CN115067411B - Three-dimensional freeze-dried coffee block product and manufacturing method and application thereof - Google Patents

Abstract

The invention relates to a method for preparing a three-dimensional freeze-dried coffee block product, which comprises the following steps: extracting the roasted coffee beans to obtain coffee liquid; freeze-drying the coffee liquid to form a coffee block product with a three-dimensional shape; the freeze drying comprises pre-freezing treatment and freeze drying treatment after the pre-freezing treatment; the pre-freezing treatment conditions comprise: reducing the temperature to be less than or equal to-20 ℃ at a cooling rate of 0.5-2 ℃/min; the conditions of the lyophilization process include: the vacuum degree of sublimation drying is less than or equal to 15Pa, the temperature of sublimation drying is-15 ℃, and the time length of sublimation drying is 25h to 50h; the vacuum degree of re-drying is less than or equal to 5Pa, the re-drying temperature is 15-30 ℃, and the re-drying time is 8-15h.

Description

Three-dimensional freeze-dried coffee block product and its production method and application

technical field

The invention relates to the technical field of food processing, in particular to a three-dimensional freeze-dried coffee block product and its production method and application.

Background technique

The coffee products currently on the market usually include instant coffee powder and instant coffee granules, and their preparation process is usually: the roasted coffee beans are pressurized, hot-extracted or cold-extracted to obtain a coffee liquid, and then the coffee liquid is dried. Powdered or granular, forming instant coffee powder or instant coffee granules.

Among them, coffee liquid drying technology generally includes two kinds of spray drying and freeze drying. Spray drying technology has the advantages of fast speed, low cost, and large output, but spray drying needs to be carried out at high temperature. Excessively high drying temperature can easily cause the escape of flavor substances in coffee, affecting the flavor and taste of coffee. Freeze-drying technology is a technology that pre-freezes the coffee liquid at low temperature, and then sublimates and dries the pre-frozen product under vacuum conditions. The freeze-drying temperature is much lower than the temperature required for spray drying. The coffee liquid drying process The escape phenomenon of flavor substances in the medium is greatly reduced, and the coffee block products have better flavor and taste. Therefore, coffee powder made by freeze-drying technology has become more and more popular among consumers in recent years.

However, the coffee block products currently on the market made by freeze-drying technology generally have obvious volume expansion, a large amount of flavor substances escape, and may even have shortcomings such as burnt feeling, which seriously affects the flavor and taste of coffee.

In addition, in addition to the drying process, the subsequent crushing process, storage, and transportation will also cause the escape of flavor substances, and the oil, protein, or other reducing components contained in coffee products will also be oxidized and deteriorated during storage and transportation. , thereby affecting the taste and flavor of coffee, and greatly shortening the sensory shelf life of coffee (that is, the time period during which sensory requirements such as taste and flavor of coffee products can meet the requirements in the predetermined sales environment from the date of production).

Contents of the invention

Based on this, it is necessary to provide a three-dimensional freeze-dried coffee block product capable of effectively reducing the escape of flavor substances and prolonging the sensory shelf life of coffee, as well as its production method and application.

One embodiment of the present invention provides a method for making a three-dimensional freeze-dried coffee block product, comprising the following steps:

Extracting roasted coffee beans to obtain coffee liquid;

Freeze-drying the coffee liquid to form a three-dimensional coffee block product;

Freeze-drying includes pre-freezing treatment and freeze-drying treatment after pre-freezing treatment;

The conditions of the pre-freezing treatment include: reducing the temperature to ≤ -20°C at a cooling rate of 0.5°C/min to 2°C/min;

The conditions of the freeze-drying treatment include: the vacuum degree of sublimation drying is ≤15Pa, the temperature of sublimation drying is -15°C~15°C, and the duration of sublimation drying is 25h~50h; the vacuum degree of re-drying is ≤5Pa, and the temperature of re-drying is The temperature is 15℃~30℃, and the drying time is 8h~15h.

In one of the embodiments, the conditions of the pre-freezing treatment further include: first lowering the temperature to -20°C~-30°C at a cooling rate of 0.5°C/min~2°C, keeping it for 2h~6h, and then lowering the temperature to -35°C ℃~-45℃, keep for 3h~6h.

In one embodiment, the conditions of the freeze-drying treatment further include: the starting temperature of the sublimation drying is -15°C~-5°C, and the ending temperature of the sublimation drying is 5°C~15°C.

