CZ220496A3 - Process of roasting coffee - Google Patents

Abstract

Coffee beans are pre-roasted by adding pressure using heated vapour. Then, further roasted under normal pressure or by adding pressure slightly using heated vapour.

Description

Technical field

The present invention relates to an improved method of roasting coffee beans as well as roasted coffee products.

BACKGROUND OF THE INVENTION

In the process of preparing roasted and ground coffee or soluble coffee, roasting of coffee beans is one of the important stages that determine the quality of the coffee.

At present, devices that use hot air, combustion gases, far infrared radiation or microwaves are considered for roasting coffee beans.

It is said that the aroma and flavor of coffee is produced by the Maillard reaction, that is, between carbohydrates, amino-terminal proteins, amino acids and the like contained in coffee beans, and that the properties of coffee vary according to the content and composition of carbohydrates, proteins and / or amino acids .

It has been suggested that the coffee beans be roasted under pressure using superheated steam. In this case, the coffee beans undergo immediate hydrolysis, and the aroma and taste of the coffee are improved, so that the quality of the roasted beans can be improved (see Japanese Patent Publication No. 256,347 / 1989). However, steaming with overheated steam tends to make coffee much more acidic, although this may lead to improved quality. For example, the undesirable odor of low quality grains (replacement side) (e.g. Coffea robusta) is reduced and the preferred odor of high quality grains (e.g. Coffea arabica) increases.

Coffee that has too strong acidity is generally not preferred by consumers. Therefore, it is important to develop a method that suppresses the acidity of the coffee while increasing its preferred smell.

The method disclosed in Japanese Patent Publication No. 256,347 / 1989 does not solve the above-mentioned problems. Therefore, this method is not able to allow full use of the steam roasting advantages.

U.S. Pat. No. 3,640,726A discloses a process for preparing Coffea robusta coffee of improved flavor, for use in roasted and ground coffee blends, separately by steam roasting and then additional roasting of Coffea robusta coffee beans under special conditions.

U.S. Patent No. 4,540,591A discloses a process for treating coffee beans of Coffea robusta by steam, roasting and blending. The green coffee beans of Coffea robusta are first contacted with the steam under pressure in the vessel. The vessel is continuously vented at a positive pressure of 6.87 to 34.4 kPa. Then, the steam-treated Coffea robusta coffee beans can either be dried and then roasted or roasted directly. Roasting in a bubbled bed or with steam under pressure is preferably such that a heavy, roasted component develops. The roasted coffee beans of Coffea robusta may then be mixed with at least one type of roasted coffee beans of Coffea arabica.

EP 0 425 824A discloses a method for improving the quality of Coffea robusta coffee by making raw coffee beans of Coffea robusta, (replacement side)

- 2a, which has been treated such that the water content of the grains is from about 30 to 45%, is subjected to a steam treatment for from about 60 to about 120 minutes at a temperature of from about 135 to 140 ° C and a pressure of about 0.3 up to 0.4 MPa. After said steam treatment, the coffee beans are processed and roasted in the usual manner.

U.S. Patent No. 3,106,470 discloses a process for roasting whole green coffee beans, which comprises preheating the beans at substantially atmospheric pressure, roasting the beans at pressurized conditions, and reheating the beans at substantially atmospheric pressure.

SUMMARY OF THE INVENTION

The present inventors have found a method comprising performing a short pressure steam roasting of coffee (pre-roasting) and then roasting the coffee at atmospheric pressure or a slight higher pressure to decompose the acids formed during said pressure roasting. This finding leads them to achieve the present invention.

The present invention relates to an improved method of roasting green coffee beans by the method of roasting

a) roast the green coffee beans by steam for a period of from 50 to 300 seconds, preferably for a duration of from 50 to 180 seconds, at a steam temperature of from 251 to 400 ° C, preferably from 251 to 300 ° C, at a positive pressure of 0; 65 to 2.00 MPa, preferably from 0.65 to (spare side)

- 2b 1.30 MPa, and then

b) finally roasting the grains of step a) with steam for a period of from 60 to 800 seconds at a steam temperature of 251 to 400 ° C under substantially atmospheric conditions, preferably at an overpressure of 0 to 90 kPa.

