CN112568396B - Preparation method of texture reconstituted instant fruit pieces and simulated fruit chips - Google Patents

Abstract

The invention discloses a method for preparing texture-reconstituted instant fruit pieces and simulated fruit chips. The auxiliary materials are mixed and homogenized to obtain the printing puree; step 3, the printing puree is 3D printed, and quick-frozen and shaped at the outlet of the 3D printer to obtain fruit pieces or fruit slices; step four, the The fruit pieces or fruit pieces are subjected to freeze-thaw treatment; in step 5, the freeze-thawed fruit pieces or fruit pieces are subjected to vacuum freeze-drying; and the instant fruit pieces and simulated fruit chips obtained by applying the above method are prepared. The invention effectively solves the problems that the 3D printing fruit pulp cannot be formed, the product has low hardness and brittleness, and the texture is soft, and provides an instant fruit block and a simulated fruit that integrates instant solubility, high brittleness and high oxidation resistance. crisp.

Description

Preparation method of texture reconstituted instant fruit pieces and simulated fruit chips

technical field

The invention relates to the field of fruit processing. More specifically, the present invention relates to a preparation method of texture reconstituted instant fruit pieces and simulated fruit chips.

Background technique

As an emerging manufacturing technology, 3D printing currently has good applications in food processing fields such as chocolate and starch foods. However, because of its strong fluidity, fruit pulp cannot be applied to 3D without adding a large amount of thickeners or coagulants. The printing technology, which directly uses fruit pulp as the printing matrix, cannot currently print a complex three-dimensional structure, and the existing technology can usually only print a single-layer graphic structure.

With the maturity of vacuum freeze-drying technology and equipment, the market of vacuum-frozen fruit chips is developing rapidly. It is favored by consumers because of its advantages of convenient consumption, nutrition and health, and easy portability. Many fruits, such as berries, are rich in anthocyanins and have various beneficial effects such as antioxidant properties and immunity enhancement. However, anthocyanins are easily degraded by external factors such as light and oxygen during processing and storage, especially because the vacuum freeze-dried fruit chips have a crisp porous network structure and a relatively large area, which makes oxygen, moisture and light easier. Exposure to anthocyanins, resulting in color fading and functional weakening caused by anthocyanin degradation, become a quality defect that is difficult to solve during storage of anthocyanin-rich fruit chips. For a long time, how to improve the stability of anthocyanins in fruit food has puzzled the food industry. On the other hand, vacuum freeze-dried natural fruit chips have the problems of low hardness and brittleness and soft texture due to the heterogeneity of the tissue structure of the fruit raw materials and the low dry matter content of the fruit cell wall.

SUMMARY OF THE INVENTION

One object of the present invention is to provide a method for preparing texture-reconstituted instant fruit pieces and simulated fruit chips, which integrates 3D printing technology and quick-freezing technology, and then integrates technologies such as freeze-thaw treatment, film coating treatment, and vacuum freeze-drying, etc. It effectively solves the problems that the 3D printing pulp cannot be formed, the product has low hardness and brittleness, and the texture is soft.

Another object of the present invention is to provide an instant fruit block and a simulated fruit chip product that integrates instant solubility, high crispness and high oxidation resistance.

In order to achieve the purpose and other advantages according to the present invention, a preparation method of textured reconstituted instant fruit pieces and simulated fruit chips is provided, including:

Step 1, squeeze the juice after the pretreatment of the fruit and filter to obtain the original fruit juice;

Step 2, adding auxiliary materials to the fruit juice, after mixing, homogenizing, to obtain the printing puree;

Step 3: 3D printing the printing puree, and quick-freezing and shaping at the outlet of the 3D printer to obtain fruit pieces or fruit slices;

Step 4, freezing and thawing the fruit pieces or fruit slices;

Step 5, vacuum freeze-drying the fruit pieces or fruit pieces after the freeze-thaw treatment, wherein,

The adjuvant includes 0.5-4% of the high amylose corn starch and 1-8% of the low-ester pectin, which account for the quality of the original fruit juice. After mixing, the pH value of the slurry is adjusted to 3.0-3.8.

Preferably, in the method for preparing the texture reconstituted instant fruit pieces and simulated fruit chips, in step 1, the fruits are berries rich in anthocyanin, including blueberries, raspberries, mulberries, strawberries, blackberries, indigo At least one of fruits and grapes.

