CA3128912C

CA3128912C - Colorful-jelly 4d printing method utilizing spontaneous color change of blueberry anthocyanins

Info

Publication number: CA3128912C
Application number: CA3128912A
Authority: CA
Inventors: Min Zhang; Chaofan GUO; Ahmed Fathy GHAZAL
Original assignee: Jiangnan University
Current assignee: Jiangnan University
Priority date: 2019-05-21
Filing date: 2019-12-06
Publication date: 2023-11-14
Anticipated expiration: 2039-12-06
Also published as: CA3128912A1; CN110122813A; CN110122813B; WO2020233101A1

Abstract

A colorful-jelly 4D printing method utilizing spontaneous color change of blueberry anthocyanins, the method comprising: thoroughly mixing two sets of ingredients, respectively; performing preparation, homogenization, gelatination, cooling, material filling, and degassing with respect to the two sets of ingredients, respectively; and using a dual-extruder printer to print out a multi-material color bearing layer and a multi-material color control layer alternately according to a pre-established 3D printing model.

Description

COLOR CHANGE OF BLUEBERRY ANTHOCYANINS
BACKGROUND OF THE INVENTION
Field of the Invention The present invention relates to a colorful-jelly 4D printing method utilizing spontaneous color change of blueberry anthocyanins, which is mainly used for 3D printing of jelly foods containing natural fruit and vegetable anthocyanins, relates to a food processing technology, and belongs to the technical field of food processing.
Description of Related Art "3D printing" has a core principle of printing layer by layer, where layers and layers are superimposed into a solid pattern. Specifically, 3D printing includes three processes. One is to use computer software, such as CAD, etc., to design a three-dimensional pattern;
the second one is to slice the three-dimensional pattern to form a multi-layer two-dimensional plan and a printing trajectory of each layer; and the third one is to use a numerical control system to control a printer path and complete the printing. Compared with traditional mold manufacturing methods, 3D
printing technology can realize the manufacture of products of a highly complex structure and improve the precision and quality of the products, save materials to the greatest extent, and allows flexible design, personalized customization, and mass customization production, so that rapid manufacturing becomes economical.
As consumers have higher and higher requirements for the taste, appearance and health of food, the degree of customization of food is also higher and higher, so that food 3D printing technology has received more and more attention and development. The goal of food 3D printing is a make-to-order production mode with higher production efficiency and lower coverage costs.
Compared with the traditional supply chain mode, 3D printing supply chain greatly reduces delivery costs and simplifies customized food services.
The so-called 4D printing, to be precise, is a material that can deform automatically. It only needs specific conditions (such as temperature, humidity, etc.) and does not need to connect any complicated electromechanical equipment to produce a fourth-dimensional change according to Date Recue/Date Received 2021-08-04 the product design. Such a change usually involves color, flavor, and shape.
Khoo et al. (2015) proposed that 4D printing is a process of constructing physical objects utilizing appropriate additive manufacturing technology, by laying a series of stimulus-responsive composite materials or multi-materials with different properties. After construction, the object responds to stimuli from the natural environment or generated by human intervention, resulting in changes in the body or chemical state over time. 4D printing technology is not only a revolution in production tools, but also a technology that induces changes in the structure of the entire business ecosystem in the future due to changes in means of production. Therefore, it is not just manufacturing technology that will be overthrown. However, the research and application of the 4D printing concept in the food field is still very limited at present. According to the colorful-jelly 4D printing method utilizing color change catalyzed by spontaneous color change of blueberry anthocyanins proposed by the present invention, two jelly materials with different properties are constructed and laid through 3D printing technology, such that the two materials blend into each other and stimulate each other at the connection and finally suffer from spontaneous color change, to achieve 4D
changes and to achieve composite 4D printing.
Anthocyanins, also known as anthocyanidins, are a class of water-soluble natural pigments widely found in plants in nature, and are colored aglycones derived from the hydrolysis of anthocyains. Most of the coloring substances in fruits, vegetables, and flowers are related to them.
Under different pH conditions in the vacuole of plant cells, anthocyanins make petals show colorful colors. Anthocyanins have a high molecular conjugate system in the molecules and contain acidic and alkaline groups, and are easily soluble in polar solvents such as water, methanol, ethanol, a dilute base, a dilute acid, etc. It has strong absorption in both the ultraviolet and visible light regions. The maximum absorption wavelength in the ultraviolet region is around 280 nm, and the maximum absorption wavelength in the visible light region is in the range of 500 to 550 nm. The color of anthocyanins changes with the change of pH, which is red at pH 7, purple when pH=7-8, and blue when pH >11. Anthocyanins belong to biological flavonoids, and the main physiological functions of flavonoids are free radical scavenging capacity and antioxidant capacity. With the development of science and technology, people pay more and more attention to the safety of food additives, and the development and utilization of natural additives has become the general trend of the development and use of additives. Anthocyanins can not only be used as nutritional fortifiers in food, but also can be used as food preservatives instead of synthetic preservatives such as benzoic acid, and can be used as food coloring agents in ordinary beverages and foods, in line with general