In one embodiment, the conditions of the freeze-drying treatment further include: the starting temperature of re-drying is 15°C-20°C, and the ending temperature of re-drying is 25°C-30°C.

In one of the embodiments, after the pre-freezing treatment, the mass content of coffee solids in the product after the pre-freezing treatment is controlled to be 25%-50%.

In one of the embodiments, the method of extracting the coffee beans is pressurized hot extraction or cold extraction.

An embodiment of the present invention provides a three-dimensional freeze-dried coffee block product, which is produced by the manufacturing method of the three-dimensional freeze-dried coffee block product described in any of the above embodiments.

In one embodiment, it is in the shape of a three-dimensional block with a porous structure inside, and the porosity is 45%-65%.

An embodiment of the present invention also provides a brewing method of a three-dimensional freeze-dried coffee block product, comprising the following steps:

Dissolving the three-dimensional freeze-dried coffee block product as described in any of the above-mentioned embodiments in water;

For every 1.5g-4.5g of the three-dimensional freeze-dried coffee block product, 100ml-400ml of water is used for dissolving.

An embodiment of the present invention also provides a coffee-flavored product, which is processed from the three-dimensional freeze-dried coffee block product as described in any of the above embodiments.

The production method of the above three-dimensional freeze-dried coffee block product adopts the freeze-drying technology to dry the coffee liquid. Firstly, the ice crystal shape of the coffee block product is controlled by strictly controlling the cooling rate of the pre-freezing treatment, so as to ensure that the finally formed coffee block product has specific The three-dimensional three-dimensional shape, and the internal porous structure has a suitable porosity to ensure that the coffee block product is instant; and then strictly control the temperature, duration and vacuum degree of sublimation and re-drying during the freeze-drying process to ensure the drying effect. It can also keep the coffee block product stable in three-dimensional shape, without collapse, shrinkage, or bubbling. It can effectively seal volatile flavor substances inside the coffee structure, reduce flavor escape, and reduce oil, protein and The air contact probability can effectively prevent the oxidation and deterioration of coffee block products, retain the flavor and taste of coffee, and prolong the sensory shelf life.

Description of drawings

Fig. 1 is the product form diagram of the coffee block product that embodiment 1～embodiment 3 and comparative example 1～comparative example 2 make;

Fig. 2 is the microscopic observation photo and scanning electron microscope scanning microcosmic atlas of the coffee block product that embodiment 1～embodiment 3 and comparative example 1～comparative example 2 make;

Fig. 3 is the product form diagram of the coffee block product that embodiment 1, embodiment 4 and comparative example 3～comparative example 5 make;

Fig. 4 is a comparison chart of lipid peroxidation value generated during storage between the coffee block product produced in Example 4 and the coffee powder product produced in Comparative Example 6.

Detailed ways

In order to facilitate the understanding of the present invention, the present invention will be more fully described below in conjunction with the embodiments and accompanying drawings. The present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, these embodiments are provided to make the understanding of the disclosure of the present invention more thorough and comprehensive.

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the technical field of the invention. The terms used herein in the description of the present invention are for the purpose of describing specific embodiments only, and are not intended to limit the present invention. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.

In the present invention, the technical features described in open form include closed technical solutions consisting of the enumerated features, as well as open technical solutions including the enumerated features.

One embodiment of the present invention provides a method for manufacturing a three-dimensional freeze-dried coffee block product, including the following steps S110 to S120.

Step S110: Extract the roasted coffee beans to obtain coffee liquid.

It can be understood that conventional methods in the field can be used for the type of coffee beans, roasting conditions, extraction process, etc., without any special limitation. It can be understood that it is only necessary that the technical indexes of the coffee liquid meet the conventional indexes in this field, and there is no special limitation.

Wherein, in a specific example, the method of extracting coffee beans may be pressurized hot extraction or cold extraction, for example. Specifically, the process conditions such as pressurized hot extraction or cold extraction are not particularly limited in an embodiment of the present invention, and conventional operations in the field can be used.

Step S120: Freeze-dry the coffee liquid to form a three-dimensional shaped coffee block product.

It can be understood that the coffee liquid before freeze-drying is usually dissolved in water, which is liquid and contains a lot of water. Through freeze-drying, the liquid coffee liquid can be frozen into a solid state first, and then the water molecules in it can be sublimated from the solid state. In this process, the water in the coffee liquid is only removed, and the original properties of the coffee itself are not changed, and the original flavor and taste of the coffee can be maintained as much as possible.