Preferably, in the preparation method of the texture reconstituted instant fruit pieces and simulated fruit chips, in step 2, the auxiliary materials include high amylose corn starch, 2-5% of the quality of the original fruit juice % low-ester pectin, 0.05-0.2% calcium chloride and 0.1-1.0 g/kg gallic acid, wherein the high amylose corn starch, low-ester pectin, calcium chloride and gallic acid, under continuous stirring conditions Next, add to the original fruit juice in sequence, and after mixing, add citric acid to adjust the pH value of the slurry to 3.0-3.8.

Preferably, in the method for preparing the textured reconstituted instant fruit pieces and simulated fruit chips, in step 3, the printing puree is preheated to 40-45°C, and then added to the hopper of the 3D printer, According to the set parameters, 3D printing is carried out.

Preferably, in the preparation method of the textured reconstituted instant fruit pieces and simulated fruit chips, in step 3, the quick-freezing and shaping is carried out with cold air as a refrigerant, the temperature of the cold air is -40°C, and the speed of the cold air is 2-5 m /s.

Preferably, the method for preparing the texture-reconstituted instant fruit pieces and the simulated fruit chips, after step 3 and before step 4, further comprises, placing the fruit pieces or fruit pieces on a -40°C cold air tunnel conveyor belt , use a nozzle to spray 20-40wt% chitosan solution, and store at -18°C after coating.

Preferably, in the preparation method of the texture reconstituted instant fruit pieces and simulated fruit chips, the freeze-thaw treatment method is: adjusting the temperature of the cold storage, changing 1°C per hour, and fluctuating at -18°C to -4°C 1-5 cycles, stay for 2-6 hours when the temperature of the cold storage reaches -4 °C, then restore the temperature of the cold storage to -18 °C, start the next cycle, after the cycle is over, restore the temperature of the cold storage to -18 °C for long-term storage;

Preferably, in the preparation method of the texture reconstituted instant fruit pieces and simulated fruit chips, the vacuum freeze-drying method is: transferring the frozen fruit pieces or fruit pieces to a vacuum freeze-drying bin for vacuum freezing Drying, the temperature of the cold trap is -50°C, the drying temperature of the radiant panel is 0-60°C, and the vacuum freeze-drying is stopped when the moisture content of the material drops below 7%.

Preferably, the method for preparing texture-reconstituted instant fruit pieces and simulated fruit chips further includes, in step 6, the vacuum freeze-dried fruit pieces or fruit pieces are packed with nitrogen in a light-proof and oxygen-insulating packaging bag. .

The present invention also provides an instant fruit block or simulated fruit chip prepared by applying the above-mentioned preparation method.

The present invention includes at least the following beneficial effects:

First, the present invention provides a novel fruit snack food that can be eaten as leisure fruit chips and instant beverages at the same time. As an instant beverage, the product of the present invention has the characteristics of being easy to carry, 100% dissolving without precipitation, and fast dissolving speed. As a fruit chip, the product of the invention has the characteristics of crisp and delicious, bright color and natural flavor, and there is no similar product on the market at present.

Second, the invention creatively integrates the quick-freezing technology and the 3D printing technology, solves the problem that the 3D printing of fruit pulp food is not easy to form, and has a good application prospect.

Third, the present invention selects berry fruits with rich colors and high anthocyanin content as raw materials, and through careful design of a steady-state mechanism based on the interaction of food size and molecules, coupled with physical oxygen barrier technology, improves the color of the product during storage. the stability of glycosides. Specifically, the scheme utilizes that the abundant carboxyl groups on the pectin molecule with low methyl esterification degree are negatively charged above its isoelectric point, and the anthocyanins are positively charged below the isoelectric point, so that the mutual binding mainly based on electrostatic interaction occurs. At the same time, the non-covalent bond "Π-Π overlap" between the small molecule gallic acid benzene ring and the anthocyanin benzene ring is used to stabilize the chemical structure of anthocyanins from two aspects, so that the B ring cannot move freely due to steric hindrance At the same time, it limits the dissociation of chemical bonds and greatly improves the chemical stability of anthocyanins; comprehensively protecting anthocyanins with different structures, gallic acid has the best combination of anthocyanins with different structures compared with flavonoids and other phenolic acids. Effect; pectin and gallic acid are widely present in natural fruit, and using them as color-protecting substances, the food prepared is green and natural.

