METHOD FOR PROCESSING GREEN COFFEE BEAN

Abstract

In the penetration step, a carbon dioxide fluid is contacted to a sample of coffee green bean inside a chamber at a temperature of 28-50 C. and a pressure of 950-3,500 psi for 3-30 minutes to allow the carbon dioxide fluid to penetrate into the sample of coffee green bean. In a pressure relief step, the pressure in the chamber is reduced to normal pressure in a time period of 2-15 minutes, allowing the carbon dioxide fluid penetrated into the sample of coffee green bean to break down cell wall of the sample of coffee green bean to obtain a sample of coffee green bean with broken cell wall.

Claims

1. A method for processing green coffee bean, comprising: a penetration step, by contacting a carbon dioxide fluid to a sample of coffee green bean inside a chamber at a temperature of 28-50 C. and a pressure of 950-3,500 psi for 3-30 minutes to allow the carbon dioxide fluid to penetrate into the sample of coffee green bean; and a pressure relief step, by reducing the pressure in the chamber to normal pressure in a time period of 2-15 minutes, allowing the carbon dioxide fluid penetrated into the sample of coffee green bean to break down cell wall of the sample of coffee green bean to obtain a sample of coffee green bean with broken cell wall.

2. The method for processing green coffee bean as claimed in claim 1, wherein in the penetration step, the carbon dioxide fluid is contacted to the sample of coffee green bean inside the chamber at the temperature of 30-45 C. and the pressure of 1,050-1,500 psi for 3-10 minutes.

3. The method for processing green coffee bean as claimed in claim 1, wherein in the pressure relief step, the pressure in the chamber is reduced to normal pressure in the time period of 2-6 minutes.

4. The method for processing green coffee bean as claimed in claim 1, further comprising a pressurizing step, by pressurizing the chamber until the chamber has the pressure of 950-3,500 psi after introducing the carbon dioxide fluid into the chamber with the sample of coffee green bean inside.

5. The method for processing green coffee bean as claimed in claim 4, wherein a sum of the time period of the pressurizing step, the time period of the penetration step and the time period of the pressure relief step is 10-45 minutes.

6. The method for processing green coffee bean as claimed in claim 1, further comprising a roasting step, by roasting the sample of coffee green bean with broken cell wall at 180-240 C. for 7-15 minutes.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0013] The present invention will become more fully understood from the detailed description given hereinafter and the accompanying drawings which are given by way of illustration only, and thus are not limitative of the present invention, and wherein:

[0014] FIG. 1 depicts an image representing the cell wall of the conventional sample of roasted coffee bean of group A1.

[0015] FIG. 2 depicts an image representing the cell wall of the sample of roasted coffee bean according to the present invention.

DETAILED DESCRIPTION OF THE INVENTION

[0016] An embodiment of a method for processing green coffee bean according to the present invention can include a penetration step and a pressure relief step.

[0017] Specifically, in the penetration step, a carbon dioxide (CO.sub.2) fluid is penetrated into a sample of coffee green bean. As an example, the sample of coffee green bean can be placed in a chamber with a temperature of 28-50 C., as well as a pressure of 950-3,500 psi. At this time, the carbon dioxide fluid in a supercritical form or a subcritical form (that is, a supercritical CO.sub.2 fluid or a subcritical CO.sub.2 fluid) can contact the sample of coffee green bean inside the chamber for 3-30 minutes, and can penetrate into the sample of coffee green bean by the property of high penetrability. Preferably, the CO.sub.2 fluid can contact the sample of coffee green bean at the temperature of 30-45 C., the pressure of 1,050-1,500 psi for 3-10 minutes.

[0018] Moreover, a pressurizing step can be carried out before the penetration step. In the pressurizing step, the CO.sub.2 fluid such as a CO.sub.2 gas or a CO.sub.2 liquid can be provided by a CO2 source. After the CO.sub.2 gas (or the CO.sub.2 liquid) is introduced into the chamber with the sample of coffee green bean inside (the chamber has the temperature of 28-50 C.), the pressure inside the chamber is increased to allow a phase transition of CO.sub.2 (the transition from the CO.sub.2 gas or the CO.sub.2 liquid to the supercritical CO.sub.2 fluid or the subcritical CO.sub.2 fluid), and the penetration step can be continuously carried out.