In one embodiment of the present invention, freeze-drying includes two links of pre-freezing treatment and freeze-drying treatment after the pre-freezing treatment.

Among them, regarding the pre-freezing process:

Specifically, the conditions of the pre-freezing treatment include: the temperature drops to ≤-20° C. at a cooling rate of 0.5° C./min to 2° C./min.

Pre-freezing is the process of gradually changing the coffee liquid from liquid to solid. The inventors have found through research that during this process, the cooling rate has an important effect on the color, surface smoothness, internal microstructure, dissolution rate, and flavor retention of coffee block products. Significantly affected.

In terms of color and surface smoothness, the faster the cooling rate, the lighter the color and smoother the surface of the final coffee block product. Therefore, in order to ensure that the coffee block product has a more beautiful color and surface smoothness, it is necessary to control the cooling rate. Can't be too slow.

In terms of internal microstructure and dissolution rate, different cooling rates will affect the size and distribution of internal cavities in the final coffee block product, mainly because the cooling rate affects the shape of ice crystals, which in turn affects the final coffee block. The three-dimensional shape of the product and the size of the internal pores are specifically manifested in the faster the cooling rate, the smaller the pores, and the finer the arrangement, which leads to the slower water infiltration rate when brewing the coffee block product, which affects the dissolution rate of the coffee block product. Therefore, in order to ensure that the final coffee block product has an appropriate dissolution rate, the cooling rate should not be too fast during the pre-freezing process.

In terms of flavor retention, appropriately increasing the cooling rate will help improve the flavor stability of coffee block products.

Based on the comprehensive consideration of various effects of the cooling rate on the color, surface smoothness, internal microstructure, dissolution rate and flavor retention of the coffee block product, the inventor found through research that the most suitable cooling rate for pre-freezing treatment is 0.5°C/min ~2°C/min.

Further, in the pre-freezing process, the final temperature of the pre-frozen product is controlled at a lower temperature of ≤-20°C, which can shape the three-dimensional shape of the final coffee block product and keep the three-dimensional shape and internal structure stable .

By controlling the cooling rate of the pre-freezing process and the final temperature of the pre-freezing process, it is also beneficial to increase the volatilization rate of water in the subsequent freeze-drying process, so that the pore distribution in the final coffee block product is more uniform, which is beneficial to the coffee block. The infiltration of water during the brewing and dissolving process of the product increases the dissolution rate and enhances the stability of the flavor.

More specifically, the process of pre-freezing treatment may be to first cool down to -20°C~-30°C at a cooling rate of 0.5°C/min~2°C, and keep it for 2h~6h to shape a specific three-dimensional structure of the coffee block product. Then lower the temperature to -35°C~-45°C and keep it for 3h~6h to further consolidate the three-dimensional shape of the coffee block product.

In a specific example, after the pre-freezing treatment, the mass content of coffee solids in the product after the pre-freezing treatment is controlled to be 25%-50%. The volume content of coffee solids is controlled within this specific range, and the solid crystals formed with water molecules are distributed according to a specific ratio, which can make the final coffee block product formed after freeze-drying have a better instant effect.

About the freeze-drying process after the pre-freezing process:

It can be understood that the freeze-drying process generally includes two steps of sublimation drying and re-drying after sublimation drying.

Specifically, the conditions of freeze-drying treatment include: the vacuum degree of sublimation drying is ≤15Pa, the temperature of sublimation drying is -15°C~15°C, and the duration of sublimation drying is 25h~50h; The temperature is 15°C~30°C, and the drying time is 8h~15h. The inventors have found through research that the vacuum degree, temperature and duration control of the sublimation drying and re-drying stages of the freeze-drying process will affect the appearance and shape of the final coffee block product. For example, sublimation drying and re-drying at too high a temperature or for too long a time can lead to darkening of the color of the coffee block product, dryness, dullness, and excessive hardness. For example, if the sublimation drying vacuum is too high, the coffee block product will be too dark and bubbles will also appear. For another example, if the re-drying vacuum is too high, the color of the coffee block product will be too light, and bubbling will also occur at the same time. Controlling the vacuum degree, temperature and duration of sublimation drying and re-drying in the freeze-drying process within the above-mentioned range can ensure that the color, shape, gloss, hardness, etc. of the final coffee block product have better quality. effect without bubbling.