Fourth, the present invention forms a layer of chitosan coating on the periphery of fruit pieces or fruit pieces through the chitosan coating treatment. On the one hand, the coating layer can effectively block the penetration of oxygen and moisture, delay and further inhibit The degradation of anthocyanins can effectively solve the problem of anthocyanin degradation during storage; the chitosan coating can also reduce the moisture absorption rate of fruit pieces or fruit pieces, and alleviate the rapid moisture absorption caused by vacuum freeze-dried fruit pieces or fruit pieces after opening the bag. the loss of crispiness.

Fifth, the present invention adopts slow freezing combined with freezing and thawing to process the quick-frozen fruit pieces or fruit pieces, so that the small ice crystals in the quick-frozen fruit pieces or fruit pieces continue to grow, and finally large ice crystals are formed; As a result, larger porosity can be formed after the sublimation of large ice crystals around the block or fruit piece. These pores can further improve the drying rate. More importantly, this process of adjusting the size of ice crystals through physical action can precisely control freeze-dried fruit. The porous network structure of the pieces or fruit pieces obtains a loose pore structure with larger pores and thicker pore walls, thereby obtaining a better crispy mouthfeel.

Other advantages, objects, and features of the present invention will appear in part from the description that follows, and in part will be appreciated by those skilled in the art from the study and practice of the invention.

Detailed ways

The present invention will be further described in detail below with reference to the embodiments, so that those skilled in the art can implement according to the description.

It should be noted that the experimental methods described in the following examples are conventional methods unless otherwise specified, and the reagents and materials can be obtained from commercial sources unless otherwise specified.

Example 1:

The invention provides a kind of artificial fruit chips, and its preparation method is as follows:

1) Selection: choose mango as raw material;

2) Pretreatment: remove the inedible part of the mango and clean it;

3) Juicing: use a belt juicer to extract mango juice;

4) Filtration: filter the mango juice, and obtain the original fruit juice after filtration;

5) Preparation: under the state of continuous stirring and homogenization, add auxiliary materials to the original fruit juice in the following order: a) add 4% high amylose corn starch; b) add 1% low-ester pectin; c) add citric acid to adjust pH to 3.8;

6) Homogenization: place the prepared fruit juice in a homogenizer and homogenize it twice;

7) 3D printing modeling: The homogenized fruit juice is heated to 40-45 ℃ through a heat exchanger, and then loaded into the hopper of the 3D printer, and the fruit slices are printed according to the program. The thickness of the fruit slices is 2mm, and the outlet of the 3D printer is Use cold air as the refrigerant for quick-freezing and shaping, the temperature of the cold air is -40°C, and the speed of the cold air is 2m/s, and the frozen fruit pieces are transferred to the cold storage for storage;

8) Freeze-thaw treatment: adjust the temperature of the cold storage, change 1 °C per hour, fluctuate from -18 °C to -4 °C for 1 cycle, stay for 6 hours when the cold storage temperature reaches -4 °C, and then restore the cold storage temperature to -18 °C for long-term storage ;

9) Vacuum freeze-drying: transfer the frozen fruit slices to a vacuum freeze-drying bin for vacuum freeze-drying, the cold trap temperature is -50°C, the drying temperature is 60°C, and the vacuum freeze-drying is stopped when the moisture content of the material drops below 7%. ;

10) Nitrogen-filled packaging: take out the dried material from the tray of the vacuum freeze dryer, select and remove damaged products, and use a light-proof and oxygen-insulating packaging bag for food for nitrogen-filling packaging;

11) Storage: Store the nitrogen-filled packaged product in a cool, dry place.

Example 2:

The invention provides a kind of instant fruit piece, and its preparation method is as follows:

1) Selection: select pears as raw materials;

2) Pretreatment: remove the inedible part of the pear and clean it;

3) Juicing: use a belt juicer to extract pear juice;

4) Filtration: filter the pear juice, and obtain the original fruit juice after filtration;

5) Preparation: under the state of continuous stirring and homogenization, add auxiliary materials to the original fruit juice in the following order: a) add 0.5% high amylose corn starch; b) add 7% low ester pectin; c) 0.05% calcium chloride ; D) adding citric acid to adjust pH to 3.1;

6) Homogenization: place the prepared fruit juice in a homogenizer and homogenize it for 3 times;