Brief explanation of the figure in the drawing

Giant. 1 shows a flow diagram of a preferred apparatus for carrying out the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The coffee beans are filled into a rotary roasting chamber connected to a pressure reservoir and flow into the chamber. Steam is injected between the rotating coffee beans through nozzles located within the roasting chamber to pre-roast the coffee beans under pressure for a short period of time.

When the temperature of the coffee beans in the chamber reaches a predetermined temperature, the steam supply is stopped and the steam is discharged from the pressurized container until the pressure approaches atmospheric pressure. The steam is then reintroduced and the final roasting is carried out at atmospheric or slightly elevated pressure. Then, when the temperature of the coffee beans in the roasting chamber reaches a predetermined temperature, the steam supply is interrupted and at the same time the roasting is stopped.

The roasting conditions are given in Table 1.

Table 1

Pre Roasting Final

(conveniently range) roasting Overpressure at 0,65 - 2.00 (0.65 - 1,30) 0 - 0.09 roasting (MPa) Inlet steam temperature (° C) 251 - 400 (251 - 300) 251-400 Roasting time 50 - 300 (50 - 180) 60-800 (with)

The roasting according to the invention is carried out, for example, using the apparatus shown in FIG. 1 and preferably the introduced steam is overheated. The reference numerals in this figure have the following meanings:

coffee bean dispensing valve hopper for coffee bean filling roasting chamber pressure tank steam dispensing valve pressure relief valve

Green coffee includes, for example, Coffea robusta, Arabic coffee, and Brazilian coffee.

The roasting during step a) can be stopped by releasing the pressure before the final roasting in step b).

DETAILED DESCRIPTION OF THE INVENTION

Examples: Two-stage steam roasting

Example 1

The Indonesian coffee EK-1 (Coffea robusta) is subjected to a two-stage steaming process using the roasting apparatus shown in Fig. 1.

The coffee bean dispensing valve 1 is opened and 1.0 kg of EK-1 Indonesian coffee bean is metered from the hopper 2 to fill the coffee beans into the roasting chamber 3. The batch is pre-primed for 2.5 minutes with superheated steam at a pressure of 850 kPa and a steam temperature of 270 ° C, and then the introduction of superheated steam is stopped by closing the steam metering valve 5.

After the overpressure inside the roasting chamber 3 is released by opening the pressure relief valve 6, the steam metering valve 5 opens again. The final roasting is carried out for 1.3 minutes with superheated steam at a pressure of 50 kPa and a steam temperature of 270 ° C. This yields 0.85 kg of roasted beans.

Example 2

The beans of Brazilian coffee # 4/5 (Coffea arabica) are subjected to a two-stage steam roasting using the roasting apparatus shown in Fig. 1.

The coffee bean dispensing valve 1 is opened and 1.0 kg of Brazilian coffee # 4/5 is dosed from the hopper 2 to fill the coffee beans into the roasting chamber 2. The batch is then overpriced within 2.5 minutes with superheated steam at a positive pressure of 1, 00 MPa at a steam temperature of 280 ° C, and then the introduction of superheated steam is stopped by closing the steam metering valve 5.

After the overpressure inside the roasting chamber 3 is released by opening the pressure relief valve 6, the steam metering valve 5 opens again. The final roasting is carried out for 1.3 minutes with superheated steam at a pressure of 50 kPa and at a steam temperature of 280 ° C. This yields 0.85 kg of roasted beans.

Example 3

The beans of Colombian coffee (Coffea arabica) are subjected to a two-stage steam roasting using the roasting apparatus shown in Fig. 1.

The coffee bean dispensing valve 1 is opened and 1.0 kg of Colombian coffee bean is metered from the hopper 2 to fill the coffee beans into the roasting chamber 3. The batch is then preheated for over 2.5 minutes with superheated steam at an overpressure of 1.30 MPa and at a steam temperature of 285 ° C, and then the introduction of superheated steam is stopped by closing the steam metering valve 5.

