A method for preparing a printing ink for smooth, hard food surfaces and its application

Abstract

This invention discloses a method for preparing printing ink for smooth, hard food surfaces, comprising the following steps: preparing a mixed solution of plant protein; mixing it with shellac in anhydrous ethanol, then adding polyol and pigment for dispersion, followed by grinding and filtration to obtain the final product. This invention enables gravure printing on the hard, smooth surfaces of food, exhibiting good adhesion, excellent ink transfer properties, clear and smooth printing, and a certain degree of water resistance. Furthermore, it controls the ink drying speed; black and white inks dry at a moderate speed to avoid cracking and peeling; color inks dry at a moderate speed to avoid clumping. It also allows for overprinting of two or more colors, and the ink has good abrasion resistance, preventing color fading during transportation after packaging.

Description

Technical Field

[0001] This invention relates to a method for preparing a printing ink for smooth, hard food surfaces and its application, specifically relating to the field of food coloring or decolorization. Background Technology

[0002] Printing patterns and text on food surfaces can create a refreshing visual experience, attracting consumers' attention. Currently, much printing on hard candies involves combining a transfer film with the candy, resulting in unnatural prints that fail to truly integrate the printed design with the food. Patterns on fruits are often achieved through sun-drying patterned bags; however, limitations in the complexity of these patterns prevent the printing of many multi-colored or intricate designs on fruit. Therefore, developing an ink that produces a natural print and can be applied to both hard and smooth food surfaces is crucial. Summary of the Invention

[0003] To enable printing on hard, smooth food surfaces, a first aspect of the present invention provides a method for preparing printing ink for smooth, hard food surfaces, comprising the following steps:

[0004] S1. Mix and stir the plant protein with an ethanol solution to dissolve and set aside, thus preparing a plant protein mixed solution;

[0005] S2 Add anhydrous ethanol to the mixing tank, add shellac while stirring, and stir continuously until the shellac is completely dissolved;

[0006] S3 Then add the plant protein mixture prepared in step S1 and stir continuously for 5-10 minutes;

[0007] S4 is added to polyols and pigments and then dispersed at high speed in a disperser until uniform;

[0008] Grind with an S5 grinder and filter to obtain the final product.

[0009] In a preferred embodiment, the ethanol solution is an aqueous solution of ethanol with a volume concentration of 75%, and the mass ratio of the plant protein to the ethanol solution is 1:(2-4).

[0010] In a preferred embodiment, the mass ratio of the plant protein to the ethanol solution is 1:3.

[0011] In a preferred embodiment, the mass ratio of the shellac to the plant protein mixture is (28-40):(1-5).

[0012] In a preferred embodiment, the plant protein mixture is a corn protein mixture.

[0013] In a preferred embodiment, the anhydrous ethanol in step S2 further includes water and an alkali, wherein the alkali is an inorganic alkali.

[0014] In a preferred embodiment, the inorganic base is selected from one or a combination of several of sodium hydroxide, potassium hydroxide, calcium hydroxide, sodium carbonate, sodium bicarbonate, and potassium carbonate.

[0015] In a preferred embodiment, the inorganic base is potassium hydroxide.

[0016] In a preferred embodiment, the water is purified water, and the weight ratio of the purified water to the polyol is (0-5):(1-10).

[0017] In a preferred embodiment, the pigment is selected from one or a combination of several of titanium dioxide, iron oxide black, allure red aluminum lake, yellow aluminum lake, and brilliant blue aluminum lake.

[0018] In a preferred embodiment, the polyol is selected from one or a combination of several of propylene glycol, ethylene glycol, glycerol, butanediol, polyethylene glycol, and sorbitol.

[0019] In a preferred embodiment, the polyol is a combination of propylene glycol and ethylene glycol. Preferably, the mass ratio of propylene glycol to ethylene glycol is (1-5):(1-5).

