Instant coffee crystal block and preparation method thereof

Abstract

The present invention provides an instant coffee crystal block and a preparation method thereof, which relates to the technical field of food processing. The method comprises incubating a coffee liquid containing 0.1-0.3 g / ml of malt powder; adding 0.1-0.2% of a composite enzyme, enzymolysis, adding 2%-8% of starch, heating, and freeze-drying after ultrasonic treatment to obtain an instant coffee crystal block. The active substances of coffee can be fully released, and solid precipitation can be degraded to make the coffee more delicate; a coffee microgel suspension is formed, and a coffee powder with a porous structure is formed by step-by-step cooling and oscillation freeze-drying; after freeze-drying, a porous coffee freeze-dried crystal block is obtained, which can maintain the freeze-dried shape of coffee on the one hand, and is convenient for carrying and transportation, and on the other hand, the porous coffee particles are more easily dissolved during the dissolution process, and the active ingredients can be retained. The technical problems in the prior art that coffee is not easy to carry and the active ingredients are easily inactivated or degraded are solved.

Description

Technical Field

[0001] The invention relates to the technical field of food processing, in particular to an instant coffee crystal block and a preparation method thereof. Background Art

[0002] Coffee products usually include instant coffee powder and instant coffee granules. The preparation process includes: pressurizing the roasted coffee beans for hot extraction or cold extraction to obtain coffee liquid, and then drying the coffee liquid to make it into powder or granules to form instant coffee powder or instant coffee granules. Coffee liquid drying technology usually includes spray drying and freeze drying. Although spray drying technology is fast, low cost and high yield, it needs to be carried out at high temperature. Too high drying temperature can easily cause the flavor substances in the coffee to escape, affecting the flavor and taste of the coffee.

[0003] However, the traditional freeze-dried coffee preparation process has problems with aroma loss, moisture absorption, insufficient retention of active ingredients, and product purity. These technical defects lead to a decrease in the aroma intensity of the final product, quality and safety, hygroscopicity problems, and inactivation or degradation of active ingredients.

[0004] In view of this, the present invention is proposed. Summary of the invention

[0005] One of the purposes of the present invention is to provide a method for preparing instant coffee crystals to at least solve one of the technical problems existing in the prior art.

[0006] A second object of the present invention is to provide an instant coffee crystal block.

[0007] In order to achieve the above-mentioned purpose of the present invention, the following technical solutions are particularly adopted:

[0008] In a first aspect, the present invention provides a method for preparing instant coffee crystals, comprising the following steps:

[0009] A. Incubate coffee liquid containing 0.1-0.3 g / ml malt powder;

[0010] B. Add 0.1-0.2% of complex enzyme, perform enzymolysis, add 2%-8% of starch, heat, perform freeze-drying after ultrasonication to obtain instant coffee crystal blocks;

[0011] The freeze drying comprises cooling from 28°C to 4°C, shaking for 5-12 minutes, cooling from 4°C to -20°C, keeping for 10-20 minutes and then shaking for 3-5 minutes, cooling from -20°C to -30°C, keeping for 10-20 minutes and then shaking for 5-10 minutes, cooling from -30°C to -40°C, shaking for 3-5 minutes and keeping for 4-6 hours;

[0012] The enzyme activity of the malt powder is ≥135U / g;

[0013] The malt powder is barley malt powder or wheat malt powder;

[0014] The incubation includes incubation at 30-60° C. for 6-12 hours.

[0015] Furthermore, the complex enzyme includes cellulase and protease, and the mass ratio of the cellulase to the protease is 1-1.5:1;

[0016] The temperature of the enzymatic hydrolysis is 40-55°C;

[0017] The enzymatic hydrolysis time is 2.5 to 4 hours.

[0018] Further, the heating includes heating at 80-100° C. for 20-40 min;

[0019] The heating also includes cooling.

[0020] Furthermore, the ultrasound includes 300-500W ultrasound for 10-30min.