Further, the inventor also found through research that, using the above-mentioned freeze-drying conditions, the flavor substances, lipids, proteins, etc. in the coffee can be effectively wrapped inside the structure of the coffee block product, which can greatly reduce the escape of the flavor substances of the coffee, and effectively It is beneficial to maintain the original flavor and taste of coffee, greatly reduces the possibility of contact with air, thereby reducing the rate of oxidative deterioration of coffee block products, and is beneficial to prolonging the sensory shelf life of coffee block products.

More specifically, the temperature at the initial stage and the final stage of sublimation drying may be the same or different. For example, the starting temperature of sublimation drying is -15°C~-5°C, and the end temperature of sublimation drying is 5°C~15°C.

More specifically, the temperature at the initial stage and the final stage of re-drying may be the same or different. For example, the starting temperature of re-drying is 15°C-20°C, and the ending temperature of re-drying is 25°C-30°C.

An embodiment of the present invention also provides a three-dimensional freeze-dried coffee block product, which is produced by the above-mentioned manufacturing method of the three-dimensional freeze-dried coffee block product. The three-dimensional freeze-dried coffee block product can not only ensure the taste and flavor of coffee, but also has a better dissolution rate, and does not need to be crushed to improve the instant effect. Compared with the traditional coffee block products that need to be crushed, It can also reduce the contact area between the coffee block product and the air, reduce oxidative deterioration and flavor escape, and help extend the shelf life of the product.

Specifically, the three-dimensional freeze-dried coffee is in the shape of a three-dimensional block with a porous structure inside, with a porosity of 45% to 65%. This three-dimensional block-shaped coffee effectively encapsulates volatile flavor substances, lipids and proteins that are prone to oxidative deterioration in its three-dimensional structure, which can greatly reduce flavor escape and oxidative deterioration, and has a longer sensory shelf life Period, and the pore structure inside the coffee block product is evenly distributed, with a suitable porosity, which can not only make the coffee block product have better quality, but also make the coffee have a more suitable instant effect.

Understandably, the above-mentioned three-dimensional freeze-dried coffee block product may be, for example, a kind of instant coffee.

One embodiment of the present invention also provides a method for brewing three-dimensional freeze-dried coffee block products, including the following steps:

Dissolving the above-mentioned three-dimensional freeze-dried coffee block product in water;

For every 1.5g~4.5g three-dimensional freeze-dried coffee block product, 100ml~400ml of water is used for dissolving.

One embodiment of the present invention also provides a coffee-flavored product, which is processed from the above-mentioned three-dimensional freeze-dried coffee block product. For example, it can be further made into cakes, biscuits, beverages and the like with coffee flavor.

The following are specific examples.

Example 1

A method for preparing a three-dimensional freeze-dried coffee block product, comprising the steps of:

Extract the roasted coffee beans to obtain coffee liquid.

The coffee liquid is freeze-dried, and freeze-drying includes pre-freezing treatment and freeze-drying treatment after the pre-freezing treatment.

The conditions of pre-freezing treatment include: first put the coffee liquid into the quick-freezing molding machine, lower the temperature from normal temperature to -30°C at a cooling rate of 2°C/min, and keep it at -30°C for 3 hours, and then lower the temperature to -30°C. Drop to -40°C for 3 hours, and the final temperature of the pre-frozen product is -40°C.

The conditions of the freeze-drying treatment include: transfer the product after the pre-freezing treatment into the freeze dryer, set the starting temperature of the sublimation drying to -5°C, set the end temperature of the sublimation drying to 5°C, linearly increase the temperature, and the duration of the sublimation drying The vacuum degree of sublimation drying is 10Pa; the starting temperature of re-drying is 20°C, the end temperature of re-drying is 25°C, the temperature rises linearly, the duration of re-drying is 15h, and the vacuum degree of re-drying is 5Pa.

Example 2

A method for preparing a three-dimensional freeze-dried coffee block product, comprising the steps of:

Extract the roasted coffee beans to obtain coffee liquid.

The coffee liquid is freeze-dried, and the freeze-drying includes pre-freezing treatment and freeze-drying treatment after the pre-freezing treatment;

The conditions of pre-freezing treatment include: first put the coffee liquid into the quick-freezing molding machine, lower the temperature from normal temperature to -25°C at a cooling rate of 1°C/min, and keep it at -25°C for 6 hours, and then lower the temperature to -25°C. Keep at -35°C for 6h, and the final temperature of the pre-frozen product is -35°C.