[0020] In a preferred embodiment, the stirring speed in the preparation method is 800-1200 r / min, the stirring temperature is 20-60℃, and the dispersion speed of the disperser in step S4 is 800-1200 r / min, the dispersion temperature is 20-30℃, and the dispersion time is 20-40 min.

[0021] In a preferred embodiment, the raw materials for preparing the white ink include, by weight: 28-40 parts shellac, 1-5 parts plant protein mixed solution, 1-5 parts purified water, 0-1 parts potassium hydroxide, 30-40 parts titanium dioxide, 30-50 parts anhydrous ethanol, 1-5 parts propylene glycol, and 1-5 parts glycerol.

[0022] In a preferred embodiment, the raw materials for preparing the black ink include, by weight: 28-40 parts shellac, 1-5 parts plant protein mixed solution, 1-5 parts purified water, 0-1 parts potassium hydroxide, 20-30 parts iron oxide black, 30-50 parts anhydrous ethanol, 1-5 parts propylene glycol, and 1-5 parts glycerol.

[0023] In a preferred embodiment, the raw materials for preparing the red ink include, by weight: 28-40 parts shellac, 1-5 parts plant protein mixture, 15-20 parts Allura Red aluminum lake, 33-55 parts anhydrous ethanol, and 2-8 parts propylene glycol.

[0024] In a preferred embodiment, the raw materials for preparing the yellow ink include, by weight: 28-40 parts shellac, 1-5 parts plant protein mixture, 15-20 parts lemon yellow aluminum lake, 33-55 parts anhydrous ethanol, and 2-8 parts propylene glycol.

[0025] In a preferred embodiment, the raw materials for preparing the blue ink include, by weight: 28-40 parts shellac, 1-5 parts plant protein mixture, 15-20 parts brilliant blue aluminum lake, 33-55 parts anhydrous ethanol, and 2-8 parts propylene glycol.

[0026] During the experiment, the applicant discovered that using a mixture of shellac and corn protein could achieve gravure printing on the hard, smooth surface of food, exhibiting good adhesion. The applicant speculates that this is because the shellac and corn protein mixture forms a binder material, allowing the added pigment powder and lake to disperse evenly within it. After printing and drying, this results in a durable and hard pattern layer with excellent adhesion to the hard, smooth surface. Furthermore, using a weight ratio of (28-40):(1-5) for the shellac and corn protein mixture results in a pattern layer with a hardness close to that of the food surface, making it less prone to peeling off.

[0027] The applicant further discovered that the powder pigments used in black and white inks are not easy to clean after printing equipment is used. In this application, potassium hydroxide is introduced into the black and white inks, which can adjust the overall pH of the ink to be slightly alkaline, promote the solubility of black and white powder pigments in ethanol, and improve the cleaning performance of the equipment.

[0028] The applicant further discovered that when the water content in the colored ink is greater than 10%, the ink clumps and the printing is not smooth. The reason is that the excessive water content in the colored ink will lead to uneven dispersion of the ink, which will affect the printing performance of the ink.

[0029] In a preferred embodiment, the prepared ink has a rotational viscosity ≥100 mPa.

[0030] In a preferred embodiment, the particle size after grinding in step S5 is ≤10μm, and it is filtered with 300-mesh nylon filter cloth.

[0031] A second aspect of the present invention provides an application of a method for preparing printing ink for smooth, hard food surfaces, which is used in pad printing gravure printing of smooth, hard foods.

[0032] In a preferred embodiment, the printing speed is 800 apples / hour when the printing ink is printed onto apples, and 1 million candies / hour when the printing ink is printed onto hard candies.

[0033] Compared with the prior art, the present invention has the following beneficial effects:

[0034] (1) The method for preparing printing ink for smooth and hard food surfaces according to the present invention uses shellac and corn protein mixed solution to achieve gravure printing on the hard and smooth surface of food. It has good adhesion to the hard and smooth surface of food, good ink transfer, clear and smooth printing, and certain water resistance.