After the overpressure inside the roasting chamber 3 is released by opening the pressure relief valve 6, the steam metering valve 5 opens again. The final roasting is carried out for 1.5 minutes with superheated steam at a pressure of 50 kPa and a steam temperature of 285 ° C. This yields 0.85 kg of roasted beans.

Example 4

Indonesian coffee beans EK-1 (Coffea robusta) are subjected to a two-stage steam roasting using the roasting apparatus shown in Fig. 1.

The coffee bean dispensing valve 8 is opened and 1.0 kg of Indonesian EK-1 coffee bean is metered from the hopper 2 to fill the coffee beans into the roasting chamber 3. The batch is then pre-primed in 2.8 minutes with superheated steam at a pressure of 850 kPa. and at a steam temperature of 270 ° C, and then the introduction of superheated steam is stopped by closing the steam metering valve 5.

After the overpressure inside the roasting chamber 3 is released by opening the pressure relief valve 6, the steam metering valve 5 opens again. The final roasting is carried out for 1.5 minutes with superheated steam at a pressure of 50 kPa and a steam temperature of 270 ° C. This yields 0.85 kg of roasted beans.

Example 5

The beans of Colombian coffee (Coffea arabica) are subjected to a two-stage steam roasting using the roasting apparatus shown in Fig. 1.

The coffee bean dispensing valve 1 is opened and 1.0 kg of Colombian coffee bean is metered from the hopper 2 to fill the coffee beans into the roasting chamber 3. The batch is then primed with superheated steam at a pressure of 850 kPa and a pressure of 850 kPa. 290 ° C, and then the introduction of superheated steam is stopped by closing the steam metering valve 5.

After the overpressure inside the roasting chamber 3 is released by opening the pressure relief valve 6, the steam metering valve 5 opens again. The final roasting is carried out for 4.0 minutes with superheated steam at a pressure of 50 kPa and a steam temperature of 290 ° C. This yields 0.85 kg of roasted beans.

Control determination: Usual roasting

Control experiment

1.0 kg of Indonesian EK-1 coffee beans (Coffea robusta) are dosed into a rotary chamber placed on a worktop of a coffee roasting machine (Fuji Royal Type R-101) manufactured by Fuji Royal Corp. and roasted with combustion gases from propane for 15 minutes. 0.85 kg of roasted beans are obtained.

Control experiment

1.0 kg of Brazilian coffee # 4/5 (Coffea arabica) is fed into a rotary chamber placed on a worktop of a coffee roaster (Fuji Royal Type R-101) manufactured by Fuji Royal Corp. and roasts with combustion gases from propane for 15 minutes. 0.85 kg of roasted beans are obtained.

Control experiment

1.0 kg of Colombian coffee beans (Coffea arabica) are dosed into a rotary chamber placed on a worktop of a coffee roaster (Fuji Royal Type R-101) manufactured by Fuji Royal Corp. and roasted with propane flue gases for a period of time. Fifteen minutes. 0.85 kg of roasted beans are obtained.

Control experiment

1.0 kg of Indonesian EK-1 coffee beans (Coffea robusta) are dosed into a rotary chamber placed on a worktop of a coffee roasting machine (Fuji Royal Type R-101) manufactured by Fuji Royal Corp. and roasted with combustion gases from propane for 15 minutes. 0.85 kg of roasted beans are obtained.

Control determination: Single-stage steam roasting

Control experiment

The beans of Indonesian coffee EK-1 (Coffea robusta) are subjected to a one-step steam roasting, using the roasting apparatus shown in Fig. 1.

The dosing valve 1 of the coffee beans is opened and 1.0 kg of Indonesian coffee EK-1 is metered from the hopper 2. to fill the coffee beans into the roasting chamber 3. The batch is then roasted for 3 minutes with superheated steam at a pressure of 350 kPa. and at a steam temperature of 250 ° C, and then the introduction of superheated steam is stopped by closing the steam metering valve 5.