2 Date Recue/Date Received 2021-08-04 requirement for natural, safe, and healthy food additives.
Li Li et al. (2019) disclosed a food 3D printing material rich in dietary fiber (Publication No.:
CN109198650A), which is made by uniformly mixing modified dietary fiber, starch, gluten protein powder, seasoning, water, vegetable oil, gelatin, etc., grinding to a fineness of below 20 um, and then treatment by a high-pressure homogenizer. According to the invention, through a series of modification treatments on dietary fiber, the particle size of dietary fiber can be reduced while the dietary fiber particles are dispersed uniformly and stably, and the content of water-soluble dietary fiber is increased, so that the prepared 3D food printing material has a high content of dietary fiber.
The surface of the dietary fiber is subjected to water-soluble treatment to further improve the taste, which can improve the taste and facilitate absorption by the human body in the preparation of food products using 3D printing, reduce the labor difficulty and intensity of operators, and reduce the maintenance cost of the 3D printer. Adding different adjuvants to make food with different flavors can be applied to a variety of 3D printers to achieve rapid printing of various flavor materials in a short time, thereby improving the printing efficiency. Xiao Junyong et al.
(2018) invented a gel candy 3D printing material and a preparation method thereof (Publication No.:
CN107668306A).
The 3D printing material uses starch and low acyl gellan gum as a gelling agent, which is conducive to remelting and can cause fast gelling at room temperature, thereby ensuring a smooth discharge during 3D printing. The use of a plant extract can improve the stability of the printing material, so that the printed candies can be stored for a long time and the phenomenon of graining is avoided.
Experiments show that the printing material provided by the present invention can be printed smoothly, and the obtained product has good sensory evaluation, and no graining or moist phenomenon is observed after 60 days at room temperature. Zhang Yun et al.
(2016) disclosed a 3D printing food material of longan and rice flour (Publication No.:
CN106213154A), which belongs to the field of 3D printing materials and consists of the following raw materials in parts by weight: 60-70 parts of rice flour, 5-8 parts of a longan extract, 8-10 parts of water, 8-10 parts of fresh milk, 8-10 parts of buckwheat flour, 3-5 parts of vegetable oil, 2-3 parts of honey, 2-3 parts of xylitol, 2-3 parts of table salt, 2-3 parts of maltodextrin, 2-3 parts of dietary fiber, 1-2 parts of an emulsifier, and 0.1-0.2 parts of an essence. The invention uses low-sugar and low-fat raw materials, contains no chemical additives, and is pollution-free and healthier. Longan contains a lot of trace elements that are beneficial to human health, the main function of which is soothing nerves and curing insomnia. The use of 3D printing can realize the diversified, personalized and automated fabrication of products, enriching the types of 3D printing food materials. The use of

3 Date Recue/Date Received 2021-08-04 nanometer rice flour can meet the process requirements of 3D printing; the use of selenium-rich rice flour supplements the selenium element required by the human body and meets the needs of different consumers. Zhang Yunjiu et al. (2017) disclosed an ice cream 3D
printer, an ice cream 3D printing method and a product thereof (Public No.: CN106578317A). The ice cream 3D printer includes a printing platform, an X-direction drive device, a Y-direction drive device, a Z-direction drive device, a material spraying system, a protective cover and a main control device. The ice cream 3D printing method includes: 1) printing a base layer composed of contour lines and ice cream powder; 2) printing a plurality of stacked base layers step by step to obtain a 3D printed ice cream. The technical solution provided by the invention can solve the technical problems of long time-consuming and high cost of 3D food printing at the present stage. The ice cream 3D printer provided by the invention has a novel structural design and a high degree of automation, and can meet the needs of consumers for diversified shapes of ice cream food; the technical solution provided by this invention solves the challenge of printing an ice cream in a few minutes by way of printing an ice cream coat, which greatly reduces the printing cost. The above several inventions mainly involve the ratio of different materials for 3D printing and the production and manufacture of machines. Different from the above inventions, the present invention mainly relates to a color-changing 4D printing method through blueberry anthocyanin catalyzed 3D
printing.
Ling Weifu (2016) provided a method for preparing color-changing rose tea (Publication No.:
CN107772019A). The method includes washing and crushing anthocyanin-rich substances such as black wolfberry, blueberry or mulberry, stirring with alcohol, filtering, settling, residue-discarding, centrifugation, heating concentration, re-centrifugation, alcohol-adding to obtain a coloring liquid, and the microwave-dried roses are subjected to natural coloring with the coloring liquid and then trypsin treatment, and then the colored roses are quickly dried through open wave drying. The beneficial effect thereof is that: the finished color-changing rose tea is rich in anthocyanins, which can be quickly precipitated to color the tea during the brewing process, so that the color changes from dark purple to light purple, dark red, light red, grass green to colorless, with simple operation, strong ornamental characteristics, and high nutritional and healthy function.
Cheng Weili (2018) invented a color-changing functional beverage and a preparation method thereof (Publication No.:
CN108236027A). The color-changing functional beverage uses anthocyanin encapsulated powder and lycopene encapsulated powder as main raw materials, and utilizes the microcapsule encapsulating effect, such that the color of the beverage can be effectively changed. When the beverage is in a static state, the pigment is adsorbed or encapsulated due to the adsorption by porous