[0035] (2) The method for preparing the smooth hard food surface printing ink of the present invention introduces potassium hydroxide into the black and white ink, which can promote the solubility of black and white powder pigments in ethanol and improve the cleaning performance of the equipment after the ink is used.

[0036] (3) The preparation method of the smooth hard food surface printing ink of the present invention controls the weight ratio of purified water to polyol in the ink to be (0-5): (2-10), which can control the drying speed of the ink. The drying speed of black and white ink will not be too fast, avoiding cracking and peeling problems; the drying speed of colored ink will not be too slow, avoiding ink clumping, and can realize the overprinting of two or more colors. The ink has good abrasion resistance and will not fade during transportation after packaging. Attached Figure Description

[0037] Figure 1 This is an image showing the effect of printing the white ink prepared in Example 1 onto the surface of an apple;

[0038] Figure 2 This is an image showing the effect of printing the red ink prepared in Example 3 onto the surface of an apple;

[0039] Figure 3 The effect of two-color overprinting of white and red inks prepared in Examples 1 and 3 onto the surface of an apple;

[0040] Figure 4 The images show the effect of printing red, yellow, and blue inks prepared in Examples 3, 4, and 5 onto the surface of an apple using three-color overprinting.

[0041] Figure 5 The effect of printing the white ink prepared for Comparative Example 1 onto the surface of an apple;

[0042] Figure 6 The effect of printing the red ink prepared in Comparative Example 3 onto the surface of an apple;

[0043] Figure 7 The effect of two-color overprinting of red and yellow inks prepared for comparative examples 3 and 4 onto the surface of an apple;

[0044] Figure 8The image shows the effect of red, yellow, and blue inks prepared for comparative examples 3, 4, and 5 being printed onto the surface of an apple using a three-color overprinting technique. Detailed Implementation

[0045] Example 1

[0046] A method for preparing a printing ink for smooth, hard food surfaces includes the following steps:

[0047] S1. Mix and stir the plant protein with an ethanol solution to dissolve and set aside, thus preparing a plant protein mixed solution;

[0048] S2 dissolves water and alkali in anhydrous ethanol and adds it to the mixing tank. During the stirring process, shellac is added and stirred continuously until the shellac is completely dissolved.

[0049] S3 Then add the plant protein mixture prepared in step S1 and stir continuously for 5 minutes;

[0050] S4 is added to polyols and pigments and then dispersed at high speed in a disperser until uniform;

[0051] Grind with an S5 grinder and filter to obtain the final product.

[0052] The water is purified water; the alkali is potassium hydroxide; the plant protein mixture is a corn protein mixture; the ethanol solution is a 75% (v / v) aqueous ethanol solution, with a corn protein to ethanol solution mass ratio of 1:3; the polyol is a combination of propylene glycol and glycerol; the pigment is titanium dioxide. The shellac was purchased from Anning Daike Fine Chemical Co., Ltd., and the corn protein was purchased from Shanghai Quanwang Biotechnology Co., Ltd.

[0053] The particle size after grinding in step S5 is ≤10μm, and it is filtered with 300-mesh nylon filter cloth.

[0054] The raw materials for preparation include, by weight: 38 parts shellac, 2 parts plant protein mixed solution, 3 parts purified water, 0.5 parts potassium hydroxide, 35 parts titanium dioxide, 40 parts anhydrous ethanol, 3 parts propylene glycol, and 3 parts glycerol.

[0055] In the preparation method, the stirring speed is 1000 r / min, the stirring temperature is 40℃, and in step S4, the dispersion speed of the disperser is 1000 r / min, the dispersion temperature is 25℃, and the dispersion time is 30 min.

