JP2001149013A - Method for roasting coffee bean - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the subject method capable of easily and surely preventing increase in the acidity of the extracted solution from a roasted product while taking advantage of such merits of a method for roasting coffee beans by using superheated steam so as to improve the extraction efficiency of a roasted product and the quality of the flavor thereof or the like. SOLUTION: This method for roasting coffee beans by using overheated steam comprises preheating coffee beans before the roasting.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an improved method for roasting coffee beans using superheated steam.

[0002]

2. Description of the Related Art
As a method for roasting coffee beans, there are methods using direct heating with a rotary pot, far-infrared heating, heating with hot air, heating with superheated steam, and the like. As a method for roasting coffee beans using superheated steam, for example, Japanese Unexamined Patent Publication No.
There are methods as disclosed in Japanese Patent Application Laid-Open No. 256347/1996 and Japanese Patent Application Laid-Open No. 6-30754. However, the method of roasting coffee beans with superheated steam has the advantages of improving the extraction efficiency of roasted products, or reducing the undesired aroma of low-grade beans, and improving the quality to further enhance the preferred aroma of high-grade beans. On the other hand, there is a problem that the acidity of the extract increases (pH decreases) as compared with other roasting methods. As a method for improving the problem of increase in sourness in the roasting method of coffee beans using superheated steam, Japanese Patent No. 2535132 proposes a two-stage pressure roasting method using superheated steam. The method is complicated in operation, and further improvement is desired in terms of effects.

Accordingly, an object of the present invention is to increase the acidity of a roasted product extract while taking advantage of the method of roasting coffee beans with superheated steam, such as improving the extraction efficiency of roasted products and improving the quality of aroma and the like. An object of the present invention is to provide a method for roasting coffee beans which can be prevented easily and reliably.

[0004]

SUMMARY OF THE INVENTION In the method for roasting coffee beans using superheated steam, the present inventors have found that the cause of the increase in the acidity of the extract of the roasted product is that the coffee beans contact the superheated steam at the start of roasting. The condensation of steam on the surface of the coffee beans causes the coffee beans to become wet for a moment, and the water adhering to the surface of the coffee beans and the water contained in the coffee beans themselves reduce the acidity when roasting the coffee beans. It was speculated that this had a significant effect on the generation of the increasing component. Then, based on such estimation, the present inventors have conducted various studies to eliminate the cause of the increase in sourness, and as a result, before roasting with superheated steam, the coffee beans are heated in advance, so that the sourness is increased. The inventors have found that the cause of the increase has been eliminated and the above object has been achieved, and the present invention has been achieved.

That is, the present invention relates to a method for roasting coffee beans, wherein roasting of coffee beans using superheated steam is performed, wherein the roasting of the coffee beans is carried out before the roasting. Is provided.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, a method for roasting coffee beans of the present invention will be described in detail. The preheating of the coffee beans in the present invention is usually performed by using hot air of 100 to 200 ° C. for 100 to 6 hours.
In a hot air of 150 to 180 ° C for 180 seconds,
This is done by exposing the coffee beans for ~ 420 seconds.

[0007] The preheating of the coffee beans depends on the roasting conditions in the post-process. However, if the preheating temperature is too low or the preheating time is too short, the suppression of increase in acidity becomes insufficient and the preheating temperature becomes too high. If the preheating time is too long, the main chemical reaction during roasting proceeds inside the coffee beans, the roasting result becomes the same as conventional hot air roasting, and the result is different from the intention of the present invention. Within the range of the preheating temperature and the preheating time, the surface temperature of the coffee beans is 100 to 200.
C., particularly preferably from 150 to 180.degree. Examples of the method of preheating the coffee beans include a method of preheating the coffee beans by electric heating while stirring the coffee beans, in addition to the method using the hot air described above.

[0008] The coffee beans preheated as described above,
Immediately roast with superheated steam. The roasting with superheated steam may be performed by a known roasting method of coffee beans with superheated steam, for example, according to the method described in JP-A-1-256347. That is, the roasting by the superheated steam is performed as follows using, for example, the fluidized roasting apparatus shown in FIGS. 1 and 2. The fluidized roasting apparatus shown in FIGS. 1 and 2 is the same as the fluidized roasting apparatus disclosed in Japanese Patent Application Laid-Open No. 1-256347.

[0009] Coffee beans are put on the perforated plate 2 via the feed rotary valve 4, and the put coffee beans are sequentially transferred to the drop 9 by the rotary feed plate 3. During this time, the steam generated by the boiler 8 is heated by the heater 6 to form superheated steam, and the superheated steam is introduced from the lower portion of the heating pot 1 into the pot. The introduced superheated steam is blown up from the lower portion to the upper portion of the perforated plate 2, roasted while flowing the coffee beans on the perforated plate 2, and then circulated and used by the blower 7. Further, the roasted coffee beans fall from the outlet 9 and are discharged through the discharge rotary valve 5.

