claim 1 wherein the beans in the first roasting chamber reach a temperature exceeding 300.degree. F. but less than 375.degree. F., and wherein the beans enters the second roasting chamber are further exposed to gas at a temperature equal to or less than that in the first roaster whereby controlled pyrolysis occurs in the second roasting chamber generating coffee flavor, color and bean expansion.
- 17. The method of claim 16 wherein the gas temperature in the first roasting chamber exceeds 500.degree. F. and the gas temperature in the second roasting chamber is 0.degree.-125.degree. F. below that in the first roasting chamber.
- 18. The method of claim 1 wherein the beans are heated in the second roasting chamber to a temperature that is between 365.degree.-450.degree. F.
- 19. The method of claim 18 wherein the beans are elevated in the second roasting chamber to a temperature not exceeding substantially the glass transition temperature and are maintained thereat for less than 30 seconds.
- 20. The method of claim 1 wherein the gas temperatures in the first roasting chamber are from 500.degree. to 630.degree. F. and in the second roasting chamber are from 460.degree. to 570.degree. F.
- 21. The method of claim 20 wherein the gas temperature in the first roasting chamber is 560.degree.-610.degree. F.
- 22. The method of claim 1 wherein at least 20% of the bed fluidizes in the first roasting chamber and wherein at least 50% of the bed fluidizes in the second roasting chamber.
- 23. The method of claim 22 wherein the beans are introduced to the first roasting chamber at a rate such that the beans are less than five inches in height when they enter in a quiescent state.
- 24. The method of claim 1 wherein the coffee exits the first roaster at 0.5-4% moisture.
- 25. The method of claim 1 wherein two or more coffee varieties to be roasted are blended after roasting and wherein the individual coffee varieties are separately roasted to their optimal colors, said varieties being Robusta, Santos, Milds and blends thereof.
- 26. The method of claim 1 wherein the coffee to be produced is blended before being roasted.
- 27. The method of claim 1 wherein the coffee comprises a blend of non-decaffeinated Robustas, Santos and Milds, the Robustas being roasted to a color of 70-90, Milds 40-60, and Santos to 50-70 photovolts.
- 28. The method of claim 1 wherein the coffee comprises a decaffeinated coffee or blend of decaffeinated coffees roasted to a color of 30 to 60 photovolts.
Parent Case Info
This application is a continuation, of application Ser. No. 696,613, filed 01/29/85 now abandoned.
US Referenced Citations (2)
Number |
Name |
Date |
Kind |
4489506 |
Brown et al. |
Dec 1984 |
|
4501761 |
Mahlmann et al. |
Feb 1985 |
|
Foreign Referenced Citations (3)
Number |
Date |
Country |
0063486 |
Oct 1982 |
EPX |
132877A |
Feb 1985 |
EPX |
8401271 |
Apr 1984 |
WOX |
Continuations (1)
|
Number |
Date |
Country |
Parent |
696613 |
Jan 1985 |
|