[0056] Example 2

[0057] A method for preparing a printing ink for smooth, hard food surfaces includes the following steps:

[0058] S1. Mix and stir the plant protein with an ethanol solution to dissolve and set aside, thus preparing a plant protein mixed solution;

[0059] S2 dissolves water and alkali in anhydrous ethanol and adds it to the mixing tank. During the stirring process, shellac is added and stirred continuously until the shellac is completely dissolved.

[0060] S3 Then add the plant protein mixture prepared in step S1 and stir continuously for 5 minutes;

[0061] S4 is added to polyols and pigments and then dispersed at high speed in a disperser until uniform;

[0062] Grind with an S5 grinder and filter to obtain the final product.

[0063] The water is purified water; the alkali is potassium hydroxide; the plant protein mixture is a corn protein mixture; the ethanol solution is a 75% (v / v) aqueous ethanol solution, with a corn protein to ethanol solution mass ratio of 1:3; the polyol is a combination of propylene glycol and glycerol; the pigment is iron oxide black. The shellac was purchased from Anning Daike Fine Chemical Co., Ltd., and the corn protein was purchased from Shanghai Quanwang Biotechnology Co., Ltd.

[0064] The particle size after grinding in step S5 is ≤10μm, and it is filtered with 300-mesh nylon filter cloth.

[0065] The raw materials for preparation include, by weight: 40 parts shellac, 5 parts plant protein mixed solution, 4 parts purified water, 0.5 parts potassium hydroxide, 40 parts iron oxide black, 50 parts anhydrous ethanol, 2 parts propylene glycol, and 2 parts glycerol.

[0066] In the preparation method, the stirring speed is 1000 r / min, the stirring temperature is 40℃, and in step S4, the dispersion speed of the disperser is 1000 r / min, the dispersion temperature is 25℃, and the dispersion time is 30 min.

[0067] Example 3

[0068] A method for preparing a printing ink for smooth, hard food surfaces includes the following steps:

[0069] S1. Mix and stir the plant protein with an ethanol solution to dissolve and set aside, thus preparing a plant protein mixed solution;

[0070] S2 Add anhydrous ethanol to the mixing tank, add shellac while stirring, and stir continuously until the shellac is completely dissolved;

[0071] S3 Then add the plant protein mixture prepared in step S1 and stir continuously for 5 minutes;

[0072] S4 is added to polyols and pigments and then dispersed at high speed in a disperser until uniform;

[0073] Grind with an S5 grinder and filter to obtain the final product.

[0074] The plant protein mixture solution is a corn protein mixture solution; the ethanol solution is a 75% (v / v) aqueous ethanol solution, and the mass ratio of corn protein to ethanol solution is 1:3; the polyol is propylene glycol; and the pigment is Allura Red aluminum lake. The shellac was purchased from Anning Daike Fine Chemical Co., Ltd., and the corn protein was purchased from Shanghai Quanwang Biotechnology Co., Ltd.

[0075] The particle size after grinding in step S5 is ≤10μm, and it is filtered with 300-mesh nylon filter cloth.

[0076] The raw materials for preparation include, by weight: 35 parts shellac, 3 parts plant protein mixed solution, 18 parts Allura Red aluminum lake, 44 parts anhydrous ethanol, and 5 parts propylene glycol.

[0077] In the preparation method, the stirring speed is 1000 r / min, the stirring temperature is 45℃, and in step S4, the dispersion speed of the disperser is 1000 r / min, the dispersion temperature is 25℃, and the dispersion time is 30 min.

[0078] Example 4

[0079] A method for preparing a printing ink for smooth, hard food surfaces includes the following steps:

[0080] S1. Mix and stir the plant protein with an ethanol solution to dissolve and set aside, thus preparing a plant protein mixed solution;

[0081] S2 Add anhydrous ethanol to the mixing tank, add shellac while stirring, and stir continuously until the shellac is completely dissolved;

[0082] S3 Then add the plant protein mixture prepared in step S1 and stir continuously for 5 minutes;

[0083] S4 is added to polyols and pigments and then dispersed at high speed in a disperser until uniform;

[0084] Grind with an S5 grinder and filter to obtain the final product.