4 Date Recue/Date Received 2021-08-04 starch and the encapsulation by whey protein, and thus the beverage is clear and transparent. When the beverage is shaken vigorously, however, as a result of the external force, the encapsulated pigment and the adsorbed pigment are released, so that the beverage appears brilliant green and red, which is aesthetically beautiful and can also attract the attention of children and young people.
In addition, since anthocyanins and lycopene have excellent antioxidant activity, they can improve human immunity and delay aging, and have certain preventive and therapeutic effects on cancer and tumors. Therefore, the beverage of the invention can not only attract customers but also have health care benefits. Huang Bingqiong (2015) invented a color-changing beverage and a processing method thereof (Publication No.: CN104957702A). The color-changing beverage includes the following raw materials in parts by weight: 130-160 parts of anthocyanin vegetable and fruit juice,

5-8 parts of miracle fruit, 30-45 parts of lemon juice, 6-10 parts of pine pollen, 1-5 parts of agar, 12-17 parts of sugar cane juice. The preparation method for the color-changing beverage includes the following steps: raw material pretreatment, stifling and pulping, spray granulation, drying, packaging, and formation of finished products. The product of the invention is rich in nutrition and can supplement a variety of vitamins and amino acids necessary for the human body. In particular, the presence of anthocyanins can delay aging and improve immunity, and is especially suitable for breakfast and afternoon tea to supplement energy. The color-changing characteristics thereof make food interesting and romantic, satisfying people's growing material and cultural needs, especially the aesthetic taste of young people. Although the above several inventions all relate to the categories of fruit and vegetable anthocyanins and color-changing foods, the main implementation methods are to achieve beverage color change by means of microcapsules or adsorption and elution. Different from the above several inventions, the color change involved in the present method is a color change that occurs under different environmental pH
conditions through diffusion of anthocyanins between the two materials printed by dual-nozzle 3D printing, which belongs to the 4D printing category of autonomous color change catalyzed by blueberry anthocyanins based on 3D printing, and has a different color change principle.
Zhong Qin (2015) invented a color-changing tea product (Publication No.:
CN105053364A), including the following components in parts by mass: 100 parts of a tea-making plant; 0.01-3.33 parts of a natural pigment; 0.5-25.0 parts of an edible alkaline additive;
wherein the natural pigment is at least one of litmus and anthocyanin. When drinking, a certain drop number of an edible acidic liquid such as lemon juice or other edible alkaline substances may be dropped into the tea to achieve the purpose of color change. The prepared color-changing tea product is good in mouth feel and Date Recue/Date Received 2021-08-04 rich in color changes, and has a certain health care effect. A preparation method of the tea product is also disclosed, and the method is simple, the processing cost is low, and the added value of the tea-making plant can be increased. Different from this invention, the color change in the present method is realized based on double-nozzle jelly 3D printing.
Zhang Min et al. (2018) disclosed a 3D printing method for dual-color sandwich desserts using a concentrated fruit pulp (Publication No.: CN108477540A), which is mainly used for the 3D
printing of gelatinous foods, relates to food processing technology, and belongs to the field of new food processing. The invention first thoroughly mixes two sets of raw materials, performs homogenization, heat preservation, cooling and material filling with respect to the two sets of raw materials, respectively; and uses a dual-nozzle printer to perform 3D printing according to a pre-made dual-color sandwich 3D printing model. By using dual-nozzle 3D printing and different designed models, the invention can print materials with different spatial shapes and quantities of sandwich effects, so that foods have richer tastes and visual effects, achieving diversified, personalized, and automated fabrication of products. Different from the 3D
printing method of dual-color desserts of the method, the present method mainly relates to blueberry anthocyanin-rich jelly and lemon pureed jelly dual-nozzle 3D printing, and a color-change 4D
printing method using anthocyanin catalysis.
SUMMARY OF THE INVENTION
Technical Problem The present method is a 4D food printing method using anthocyanin catalysis to achieve color change on the basis of food 3D printing, which can enrich the ideas and types of 3D printing of foods.
Technical Solution A colorful-jelly 4D printing method utilizing spontaneous color change of blueberry anthocyanins, specifically including:
(1) ultrasonic-coordinated vacuum extraction of anthocyanins:
a. fresh and high-quality blueberry fruits are weighed, and placed in a -80 C
refrigerator for freezing and slow thawing;
b. hydrochloric acid and ethanol are formulated into an anthocyanin extractant;