The overpressure inside the roasting chamber 3 is released by opening the pressure relief valve 6. This yields 0.85 kg of roasted beans.

Control experiment F

The grains of Brazilian coffee # 4/5 (Coffea arabica) are subjected to one-step steam roasting, using the roasting apparatus shown in Figure 1.

The coffee bean dispensing valve 1 is opened and 1.0 kg of Brazilian coffee # 4/5 is metered from the hopper 2 to fill the coffee beans into the roasting chamber 3. The batch is then roasted for 3 minutes with superheated steam at a pressure of 350 kPa. and at a steam temperature of 250 ° C, and then the introduction of superheated steam is stopped by closing the steam metering valve 5.

The overpressure inside the roasting chamber 3 is released by opening the pressure relief valve 6. This yields 0.85 kg of roasted beans.

Control experiment

The grains of Colombian coffee (Coffea arabica) are subjected to a one-stage steam roasting, using the roasting apparatus shown in Fig. 1.

The coffee bean dispensing valve 1 is opened and 1.0 kg of Colombian coffee bean is metered from the hopper 2 to fill the coffee beans into the roasting chamber 3. The batch is then roasted for over 2 minutes with superheated steam at a pressure of 350 kPa and a steam temperature. 250 ° C, and then the introduction of superheated steam is stopped by closing the steam metering valve 5.

The overpressure inside the roasting chamber 3 is released by opening the pressure relief valve 6. This yields 0.85 kg of roasted beans.

Control experiment H

Indonesian coffee beans (Coffea robusta) are subjected to steam roasting, using the roasting apparatus shown in Fig. 1, and then the final hot gas roasting, using a conventional roasting method.

The coffee bean metering valve 1 is opened and 1.0 kg of Indonesian EK-1 coffee bean is metered from the hopper 2 to fill the coffee beans into the roasting chamber 3. The batch is then roasted for 2.8 minutes with superheated steam at a pressure of 850 kPa and at a steam temperature of 270 ° C in order to obtain pre-roasted grains. These grains are further subjected to a final roasting over a 8.5 minute roasting period on a worktop of a coffee roaster (Fuji Royal Type R-101) manufactured by Fuji Royal Corp.. 0.85 kg of roasted beans are obtained. Thus, the final roasting is carried out without steam.

Control experiment

The grains of Colombian coffee (Coffea arabica) are subjected to a one-stage steam roasting, using the roasting apparatus shown in Fig. 1.

The coffee bean dispensing valve 1 is opened and 1.0 kg of Colombian coffee beans are dosed from the hopper 2 to fill the coffee beans into the roasting chamber 3. The batch is then roasted for 4.8 minutes with superheated steam at a pressure of 850 kPa and at a steam temperature. 290 ° C, and then the introduction of superheated steam is stopped by closing the steam metering valve 5.

The overpressure inside the roasting chamber 3 is released by opening the pressure relief valve 6. This yields 0.85 kg of roasted beans.

Comparison of roasted grains

The resulting roasted coffee beans are ground in a conventional manner and extracted in a funnel through filter paper, using 175 g of hot water per 10 g of ground coffee. The extract is evaluated and the results are given below.

Method of evaluating odor and taste

The quality of the extract is evaluated by seven members of the expert team according to our evaluation methods below. The number of points allocated to roasted grains obtained by conventional roasting corresponds to zero (0). Grains obtained after roasting using superheated steam and grains obtained after two-stage pressure roasting are evaluated according to the following five-step scale:

grade rating

-2 very weak -1 weak weak 0 comparable + 1 weakly strong + 2 very strong

Method for determination of extraction efficiency

A container containing 10 g of ground roasted grains is filled with 170 g of boiling water. The ground coffee is then extracted with stirring in a bath adjusted to 95 ° C. Thereafter, the weight of the extraction residue is divided by the weight of the ground coffee (10 grams) and the value obtained is used to determine the extraction efficiency. The value for conventional roasting represents the extraction efficiency 100. The extraction efficiency for single-stage steam roasting and two-stage pressure roasting is determined as the ratio of the above values obtained by both roasting methods to the value for conventional roasting.