7) 3D printing modeling: the homogenized fruit juice is heated to 40-45℃ through a heat exchanger, and then loaded into the hopper of the 3D printer, and the fruit pieces are printed according to the program. The shape of the fruit pieces is 10mm*10mm*15mm Cuboid, use cold air as the refrigerant at the exit of the 3D printer for quick-freezing and shaping, the temperature of the cold air is -40°C, and the speed of the cold air is 5m/s, and the frozen fruit pieces are transferred to the cold storage for storage;

8) Freeze-thaw treatment: adjust the temperature of the cold storage, change 1 °C per hour, fluctuate from -18 °C to -4 °C for 5 cycles, stay for 3 hours when the temperature of the cold storage reaches -4 °C, and then restore the temperature of the cold storage to -18 °C for long-term storage ;

9) Vacuum freeze-drying: transfer the frozen fruit pieces to a vacuum freeze-drying bin for vacuum freeze-drying, the temperature of the cold trap is -50°C, the drying temperature is 50°C, and the vacuum freeze-drying is stopped when the moisture content of the material drops below 7%. ;

10) Nitrogen-filled packaging: take out the dried material from the tray of the vacuum freeze dryer, select and remove damaged products, and use a light-proof and oxygen-insulating packaging bag for food for nitrogen-filling packaging;

11) Storage: Store the nitrogen-filled packaged product in a cool, dry place.

Example 3:

The invention provides a kind of instant fruit piece, and its preparation method is as follows:

1) Selection: choose blueberries as raw materials;

2) Pretreatment: remove the inedible parts of blueberries and clean them;

3) Juicing: use a belt juicer to extract blueberry juice;

4) Filtration: filter the blueberry juice, and obtain the original fruit juice after filtration;

5) Preparation: under the state of continuous stirring and homogenization, add auxiliary materials to the original fruit juice in the following order: a) add 1.5% high amylose corn starch; b) add 3.5% low ester pectin; c) 0.1% calcium chloride and 0.5g/kg of gallic acid; d) adding citric acid to adjust pH to 3.4;

6) Homogenization: place the prepared fruit juice in a homogenizer and homogenize it twice;

7) 3D printing modeling: The homogenized fruit juice is heated to 40-45 ℃ through a heat exchanger, and then loaded into the hopper of the 3D printer, and the fruit pieces are printed according to the program. The shape of the fruit pieces is a cube with a side length of 10mm. , at the exit of the 3D printer, use cold air as the refrigerant for quick-freezing and shaping, the temperature of the cold air is -40°C, and the speed of the cold air is 3.5m/s, and the frozen fruit pieces are transferred to the -18°C cold storage for storage;

8) Freeze-thaw treatment: adjust the temperature of the cold storage, change 1 °C per hour, fluctuate from -18 °C to -4 °C for 4 cycles, stay for 4 hours when the cold storage temperature reaches -4 °C, and then restore the cold storage temperature to -18 °C for long-term storage ;

9) Vacuum freeze-drying: transfer the frozen fruit pieces to a vacuum freeze-drying bin for vacuum freeze-drying, the temperature of the cold trap is -50°C, the drying temperature is 50°C, and the vacuum freeze-drying is stopped when the moisture content of the material drops below 7%. ;

10) Nitrogen-filled packaging: take out the dried material from the tray of the vacuum freeze dryer, select and remove damaged products, and use a light-proof and oxygen-insulating packaging bag for food for nitrogen-filling packaging;

11) Storage: Store the nitrogen-filled packaged product in a cool, dry place.

Example 4:

The present invention provides an instant fruit block, the preparation method of which is the same as that of Example 3, except that, after 7) 3D printing modeling and 8) before freezing and thawing, the frozen fruit block is placed in a -40°C cold air tunnel On the conveyor belt, a high-pressure nozzle is used to spray 30wt% chitosan solution. After the coating is finished, it is placed in a -18°C low-temperature refrigerator for long-term storage, and the storage period can reach 12 months.

