A red colorant containing isothiocyanate and a preparation method and application thereof

Abstract

The application discloses a preparation method of a red colorant containing isothiocyanate, and comprises the following steps: S1, obtaining sprouted mustard seedlings and mustard stem stalks, freezing and homogenizing the two, ultrasonic-assisted enzymolysis, pressure-assisted enzymolysis, impurity removal and distillation treatment, and obtaining mustard extract containing isothiocyanate; S2, taking mustard heads, freezing, thawing, preparing pulp and filtering residues, heating and stirring, centrifugation and ultrafiltration, precision filtration treatment, UHT sterilization and aseptic filling, and obtaining red refined mustard pulp; and S3, emulsifying the mustard extract, the red refined mustard pulp of the mustard heads and alcohol and glycerol components, and obtaining the red colorant containing isothiocyanate. The red colorant containing isothiocyanate has coloring and sterilization functions, can pass through a food spray drawing machine, is used for coloring pictographic bread, has smooth and beautiful coloring, and has good microbial control; and when the deep ultraviolet sterilization equipment is used for high-efficiency sterilization of cold-processed bread, the red colorant containing isothiocyanate is not prone to discoloration.

Description

Technical Field

[0001] This invention relates to the field of food processing technology, and in particular to a red colorant containing isothiocyanate, its preparation method, and its application. Background Technology

[0002] Figurative breads, with their animal or vegetable shapes, vibrant colors, and delicious aroma and flavor, are beloved by consumers. On industrial production lines, the overall shape of a figurative bread is created using molds to outline its outer contours, while the detailed inner surfaces or facial features are outlined using a spray-painting process after baking and slicing. The performance of the coloring agents (also known as food colorings) used for bread spray-painting is fundamental to achieving various color schemes for the bread, and several factors must be considered simultaneously:

[0003] Firstly, the colorant is used to color the bread through the inkjet printer. The consistency and viscosity of the colorant will affect the smoothness and speed of the inkjet printing. It needs to be able to support its flow in the inkjet printing pipe and nozzle to achieve the coloring of the bread.

[0004] Secondly, on industrial production lines, the efficiency of the inkjet printing process, namely inkjet printing speed and drying and setting time, must be matched with the processes before and after the process. The faster the drying and setting, the more efficient the production line. Otherwise, it will easily affect the production efficiency of the bread industry.

[0005] Thirdly, industrially baked goods have a long shelf life, which requires stable coloring agents and color protection technology to prevent fading and maintain the aesthetic appearance of the sprayed color.

[0006] Fourthly, since the inkjet printing process occurs after baking and slicing but before inner packaging, it falls under the category of cold-processed bread. Therefore, thorough sterilization and disinfection are necessary to prevent microbial growth. To better control the microorganisms in cold-processed bread, strict control must be exercised over the sterilization process during inkjet printing and coloring. This includes ensuring that the coloring agent itself meets the microbial standards for cold-processed bread, and that the colored bread is effectively sterilized before inner packaging.

[0007] Given the above four factors, it is necessary to adjust the ratio and process of the compound colorant to ensure the smoothness of inkjet printing, drying speed, oxidation resistance and stability, and cleanliness.

[0008] Isothiocyanates possess strong broad-spectrum antibacterial properties. Isothiocyanates are obtained through the hydrolysis of glucosinolates in mustard stems and stalks, a reaction catalyzed by β-glucosinolate hydrolase. Glucosinolates and β-glucosinolate hydrolases exist in different locations within plant tissues. Only when plant tissues are damaged, such as during chewing or crushing, and the cell structure is disrupted, is myrosinase released and comes into contact with the substrate glucosinolates. In the presence of water, this catalyzes the formation of a glucose molecule and an unstable glycosidic ligand intermediate. Subsequently, depending on the hydrolysis environment, the intermediate ultimately yields products such as isothiocyanates, thiocyanates, nitrile compounds, and cyclothiocyanates. The activity of β-glucosinolate hydrolase, also known as myrosinase, is mainly influenced by factors such as temperature, water activity, and pH. Du Xiling and Li Zhenchao's study, "Research on the Antibacterial Effect of Wasabi Essential Oil," indicates that isothiocyanates have antibacterial effects against Staphylococcus aureus, Escherichia coli, Proteus, and Penicillium, with the most significant inhibitory effect against Staphylococcus aureus. Isothiocyanates possess strong antibacterial and preservative properties, effectively inhibiting the growth of bacteria, molds, yeasts, and other microorganisms, thus significantly improving the storability of food. They also have antioxidant and antiparasitic effects, and can increase appetite, promote blood circulation, and prevent tooth decay and cancer.