The conditions of freeze-drying treatment include: transfer the product after pre-freezing treatment into a freeze dryer, set the starting temperature of sublimation drying to -15°C, set the end temperature of sublimation drying to 5°C, linearly increase the temperature, and the duration of sublimation drying The vacuum degree of sublimation drying is 10Pa; the starting temperature of re-drying is 20°C, the end temperature of re-drying is 25°C, the temperature rises linearly, the duration of re-drying is 15h, and the vacuum degree of re-drying is 5Pa.

Example 3

A method for preparing a three-dimensional freeze-dried coffee block product, comprising the steps of:

Extracting roasted coffee beans to obtain coffee liquid;

The coffee liquid is freeze-dried; freeze-drying includes pre-freezing treatment and freeze-drying treatment after the pre-freezing treatment;

The conditions of pre-freezing treatment include: first put the coffee liquid into the quick-freezing molding machine, lower the temperature from normal temperature to -20°C at a cooling rate of 0.5°C/min, and keep it at -20°C for 2 hours, and then lower the temperature to -20°C. Decrease to -45°C for 3 hours, and the final temperature of the pre-frozen product is -45°C.

The conditions of the freeze-drying treatment include: transfer the product after the pre-freezing treatment into the freeze dryer, set the starting temperature of the sublimation drying to -5°C, set the end temperature of the sublimation drying to 5°C, linearly increase the temperature, and the duration of the sublimation drying The vacuum degree of sublimation drying is 10Pa; the starting temperature of re-drying is 20°C, the end temperature of re-drying is 25°C, the temperature rises linearly, the duration of re-drying is 15h, and the vacuum degree of re-drying is 5Pa.

Example 4

A method for preparing a three-dimensional freeze-dried coffee block product, comprising the steps of:

Extracting roasted coffee beans to obtain coffee liquid;

The coffee liquid is freeze-dried; freeze-drying includes pre-freezing treatment and freeze-drying treatment after the pre-freezing treatment;

The conditions of pre-freezing treatment include: first put the coffee liquid into the quick-freezing molding machine, lower the temperature from normal temperature to -30°C at a cooling rate of 2°C/min, and keep it at -30°C for 3 hours, and then lower the temperature to -30°C. Drop to -40°C for 3 hours, and the final temperature of the pre-frozen product is -40°C.

The conditions of freeze-drying treatment include: transfer the product after pre-freezing treatment into a freeze dryer, set the starting temperature of sublimation drying to -5°C, set the end temperature of sublimation drying to 15°C, linearly increase the temperature, and the duration of sublimation drying The vacuum degree of sublimation drying is 12Pa; the starting temperature of re-drying is 25°C, the end temperature of re-drying is 30°C, the temperature rises linearly, the duration of re-drying is 10h, and the vacuum degree of re-drying is 4Pa.

Comparative example 1

A method for preparing a three-dimensional freeze-dried coffee block product, comprising the steps of:

Extracting roasted coffee beans to obtain coffee liquid;

The coffee liquid is freeze-dried; freeze-drying includes pre-freezing treatment and freeze-drying treatment after the pre-freezing treatment;

The conditions of pre-freezing treatment include: first put the coffee liquid into the quick-freezing molding machine, lower the temperature from normal temperature to -30°C at a cooling rate of 3°C/min, and keep it at -30°C for 3 hours, and then lower the temperature to -30°C. Drop to -40°C for 3 hours, and the final temperature of the pre-frozen product is -40°C.

The conditions of the freeze-drying treatment include: transfer the product after the pre-freezing treatment into the freeze dryer, set the starting temperature of the sublimation drying to -5°C, set the end temperature of the sublimation drying to 5°C, linearly increase the temperature, and the duration of the sublimation drying The vacuum degree of sublimation drying is 10Pa; the starting temperature of re-drying is 20°C, the end temperature of re-drying is 25°C, the temperature rises linearly, the duration of re-drying is 15h, and the vacuum degree of re-drying is 5Pa.

Comparative example 2

A method for preparing a three-dimensional freeze-dried coffee block product, comprising the steps of:

Extracting roasted coffee beans to obtain coffee liquid;

The coffee liquid is freeze-dried; freeze-drying includes pre-freezing treatment and freeze-drying treatment after the pre-freezing treatment;

The pre-freezing conditions include: first put the coffee liquid into the quick-freezing molding machine, lower the temperature from room temperature to -30°C at a cooling rate of 0.2°C/min, and keep it at -30°C for 3 hours, and then lower the temperature to -30°C. Drop to -40°C for 3 hours, and the final temperature of the pre-frozen product is -40°C.