Example 5:

The invention provides a kind of instant fruit piece, and its preparation method is as follows:

1) Select: choose strawberry and raspberry as raw materials, and the mass ratio of strawberry and raspberry is 6:1;

2) Pretreatment: remove the inedible parts of strawberries and raspberries and clean them;

3) Juicing: use a belt juicer to extract juice;

4) Filtration: filter the fruit juice, and obtain the original fruit juice after filtration;

5) Preparation: under the state of continuous stirring and homogenization, add auxiliary materials to the fruit juice in the following order: a) add 1.0% high amylose corn starch; b) add 4.5% low-ester pectin; c) 0.12% calcium chloride and 0.4g/kg of gallic acid; d) adding citric acid to adjust pH to 3.5;

6) Homogenization: place the prepared fruit juice in a homogenizer and homogenize it twice;

7) 3D printing modeling: The homogenized fruit juice is heated to 40-45 ℃ through a heat exchanger, and then loaded into the hopper of the 3D printer, and the fruit pieces are printed according to the program. The shape of the fruit pieces is a cube with a side length of 10mm. , at the exit of the 3D printer, use cold air as the refrigerant for quick-freezing and shaping, the temperature of the cold air is -40°C, and the speed of the cold air is 3.5m/s, and the frozen fruit pieces are transferred to the -18°C cold storage for storage;

8) Film coating: place the frozen fruit pieces on the -40 ℃ cold air tunnel conveyor belt, use a high-pressure nozzle to spray 20wt% chitosan solution, and after the coating film is completed, place it in a -18 ℃ low temperature cold storage for long-term storage;

8) Freeze-thaw treatment: adjust the temperature of the cold storage, change 1 °C per hour, fluctuate from -18 °C to -4 °C for 4 cycles, stay for 4 hours when the cold storage temperature reaches -4 °C, and then restore the cold storage temperature to -18 °C for long-term storage ;

9) Vacuum freeze-drying: transfer the frozen fruit pieces to the vacuum freeze-drying bin for vacuum freeze-drying, the temperature of the cold trap is -50°C, the drying temperature is 60°C, and the vacuum freeze-drying is stopped when the moisture content of the material drops below 7%. ;

10) Nitrogen-filled packaging: take out the dried material from the tray of the vacuum freeze dryer, select and remove damaged products, and use a light-proof and oxygen-insulating packaging bag for food for nitrogen-filling packaging;

11) Storage: Store the nitrogen-filled packaged product in a cool, dry place.

Comparative Example 1:

The present invention provides an instant fruit piece, the preparation method of which is the same as that of Example 4, except that 5) deployment: under the state of continuous stirring and homogenization, add auxiliary materials to the original fruit juice in the following order: a) add 1.5 % high amylose corn starch; b) add 3.5% low ester pectin; c) 0.1% calcium chloride; d) add citric acid to adjust pH to 3.4.

Comparative Example 2:

The present invention provides an instant fruit block, the preparation method of which is the same as that of Example 4, except that 8) freeze-thaw treatment is not performed.

Comparative Example 3:

The present invention provides an instant fruit block, the preparation method of which is the same as that of Example 4, the difference is that, in 7), the 3D printed fruit block is directly placed on the -40 ℃ cold air tunnel conveyor belt without quick freezing and shaping, Treated with chitosan coating.

Comparative Example 4:

The instant fruit pieces are prepared according to the process of the existing solid fruit juice freeze-dried products on the market. Specifically, after cleaning the blueberries and removing the inedible parts, beating, adding 12% sucrose and 0.5% citric acid to the slurry, and after mixing, the slurry was introduced into a silica gel mold at -18°C Freeze, and then transfer the frozen fruit pieces to the vacuum freeze-drying bin for vacuum freeze-drying. The temperature of the cold trap is -50 °C, the drying temperature is 40 °C, and the moisture content of the material drops below 7%, stop the vacuum freeze-drying, and then Take out the dried materials from the tray of the vacuum freeze dryer, select and remove the damaged products, pack them with nitrogen in a light-proof and oxygen-insulating packaging bag for food, and store them in a cool and dry place. 10mm cube.

Experimental example 1:

Quality analysis was carried out on the instant fruit pieces prepared from berries, and the specific analysis results are shown in the following table. In the table, S3, S4, S5 represent the products prepared in Example 3, Example 4 and Example 5, respectively, D1, D2, D3, D4 represent Comparative Example 1, Comparative Example 2, Comparative Example 3 and Comparative Example 4, respectively products prepared in.