[0009] Research on the application of isothiocyanates in colorants is limited. Isothiocyanates possess antibacterial, antioxidant, and volatile properties, meeting the requirements for bactericidal and color-protecting effects as colorants. However, further research is needed on how to color them, control oil and water solubility to maintain the solubility and flowability of the colorant, and control the evaporation rate to ensure the sustained effectiveness of the antibacterial and color-producing properties of the colorant.

[0010] Ultraviolet (UV) sterilization of colored bread is an important sterilization method for cold-processed foods. Deep UV sterilization involves using deep UV LEDs to excite UV-C ultraviolet light (UV refers to ultraviolet radiation; according to the International Commission on Illumination, UV-C refers to the short-wavelength segment of ultraviolet radiation with wavelengths of 200-280 nm). Deep UV light irradiation damages the structure of DNA and RNA molecules, affecting DNA replication and RNA transcription and translation, ultimately leading to cell apoptosis or virus inactivation. Since DNA and RNA are widely present in living organisms, UV radiation is not targeted at specific microorganisms and is a broad-spectrum sterilization method. How to ensure that colored bread retains good color after deep UV sterilization is also a challenge in this field.

[0011] To achieve coloring and microbial control in cold-processed figurative toast, a coloring agent for inkjet printing, its preparation method, and its application in deep ultraviolet sterilization equipment are needed. Summary of the Invention

[0012] The purpose of this invention is to provide a method for preparing a red colorant containing isothiocyanate, thereby obtaining a red colorant containing isothiocyanate with good coloring properties, smooth coloring process, and good cleanliness.

[0013] To achieve the above objectives, the solution of the present invention is: the preparation of a red colorant containing isothiocyanate, comprising the following steps:

[0014] S1: Preparation of mustard extract containing isothiocyanate: Germinated mustard seedlings and blanched mustard stems and stalks were obtained, and the two were frozen, homogenized, subjected to ultrasonic enzymatic hydrolysis, pressure-regulated enzymatic hydrolysis, impurity removal and distillation to obtain mustard extract containing isothiocyanate.

[0015] S2: Preparation of red refined mustard pulp: Take root mustard tubers, freeze, thaw, pulp and filter residue, heat and stir, centrifuge and ultrafiltration, fine filtration, UHT sterilization and aseptic filling to obtain red refined mustard pulp;

[0016] S3: Preparation of red colorant containing isothiocyanate: Emulsify the components of mustard extract, red mustard pulp, alcohol and glycerin to obtain a red colorant containing isothiocyanate.

[0017] Furthermore, in step S1, the method for preparing the isothiocyanate-containing mustard extract is as follows:

[0018] (1) After the mustard seeds are selected, cleaned, disinfected, and soaked in water, they are placed in a 27±2℃ incubator under light for 4 to 8 days. On the second day of cultivation, a 25mmol / L MgSO4 solution is sprayed to obtain germinated mustard seedlings. After the germinated mustard seedlings are screened, roots are removed, and they are washed, they are kept in hot water at 75±10℃ for 10±3 minutes, and then transferred to clean ice blocks to spread out and cool down quickly.

[0019] (2) Blanch the mustard stems and stalks in steam for 200±10 seconds, then transfer them to clean ice blocks and spread them out to cool down quickly.

[0020] (3) Cooled sprouted mustard seedlings and mustard stems were bagged, sealed, and frozen at -18℃ for 24 hours.

[0021] (4) Grind frozen vegetables and distilled water into a paste at a ratio of 1:1.2 (w / v);

[0022] (5) Ultrasonic water bath enzymatic hydrolysis, at a temperature of 30-35℃ for 1-2 hours;

[0023] (6) Add maltitol, wherein the mass ratio of enzymatic hydrolysate to maltitol is 2:1. Transfer to a clean polypropylene packaging bag, vacuum seal at -100KPa, then pressurize to 200MPa at a rate of 1MPa / s, maintain for 10min and then depressurize.