Analytical methodology

1. Determination of volatile fragrance compounds

2-Methylisoborneol (MIB) is measured according to data reported in reference 1. Pyrazines, (E) -2-nonenal and (E, E) -2,4-decadienal are determined by gas chromatography and mass spectrum, after isolation. by simultaneous distillation and extraction (SDE) according to the data reported under reference 2.

References:

(1) H. Bade-Wegner, W. Holscher, G. G. Vitzthum, Quantification of 2-methylisoborneol in Roasted Coffee by GC-MS. 15 ^e Colloque, Montpellier, 1993, ASIC, Paris, pp. 537 et seq. (1993).

(2) J. Boosfeld, H. Bade-Wegner, H. Balzer, W. Holschser, G. G. Vitzthum, Characterization of Unsaturated Aldehydes in Green Coffea. 15 ^e Colloque, Montpellier, 1993 ASIC, Paris, p. 550 et seq. (1993).

2. Determination of pH and titratable acidity (TA)

These values are measured in a beverage which is prepared by adding 130 ml of boiling distilled water to 7.00 g of ground coffee. The mixture is left for exactly 5 minutes. After cooling to room temperature, distilled water is added again to an accurate weight of 137 g. The brewed beverage is filtered and the pH is measured at 20 ° C. To determine the titratable acidity, use 25 ml of the filtrate, after dilution with 25 ml of water. The acidity is titrated to the end point 6.0 with 0.1 N sodium hydroxide solution.

Calculation:

ml of 1.0N NaOH solution TA = 100 g dry matter ml x 137 x 0.1 x 100 x 100 x 7 dry matter

3. The color of the coffee is determined by grinding roasted coffee and sieving, using a 20 mesh sieve (U.S. No. 50) and a pan, passing through a 20 mesh sieve (U.S. No. 50).

50), and the retained fraction from the ladle is collected, placed in a container having a diameter of 38.1 mm and a depth of 12.7 mm and pressed under a pressure of 8244 kPa with a 34.9 mm ram. The compressed coffee is placed under the color search photoelectric unit in the measuring device, and the difference in reflected light at a wavelength of 595 μη between the normalized color of the plate and the coffee is expressed as units of color on the scale of the machine. If a lightly roasted coffee is placed under the search unit, the reflected light is greater than the normalized value and the latch moves to a higher reading.

The color measuring device is a photoelectric color detecting unit, model y1O-Y for determining the reflection, made by Photovolt Company as model 610. The standardized color plate used is a brown ceramic plate. The normalized brown plate has the following reflectance curve, using magnesium oxide, which represents 100% reflectance.

Wavelength (μίτι).

Reflectance

Percent reflection

580 14.0 600 17.0 620 21.4 650 26.0 700 24.3 Table 2 Results of scent and taste evaluation Single stage Two-stage Usually roasting roasting roasting steam steam (control experiment A) i (control experiment E) (Example 1) Coffee Indonesian Indonesian Indonesian grains EK-1 EK-1 EK-1 Efficiency 100 ALIGN! 115 116 extraction Scent cereal 0 -1 -2 silage 0 0 + 1 walnut scent 0 -1 + 1

Table 2 - continued

Coffee grains Usually roasting (control experiment A) Indonesian EK-1 Single stage roasting steam (control experiment E) Indonesian EK-1 Two-stage roasting steam ) (Example 1) Indonesian EK-1 Taste sour 0 + 2 + 1 bitter 0 0 0 astringent 0 0 0

For two-stage roasting steaming unwanted odors (grain smell), characteristic of Coffea robusta, distinctly decrease and acidity increase is suppressed, compared with one- step roasting with steam. Table 3 Analysis results Single stage Two-stage Usually roasting roasting roasting steam steam

(Control Experiment A) (Control Experiment E) (Example 1)

Coffee Indonesian Indonesian Indonesian grains EK-1 EK-1 EK-1 MIB 300 - 400 310 70

(ng / kg)