[0021] Furthermore, during the freeze drying, the temperature drops from 28°C to 4°C at a rate of 1.0-1.5°C / min, from 4°C to -20°C at a rate of 1.0-2.0°C / min, from -20°C to -30°C at a rate of 1.5-2.5°C / min, and from -30°C to -40°C at a rate of 2.0-2.5°C / min.

[0022] Furthermore, the oscillation speed during the freeze-drying is 200-500 rpm.

[0023] Furthermore, the coffee liquid is obtained by extracting roasted coffee beans;

[0024] The extraction includes cold extraction or pressure extraction.

[0025] In a second aspect, the present invention provides an instant coffee crystal block prepared by the above-mentioned preparation method.

[0026] Beneficial effects:

[0027] The present invention provides a method for preparing instant coffee crystal blocks, which is incubated by adding malt powder, and the coffee liquid is treated with the natural enzyme of the malt powder, and then treated with a composite enzyme, so that the coffee active substances can be fully released, the solid precipitation can be degraded, and the coffee can be made more delicate; by adding starch and heating steps, a coffee microgel network can be formed, and the network is broken by ultrasound to form a coffee microgel suspension, and the coffee powder with a porous structure is formed by step-by-step cooling and oscillation freeze drying; after freeze drying, a porous coffee freeze-dried crystal block is obtained, which can maintain the freeze-dried shape of the coffee on the one hand, and is easy to carry and transport, and on the other hand, the porous coffee particles are more easily dissolved during the dissolution process, and the active ingredients can be retained. The technical problems in the prior art that coffee is not easy to carry and the active ingredients are easily inactivated or degraded are solved. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0029] Figure 1 This is a finished picture of instant coffee crystal blocks provided in Example 1 of the present invention. DETAILED DESCRIPTION

[0030] Unless otherwise defined herein, scientific and technical terms used in conjunction with the present invention shall have the meanings commonly understood by those of ordinary skill in the art. The meaning and scope of the terms should be clear, however, in the case of any potential ambiguity, the definitions provided herein take precedence over any dictionary or external definitions. In this application, unless otherwise stated, the use of "or" means "and / or". In addition, the use of the term "including" and other forms is non-limiting.

[0031] The methods and techniques of the present invention are generally performed according to conventional methods well known in the art and as described in various general and more specific references that are cited and discussed throughout the present specification unless otherwise indicated.

[0032] In one aspect, the present invention provides a method for preparing instant coffee crystals, comprising the following steps:

[0033] A. Incubate coffee liquid containing 0.1-0.3 g / ml malt powder;

[0034] B. Add 0.1-0.2% complex enzyme, perform enzymolysis, add 2-8% starch, heat, and perform freeze-drying after ultrasonic treatment;

[0035] The freeze drying comprises cooling from 28°C to 4°C, shaking for 5-12 minutes, cooling from 4°C to -20°C, keeping for 10-20 minutes and then shaking for 3-5 minutes, cooling from -20°C to -30°C, keeping for 10-20 minutes and then shaking for 5-10 minutes, cooling from -30°C to -40°C, shaking for 3-5 minutes and keeping for 4-6 hours;

[0036] The enzyme activity of the malt powder is ≥135U / g;

[0037] The malt powder is barley malt powder or wheat malt powder;

[0038] The incubation includes incubation at 30-60° C. for 6-12 hours.

[0039] By adding malt powder for incubation, using the natural enzyme of malt powder to treat coffee liquid, and then after composite enzyme treatment, the active substances of coffee can be fully released, the solid precipitation can be degraded, and the coffee can be made more delicate; by adding starch and heating steps, a coffee microgel network can be formed, and the network can be broken by ultrasound to form a coffee microgel suspension, which can be freeze-dried by step-by-step cooling and oscillation to form a porous coffee powder; after freeze-drying, a porous coffee freeze-dried crystal block can be obtained, which can maintain the freeze-dried shape of coffee on the one hand, and is easy to carry and transport, and on the other hand, the porous coffee particles are easier to dissolve during the dissolution process, and the active ingredients can be retained. The technical problems of the prior art that coffee is not easy to carry and the active ingredients are easy to inactivate or degrade are solved.