The specific test methods for each indicator are as follows:

1) Determination of anthocyanin retention rate (%)

The total anthocyanin content in the samples was determined by UV spectrophotometry. The anthocyanins in the samples were extracted with 2% hydrochloric acid methanol solution, filtered and measured at 530 nm. The total anthocyanin content was calculated by the standard curve, and the total anthocyanin retention rate of the samples was analyzed. The content of cyanidin-3-glucoside in the samples was determined by high performance liquid chromatography-mass spectrometry coupled with HPLC-MS. The cyanidin-3-glucoside in the samples was extracted with 2% hydrochloric acid methanol solution, filtered and determined by liquid phase method. The cyanidin-3-glucoside content and retention were calculated from the standard curve obtained from the standard. The anthocyanin retention rate was calculated according to the weights of total anthocyanins and cyanidin-3-glucoside of 40% and 60%, respectively.

2) Measurement of color difference value (ΔE value)

The color of the instant fruit pieces was measured by a colorimeter. In this experiment, the △L, △a, △b, and △E values were used to represent the color (L, a, b) of the tested sample and the fresh sample (L*, a*, b*) color difference value. The calculation method of △E is as follows:

In the formula, L and L* are the brightness values of fresh fruit and dried chips, respectively; a, a* are the red and green values of fresh fruit and dried chips, respectively; b and b* are the yellowness of fresh fruit and dried chips, respectively. Blue value; ΔL is the total color difference value.

3) Pore characteristic analysis

The micro-CT scan was used, and the internal average pore diameter μm and the pore wall thickness μm were obtained after analysis by the micro-CT self-contained analysis software.

4) Drying time (h)

The time required for freezing the resulting block to be dried in a vacuum freeze dryer until the moisture content of the material drops below 7%.

5) Determination of hardness and brittleness

Measured with TA-XT2i/50 type physical property analyzer, and selected fruit pieces with similar shape and size for texture determination. After quickly taking out the sample from the package, use the physical property analyzer to do the cutting test, repeat 10 times, and finally take the average value. The brittleness is expressed by the number of peaks produced by the test, and the unit is "pieces". The test value increases in a positive correlation within a certain range. The more peaks, the better the crispness of the product, and vice versa, the worse the crispness of the product.

6) Dissolution rate (%)

Take 10 g of the freeze-dried sample, put it in 100 mL of water, stir and mix, and filter with filter paper. Dry the filtered residue and weigh the filter residue. Dissolution rate=(original lyophilized sample weight-filter residue weight)/original lyophilized sample weight*100%.

7) Turbidity

Take 2 g of instant fruit pieces, rehydrate at 1:10, shake well, and centrifuge at 4000 r/min for 15 min. After the supernatant was thoroughly mixed, it was placed in a cuvette, and its absorbance was measured at 660 nm with a spectrophotometer, using distilled water as a reference. Turbidity is expressed as the ratio of the absorbance after centrifugation to the absorbance before centrifugation.

8) Collapse rate (%)

Measure the height of the material after printing and drying, the slump rate = (set printing height - material height) / set printing height * 100%

9) Determination of shelf life

The product was stored at 25°C, the quality of the product was tracked, and the end point of the shelf life was the degradation of more than 50% of pelargonidin-3-glucoside in the product, or the decrease of a value of more than 20%.

S3 S4 S5 D1 D2 D3 D4 Anthocyanin retention rate/% 70 92 85 40 85 90 42 Color change rate (ΔE value) 4.56 1.46 1.25 12.01 1.85 1.28 10.8 Average pore diameter/μm 232 275 256 242 143 232 154 Average wall thickness/μm 25.3 22.5 25.4 20.2 16.4 20.1 16.2 drying time/h 13.5 14 14 14 18 14 20 crispness/pc 43 42 45 42 1 40 twenty three Dissolution rate/% 100 100 100 100 100 100 82 Turbidity 1.06 1.05 1.08 1.07 1.07 1.08 1.65 Collapse rate/% 1.8 1.8 2.0 2.2 2.1 36 5.6 Shelf life/month 12 twenty four twenty four 12 twenty four twenty four 12

As can be seen from the above table, Example 4 is the optimal process of the present invention. Compared with Example 4, the anthocyanin retention rate of the instant fruit pieces in Example 3 and Comparative Example 1 was significantly reduced, the color value change rate was significantly increased, and the shelf life was shortened. Both gallic acid were beneficial to improve the retention rate of anthocyanins and inhibit the degradation of anthocyanins, and the protective effect of gallic acid on anthocyanins was stronger than that of chitosan coating treatment. Compared with Example 4, the average pore diameter, average wall thickness and brittleness of the instant fruit pieces in Comparative Example 2 were significantly reduced, and the drying time was prolonged. Loose pore structure with larger pores and thicker pore walls. Compared with Example 4, the collapse rate of the instant fruit pieces in Comparative Example 3 was significantly increased, which means that after 3D printing, the use of cold air quick freezing can maintain the shape of the fruit pulp after 3D printing, and the formability is good. Compared with Example 4, the anthocyanin retention rate, average pore diameter, average wall thickness, brittleness, dissolution rate and shelf life of the instant fruit pieces in Comparative Example 4 were significantly reduced, and the color change rate, drying time, turbidity, The collapse rate is significantly increased, which shows that the preparation method of the present invention can obtain the instant fruit block with high anthocyanin retention rate, 100% dissolution without precipitation, and the combination of instant solubility, high crispness and high oxidation resistance.