Table 3 - continued

coffee beans

Usual roasting (control trial A) Indonesian

EK-1

One-stage steam roasting control experiment Indonesia

EK-1

Two-stage steam roasting

E) (Example 1) Indonesian

EK-1 (E) -2-nonenal 300 (µg / kg) (E, E) -2,4 decadenal 550 (pg / kg) pH 5.69

TA (end point, 1.70 pH = 6.0)

260 195

530 470

5.42 5.47

3.75 2.94

Coffea robusta and Coffea arabica are the most important botanical varieties. These show characteristic sensory differences. Coffea robusta usually grows in lower altitudes and at higher humidity. The smell of Coffea robusta shows a stronger acidity, with a cereal, musty smell, which is sometimes described by researchers as earthy.

Local smell preferences vary. Coffea robusta is generally preferred in France or Italy, while consumers in the US, Japan and Central Europe prefer milder and more fruitlike Coffea arabica aromas. Especially in these countries, great technical effort is being made to exploit the clear price differences between Coffea arabica and Coffea robusta and to remove the undesirable cereal, musty essential component of Coffea robusta. Recently, 2-methylisoborneol has been recognized as a major component of fragrance (reference 3).

Although present in trace amounts, 2-methylisoborneol acts as a strong odor. 2-Methylisoborneol is the cause of the cereal and musty odor due to its extremely low threshold of 2.5 to 5 parts per trillion (ppt) in the beverage. A test method to satisfactorily determine the quantitative amount of 2-methylisoborneol in roasted coffee at ppt level was only recently developed (reference 1).

The results contained in the above table show that the 2-methylisoborneol content is significantly lower at the two-stage roasting in Example 1 (70 ng / kg), compared to the one-stage roasting in the E control (310 ng / kg). The value of 310 ng / kg is in the range of the naturally occurring content of 2-methylisoborneol in roasted Indonesian coffee Coffea robusta (reference 1).

As can be seen from the above table, another advantage of two-stage steam roasting is evidenced by a stronger reduction in unwanted unsaturated aldehydes such as (E) -2-nonenal or (E, E) -2,4-decadienal, as compared to conventional roasting and single-stage roasting. steam.

These unsaturated aldehydes are defective lipid oxidation products and it can be demonstrated that in roasted coffee they mainly contribute to the undesirable woody, carton-like or oily essential flavor in coffee (references 2, and 5).

The preceding table also shows that two-stage steaming of Coffea robusta with steam provides an opportunity to produce selectively low acidity, which results in significantly lower titratable acidity and weaker higher pH. Differences in pH values are sensory significant because the sensitivity of human taste is able to distinguish differences in pH values by approximately 0.03 units (reference 6). According to the literature, titratable acidity is titrated to a pH end point of 6.0, which is better in line with the human perception of the acidity of coffee (reference 7),

References:

(3) 0. G. Vitzthum, C. Weisemann, , R. Becker, H.S. Kohler, Cáfe, Cacao, The, Vol. XXXIV, 27 36 (1990). (4) w. Holscher, G. Vitzthum, H. Steinhart,

Identification and Sensorial Evaluation of Aroma-Impact Compounds in Roasted Colombian Coffee, Cafea, Cacao, The 34 205-212 (1990).

(5) T. H. Parliment, W. Clinton, R. Scarpellino, J. Agric. Food Chem. 21, 485-487 (1973).

(6) M. Sivetz, Food Technology 26 (5), 70-77 (1972).

(7) HG Maier, C. Balcke, FC Thies, Lebensm. Chem. Gerichtl. Chem. 37, ^31-83 (1983).

Table 4

Coffee grains Usually roasting (control experiment D) Indonesian EK-1 Roasting steam and gas (control experiment Indonesian EK-1 Two-stage roasting steam H) (Example 4) Indonesian EK-1 Efficiency 100 ALIGN! 102 116 extraction Scent cereal 0 -1 -2 silage 0 + 1 + 3 walnut scent 0 0 + 2 Taste sour 0 + 1 +1 bitter 0 0 0 astringent 0 0 0

In two-stage steam roasting, the undesirable odor (grain odor) characteristic of Coffea robusta is reduced, and a pleasant nutty aroma is evident.