[0040] During the freeze-drying process, the instant coffee crystals can be freeze-dried separately in separate packaging containers to obtain instant coffee crystals of different shapes.

[0041] The concentration of malt powder in the coffee liquid may be, but is not limited to, 0.1 g / ml, 0.13 g / ml, 0.15 g / ml, 0.18 g / ml, 0.2 g / ml, 0.23 g / ml, 0.25 g / ml, 0.28 g / ml or 0.3 g / ml, and may be any value between 0.1 and 0.3 g / ml.

[0042] The added amount of the complex enzyme may be, but is not limited to, 0.1%, 0.11%, 0.12%, 0.13%, 0.14%, 0.15%, 0.16%, 0.17%, 0.18%, 0.19% or 0.2%, and may be any value between 0.1% and 0.2%.

[0043] The added amount of the starch may be, but is not limited to, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 5.5%, 6%, 6.5%, 7%, 7.5% or 8%, and may be any value between 2% and 8%.

[0044] The incubation temperature may be, but is not limited to, 30°C, 33°C, 35°C, 38°C, 40°C, 43°C, 45°C, 48°C, 50°C, 53°C, 55°C, 58°C or 60°C, and may be any value between 30 and 60°C.

[0045] The incubation time may be, but is not limited to, 6 h, 7 h, 8 h, 9 h, 10 h, 11 h or 12 h, and may be any value between 6 and 12 h.

[0046] In some specific embodiments, the complex enzyme includes cellulase and protease, and the mass ratio of the cellulase to the protease is 1-1.5:1.

[0047] The molecular weight of the coffee liquid solid matter is reduced by enzymolysis with cellulase and protease, wherein the enzymolysis temperature is 40-55°C and the enzymolysis time is 2.5-4 hours.

[0048] The mass ratio of the cellulase to the protease may be, but is not limited to, 1:1, 1.1:1, 1.2:1, 1.3:1, 1.4:1 or 1.5:1, or any value between 1 and 1.5:1.

[0049] The temperature of the enzymatic hydrolysis may be, but is not limited to, 40°C, 41°C, 42°C, 43°C, 44°C, 45°C, 46°C, 47°C, 48°C, 49°C, 50°C, 51°C, 52°C, 53°C, 54°C or 55°C, and may be any value between 40 and 55°C.

[0050] The enzymatic hydrolysis time may be, but is not limited to, 2.5 h, 2.6 h, 2.7 h, 2.8 h, 2.9 h, 3 h, 3.1 h, 3.2 h, 3.3 h, 3.4 h, 3.5 h, 3.6 h, 3.7 h, 3.8 h, 3.9 h or 4 h, and may be any value between 2.5 and 4 h.

[0051] In some specific embodiments, the heating comprises heating at 80-100° C. for 20-40 min.

[0052] In some specific embodiments, the heating further comprises cooling.

[0053] In some specific embodiments, the ultrasound comprises 300-500W ultrasound for 10-30 min.

[0054] The power of the ultrasound may be, but is not limited to, 300W, 330W, 350W, 380W, 400W, 430W, 450W, 480W or 500W, and may be any value between 300 and 500W.

[0055] The ultrasound time may be, but is not limited to, 10 min, 13 min, 15 min, 18 min, 20 min, 23 min, 25 min, 28 min or 30 min, and may be any value between 10 and 30 min.

[0056] In some specific embodiments, the rate of decreasing from 28°C to 4°C during the freeze-drying is 1.0~1.5°C / min, the rate of decreasing from 4°C to -20°C is 1.0~2.0°C / min, the rate of decreasing from -20°C to -30°C is 1.5~2.5°C / min, and the rate of decreasing from -30°C to -40°C is 2.0~2.5°C / min.

[0057] In some specific embodiments, the oscillation speed during the freeze-drying is 200-500 rpm.