6 Date Recue/Date Received 2021-08-04 c. the frozen fresh blueberry fruits are mixed with the anthocyanin extractant in a mass ratio of 1:20;
d. an extraction mixture is homogenized in a low-speed homogenizer for 25-35 s and transferred to a vacuum flask, and a vacuum pump is used to extract the air in the flask to maintain an air pressure in the flask at 0.07-0.09 MPa for 10 min to remove oxygen in an extract;
e. the vacuum flask connected to the vacuum pump is placed in an ultrasonic bath at 50-53.5 C
with the air pressure maintained at 0.07-0.09 MPa, with the extraction time being 25-30 min;
f. the extract is filtered, adjusted to a pH of 7.0-7.2, and freeze-dried to obtain anthocyanin powder;
(2) preparation of color bearing layer material:
g. mixing: the anthocyanin powder extracted from the blueberry in step (1), potato starch, pectin, an essence, and purified water are added into a mixer to mix evenly;
h. homogenization: the mixed material in step g is sent to a homogenizer to homogenize at 3.0-3.5 MPa for 10-15 mM, so that the particle size of the homogenized material is less than 20 1.1m;
i. gelation: the material obtained in step h is held at 53.5 C for 15-20 min;
j. cooling: the color bearing layer material obtained in step i is cooled to room temperature for later use;
(3) preparation of color control layer material:
k. mixing: concentrated lemon juice, NaCO3, pectin and potato starch are added into a mixer to mix evenly;
1. homogenization: the mixed material in step k is sent to the homogenizer to homogenize at 3.0-3.5 MPa for 10-15 min, so that the particle size of the homogenized material is less than 20 um;
m. gelation: the material obtained in step 1 is held at 53.5 C for 15-20 min;
n. cooling: the color control layer material obtained in step m is cooled to room temperature for later use;
(4) filling materials: the color bearing layer and color control layer materials prepared in steps (2) and (3) are filled into two printing cylinders for solid filling, respectively, and the cylinders are placed into a vacuum chamber with a vacuum of 0.07-0.09 MPa for degassing to remove bubbles

7 Date Recue/Date Received 2021-08-04 therein;
(5) printing: a dual-nozzle 3D printer is used to perform dual-material 3D
printing and laying according to a pre-established dual-color 3D printing model, where multiple layers of color bearing layer with different anthocyanin concentrations and color control layer with different pH values are alternately laid layer by layer through the dual nozzles, to finally form a colorful jelly with a 3D shape.
In the step b, the anthocyanin extractant is an aqueous solution of 0.01% HC1 and 70% ethanol.
In the step e, the parameters of an ultrasound generating device in the ultrasonic bath are 20-25 kHz and 2 W/g.
In the step f, the freeze-drying conditions are: drying for 20-24 h at a cold trap temperature of -80 C and a pressure of 220 Pa.
In the step g, the raw material formula is calculated in parts by weight: 1 to 2 parts of anthocyanin powder, 100 to 150 parts of potato starch, 10 to 20 parts of pectin, 0.1 to 0.2 parts of an essence, and 100 parts of purified water;
In the step k, the raw material formula is calculated in parts by weight: 100 parts of concentrated lemon juice, 0 to 7 parts of NaCO3, 10 to 20 parts of pectin and 75 to 125 parts of potato starch.
The starch formed after the gelatinization of potato starch has good gel properties and high transparency; pectin provides elasticity and texture properties for jelly;
concentrated lemon juice and lemon essential oil can provide flavor and taste for jelly; NaCO3 can adjust the pH of the color control layer to regulate the color change. The essence is white lemon essential oil.
The color bearing layer material has a viscosity of 1500-8000 Pa- s, an elastic modulus of 1800-3200 Pa, a viscosity modulus of 300-500 Pa, and a pH value of 5.1-5.2. The color at the formation of the color bearing layer is expressed in standard Lab as: L*=66.85 2.44, e=67.44 2.62, b*=-34.61 3.65, red purple.
The color control layer material has a viscosity of 4300-10000 Pa-s, an elastic modulus of 2600-9200 Pa, a viscosity modulus of 320-1000 Pa, and a pH value of 2.4-11.2.
The final color change is adjusted by adjusting the pH value of the color control layer. The color of the jelly formed by the final color change is expressed in standard Lab value as: red when L*=59.44 2.76, e=67.59 8.81, b*=36.66 12.86, pH=2.4; purple when L*=50.43 4.50, e=59.66 12.43, b*
=-