Although the embodiment of the present invention has been disclosed as above, it is not limited to the application listed in the description and the embodiment, and it can be applied to various fields suitable for the present invention. For those skilled in the art, it can be easily Therefore, the invention is not limited to the specific details without departing from the general concept defined by the appended claims and the scope of equivalents.

Claims (7)

1. The preparation method of the texture recombinant instant fruit block or the simulated fruit crisp chip is characterized by comprising the following steps:

step one, pretreating fruits, juicing and filtering to obtain fruit raw juice;

adding auxiliary materials into the fruit raw juice, uniformly mixing, and homogenizing to obtain printing raw juice;

step three, 3D printing is carried out on the printing raw stock, and quick-freezing shaping is carried out at the outlet of a 3D printer to obtain fruit blocks or fruit slices;

step four, performing freeze thawing treatment on the fruit blocks or the fruit slices;

step five, carrying out vacuum freeze drying on the fruit blocks or fruit pieces subjected to freeze thawing treatment, wherein,

the auxiliary materials comprise 1-2% of high amylose corn starch, 2-5% of low ester pectin, 0.05-0.2% of calcium chloride and 0.1-1.0g/kg of gallic acid, wherein the high amylose corn starch, the low ester pectin, the calcium chloride and the gallic acid are sequentially added into the fruit raw juice under the condition of continuous stirring, and after uniform mixing, citric acid is added to adjust the pH value of the pulp to 3.0-3.8;

placing the fruit blocks or fruit pieces on a cold air tunnel conveyor belt at the temperature of minus 40 ℃, spraying 20-40wt% of chitosan solution by using a nozzle, and storing at the temperature of minus 18 ℃ after film coating is finished;

the freeze-thaw treatment method comprises the following steps: adjusting the temperature of the cold storage, changing by 1 ℃ per hour, fluctuating for 1-5 cycles from-18 ℃ to-4 ℃, staying for 2-6 hours when the temperature of the cold storage reaches-4 ℃, then recovering the temperature of the cold storage to-18 ℃, starting the next cycle, and recovering the temperature of the cold storage to-18 ℃ for long-term storage after the cycle is finished.

2. The method of making a texturized, reconstituted, instant fruit piece or simulated fruit crisp according to claim 1, wherein in step one, the fruit is an anthocyan-rich berry comprising at least one of blueberry, raspberry, mulberry, strawberry, blackberry, lonicera edulis, and grape.

3. The method according to claim 1, wherein the printing stock is preheated to 40-45 ℃ and then added into a hopper of a 3D printer, and 3D printing is performed according to set parameters.

4. The method for preparing the restructured instant fruit pieces or the simulated fruit crisps according to claim 1, wherein in the third step, the quick-freezing and shaping are carried out by taking cold air as a cooling medium, wherein the temperature of the cold air is-40 ℃, and the wind speed of the cold air is 2-5 m/s.

5. The method of preparing a textured reconstituted instant fruit piece or simulated fruit crisp according to claim 1 wherein the vacuum freeze drying comprises: transferring the frozen fruit blocks or fruit pieces to a vacuum freeze drying bin for vacuum freeze drying, wherein the temperature of a cold trap is-50 ℃, the drying temperature is 0-60 ℃, and when the moisture content of the material is reduced to below 7%, the vacuum freeze drying is stopped.

6. The method for preparing the instant fruit blocks or the simulated fruit crisps according to claim 1, further comprising a sixth step of performing nitrogen-filled packaging on the fruit blocks or the fruit slices subjected to vacuum freeze drying by adopting a light-resistant oxygen-insulating packaging bag.

7. Instant fruit pieces or simulated fruit crisps obtained by applying the preparation method according to any one of claims 1 to 6.