Coffee bean fermentation method using distiller's yeast as leavening agent

Abstract

The invention discloses a coffee bean fermentation method using distiller's yeast as a leavening agent, and belongs to the technical field of coffee. The coffee bean fermentation method using the distiller's yeast as the leavening agent comprises the following steps: selecting mature coffee cherries, shelling and drying to obtain shelled coffee cherries; mixing the shelled coffee cherries with a distiller's yeast leavening agent, and performing sealed fermentation, drying and baking treatment to obtain a coffee bean finished product. Compared with a traditional method without fermentation and natural fermentation, the designed coffee bean fermentation method with the distiller's yeast as the leavening agent has the advantages that the fragrance, the acid quality and the sweet taste of coffee can be more outstanding, the mellowness is higher, meanwhile, the coffee has a more lasting tail note, the quality of the Robursta coffee beans can be greatly improved, and therefore the product profit is increased; and the method has good application value.

Description

Technical Field

[0001] The invention relates to the technical field of coffee, in particular to a coffee bean fermentation method using koji as a fermentation agent. Background Art

[0002] Coffee, as one of the most popular beverages in the world, is of great concern to consumers for its quality and flavor. As the core raw material of coffee, the variety, growing conditions, picking time and subsequent processing methods of coffee beans all have a crucial impact on the flavor and quality of coffee. These differences directly determine the final flavor characteristics of coffee.

[0003] Arabica coffee beans (Coffea arabica) are famous for their unique acidity, aroma, sweetness, bitterness, taste and aftertaste. With high acidity and rich and diverse aroma, they are deeply loved by consumers and are one of the most popular coffee bean varieties in the world, occupying a large share of the world coffee market. However, Arabica coffee trees have poor resistance to diseases and pests, and have high requirements for the growing environment, resulting in low average yields, so the price has remained high.

[0004] In contrast, Robusta coffee beans (Coffea canephora) are highly adaptable and have a high fruit-bearing rate per plant, so they are relatively abundant and widely planted around the world. Due to the high yield and low planting cost of Robusta coffee beans, their price is usually much lower than that of Arabica coffee beans. They are one of the mainstream coffee varieties and have an irreplaceable position in the commercial market. However, Robusta coffee beans have a distinct bitter flavor, and if not handled properly, they are very likely to have negative flavors such as earthy and rubbery flavors. Therefore, they are relatively unpopular with consumers and are difficult to be classified in the high-quality coffee market. They are usually used as raw materials for instant coffee and espresso.

[0005] Therefore, how to design a coffee bean processing method to enhance the flavor and taste of Robusta coffee beans is the key to expanding the consumer market for Robusta coffee beans and increasing product profits. Summary of the invention

[0006] The purpose of the present invention is to provide a coffee bean fermentation method using koji as a fermentation agent to solve the above-mentioned problems in the background technology. Compared with the traditional method without fermentation and natural fermentation, the coffee bean fermentation method using koji as a fermentation agent designed by the present invention can make the aroma, acidity and sweetness of coffee more outstanding, with higher mellowness and more lasting aftertaste, which can greatly improve the quality of Robusta coffee beans, thereby increasing product profits and having good application value.

[0007] To achieve the above object, the present invention provides the following technical solutions:

[0008] One of the technical solutions of the present invention is to provide a coffee bean fermentation method using koji as a fermentation agent, comprising the following steps:

[0009] (1) selecting ripe coffee cherries, shelling them, and drying them to obtain shelled coffee cherries;

[0010] (2) The shelled coffee berries are mixed with a koji fermentation agent, sealed for fermentation, dried, and roasted to obtain finished coffee beans.

[0011] Preferably, the coffee cherries are of Robusta variety.

[0012] Preferably, the koji fermentation agent is high-temperature Daqu, medium-temperature Daqu and Xiaoqu.

[0013] Preferably, in step (1), the drying is performed to a water content of 20-23 wt%.

[0014] Preferably, the added amount of the koji fermentation agent is 5-10wt% of the mass of the shelled coffee fruit.

[0015] Preferably, the koji fermentation agent is a koji fermentation agent that is crushed to pass through a 40-mesh sieve.

[0016] Preferably, the sealed fermentation comprises the following steps: first fermenting at 30-35°C for 8-10 hours, and then fermenting at 25-28°C for 16-18 hours.

[0017] Preferably, during the sealed fermentation process, the loading amount of the raw material system is 60-80 vol% of the volume of the fermentation tank.

[0018] Preferably, in step (2), the drying is performed to a water content of 11-13 wt%.

[0019] Preferably, the drying method is oven drying, and the drying temperature is 50-60°C.

