Processes for treating roasted coffee beans with steam
The present invention aims to provide a steam treatment process for stably preparing steam-treated roasted coffee beans having constant flavor quality by reducing variation in the degree of roasting between different sites in the system during steam treatment of roasted coffee beans without complicating operation processes or increasing costs. Steam at a temperature lower than the temperature necessary to advance the degree of roasting of coffee beans is supplied to an apparatus in which the roasted coffee beans are placed until condensed liquid produced in the apparatus has been discharged from the apparatus, and then, the temperature of steam supplied into the apparatus is raised until a temperature becomes sufficient for advancing the degree of roasting of coffee beans.
1 . A process for treating roasted coffee beans with steam comprising the steps of:
(1) continuously supplying steam into an apparatus in which roasted coffee beans are placed at a temperature lower than a target temperature for attaining a predetermined degree of roasting until condensed liquid produced by the steam supply is discharged from the apparatus; and
(2) then, raising the temperature of steam supplied to the apparatus until the target temperature is attained in the apparatus.
2 . The process according to claim 1 , wherein the target temperature is 160° C. or higher.
3 . The process according to claim 1 , further comprising the step (3) of essentially continuously maintaining a temperature exceeding 160° C. in the apparatus for a predetermined period.
4 . The process according to claim 3 , wherein the temperature exceeding 160° C. is kept for 1 second to 1 hour.
5 . The process according to claim 1 , wherein a temperature difference between at least two temperature measurement sites selected from the roasted coffee beans-accommodating apparatus, near the steam inlet of the apparatus and near the steam outlet of the apparatus, is calculated, and once the temperature difference has come within a predetermined range, the process proceeds from step (1) to (2).
6 . The process according to claim 5 , wherein the temperature measurement sites are near the steam inlet and near the steam outlet of the apparatus, and the process proceeds from step (1) to (2) when the temperature difference between the measurement sites falls within 10° C.
7 . The process according to claim 5 , wherein the temperature measurement sites are placed at the steam inlet and the steam outlet of the apparatus, and the process proceeds from step (1) to (2) when the temperature difference between the measurement sites falls within 5° C.
8 . The process according to claim 6 , wherein the steam feed is feedback-controlled by using the steam outlet temperature as a controlled variable in step (1).
9 . The process according to claim 1 , wherein the point when the process proceeds from step (1) to (2) is the point when condensed liquid is presumed to have been discharged depending on the particular condition under which step (1) is performed.
10 . The process according to claim 9 , wherein the supply of steam in step (1) is performed at 150° C. or less.
11 . The process according to claim 9 , wherein the point when condensed liquid is presumed to have been discharged, is the point presumed by performing step (1) in an apparatus which is the same type as that used in the process, capable of measuring the steam temperatures at the inlet and outlet sites of the apparatus and in which the same amount of roasted coffee beans is placed, and determining the time required for the difference of the steam temperatures at the inlet and outlet sites to be 10° C. or less, preferably 5° C. or less.
12 . A process for treating roasted coffee beans with steam by supplying steam to an apparatus in which roasted coffee beans are placed, wherein the steam is essentially continuously held at a temperature exceeding 160° C. for a predetermined period.
13 . The process according to claim 12 , wherein the temperature exceeding 160° C. is held for 1 second to 1 hour.
14 . A process for treating roasted coffee beans with steam by supplying steam to an apparatus in which roasted coffee beans are placed, comprising calculating a temperature difference between at least two temperature measurement sites in the flow passages of steam, and, once the temperature difference has come within a predetermined range, controlling the temperature of the supplied steam so that the temperature exceeds 160° C.
15 . A process for treating roasted coffee beans with steam by supplying steam to an apparatus in which roasted coffee beans are placed, comprising calculating a temperature difference between at least two temperature measurement sites in the flow passages of steam; once the temperature difference falls within a predetermined range, controlling the temperature of the supplied steam so that the temperature exceeds 160° C.; and, essentially continuously keeping the temperature of the steam higher than 160° C. for a predetermined period.
16 . The process according to claim 15 , wherein the temperature is higher than 160° C. is kept for 1 second to 1 hour.
17 . The process according to claim 14 , wherein the temperature difference at the measurement sites is within 10° C.
18 . The process according to claim 14 , wherein the predetermined temperature difference is within 5° C.
19 . The process according to claim 12 , comprising keeping the temperatures at all of at least one temperature measurement site in the flow passages of steam in the apparatus lower than 150° C. for a predetermined period, and then controlling the temperature of the supplied steam higher than 160° C.
20 . A steam-treated roasted coffee bean obtainable by the steam treatment process according to claim 1 .
21 . A coffee drink made by use of the steam-treated, roasted coffee bean according to claim 20 .