[0019] Then, in the pressure relief step, the pressure inside the chamber is reduced to the normal pressure (about 14.7 psi) in a short time period. At this time, due to the rapid change of the pressure, the supercritical CO.sub.2 fluid (or the subcritical CO.sub.2 fluid) penetrated into the sample of coffee green bean can break down the cell wall of the sample of coffee green bean to obtain a sample of coffee green bean with broken cell wall. Preferably, in the pressure relief step, the pressure inside the chamber is reduced to the normal pressure in the time period of 2-15 minutes.

[0020] It is worthy to be noted that polyphenols such as chlorogenic acid can be dissolved in the supercritical CO.sub.2 fluid. Thus, in order to shorten the time period that the sample of coffee green bean contacts to the supercritical CO.sub.2 fluid, to prevent the polyphenols in the sample of coffee green bean from dissolving in the supercritical CO.sub.2, and to prevent the dissolved polyphenols from bringing out by the supercritical CO.sub.2 fluid, in this embodiment, sum of the time period of the pressurizing step, the time period of the penetration step and the time period of the pressure relief step is 10-45 minutes. With such performance, flavor loss of the sample of coffee green bean can be prevented.

[0021] After the penetration step and the pressure relief step, a roasting step can also be carried out. In the roasting step, the sample of coffee green bean with broken cell wall can be roasted at 180-240 C. for 7-15 minutes to obtain a sample of roasted coffee bean. At this time, due to the breakdown of the cell wall of the sample of coffee green bean by the supercritical CO.sub.2 fluid (or the subcritical CO.sub.2 fluid), in the roasting step, the CO.sub.2 gas and a water vapor produced inside the sample of coffee green bean can escape rapidly, preventing from smoldering inside the sample of coffee green bean. Thus, the breakdown of chlorogenic acid due to the smoldering of the CO.sub.2 gas and the water vapor can be prevented, and the sample of roasted coffee bean retaining the large amount of chlorogenic acid can be obtained.

[0022] Referring to TABLE 1, 10 grams of the conventional sample of roasted coffee bean (group A1) contains about 50-110 milligrams of chlorogenic acid, while 10 grams of the sample of roasted coffee bean according to the present invention (group A2) contains about 150-290 milligrams of chlorogenic acid. That is, after the roasting step, the sample of coffee green bean with broken cell wall retains the large amount of chlorogenic acid.

TABLE-US-00001 TABLE 1 Penetration Pressure Relief Roasting Groups Step Step Step A1 X X A2

[0023] In addition, electron microscopy is used to demonstrate the cell wall of the conventional sample of roasted coffee bean (group A1), as well as the cell wall of the sample of roasted coffee bean according to the present invention (group A2). Referring to FIGS. 1-2, breakdown and deformation of the cell wall can be significantly observed in the sample of roasted coffee bean according to the present invention, suggesting that in the roasting step, the CO.sub.2 gas and the water vapor produced inside the sample of coffee green bean can escape rapidly.

[0024] Accordingly, in the method for processing green coffee bean according to the present invention, the supercritical CO.sub.2 fluid (or the subcritical CO.sub.2 fluid) can penetrate into the sample of coffee green bean, and act to breakdown the cell wall of the sample of coffee green bean in the short time period. Thus, in the followed roasting step, the CO.sub.2 gas and the water vapor produced inside the sample of coffee green bean can escape rapidly, and the sample of roasted coffee bean retaining the large amount of chlorogenic acid can be obtained.

[0025] Although the invention has been described in detail with reference to its presently preferable embodiment, it will be understood by one of ordinary skill in the art that various modifications can be made without departing from the spirit and the scope of the invention, as set forth in the appended claims.