The conditions of the freeze-drying treatment include: transfer the product after the pre-freezing treatment into the freeze dryer, set the starting temperature of the sublimation drying to -5°C, set the end temperature of the sublimation drying to 5°C, linearly increase the temperature, and the duration of the sublimation drying The vacuum degree of sublimation drying is 10Pa; the starting temperature of re-drying is 20°C, the end temperature of re-drying is 25°C, the temperature rises linearly, the duration of re-drying is 15h, and the vacuum degree of re-drying is 5Pa.

Comparative example 3

A method for preparing a three-dimensional freeze-dried coffee block product, comprising the steps of:

Extracting roasted coffee beans to obtain coffee liquid;

The coffee liquid is freeze-dried; freeze-drying includes pre-freezing treatment and freeze-drying treatment after the pre-freezing treatment;

The conditions of pre-freezing treatment include: put the coffee liquid into the quick-freezing molding machine, first lower the temperature from normal temperature to -30°C at a cooling rate of 2°C/min, and keep it at -30°C for 3 hours, and then lower the temperature to -30°C. Drop to -40°C for 3 hours, and the final temperature of the pre-frozen product is -40°C.

The conditions of freeze-drying treatment include: transfer the product after pre-freezing treatment into a freeze dryer, set the starting temperature of sublimation drying to -5°C, set the end temperature of sublimation drying to 20°C, linearly increase the temperature, and the duration of sublimation drying The sublimation drying vacuum is 10 Pa; the starting temperature of re-drying is 20°C, the end temperature of re-drying is 35°C, the temperature rises linearly, the duration of re-drying is 15 h, and the vacuum degree of re-drying is 5Pa.

Comparative example 4

A method for preparing a three-dimensional freeze-dried coffee block product, comprising the steps of:

Extracting roasted coffee beans to obtain coffee liquid;

The coffee liquid is freeze-dried; freeze-drying includes pre-freezing treatment and freeze-drying treatment after the pre-freezing treatment;

The conditions of pre-freezing treatment include: first put the coffee liquid into the quick-freezing molding machine, lower the temperature from normal temperature to -30°C at a cooling rate of 2°C/min, and keep it at -30°C for 3 hours, and then put the material Turn to -40°C for 3 hours, and the final temperature of the pre-frozen product is -40°C.

The conditions of the freeze-drying treatment include: transfer the product after the pre-freezing treatment into the freeze dryer, set the starting temperature of the sublimation drying to -5°C, set the end temperature of the sublimation drying to 5°C, linearly increase the temperature, and the duration of the sublimation drying 50h, the vacuum degree of sublimation drying is 25Pa; the start temperature of re-drying is 20℃, the end temperature of re-drying is 25℃, the temperature rises linearly, the duration of re-drying is 15h, and the vacuum degree of re-drying is 5Pa.

Comparative example 5

A method for preparing a three-dimensional freeze-dried coffee block product, comprising the steps of:

Extracting roasted coffee beans to obtain coffee liquid;

The coffee liquid is freeze-dried, and freeze-drying includes pre-freezing treatment and freeze-drying treatment after the pre-freezing treatment.

The conditions of pre-freezing treatment include: first put the coffee liquid into the quick-freezing molding machine, lower the temperature from normal temperature to -30°C at a cooling rate of 2°C/min, and keep it at -30°C for 3 hours, and then lower the temperature to Keep at -40°C for 3 hours, and the final temperature of the pre-frozen product is -40°C.

The conditions of the freeze-drying treatment include: transfer the product after the pre-freezing treatment into the freeze dryer, set the starting temperature of the sublimation drying to -5°C, set the end temperature of the sublimation drying to 5°C, linearly increase the temperature, and the duration of the sublimation drying 50h, the vacuum degree of sublimation drying is 10Pa; the start temperature of re-drying is 20°C, the end temperature of re-drying is 25°C, the temperature rises linearly, the duration of re-drying is 15h, and the vacuum degree of re-drying is 15Pa.

Comparative example 6

A method for preparing a powdered coffee block product, comprising the steps of:

The three-dimensional freeze-dried coffee block after freeze-drying in Example 4 was directly crushed into coffee powder with a particle size of less than 20 meshes with a pulverizer.