[0058] In some specific embodiments, the coffee liquid is obtained by extracting roasted coffee beans;

[0059] The extraction includes cold extraction or pressure extraction.

[0060] According to another aspect of the present invention, there is also provided an instant coffee crystal block, which is prepared by the above-mentioned preparation method.

[0061] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0062] Coffee liquid: The raw coffee beans are medium roasted, cooled, ground, sieved, and then cold extracted to obtain coffee liquid with a concentration of 13%.

[0063] Compound enzyme: Mix cellulase and protease in a 1:1 mass ratio for later use.

[0064] Barley sprout powder: enzyme activity is 190U / g.

[0065] In order to facilitate subsequent testing, the following embodiments and comparative examples were prepared using a columnar container with a liquid volume of 19 g during the freeze-drying stage, so that the size and shape of the prepared instant coffee crystals were consistent.

[0066] Example 1

[0067] An instant coffee crystal block is prepared according to the following steps:

[0068] (1) Incubate coffee solution containing 0.2 g / ml barley germination powder at 50°C for 8 h;

[0069] (2) Add 0.15% of complex enzyme, perform enzymolysis at 45°C for 3.5 h, add 5% of starch, heat at 100°C for 20 min, ultrasonicate at 400 W for 20 min, and then freeze-dry to obtain instant coffee crystals.

[0070] The freeze drying process includes cooling from 28°C to 4°C at a rate of 1.0°C / min, shaking for 12 minutes, cooling from 4°C to -20°C at a rate of 1.5°C / min, maintaining for 15 minutes and then shaking for 4 minutes, cooling from -20°C to -30°C at a rate of 2.0°C / min, maintaining for 15 minutes and then shaking for 7 minutes, cooling from -30°C to -40°C at a rate of 2.5°C / min, shaking for 3 minutes, and maintaining for 4 hours. The shaking speed is 500 rpm.

[0071] Example 2

[0072] An instant coffee crystal block is prepared according to the following steps:

[0073] (1) Incubate coffee solution containing 0.1 g / ml barley germinated powder at 60 °C for 6 h, then heat at 90 °C for 30 min and cool;

[0074] (2) Add 0.2% of complex enzyme, perform enzymolysis at 55°C for 2.5 h, add 2% of starch, heat at 90°C for 30 min, perform ultrasound at 300 W for 30 min, and then freeze-dry to obtain instant coffee crystals.

[0075] The freeze drying process includes cooling from 28°C to 4°C at a rate of 1.5°C / min, shaking for 5 minutes, cooling from 4°C to -20°C at a rate of 2.0°C / min, maintaining for 20 minutes and then shaking for 5 minutes, cooling from -20°C to -30°C at a rate of 2.5°C / min, maintaining for 10 minutes and then shaking for 10 minutes, cooling from -30°C to -40°C at a rate of 2.5°C / min, shaking for 5 minutes, and maintaining for 6 hours. The shaking speed is 400rpm.

[0076] Example 3

[0077] An instant coffee crystal block is prepared according to the following steps:

[0078] (1) Incubate coffee solution containing 0.3 g / ml barley germinated powder at 30 °C for 12 h, then heat at 80 °C for 40 min and cool;

[0079] (2) Add 0.1% of complex enzyme, perform enzymolysis at 40°C for 4 h, add 8% of starch, heat at 80°C for 40 min, perform ultrasound at 500 W for 10 min, and then freeze-dry to obtain instant coffee crystals.

[0080] The freeze drying process includes cooling from 28°C to 4°C at a rate of 1.2°C / min, shaking for 8 minutes, cooling from 4°C to -20°C at a rate of 1.0°C / min, maintaining for 10 minutes and then shaking for 3 minutes, cooling from -20°C to -30°C at a rate of 1.5°C / min, maintaining for 20 minutes and then shaking for 5 minutes, cooling from -30°C to -40°C at a rate of 2.0°C / min, shaking for 4 minutes, and maintaining for 5 hours. The shaking speed is 200 rpm.