[0085] The plant protein mixture solution is a corn protein mixture solution; the ethanol solution is a 75% (v / v) aqueous ethanol solution, and the mass ratio of corn protein to ethanol solution is 1:3; the polyol is propylene glycol; and the pigment is tartrazine aluminum lake. The shellac was purchased from Anning Daike Fine Chemical Co., Ltd., and the corn protein was purchased from Shanghai Quanwang Biotechnology Co., Ltd.

[0086] The particle size after grinding in step S5 is ≤10μm, and it is filtered with 300-mesh nylon filter cloth.

[0087] The raw materials for preparation include, by weight: 28 parts shellac, 1 part plant protein mixed solution, 15 parts tartrazine aluminum lake, 33 parts anhydrous ethanol, and 5 parts propylene glycol.

[0088] In the preparation method, the stirring speed is 1000 r / min, the stirring temperature is 45℃, and in step S4, the dispersion speed of the disperser is 1000 r / min, the dispersion temperature is 25℃, and the dispersion time is 30 min.

[0089] Example 5

[0090] A method for preparing a printing ink for smooth, hard food surfaces includes the following steps:

[0091] S1. Mix and stir the plant protein with an ethanol solution to dissolve and set aside, thus preparing a plant protein mixed solution;

[0092] S2 Add anhydrous ethanol to the mixing tank, add shellac while stirring, and stir continuously until the shellac is completely dissolved;

[0093] S3 Then add the plant protein mixture prepared in step S1 and stir continuously for 5 minutes;

[0094] S4 is added to polyols and pigments and then dispersed at high speed in a disperser until uniform;

[0095] Grind with an S5 grinder and filter to obtain the final product.

[0096] The plant protein mixture solution is a corn protein mixture solution; the ethanol solution is a 75% (v / v) aqueous ethanol solution, and the mass ratio of corn protein to ethanol solution is 1:3; the polyol is propylene glycol; and the pigment is brilliant blue aluminum lake. The shellac was purchased from Anning Daike Fine Chemical Co., Ltd., and the corn protein was purchased from Shanghai Quanwang Biotechnology Co., Ltd.

[0097] The particle size after grinding in step S5 is ≤10μm, and it is filtered with 300-mesh nylon filter cloth.

[0098] The raw materials for preparation include, by weight: 40 parts shellac, 5 parts mixed solution of plant protein, 20 parts brilliant blue aluminum lake, 55 parts anhydrous ethanol, and 8 parts propylene glycol.

[0099] In the preparation method, the stirring speed is 1000 r / min, the stirring temperature is 45℃, and in step S4, the dispersion speed of the disperser is 1000 r / min, the dispersion temperature is 25℃, and the dispersion time is 30 min.

[0100] Comparative Example 1

[0101] A method for preparing a printing ink for smooth, hard food surfaces is disclosed. The preparation method is the same as in Example 1, except that the raw materials, by weight, include: 30 parts of a mixed solution of plant protein, 20 parts of purified water, 35 parts of titanium dioxide, 40 parts of anhydrous ethanol, 3 parts of propylene glycol, and 8 parts of glycerol. The plant protein was purchased from Shanghai Quanwang Biotechnology Co., Ltd.

[0102] Comparative Example 2

[0103] A method for preparing a printing ink for smooth, hard food surfaces is disclosed. The preparation method is the same as in Example 2, except that the raw materials, by weight, include: 30 parts of a mixed solution of plant protein, 20 parts of purified water, 25 parts of iron oxide black, 40 parts of anhydrous ethanol, 3 parts of propylene glycol, and 8 parts of glycerol. The plant protein was purchased from Shanghai Quanwang Biotechnology Co., Ltd.