Fig. 1 shows the product morphology of the three-dimensional freeze-dried coffee block products produced in Example 1-Example 3 and Comparative Example 1-Comparative Example 2. It can be seen that as the cooling rate continues to accelerate, the color of the three-dimensional freeze-dried coffee block product obtained gradually becomes lighter, and the surface smoothness gradually increases. Compared with Examples 1 to 3, the three-dimensional freeze-dried coffee block product obtained in Comparative Example 2 has too dark a color and a rough surface because the cooling rate is too low.

Figure 2 shows the general microscopic observation and SEM scanning microscopic atlas of the three-dimensional freeze-dried coffee block products produced in Examples 1 to 3 and Comparative Examples 1 to 2. It can be seen that as the cooling rate continues to accelerate, the internal pores of the produced three-dimensional freeze-dried coffee block product continue to decrease, and the arrangement fineness gradually increases. Compared with Examples 1 to 3, the three-dimensional freeze-dried coffee block product produced in Comparative Example 1 has the smallest pores and the densest arrangement.

The three-dimensional freeze-dried coffee block products produced in Examples 1~Example 3 and Comparative Example 1~Comparative Example 2 were tested for dissolution rate. The test method is: refer to the third method for the determination of dissolution and release in the Chinese Pharmacopoeia 2020 edition (Small cup method), set the rotation speed of the stirring paddle of the dissolution apparatus to 30rpm, 200ml of water as the medium, and the water temperature at 25°C, and record the time (s) for complete dissolution after adding the coffee block product. The results of the dissolution rate test are shown in Table 1 below.

It can be seen that with the acceleration of the cooling rate, the dissolution rate of the prepared three-dimensional freeze-dried coffee block product in water gradually decreases. Compared with Examples 1 to 3, the three-dimensional freeze-dried coffee block product produced in Comparative Example 1 has a slower dissolution rate in water and adhesion to the bottom of the cup, so it is not suitable for instant coffee.

Fig. 3 shows the product morphology of the three-dimensional freeze-dried coffee block products produced in Example 1, Example 4, Comparative Example 3-Comparative Example 5. It can be seen that compared with Example 1 and Example 4, due to the high temperature of sublimation drying and re-drying in Comparative Example 3, the color of the three-dimensional freeze-dried coffee block product obtained is dark, dark black, and the coffee block is dry and dull. The hardness is too large; in comparative example 4, due to the high degree of vacuum in the sublimation stage, the color of the obtained three-dimensional freeze-dried coffee block product is relatively dark, and bubbling occurs; in comparative example 5, due to the high degree of vacuum in the re-drying stage, the obtained three-dimensional Freeze-dried coffee block products are light in color, but bubbles also appear.

The sensory differences such as the local flavor and mouthfeel of the coffee block product that embodiment 1～embodiment 4 and comparative example 1～comparative example 5 are made evaluate, and evaluation method is: recruit 20 consumers to taste roasted nut aroma, coffee aroma, The intensity of fruity aroma, sweetness, sourness, bitterness, and astringency are scored. The full score of each index is 4 points. The higher the score, the more obvious the feeling. The evaluation results are shown in Table 2 below.

As can be seen from Table 2, compared with Comparative Example 1 to Comparative Example 2, the conditions of pre-freezing treatment have different effects on the sweetness, sourness, bitterness and astringency of coffee under the same freeze-drying conditions in Examples 1 to 3. The taste has little effect, but it has a great influence on the roasted nut aroma, fruit aroma and coffee aroma retention of coffee. The coffee aroma of Examples 1 to 3 is not much different from that of Comparative Example 1, but significantly better than that of Comparative Example 2.

Compared with Comparative Examples 3 to 5 in Example 1 and Example 4, under the same pre-freezing treatment conditions, the aroma of roasted nuts, fruit and coffee in Example 1 and Example 4 are significantly better than those in Comparative Examples 3 to 5. In Comparative Example 5, the sweetness of Example 1 and Example 4 is significantly higher than that of Comparative Example 5, while the bitterness and astringency are lower than that of Comparative Example 5.

The coffee block products produced in Example 1 and Comparative Example 6 were placed under sealed conditions at room temperature, and the sensory effects of the coffee block products after different storage times were evaluated and the evaluation of changes in lipid peroxidation value was evaluated. The sensory quality evaluation method is as follows: 20 consumers are recruited to rate the intensity of roasted nut aroma, coffee aroma, fruit aroma, sweetness, sourness, bitterness, astringency and hala taste of the sample. The full score of each index is 4 points, and the score The higher the representative feeling is, the more obvious it is. The change of lipid peroxidation value was determined by GB/T 5538-1995 method.