[0081] Comparative Example 1

[0082] The difference from Example 1 is that no barley malt powder is added, and step (1) is to incubate the coffee liquid at 50° C. for 8 h and then heat it at 100° C. for 20 min.

[0083] Comparative Example 2

[0084] The difference from Example 1 is that no complex enzyme is added, and step (2) is to add 5% starch, heat at 100° C. for 20 min, and ultrasonicate at 400 W for 20 min, and then freeze-dry to obtain instant coffee crystals.

[0085] Comparative Example 3

[0086] The difference from Example 1 is that starch is not added, and step (2) is to add 0.15% of complex enzyme, perform enzymolysis at 45°C for 3.5 h, heat at 100°C for 20 min, and perform ultrasound at 400 W for 20 min, followed by freeze drying to obtain instant coffee crystals.

[0087] Comparative Example 4

[0088] The difference from Example 1 is that ultrasound is not performed, (2) 0.15% of complex enzyme is added, enzymolysis is carried out at 45°C for 3.5 hours, 5% of starch is added, heating is carried out at 100°C for 20 minutes, and freeze-drying is performed to obtain instant coffee crystals.

[0089] Comparative Example 5

[0090] The difference from Example 1 is that single-step cooling freeze drying is used instead of stage cooling freeze drying, and the freeze drying comprises cooling from 28°C to -40°C at a rate of 1.0°C / min and maintaining for 4 hours.

[0091] Comparative Example 6

[0092] The difference from Example 1 is that freeze drying includes decreasing from 28°C to -20°C at a rate of 1.0°C / min, maintaining for 15 min and then shaking for 4 min, decreasing from -20°C to -30°C at a rate of 2.0°C / min, maintaining for 15 min and then shaking for 7 min, decreasing from -30°C to -40°C at a rate of 2.5°C / min, shaking for 3 min, and maintaining for 4 h.

[0093] Comparative Example 7

[0094] The difference from Example 1 is that freeze drying includes decreasing the temperature from 28°C to 4°C at a rate of 1.0°C / min, decreasing the temperature from 4°C to -20°C at a rate of 1.5°C / min, maintaining for 15 min, decreasing the temperature from -20°C to -30°C at a rate of 2.0°C / min, maintaining for 15 min, and then decreasing the temperature from -30°C to -40°C at a rate of 2.5°C / min, and maintaining for 4 h.

[0095] Comparative Example 8

[0096] The difference from Example 1 is that the preparation is carried out according to the following steps:

[0097] The coffee liquid is taken and freeze-dried to obtain instant coffee crystals.

[0098] Among them, freeze drying includes decreasing from 28°C to 4°C at a rate of 1.0°C / min, shaking for 12 minutes, decreasing from 4°C to -20°C at a rate of 1.5°C / min, keeping for 15 minutes and then shaking for 4 minutes, decreasing from -20°C to -30°C at a rate of 2.0°C / min, keeping for 15 minutes and then shaking for 7 minutes, decreasing from -30°C to -40°C at a rate of 2.5°C / min, shaking for 3 minutes, and keeping for 4 hours.

[0099] Test 1: Dissolution rate test

[0100] The solubility test was performed on the instant coffee crystals prepared in Examples 1 to 3 and Comparative Examples 1 to 7, respectively. The test method was performed according to the small cup method in the dissolution and release determination method of the Chinese Pharmacopoeia 2020. Specifically, the stirring paddle speed of the dissolution apparatus was set to 30 rpm, 200 ml of water was used as the medium, the water temperature was 25 ° C, and the time for the instant coffee crystals to be completely dissolved after being added was recorded. The specific results are shown in Table 1.

[0101] Table 1

[0102]

[0103] As shown in Table 1, there is no adhesion in Examples 1 to 3 and Comparative Examples 1 to 2, but the dissolution rate of Examples 1 to 3 is better than that of Comparative Examples 1 and 2. Compared with Example 1, the dissolution time of Comparative Examples 1 to 8 is lower than that of Example 1. It can be seen that there is an interaction between the addition of malt powder in step (1), the use of complex enzymes and starch in step (2), and ultrasonic treatment, and the freeze-drying step, which not only affects the dissolution time, but also causes adhesion due to the larger particle size of the coffee particles than in the examples, resulting in inability to completely dissolve.