[0024] (7) After centrifugation for solid-liquid separation, resin adsorption is performed. After adsorption is completed, impurities are eluted with 4 times the resin column volume of deionized water and 4 times the resin column volume of ethanol / water solution (ethanol volume percentage 20%). Then, elution is performed with 6 times the resin column volume of ethanol / water solution (ethanol volume percentage 75%). The eluent is distilled under reduced pressure to recover ethanol and obtain mustard extract containing isothiocyanate.

[0025] Furthermore, in step S2, the method for preparing the red refined mustard tuber liquid is as follows:

[0026] (1) Freezing: Fresh root mustard heads were frozen at -18±2℃ for 25±1h;

[0027] (2) Thawing: Thaw at room temperature;

[0028] (3) Juice preparation: Grind the mustard tuber into a pulp, filter to remove residue, and obtain mustard tuber juice;

[0029] (4) Heating: Heat the mustard juice at 75℃~80℃ with stirring. When the juice turns from light yellow to red, continue stirring and heating for 60~80 minutes to fully dissolve the red color; then boil at 92℃~95℃ for 8~10 minutes with stirring to denature and precipitate the protein.

[0030] (5) Centrifuge to remove impurities, then pass through an ultrafiltration membrane to cut off the molecular weight of 8000Da to 10000Da, filter out pectin and other high molecular weight carbohydrates, and then use a precision filter membrane with a pore size of 0.22 to 0.45μm to remove microorganisms and other impurities.

[0031] (6) Vacuum concentration to an optical density OD520nm≥2.5;

[0032] (7) UHT sterilization: 118℃, 20s ultra-high temperature instantaneous sterilization followed by aseptic filling.

[0033] Furthermore, in step S3, the method for preparing the red colorant containing isothiocyanate is as follows:

[0034] Weigh each component according to the component ratio. First, stir the isothiocyanate-containing mustard extract with the emulsifier evenly and set aside. Then, slowly stir the refined red mustard pulp with citric acid, tea polyphenols, glycerin, and 95% alcohol to dissolve. After mixing the two parts, shear emulsify them at (4000~6000)±200r / min for 1.5±0.5min, and then seal and package them.

[0035] Furthermore, the components of the red colorant containing isothiocyanate are as follows: 10%–15% isothiocyanate-containing mustard extract, 10%–17% refined red mustard pulp, 38%–42% glycerol, 31%–34% 95% alcohol, 0.8%–1.5% tea polyphenols, 0.1%–0.4% citric acid, and 0.5%–0.8% emulsifier.

[0036] The purpose of this invention is to provide an application of a red colorant containing isothiocyanate in the production of cold-processed deep ultraviolet sterilized shaped bread.

[0037] To achieve the above objectives, the solution of the present invention is: a red colorant containing isothiocyanate, wherein the red colorant containing isothiocyanate is prepared by the above-described method for preparing a red colorant containing isothiocyanate.

[0038] The purpose of this invention is to provide an application of a red colorant containing isothiocyanate in the production of cold-processed deep ultraviolet sterilized figurative bread. Bread printed with this colorant retains a high degree of color intensity after deep ultraviolet sterilization, which not only makes the cold-processed figurative bread present a vivid and well-colored printed pattern, but also ensures good microbial control.

[0039] To achieve the above objectives, the solution of the present invention is: the application of a red colorant containing isothiocyanate in the production of cold-processed deep ultraviolet sterilized shaped bread, comprising the following steps:

[0040] Prepare bread slices to obtain uncolored figurative bread slices, outline and color them, sterilize them with deep ultraviolet sterilization equipment, and then package them to obtain cold-processed figurative bread.

[0041] Furthermore, the specific steps include:

[0042] (1) Prepare the colorant: Install the red colorant containing isothiocyanate into the inkjet printer and set it aside;

[0043] (2) Preparation of figurative bread slices: Weigh each ingredient of the three-color dough according to the known bread weight proportions, and after mixing, dividing, rolling, shaping, putting into molds, fermenting, baking, cooling, and slicing, uncolored figurative bread slices are obtained.