Table 5 scent and taste evaluation results

Coffee grains Usually Roasting (control experiment B) Brazilian # 4/5 Single stage roasting steam (control experiment Brazilian # 4/5 Two-stage roasting steam F) (Example 2) Brazilian # 4/5 Efficiency 100 ALIGN! 113 116 extraction Scent cereal 0 -2 + 2 silage 0 -1 -1 walnut scent 0 0 + 2 Taste sour 0 + 1 0 bitter 0 0 0 astringent 0 0 0

In two-stage coffee roasting, the floral aroma (preferred aroma) is clearly increased and a nut aroma is present. The acidity is suppressed to the same level as in the conventional roasting process.

Table 6

Single stage Two-stage Usually roasting roasting roasting steam steam (control experiment C) (control experiment G) (Example 3) Coffee Colombian Colombian Colombian

doe

Extraction efficiency 100

Cereal flavor 0 Silage 0 Nutty flavor 0

Taste sour 0 bitter 0 sour 0

104 o

+ 1 o

O

105 + 1 o

+1 o

o o

A two-stage steam roasting process enhances the favorable floral aroma characteristic of Colombian coffee grains, as well as a nutty aroma. The acidity is suppressed to the same level as in the conventional roasting process.

Table 7

Results of scent and taste evaluation

Single stage Single stage Two-stage Usually Roasting roasting roasting roasting steam steam steam (control experiment C) (Control Experiment G} (Control Experiment I) (Example 5) Coffee Colombian Colombian 7 and 1 n 1 · 1 1 L L · □ J \ UiLkilU / X J Οι V- ·. Colombian grains

Scent obiiné silage walnut aroma

Taste sour bitter astringent

-1 +2 +1 +1

C -1 +1 + i τΐ -d

0 C

D 0

As judged by the members of the expert team assessing taste, the two-stage steam roasting process enhances the floral character of Colombian Coffea arabica coffee, creating an overall character more similar to the solid high-growth Coffea arabica varieties (for example known as Costa Rican and Kenyan Strictly High Grown Beans).

Table 8

Analysis results

Single stage Single stage Two-stage Usually roasting roasting roasting roasting steam steam steam (control experiment C) (control experiment G) (control experiment I) (Example 5) Coffee Colombian Colombian Colombian Colombian grains Pyrazines 3290 1660 3180 5140 fpg / kg) (Ε, Ξ) -2,4- dekadienal 210 270 100 ALIGN! 140 (kg / kg) pH 5,05 4.84 4.65 4.92 TA (end point, 7.78 10.83 12.35 8.90

pa - 6.0)

This analysis confirms that a two-stage pressure roasting reduces the increase in acidity (as shown by pH and titratable acidity), while increasing the floral character (as shown at the desired pyrazine level with a decrease in unwanted (E, E) -2,4-decadienal level) ).

A number of experiments on Colombian green coffee are conducted to compare the present invention with the conditions set forth in Japanese Patent Publication No. 256,347 / 1989 against the roasted standard of Colombian coffee.

Six separate experimental experiments are carried out by repeating the conditions of the invention (Tests 1 to 6). In all of these six experiments, the superheated steam temperature is adjusted to 290 ° C at pre-roasting and final roasting. The overpressure at pre-roasting is 850 kPa and at the final roasting is 50 kPa. Pre-roasting and final roasting times, as well as total pyrazine values and titratable acidity of the roasted samples, are given in the table below. Three separate, one-stage roasting experiments are also conducted, under the conditions set forth in Japanese Patent Publication No. 256,347 / 1989 using a steam temperature of 250 ° C and five separate experimental experiments carried out at a steam pressure of 85 kPa at a temperature of 85 kPa. set at 290 ° C, without the second roasting stage.

Table 9 below lists the roasting time, pressure, total pyrazine content, and titratable acidity values for two-stage and one-stage roasted samples. Also included is a sample of Colombian coffee roasted in a conventional manner consisting of roasting for 15 minutes in a 55 Roast Color.