[0104] Test 2

[0105] The instant coffee crystal blocks prepared in Examples 1 to 3 and Comparative Examples 1 to 8 were subjected to sensory evaluation, and the specific evaluation criteria are shown in Table 2. Ten adults, with a male-female ratio of 1:1 and an age of 25 to 40 years old, were randomly selected, and each portion of the instant coffee crystal blocks of each Example and Comparative Example was dissolved in 200 ml of water for standby use. After evaluating each Example, the mouth was rinsed with clean water, and the next sample was evaluated after the taste was eliminated. Ten scores were obtained for each sample, and the average was taken. The results are shown in Table 3.

[0106] Table 2

[0107]

[0108] Table 3

[0109]

[0110] As shown in Table 3, the sensory evaluation scores of the instant coffee crystals of Examples 1 to 3 are all higher than those of the comparative examples, with a strong coffee aroma, moderate sweetness and bitterness, and smooth taste. It can be seen that the preparation method of the instant coffee crystals provided by the present invention can not only increase the dissolution rate and avoid adhesion, but also release and retain active substances, improve the taste, and increase the coffee flavor. Taking the finished product of the instant coffee crystals provided in Example 1 as an example, this embodiment is prepared by a columnar container with a liquid volume of 19g, as shown in FIG. Figure 1 It is shown as a columnar shape with regular shape.

[0111] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing instant coffee crystals, characterized in that: The following steps are involved: A. Incubate coffee liquid containing 0.1-0.3 g / ml malt powder; B. Add 0.1-0.2% of complex enzyme, perform enzymolysis, add 2%-8% of starch, heat, perform freeze-drying after ultrasonication to obtain instant coffee crystal blocks; The freeze drying comprises cooling from 28°C to 4°C, shaking for 5-12 minutes, cooling from 4°C to -20°C, keeping for 10-20 minutes and then shaking for 3-5 minutes, cooling from -20°C to -30°C, keeping for 10-20 minutes and then shaking for 5-10 minutes, cooling from -30°C to -40°C, shaking for 3-5 minutes and keeping for 4-6 hours; The enzyme activity of the malt powder is ≥135U / g; The malt powder is barley malt powder or wheat malt powder; The incubation includes incubating at 30-60° C. for 6-12 hours; The complex enzyme comprises cellulase and protease, and the mass ratio of the cellulase to the protease is 1-1.5:

1.

2. The preparation method according to claim 1, characterized in that: The temperature of the enzymatic hydrolysis is 40-55°C; The enzymatic hydrolysis time is 2.5 to 4 hours.

3. The preparation method according to claim 1, characterized in that: The heating includes heating at 80-100° C. for 20-40 min; The heating also includes cooling.

4. The preparation method according to claim 1, characterized in that: The ultrasound includes 300-500W ultrasound for 10-30min.

5. The preparation method according to claim 1, characterized in that: The rate of decreasing the temperature from 28°C to 4°C during freeze drying is 1.0-1.5°C / min, the rate of decreasing the temperature from 4°C to -20°C is 1.0-2.0°C / min, the rate of decreasing the temperature from -20°C to -30°C is 1.5-2.5°C / min, and the rate of decreasing the temperature from -30°C to -40°C is 2.0-2.5°C / min.

6. The preparation method according to claim 1, characterized in that: The oscillation speed during the freeze drying is 200-500 rpm.

7. The preparation method according to any one of claims 1 to 6, characterized in that The coffee liquid is obtained by extracting roasted coffee beans; The extraction includes cold extraction or pressure extraction.

8. An instant coffee crystal block, characterized in that: Prepared by the preparation method according to any one of claims 1 to 7.

Images