8 Date Recue/Date Received 2021-08-04 38.70 6.87, pH=7; and blue when L*=27.83 4.19, a*=17 .60 6 .98 , b*=-31.04 12.26, pH=11.2.
In the step (5), the printing speed is 20-25 mm/s, and the extrusion speed is 25-30 mm3/s; when a bottom layer and a shell are printed, the printing speed is 50% of the normal speed; the position of nozzle 2 relative to nozzle 1 is set as X = 62.5 mm, Y = -0.5 mm. The nozzle diameter of the dual-nozzle 3D printer is 0.85 mm.
Advantageous Effect 1. The present method extracts anthocyanins in blueberries using ultrasonic wave-coordinated vacuum, which can improve the extraction efficiency of anthocyanins while reducing the oxidation of anthocyanins;
2. Anthocyanins extracted from blueberries have good antioxidant properties and bright color and lustre;
3. The present invention is a food 4D color change printing method realized on the basis of dual-nozzle printing and laying;
4. Different jelly materials laid by 3D can spontaneously migrate into each other and stimulate each other to achieve color change;
5. Using NaCO3 to adjust the pH of the color control layer finally realizes the control of color;
6. Multiple layers of different color bearing layers and color control layers are laid alternately layer by layer through dual nozzles, to finally achieve multi-color change, so that jelly can appear multiple colors at the same time;
7. The gelation temperature of the material is 50-53.5 C, at which temperature, it can be ensured that the potato starch is fully gelatinized and the loss of anthocyanins is small.
DETAILED DESCRIPTION OF THE INVENTION
The present invention will be described below in connection with specific examples.
Example 1: colorful-jelly 4D printing method utilizing spontaneous color change of blueberry anthocyanins (dual-color) Fresh and high-quality blueberry fruits were weighed, and placed in a -80 C
refrigerator for