The sensory evaluation results of the coffee block products prepared in Example 4 and Comparative Example 6 after different storage times are shown in Table 3 below.

It can be seen from Table 3 that compared with the coffee block product produced in Example 4, the coffee powder product produced in Comparative Example 1 has a lighter aroma of roasted nuts, coffee, and fruit in Comparative Example 1. The sensory quality of the coffee block product produced in Example 4 has changed little after being placed for 18 months, only the hala taste has been enhanced to a certain extent, and a slight hala taste only appeared after 12 months, and the hala taste is still unchanged after 18 months. obvious. The coffee block product produced in Comparative Example 6 will lose flavors such as roasted nuts, coffee, and fruit as the storage time prolongs, and a heavier hala flavor will begin to appear in the 6th month. It can be seen that the sensory shelf life of coffee block products is better than that of coffee powder products.

Fig. 4 has shown the change situation of the lipid peroxidation value of the coffee block product that embodiment 4 and comparative example 6 make, and it can be seen that, compared with comparative example 6, the coffee block product that embodiment 4 makes is lipid peroxidation value during storage. The amount of mass peroxide value generated is less.

The technical features of the above embodiments can be combined arbitrarily. To make the description concise, all possible combinations of the technical features in the above embodiments are not described. However, as long as there is no contradiction in the combination of these technical features, they should be It is considered to be within the range described in this specification.

The above examples only express several implementation modes of the present invention, and the description thereof is relatively specific and detailed, but it should not be construed as limiting the scope of the patent for the invention. It should be pointed out that those skilled in the art can make several modifications and improvements without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent for the present invention should be based on the appended claims.

Claims (10)

1. A method for making a three-dimensional freeze-dried coffee block product is characterized by comprising the following steps:

extracting the roasted coffee beans to obtain coffee liquid;

freeze-drying the coffee liquid to form a coffee block product with a three-dimensional shape;

the freeze drying comprises pre-freezing treatment and freeze drying treatment after the pre-freezing treatment;

the pre-freezing treatment conditions comprise: reducing the temperature to be less than or equal to-20 ℃ at a cooling rate of 0.5-2 ℃/min;

the conditions of the lyophilization process include: the vacuum degree of sublimation drying is less than or equal to 15Pa, the temperature of sublimation drying is-15 ℃, and the time length of sublimation drying is 25h-50h; the vacuum degree of re-drying is less than or equal to 5Pa, the temperature of re-drying is 15-30 ℃, and the time length of re-drying is 8-15h.

2. The method of making a three-dimensional lyophilized coffee block product of claim 1, wherein the pre-freezing conditions further comprise: cooling to-20 ℃ to-30 ℃ at a cooling rate of 0.5 ℃/min-2 ℃, keeping for 2h to 6h, then cooling to-35 ℃ to-45 ℃, and keeping for 3h to 6h.

3. The method of making a stereolyophilized coffee block product of claim 1, wherein the conditions of the lyophilization process further comprise: the initial temperature of sublimation drying is-15 ℃ to-5 ℃, and the termination temperature of sublimation drying is 5 ℃ to 15 ℃.

4. The method of making a stereolyophilized coffee block product of claim 1, wherein the conditions of the lyophilization process further comprise: the initial temperature of the redrying is 15-20 ℃, and the final temperature of the redrying is 25-30 ℃.

5. The method of making the stereolyophilized coffee block product of any of claims 1~4 wherein after the pre-freezing process, the mass content of coffee solids in the pre-frozen product is controlled to be 25% to 50%.

6. The method of making a stereolyophilized coffee block product of any of claims 1~4, wherein said coffee beans are extracted by pressurized hot or cold extraction.

7. A solid freeze-dried coffee block product, characterized in that it is made by the method of any one of claims 1~6.

8. The solid freeze-dried coffee block product according to claim 7, wherein the solid freeze-dried coffee block product is in a solid block shape, the inside of the solid block product is provided with a porous structure, and the porosity is 45% -65%.

9. A brewing method of a three-dimensional freeze-dried coffee block product is characterized by comprising the following steps:

dissolving the stereolyophilized coffee block product of any one of claims 7~8 in water;

and dissolving 1.5 to 4.5g of the three-dimensional freeze-dried coffee block product in 100ml to 400ml of water.

10. A coffee flavored product made from the stereolyophilized coffee block product of any of claims 7~8.

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