[0044] (3) Coloring the pictographic bread slice: Place the pictographic bread slice under the nozzle of the inkjet printer and outline and color it according to the pictographic trajectory to obtain the colored pictographic bread slice;

[0045] (4) Deep ultraviolet sterilization: Place the colored figurative bread slices in a deep ultraviolet sterilization device, set the sterilization temperature and humidity, sterilization distance and sterilization conveyor belt speed, and obtain sterilized cold-processed figurative bread slices;

[0046] (5) Packaging: The sterilized cold-processed shaped bread slices are passed through an inner packaging machine, and nitrogen is simultaneously filled and oxygen absorber is added to obtain the cold-processed shaped bread.

[0047] Furthermore, in the deep ultraviolet sterilization equipment, the wavelength range of the sterilization lamp is 200-300nm, the half-wavelength is <15nm, the total emissivity is >100mW, the sterilization temperature and humidity are 45-55% and 22-28℃, the sterilization distance is 6-10cm, and the sterilization conveyor belt speed is 20-30cm / s.

[0048] After adopting the above solution, the beneficial effects of the present invention are as follows:

[0049] 1. The method for preparing the red colorant containing isothiocyanate of the present invention provides a novel approach for the preservation and antioxidant color protection of colorants. The method involves preparing mustard extract containing isothiocyanate and refined mustard pulp from mustard greens, and then mixing and emulsifying the two to prepare the red colorant containing isothiocyanate. The red colorant containing isothiocyanate has high color intensity, a color value of 12-20, good cleanliness, and sterilization function. It can be used for coloring figurative bread using a food inkjet printer, with smooth and beautiful coloring and good microbial control.

[0050] 2. The red colorant containing isothiocyanate prepared in this invention is applied to the production of cold-processed figurative bread. With the application of deep ultraviolet sterilization equipment, it still maintains a high degree of color after deep ultraviolet sterilization. This not only makes the spray-painted patterns of the cold-processed figurative bread vivid and colorful, but also ensures good microbial control, making it a high-quality baked product with a strong market competitiveness. Attached Figure Description

[0051] Figure 1 This is a gas chromatogram of isothiocyanate standard solution (0.1 mg / mL). Detailed Implementation

[0052] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0053] This invention provides a method for preparing a red colorant containing isothiocyanate, comprising the following steps:

[0054] Step S1: Preparation of mustard extract containing isothiocyanate:

[0055] (1) After the mustard seeds are selected, cleaned, disinfected, and soaked in water, they are placed in a 27±2℃ incubator under light for 4 to 8 days. On the second day of cultivation, a 25mmol / L MgSO4 solution is sprayed to obtain germinated mustard seedlings. After the germinated mustard seedlings are screened, roots are removed, and they are washed, they are kept in hot water at 75±10℃ for 10±3 minutes, and then transferred to clean ice blocks to spread out and cool down quickly.

[0056] (2) Blanch the mustard stems and stalks in steam for 200±10 seconds, then transfer them to clean ice blocks and spread them out to cool down quickly.

[0057] (3) Cooled sprouted mustard seedlings and mustard stems were bagged, sealed, and frozen at -18℃ for 24 hours.

[0058] (4) Grind frozen vegetables and distilled water into a paste at a ratio of 1:1.2 (w / v);

[0059] (5) Ultrasonic water bath enzymatic hydrolysis, at a temperature of 30-35℃ for 1-2 hours;

[0060] (6) Add maltitol, wherein the mass ratio of enzymatic hydrolysate to maltitol is 2:1. Transfer to a clean polypropylene packaging bag, vacuum seal at -100KPa, then pressurize to 200MPa at a rate of 1MPa / s, maintain for 10min and then depressurize.

[0061] (7) After centrifugation for solid-liquid separation, resin adsorption is performed. After adsorption, impurities are eluted with 4 times the resin column volume of deionized water and 4 times the resin column volume of ethanol / water solution (ethanol volume percentage 20%). Then, 6 times the resin column volume of ethanol / water solution (ethanol volume percentage 75%) is used for elution. The eluent is distilled under reduced pressure (vacuum degree 0.09 MPa, temperature 40±2℃) to recover ethanol and obtain mustard extract containing isothiocyanate.