[0010] The roast condition is that the temperature of the superheated steam is 20
0-250 ° C, preferably 200-235 ° C, pressure 9
8 to 600 kPa (gauge), preferably 196 to 450
kPa (gauge), and heating time is 50 to 200 seconds, preferably 80 to 150 seconds.

Further, as disclosed in Japanese Patent Application Laid-Open No. 6-30754, when the above-mentioned roasting with superheated steam is performed, the flow rate of the superheated steam introduced from the lower portion of the heating pot 1 into the inside of the pot is controlled by the roasting start time. It is preferable to decrease the value from the time to the end of the roast. Since the heating time of the roast is as short as 50 to 200 seconds as described above, the flow rate of the superheated steam is practically reduced in a few steps. For example, if the size is reduced in two stages, the former stage is 1 to 4 m / sec,
The flow rate in the subsequent stage may be 0.5 to 2 m / sec. By gradually reducing the flow rate of the superheated steam in this manner, the roasting of the coffee beans can be performed uniformly and the roasting efficiency can be improved.

The roasted coffee beans are water-cooled (water quenched) if necessary.
Products. The roasted coffee beans obtained by the method of the present invention may be used as regular coffee according to a conventional method, or may be used for liquid coffee or instant coffee.

[0013]

EXAMPLES The present invention will be specifically described below with reference to examples.

Example 1 Coffee beans (Colombia EX) were preheated under the preheating conditions shown in Table 1 below, and then roasted under roasting conditions shown in Table 1 below to obtain roasted coffee beans (Sample No. N).
-1, H3-1 and H5-1) were obtained, respectively. The roasted coffee beans of Sample Nos. H3-1 and H5-1 are products of the present invention, and the roasted coffee beans of Sample No. N-1 are comparative products. About each obtained roasted coffee bean, pH value measurement and acidity evaluation were performed as follows. After roasted coffee beans were pulverized and homogenized by mixing well, 15 g of the pulverized product was extracted with 300 ml of boiling ion-exchanged water for 1 minute. Thereafter, the mixture was filtered by the Carita method, and the pH value of coffee (extract) was measured.
In addition, coffee tasting was performed by six persons, and the acidity was evaluated. The evaluation criteria for sourness are based on the sourness of coffee extracted from coffee beans (Columbia EX) roasted by a semi-open flame, and the sourness is strong (+2), slightly strong (+1), or equivalent to the sourness ( 0), slightly weak (-1), and weak (-2) were rated on a total of 9 levels in between.
The results are shown in Table 2 below. As is clear from the results shown in Table 2 below, a decrease in acidity due to preheating before roasting was observed from both the pH value and the tasting.

[0015]

[Table 1]

[0016]

[Table 2]

Example 2 Roasted coffee beans (sample Nos. N-2, H3-2 and H5-2) were obtained in the same manner as in Example 1 except that the preheating conditions and roasting conditions shown in Table 3 below were used. Was. The roasted coffee beans of Sample Nos. H3-2 and H5-2 are products of the present invention, and the roasted coffee beans of Sample No. N-2 are comparative products. For each of the obtained roasted coffee beans, the pH value was measured and the acidity was evaluated in the same manner as in Example 1. The results are shown in Table 4 below.
Shown in As is evident from the results shown in Table 4 below,
From both values and tasting, a decrease in acidity due to preheating before roasting was observed.

[0018]

[Table 3]

[0019]

[Table 4]

[0020]

According to the method for roasting coffee beans of the present invention, the roasted product can be extracted while taking advantage of the method for roasting coffee beans with superheated steam, such as improvement in extraction efficiency of roasted products and improvement in quality such as aroma. An increase in the sourness of the liquid can be easily and reliably prevented.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a fluid roasting apparatus suitably used in the present invention.

FIG. 2 is a view taken in the direction of arrows AA in FIG. 1;

[Explanation of symbols]

 Reference Signs List 1 heating pot 2 perforated plate 3 rotary feed plate 4 rotary valve 5 discharge rotary valve 6 heater 7 blower 8 boiler 9 outlet

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Attack Kamakura 861-2 Shimoaso, Aso-ku, Kawasaki-shi, Kanagawa 22-503 Asodai F-term (reference) 4B027 FB21 FC01 FC02 FQ02 FR05 FR07

Claims (2)

[Claims] 1. A roasting method for roasting coffee beans using superheated steam, wherein the roasting method for roasting coffee beans is performed before the roasting. 2. Preheating the coffee beans at 100 to 200 ° C.
The method of roasting coffee beans according to claim 1, wherein the roasting is performed for 100 to 600 seconds with the hot air.