9 Date Recue/Date Received 2021-08-04 freezing and slow thawing. 0.01% hydrochloric acid and 70% ethanol were formulated into an aqueous solution as an anthocyanin extractant. The frozen fresh blueberry fruits were mixed with the extractant in a mass ratio of 1:20, and placed in a low-speed homogenizer to homogenate for 25 s and transferred to a vacuum flask, and a vacuum pump was used to extract the air in the flask to maintain an air pressure in the flask at 0.07 MPa for 10 min to remove oxygen in an extract. The vacuum flask connected to the vacuum pump was placed in an ultrasonic bath at 53.5 C, 20 kHz, and 2 W/g with the air pressure maintained at 0.07 MPa, with the extraction time being 25 min.
The extract was filtered, adjusted to a pH of 7, and freeze-dried for 20 h under the conditions of a cold trap temperature of -80 C and a pressure of 220 Pa.
100 parts of potato starch, 1 part of the blueberry anthocyanin powder extracted above, 20 parts of pectin, 100 parts of purified water, and 0.1 part of white lemon essential oil were weighed and added to a mixer to mix evenly; and the mixed material was sent to a homogenizer to homogenize at 3.0-3.5 MPa for 10 min, so that the particle size of the homogenized material was less than 20 pm. The homogenized material was held at 53.5 C for 15 min, and cooled to room temperature, to make a color bearing layer material. The pH at the formation of the color bearing layer = 5.1, pale red purple (L*=68.58, a*=69.30, b*=-32.03).
75 parts of potato starch, 20 parts of pectin and 100 parts of concentrated lemon juice were weighed and added to a mixer to mix evenly; and the mixed material was sent to a homogenizer to homogenize at 3.0 MPa for 10 min, so that the particle size of the homogenized material was less than 20 pm. The homogenized material was held at 53.5 C for 15 min, and cooled to room temperature, to make a first color control layer material, where the pH was 2.4. 4 parts of NaCO3 were added on the basis of the first color control layer material to make a second color control layer material, where the pH was 7.
The three materials were filled into printing cylinders, respectively, for an even filling and the cylinders were placed into a vacuum chamber with a vacuum of 0.07 MPa for degassing to remove bubbles therein. For printing, a nozzle with a diameter of 0.85 mm was selected, the printing speed was set to 20 mm/s, and the extrusion rate was set to 25 mm3/s; the position of nozzle 2 relative to nozzle 1 was set to X=62.5 mm, Y=-0.5 mm. When a product shell was printed, the printing speed was set to 50% of the normal printing speed. Nozzle 1 was used to print the color bearing layer material, nozzle 2 was used to print alternately the two color control layer materials, and a pre-designed multi-layer 3D model was used for alternate printing, laying and forming according to the color bearing layer - the first color control layer (pH=2.4) - the color bearing layer - the second Date Recue/Date Received 2021-08-04 color control layer (pH=7), and so on. The printed jelly was able to achieve two color changes of light red (L*=61.39, a*=73.81, b *=45.76) and light purple (L*=53.61, a*=68.45, b*=-33.85) in 2 min.
Example 2: colorful-jelly 4D printing method utilizing spontaneous color change of blueberry anthocyanins (tri-color) Fresh and high-quality blueberry fruits were weighed, and placed in a -80 C
refrigerator for freezing and slow thawing. 0.01% hydrochloric acid and 70% ethanol were formulated into an aqueous solution as an anthocyanin extractant. The frozen fresh blueberry fruits were mixed with the extractant in a mass ratio of 1: 20, and placed in a low-speed homogenizer to homogenate for 35 s and transferred to a vacuum flask, and a vacuum pump was used to extract the air in the flask to maintain an air pressure in the flask at 0.09 MPa for 10 min to remove oxygen in an extract. The vacuum flask connected to the vacuum pump was placed in an ultrasonic bath at 52 C, 20 kHz, and 2 W/g with the air pressure maintained at 0.09 MPa, with the extraction time being 30 min. The extract was filtered, adjusted to a pH of 7.2, and freeze-dried for 20 h under the conditions of a cold trap temperature of -80 C and a pressure of 220 Pa.
150 parts of potato starch, 10 part of pectin, 2 parts of the blueberry anthocyanin powder extracted above, 100 parts of purified water, and 0.2 part of white lemon essential oil were weighed and added to a mixer to mix evenly; and the mixed material was sent to a homogenizer to homogenize at 3.5 MPa for 15 min, so that the particle size of the homogenized material was less than 20 um. The homogenized material was held at 53.5 C for 20 min, and cooled to room temperature, to make a color bearing layer material. The pH at the formation of the color bearing layer= 5.2, red purple (L*=65.12, a*=65.59, b*=-37.19).
100 parts of potato starch, 10 parts of pectin, 4 parts of NaCO3 and 100 parts of concentrated lemon juice were weighed and added to a mixer to mix evenly; and the mixed material was sent to a homogenizer to homogenize at 3.5 MPa for 15 min, so that the particle size of the homogenized material was less than 20 um. The homogenized material was held at 53.5 C for 20 min, and cooled to room temperature, to make a first color control layer material, where the pH was 2.4; 4 parts of NaCO3 were added on the basis of the first color control layer material, to make a second color control layer material, where the pH was 7; and 7 parts of NaCO3 were added on the basis of the first color control layer material to make a third color control layer material, where the pH was 11.2.