[0020] Preferably, the baking machine has a power of 1.5, a pot temperature of 180° C., and a baking time of 8 minutes.

[0021] The second technical solution of the present invention is to provide a finished coffee bean product obtained according to the above-mentioned coffee bean fermentation method.

[0022] The beneficial technical effects of the present invention are as follows:

[0023] Compared with the traditional method without fermentation and natural fermentation, the coffee bean fermentation method designed by the present invention using koji as a fermentation agent can make the aroma, acidity and sweetness of coffee more outstanding, with higher body and longer-lasting aftertaste, which can greatly improve the quality of Robusta coffee beans, thereby increasing product profits and having good application value.

[0024] Compared with the preparation of coffee beans by fermentation with a single strain of bacteria, the koji fermentation designed in the present invention is a complex strain fermentation technology with richer taste levels, which can solve the problem of unstable taste of naturally fermented coffee. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0026] Figure 1 The following are the physical pictures of the shelled coffee fruit and the finished coffee beans in Example 1. Among them, (a) is the shelled coffee fruit, and (b) is the finished coffee beans. DETAILED DESCRIPTION

[0027] Now, various exemplary embodiments of the present invention are described in detail, and this detailed description should not be considered as a limitation of the present invention, but should be understood as a more detailed description of certain aspects, characteristics and embodiments of the present invention. It should be understood that the terms described in the present invention are only for describing specific embodiments and are not used to limit the present invention.

[0028] In addition, for the numerical range in the present invention, it is understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. The intermediate value in any stated value or stated range, and each smaller range between any other stated value or intermediate value in the range is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded in the scope.

[0029] Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which the invention pertains. Although only preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein may also be used in the practice or testing of the present invention.

[0030] The words “include,” “including,” “have,” “contain,” etc. used in the present invention are open-ended terms, meaning including but not limited to.

[0031] The variety of coffee cherries used in the following embodiments and comparative examples of the present invention is Robusta, which was purchased from coffee farmers in Xinglong, Hainan, with a market price of about 3 yuan / kg.

[0032] The high-temperature Daqu used in the following embodiments of the present invention was purchased from the sauce-flavored Daqu of Luzhou Ruihua Biological Qu Making Co., Ltd.; the medium-temperature Daqu used was purchased from the strong-flavored wine koji of Yufeng Biotechnology Co., Ltd.; and the Xiaoqu used was purchased from the sweet wine koji II of Jinniang Brewing Co., Ltd.

[0033] All raw materials used in the following examples and comparative examples of the present invention are commercially available products.

[0034] Example 1

[0035] A coffee bean fermentation method using koji as a fermentation agent, the specific steps are as follows:

[0036] (1) selecting fresh ripe coffee cherries, shelling them, and drying them to a moisture content of 23 wt % to obtain shelled coffee cherries;

[0037] (2) grinding the high-temperature Daqu to pass through a 40-mesh sieve, then mixing it with shelled coffee cherries (the amount of the high-temperature Daqu added is 10 wt% of the mass of the shelled coffee cherries), loading it into a fermentation tank (the filling amount of the raw material system is 80 vol% of the volume of the fermentation tank), and sealing and fermenting it; the specific steps of the sealed fermentation are: first fermenting at 35° C. for 8 h, and then fermenting at 25° C. for 18 h;

[0038] (3) The sealed fermented raw material system is sent to an oven, dried at 60° C. to a moisture content of 11-13 wt %, and then roasted (medium roasting is adopted, the roasting machine power is 1.5, the pot temperature is 180° C., and the roasting time is 8 min) to obtain finished coffee beans.

[0039] Figure 1 The following are the physical pictures of the shelled coffee fruit and the finished coffee beans in Example 1. Among them, (a) is the shelled coffee fruit, and (b) is the finished coffee beans.

[0040] Example 2

[0041] A coffee bean fermentation method using koji as a fermentation agent, the specific steps are as follows:

[0042] (1) selecting fresh ripe coffee cherries, removing the shells, and drying the cherries to a moisture content of 22 wt % to obtain shelled coffee cherries;

[0043] (2) Grinding the medium-temperature Daqu to pass through a 40-mesh sieve, then mixing it with shelled coffee cherries (the amount of the medium-temperature Daqu added is 8 wt% of the mass of the shelled coffee cherries), loading it into a fermentation tank (the filling amount of the raw material system is 70 vol% of the volume of the fermentation tank), and sealing and fermenting it; the specific steps of the sealed fermentation are: first fermenting at 33° C. for 9 h, and then fermenting at 27° C. for 17 h;

[0044] (3) The sealed fermented raw material system is sent to an oven, dried at 55° C. to a moisture content of 11-13 wt %, and then roasted (medium roasting is adopted, the roasting machine power is 1.5, the pot temperature is 180° C., and the roasting time is 8 min) to obtain finished coffee beans.