As the results show, the titratable acidity of the samples prepared according to the invention is increased from 7.78 to 8.33 TA. This comparison is favorable in view of the unacceptably high titratable acidity of 11.12 and 12.44, which is achieved with a single-stage roasting.

Samples from one-stage roasting are reported to be strikingly acidic by trained taste team members. The samples prepared using the present invention have a pleasant characteristic aroma of fruits and flowers that can be analytically evidenced based on the total pyrazine number, which is significantly higher than the samples from single-stage roasting.

Table 9

Sample Time Time Total Overpressure at Overpressure at from the two-stage Total Sarva pre-final time overpricing final roasting pyrazines English Translation: roasting roasting 1 (pg / kg) TA L (s) (5) (with) (kPa) (kPa)

According to the invention:

1 4445 7.35 58.5 52 332 384 350 50 2 456C 9.08 59.7 75 256 331 850 50 3 5140 8.90 60.6 71 237 308 850 50 4 6015 9.39 59.3 87 215 302 850 50 5 1750 3.73 59.0 99 192 381 850 50 6 7085 9.05 55.6 116 120 236 850 50 Diameter 4830 8.33 from 1 to 6 Standard 3290 7.78 55.0 900

Japanese published

Application No. 256 347/1989: Pattern of single - stage roasting 1 1 1660 10.33 60.0 - - 144 - 350 2 1750 10.55 55.0 - - 130 - 450 3 1565 11.98 56.0 - - 177 - 600 Diameter 1660 11.12

from 1 to 3

Table 9 - continued

Sample Time Time Time Total Overpressure at. Overpressure at 2 dVCiiatupnCVSuC Overall Bsrvs before- final time overpricing final roasting pyrazines roasting English Translation: roasting roasting ♦ (pg / kg) TA (L) (with) (with) (with) (kPa) (kPa)

temperature 290 ° C overpressure 850 kPa

1 3220 12.44 57.5 - - 138 - 850 2 3305 12.00 59.8 - - 197 - 850 3 3130 12.86 60.6 - - 290 - 350 4 2673 12.38 55.4 - - 299 - 850 5 2475 11.79 61.0 - - 355 - 850 Diameter T, '-F' 11 .H 11

from 1 to 5

Effects of the invention

1) According to the present invention, undesirable odor (cereal odor) of Coffea robusta grains (e.g. Indonesian coffee EK-1) having low quality can be noticeably reduced.

2) Full-flavored coffee grains are obtained, with the beneficial (floral / nut) aroma of high quality Coffea arabica grains (e.g., Brazilian coffee # 4/5, Colombian coffee and the like) remarkably increased.

3) Rich coffee flavors are obtained which are devoid of the highly acidic taste observed using a one-stage overheated steam method.

4) Coffee beans are obtained with high efficiency extraction and evenly roasted.

Claims (9)

PATENT CLAIMS What is claimed is: 1. A method of improved roasting of green coffee beans, characterized by: (a) roast the green coffee beans by steam for a time period of 50 to 300 seconds at a steam temperature of 251 to 400 ° C under a positive pressure of 0,65 to 2,00 MPa and then b) finally roasting the grains of step a) with steam for a time period of 60 to 800 seconds at a steam temperature of 251 to 400 ° C under substantially atmospheric conditions. The process according to claim 1, wherein the steam temperature in step a) is from 251 to 300 ° C and the time period in step a) is from 50 to 180 seconds. The process according to claim 1, characterized in that the substantially atmospheric pressure in step b) varies from an overpressure of 0 to 90 kPa. The process according to claim 1 or 2, wherein the overpressure in step a) is from 0.65 to 1.30 MPa. The method of claim 1, wherein the green coffee comprises Coffea robusta. The method of claim 1, wherein the green coffee comprises Coffea arabica. The method of claim 1, wherein the green coffee comprises Brazilian coffee. (spare page) - 30 The method of claim 1, wherein the steam in step a) is superheated steam. The method of claim 1, wherein the roasting during step a) is stopped by releasing the pressure prior to the final roasting of step b).