[0104] Comparative Example 3

[0105] A method for preparing a printing ink for smooth, hard food surfaces, the preparation method being the same as in Example 3, except that the raw materials, by weight, include: 30 parts of a mixed solution of plant protein, 20 parts of purified water, 25 parts of Allura Red aluminum lake, 40 parts of anhydrous ethanol, 3 parts of propylene glycol, and 8 parts of glycerol. The plant protein was purchased from Shanghai Quanwang Biotechnology Co., Ltd.

[0106] Comparative Example 4

[0107] A method for preparing a printing ink for smooth, hard food surfaces is disclosed. The preparation method is the same as in Example 4, except that the raw materials, by weight, include: 30 parts of a mixed solution of plant protein, 20 parts of purified water, 25 parts of yellow aluminum lake, 40 parts of anhydrous ethanol, 3 parts of propylene glycol, and 8 parts of glycerol. The plant protein was purchased from Shanghai Quanwang Biotechnology Co., Ltd.

[0108] Comparative Example 5

[0109] A method for preparing a printing ink for smooth, hard food surfaces is disclosed. The preparation method is the same as in Example 5, except that the raw materials, by weight, include: 30 parts of a mixed solution of plant protein, 20 parts of purified water, 25 parts of brilliant blue aluminum lake, 40 parts of anhydrous ethanol, 3 parts of propylene glycol, and 8 parts of glycerol. The plant protein was purchased from Shanghai Quanwang Biotechnology Co., Ltd.

[0110] Performance testing

[0111] Printing performance evaluation: Printing was evaluated using a pad printing machine at a speed of 800 pieces / hour. The printed object was apples. During printing, 5 grams of edible alcohol were added every 5 minutes to prevent ink skinning and excessive viscosity changes (added in a precise droplet manner). See the printed result image below. Figure 1-4 .

[0112] Drying speed: The drying time of the edible natural inks prepared in Examples 1-5 and Comparative Examples 1-5 was timed using a stopwatch;

[0113] Stability: After the finished product is packaged and stored for 6 months, observe whether the ink bleeds off.

[0114] The test results are shown in Table 1.

[0115] Table 1

[0116]

Claims

1. A method for preparing a printing ink for hard glossy food surfaces, characterized in that The method comprises the following steps: S1: mixing plant protein with ethanol solution and stirring to dissolve, to prepare a plant protein mixed solution; S2: adding anhydrous ethanol into a mixing barrel, adding shellac during stirring, and continuously stirring until the shellac is completely dissolved; S3: then adding the plant protein mixed solution prepared in step S1, and continuously stirring for 5-10 min; S4: adding polyol and pigment, and uniformly dispersing in a disperser at high speed; S5: grinding in a grinder, and filtering to obtain the product; The mass ratio of the shellac to the plant protein mixed solution is (28-40):(1-5); The plant protein mixed solution is a corn protein mixed solution; The anhydrous ethanol in step S2 further comprises water and a base, the base is an inorganic base, and the inorganic base is potassium hydroxide; The water is purified water, and the weight ratio of the purified water to the polyol is (0-5):(1-10); The pigment is selected from one or a combination of several of titanium dioxide and black iron oxide.

2. The method of preparing a printing ink for glossy hard food surfaces according to claim 1, characterized in that, The ethanol solution is an ethanol aqueous solution with a volume concentration of 75%, and the mass ratio of the plant protein to the ethanol solution is 1:(2-4).

3. The method of preparing a printing ink for glossy hard food surfaces according to claim 1, characterized in that, The polyol is selected from one or a combination of several of propylene glycol, ethylene glycol, glycerol, butylene glycol, polyethylene glycol, and sorbitol.

4. The method of preparing a printing ink for glossy hard food surfaces according to claim 1, characterized in that, In the preparation method, the stirring speed is 800-1200 r / min, the stirring temperature is 20-60℃, the dispersing speed of the disperser in step S4 is 800-1200 r / min, the dispersing temperature is 20-30℃, and the dispersing time is 20-40 min.

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