Date Recue/Date Received 2021-08-04 The four materials were filled into printing cylinders, respectively, for an even filling and the cylinders were placed into a vacuum chamber with a vacuum of 0.09 MPa for degassing to remove bubbles therein.
For printing, a nozzle with a diameter of 0.85 mm was selected, the printing speed was set to 25 mm/s, and the extruding speed was set to 30 mm3/s; nozzle 1 was used to print the color bearing layer material, nozzle 2 was used to print alternately the two color control layer materials, and a pre-designed multi-layer 3D model was used for alternate printing, laying and forming according to the color bearing layer - the first color control layer (pH=2.4) - the color bearing layer - the second color control layer (pH=7) - the color bearing layer - the third color control layer (pH=11.2), and so on. The printed jelly was able to achieve three color changes of red (L*=57.48, a*=61.36, b*=27.56), purple (L*=47.25, a*=50.87, b*=-43.56) and blue (L*=24.86, a*=12.67, b*=-39.71) in 2 min.
Example 3: colorful-jelly 4D printing method utilizing spontaneous color change of blueberry anthocyanins (hex-color) Fresh and high-quality blueberry fruits were weighed, and placed in a -80 C
refrigerator for freezing and slow thawing. 0.01% hydrochloric acid and 70% ethanol were formulated into an aqueous solution as an anthocyanin extractant. The frozen fresh blueberry fruits were mixed with the extractant in a mass ratio of 1: 20, and placed in a low-speed homogenizer to homogenate for 25-35 s and transferred to a vacuum flask, and a vacuum pump was used to extract the air in the flask to maintain an air pressure in the flask at 0.08 MPa for 10 min to remove oxygen in an extract.
The vacuum flask connected to the vacuum pump was placed in an ultrasonic bath at 50 C, 20 kHz, and 2 W/g with the air pressure maintained at 0.08 MPa, with the extraction time being 25 min.
The extract was filtered, adjusted to a pH of 7, and freeze-dried for 24 h under the conditions of a cold trap temperature of -80 C and a pressure of 220 Pa.
125 parts of potato starch, 15 part of pectin, 1 parts of the blueberry anthocyanin powder extracted above, 100 parts of purified water, and 0.2 part of white lemon essential oil were weighed and added to a mixer to mix evenly; and the mixed material was sent to a homogenizer to homogenize at 3.5 MPa for 15 min, so that the particle size of the homogenized material was less than 20 um. The homogenized material was held at 53.5 C for 20 min, and cooled to room temperature, to make a first color bearing layer material. The pH at the formation of the first color bearing layer = 5.1, pale red purple (L*=68.58, a*=69.30, b*=-32.03). 1 part of the blueberry anthocyanin powder extracted above was added on the basis of the first color bearing layer material, to make a second color bearing layer material. The pH at the formation of the layer = 5.2, red purple Date Recue/Date Received 2021-08-04 (L*=65.12, a*=65.59, b*=-37.19).
125 parts of potato starch, 15 parts of pectin and 100 parts of concentrated lemon juice were weighed and added to a mixer to mix evenly; and the mixed material was sent to a homogenizer to homogenize at 3.5 MPa for 15 min, so that the particle size of the homogenized material was less than 20 pm. The homogenized material was held at 53.5 C for 20 min, and cooled to room temperature, to make a first color control layer material, where the pH was 2.4; 4 parts of NaCO3 were added on the basis of the first color control layer material, to make a second color control layer material, where the pH was 7; 7 parts of NaCO3 were added on the basis of the first color control layer material, to make a third color control layer material, where the pH was 11.2.
The five materials were filled into printing cylinders, respectively, for an even filling and the cylinders were placed into a vacuum chamber with a vacuum of 0.08 MPa for degassing to remove bubbles therein. For printing, a nozzle with a diameter of 0.85 mm was selected, the printing speed was set to 20 mm/s, and the extrusion rate was set to 30 mm3/s; the position of nozzle 2 relative to nozzle 1 was set to X=62.5 mm, Y= -0.5 mm. When a product shell was printed, the printing speed was set to 50% of the normal printing speed. A pre-designed multilayer 3D
model was used for alternate printing of different color bearing layers and color control layers, and laying and forming.
The printed jelly was able to achieve six color changes of pale red (L*=61.39, a*=73.81, b*=45.76), pale purple (L*=53.61, a*=68.45, b*=-33.85), pale blue (L*=30.79, a*=22.53, b*=-22.369), red (L*=57.48, a*-61.36, b*=27.56), purple (L*=47.25, a*=50.87, b*=-43.56) and blue (L*=24.86, a*=12.67, b*=-39.71) in 2 min.