[0045] Example 3

[0046] A coffee bean fermentation method using koji as a fermentation agent, the specific steps are as follows:

[0047] (1) selecting fresh ripe coffee cherries, shelling them, and drying them to a moisture content of 20 wt % to obtain shelled coffee cherries;

[0048] (2) crushing the Xiaoqu until it passes through a 40-mesh sieve, then mixing it with shelled coffee cherries (the amount of Xiaoqu added is 5 wt% of the mass of the shelled coffee cherries), loading it into a fermentation tank (the filling amount of the raw material system is 60 vol% of the volume of the fermentation tank), and sealing and fermenting it; the specific steps of sealed fermentation are: first fermenting at 30° C. for 10 h, and then fermenting at 28° C. for 16 h;

[0049] (3) The sealed fermented raw material system is sent to an oven, dried at 50° C. to a moisture content of 11-13 wt %, and then roasted (medium roasting is adopted, the roasting machine power is 1.5, the pot temperature is 180° C., and the roasting time is 8 min) to obtain finished coffee beans.

[0050] Comparative Example 1

[0051] A method for preparing naturally fermented coffee beans, the specific steps are as follows:

[0052] (1) selecting fresh ripe coffee cherries, shelling them, and drying them to a moisture content of 20 wt % to obtain shelled coffee cherries, and then naturally fermenting the shelled coffee cherries at 30° C. for 10 h and then at 28° C. for 16 h;

[0053] (2) The fermented coffee beans in step (1) are placed in an oven, dried at 50° C. to a moisture content of 11-13 wt %, and then roasted (medium roasting, roaster power of 1.5, pot temperature of 180° C., roasting time of 8 min) to obtain naturally fermented coffee beans.

[0054] Effect verification

[0055] In order to verify the quality of the coffee beans produced by the present invention, the following tests were conducted on each embodiment and comparative example. The evaluation method involved in this patent is SCA (Specialty Coffee Association), that is, the cupping method is used for evaluation, and the coffee brewing method is a hand-brewed coffee brewing method; in Example 1, the aroma is analyzed by gas chromatography-mass spectrometry (GC-MS), and its quality is evaluated in combination with the cupping method; the product quality of Examples 2-3 is evaluated by cupping, and a comparative analysis is performed with the product of Example 1. The coffee quality evaluation in the present invention refers to the international standard evaluation system (SCA) and adopts a 10-point system. The test results are shown in Table 1.

[0056] Table 1 Coffee bean test results

[0057]

[0058] Table 2 Coffee bean aroma analysis results

[0059]

[0060] As can be seen from Table 2, the content of pleasant aromas such as fruity aroma in Example 1 is significantly increased compared with that in Comparative Example 1, and the unpleasant odor is significantly reduced; in addition, the product fermented by koji also produces a pleasant aroma that natural fermentation does not have.

[0061] The embodiments described above are only descriptions of the preferred modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A coffee bean fermentation method using koji as a fermentation agent, characterized in that: The following steps are involved: (1) selecting ripe coffee cherries, shelling them, and drying them to obtain shelled coffee cherries; (2) The shelled coffee berries are mixed with a koji fermentation agent, sealed for fermentation, dried, and roasted to obtain finished coffee beans.

2. The coffee bean fermentation method according to claim 1, characterized in that: The variety of the coffee cherries is Robusta.

3. The coffee bean fermentation method according to claim 1, characterized in that: The koji fermentation agents are high-temperature Daqu, medium-temperature Daqu and Xiaoqu.

4. The coffee bean fermentation method according to claim 1, characterized in that: In step (1): the drying is performed to a water content of 20-23 wt%.

5. The coffee bean fermentation method according to claim 1, characterized in that: The addition amount of the koji fermentation agent is 5-10wt% of the mass of the shelled coffee fruit.

6. The coffee bean fermentation method according to claim 1, characterized in that: The sealed fermentation comprises the following steps: firstly fermenting at 30-35°C for 8-10 hours, and then fermenting at 25-28°C for 16-18 hours.

7. The coffee bean fermentation method according to claim 1, characterized in that: In step (2): the drying is performed to a water content of 11-13 wt%.

8. The coffee bean fermentation method according to claim 1, characterized in that: The baking was carried out at a power of 1.5, a temperature of 180° C. and a baking time of 8 minutes.

9. A finished coffee bean product obtained by the coffee bean fermentation method according to any one of claims 1 to 8.

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