Date Recue/Date Received 2021-08-04

Claims

Claims What is claimed is:
1. A
colorful-jelly 4D printing method utilizing a spontaneous color change of blueberry anthocyanins, comprising:
(1) an ultrasonic-coordinated vacuum extraction of the anthocyanins, comprising:
a. placing blueberry fruits in a -80 C freezer for a sufficient time so as to prepare frozen blueberry fruits;
b. formulating hydrochloric acid and ethanol into an anthocyanin extractant;
c. mixing the frozen blueberry fruits with the anthocyanin extractant in a mass ratio of 1: 20 to prepare an extraction mixture of the frozen blueberry fruits and the anthocyanin extractant;
d. homogenizing the extraction mixture in a low-speed homogenizer for 25-35 seconds to prepare a homogenized extract mixture, transferring the homogenized extract mixture to a vacuum flask connected to a vacuum pump, and using the vacuum pump to maintain an air pressure in the vacuum flask at 0.07-0.09 MPa for 10 mins to remove oxygen in the homogenized extract mixture;
e. placing the vacuum flask in an ultrasonic bath at 50-53.5 C to obtain an extract, the air pressure in the vacuum flask being maintained at 0.07-0.09 M Pa for 25-30 mins; and f. filtering the extract to obtain a filtrate, adjusting the filtrate to a pH
of 7.0-7.2, and freeze-drying the filtrate to obtain a powder comprising the anthocyanins;
(2) preparation of a color bearing layer material, comprising:
g. mixing the powder comprising the anthocyanins from the step (1), potato starch, pectin, an essence, and purified water to obtain an anthocyanin mixture;
h. homogenizing the anthocyanin mixture at 3.0-3.5 MPa for 10-15 mins to obtain a homogenized anthocyanin mixture having a particle size less than 20 gm;
i. gelatinizing the homogenized anthocyanin mixture at 53.5 C for 15-20 mins to obtain a gelatinized anthocyanin material; and j. cooling the gelatinized anthocyanin material to room temperature to obtain the color bearing layer material;
(3) preparation of a color control layer material:

Date recue/Date received 2023-03-29 k. mixing concentrated lemon juice, NaCO3, pectin and potato starch to obtain a control mixture;

1. homogenizing the control mixture at 3.0-3.5 MPa for 10-15 mins to obtain a homogenized control mixture having a particle size less than 20 Inn;
m. gelatinizing the homogenized control mixture at 53.5 C for 15-20 mins to obtain a gelatinized control material; and n. cooling the gelatinized control material to room temperature to obtain the color control layer material;
(4) filling, comprising filling the color bearing layer material and the color control layer material into two printing cylinders, respectively, and placing the printing cylinders into a vacuum chamber with a vacuum of 0.07-0.09 MPa for degassing; and (5) printing, comprising using a dual-nozzle 3D printer comprising a first nozzle and a second nozzle to perform a dual-material 3D printing and layering according to a pre-established dual-color 3D printing model, to produce layers of the color bearing layer material altemately laid with layers of the color control layer material to form the colorful jelly with a 3D shape, wherein the color bearing layer material has a viscosity of 1500-8000 Pa- s, an elastic modulus of 1800-3200 Pa, a viscosity modulus of 300-500 Pa, and a pH value of 5.1-5.2; the color of the layers of the color bearing layer material is expressed in standard Lab as: L*=66.85 2.44, a*=67.44 2.62, b*=-34.61 3.65, red purple; and the color control layer material has a viscosity of 4300-10000 Pa-s, an elastic modulus of 2600-9200 Pa, a viscosity modulus of 320-1000 Pa, and a pH value of 2.4-11.2;
a color change of the layers of the color control material is adjusted by adjusting pH values of the layers of the color control layer material; and the color change is expressed in standard Lab as:
red when L
*=59.44 2.76, a*=67.59 8.81, b*=36.66 12.86, pH=2.4; purple when L *=50.43 4.50, e=59.66 12.43, b*=-38.70 6.87, pH=7; and blue when L*=27.83 4.19, e=17.60 6.98, b *=-31.04 12.26, pH=11.2.

2.
The colorful-jelly 4D printing method according to claim 1, wherein in the step b, the anthocyanin extractant is an aqueous solution of 0.01% HC1 and 70% ethanol; in the step e, parameters of an ultrasound generating device in the ultrasonic bath are 20-25 kHz and 2 W/g; and in the step f, the freeze-drying is carried out for 20-24 hrs at a cold trap temperature of -80 C and a pressure of 220 Pa.
Date recue/Date received 2023-03-29

3. The colorful-jelly 4D printing method according to claim 1 or claim 2, wherein in the step g, 1 to 2 parts by weight of the powder comprising the anthocyanins, 100 to 150 parts by weight of the potato starch, 10 to 20 parts by weight of the pectin, 0.1 to 0.2 parts by weight of the essence, and 100 parts by weight of the purified water are mixed; in the step k, 100 parts by weight of the concentrated lemon juice, 1 to 7 parts by weight of the NaCO3, 10 to 20 parts by weight of the pectin and 75 to 125 parts by weight of the potato starch are mixed.

4. The colorful-jelly 4D printing method according to any one of claims 1-3, wherein in the step (5), the printing is carried out at a printing speed of 20-25 mm/s, and an extruding speed of 25-30 mm3/s; when a bottom layer and a shell of the colorful jelly are printed, the printing speed is reduced to 50%; the position of the second nozzle relative to the first nozzle is set as X = 62.5 mm, Y = -0.5 mm; and the first nozzle and the second nozzle have a nozzle diameter of 0.85 mm.

Date recue/Date received 2023-03-29