[0062] Step S2: Preparation of refined red mustard tuber pulp:

[0063] (1) Freezing: Fresh root mustard heads were frozen at -18±2℃ for 25±1h;

[0064] (2) Thawing: Thaw at room temperature;

[0065] (3) Juice preparation: Grind the mustard tuber into a pulp, filter to remove residue, and obtain mustard tuber juice;

[0066] (4) Heating: Heat the mustard juice at 75℃~80℃ with stirring. When the juice turns from light yellow to red, continue stirring and heating for 60~80 minutes to fully dissolve the red color; then boil at 92℃~95℃ for 8~10 minutes with stirring to denature and precipitate the protein.

[0067] (5) Centrifuge to remove impurities, then pass through an ultrafiltration membrane to cut off the molecular weight of 8000Da to 10000Da, filter out pectin and other high molecular weight carbohydrates, and then use a precision filter membrane with a pore size of 0.22 to 0.45μm to remove microorganisms and other impurities.

[0068] (6) Vacuum concentration to an optical density OD520nm≥2.5;

[0069] (7) UHT sterilization: 118℃, 20s ultra-high temperature instantaneous sterilization followed by aseptic filling.

[0070] Step S3: Preparation of a red colorant containing isothiocyanate:

[0071] The components and proportions of each raw material are as follows: 10%–15% isothiocyanate-containing mustard extract, 10%–17% refined red mustard pulp, 38%–42% glycerol, 31%–34% 95% alcohol, 0.8%–1.5% tea polyphenols, 0.1%–0.4% citric acid, and 0.5%–0.8% emulsifier (mono- and diglyceride fatty acid esters: polyglyceride fatty acid esters = 2:1).

[0072] Weigh out the following components according to the ratio: isothiocyanate-containing mustard extract, red mustard pulp, glycerin, 95% alcohol, tea polyphenols, citric acid, and emulsifier. First, stir slowly to dissolve, then shear emulsify at (4000~6000)±200r / min for 1.5±0.5min, and seal and package.

[0073] The following study examines the influencing factors in the preparation process of red colorants containing isothiocyanates from multiple perspectives.

[0074] Example 1: Preparation process parameters of mustard extract containing isothiocyanate

[0075] The method for preparing the red colorant containing isothiocyanate in this embodiment includes the following steps:

[0076] Step S1: Preparation of mustard extract containing isothiocyanate:

[0077] (1) After selecting and removing impurities from mustard seeds, disinfecting them, and soaking them in water, the seeds were placed in a 27±2℃ incubator under light for 6 days. Starting from the second day of cultivation, a 25mmol / L MgSO4 solution was sprayed to obtain germinated mustard seedlings. After screening, removing roots, and washing the germinated mustard seedlings, 1kg of the seedlings was placed in hot water at 75±10℃ for 10±3 minutes, and then transferred to clean ice blocks to cool down quickly.

[0078] (2) Take 1 kg of mustard stems and stalks and steam them for 200±10 seconds, then transfer them to clean ice blocks and spread them out to cool down quickly.

[0079] (3) Cooled sprouted mustard seedlings and mustard stems were bagged, sealed, and frozen at -18℃ for 24 hours.

[0080] (4) Mix frozen vegetables and distilled water at a ratio of 1:1.2 (w / v) and grind them into a paste;

[0081] (5) Ultrasonic water bath enzymatic hydrolysis, at a temperature of 30-35℃ for 1-2 hours;

[0082] (6) Add maltitol, wherein the mass ratio of enzymatic hydrolysate to maltitol is 2:1. Transfer to a clean polypropylene packaging bag, vacuum seal at -100KPa, then pressurize to 200MPa at a rate of 1MPa / s, maintain for 10min and then depressurize.

[0083] (7) After centrifugation for solid-liquid separation, resin adsorption was performed. After adsorption, impurities were eluted with 4 times the resin column volume of deionized water and 4 times the resin column volume of ethanol / water solution (ethanol volume percentage 20%). Then, 6 times the resin column volume of ethanol / water solution (ethanol volume percentage 75%) was used for elution. The eluent was distilled under reduced pressure (vacuum degree 0.09 MPa, temperature 40±2℃) to recover ethanol, yielding 450g of mustard extract containing isothiocyanate, with an isothiocyanate content of 2610μg / g.

[0084] Step S2: Preparation of refined red mustard tuber pulp:

[0085] (1) Freezing: Take 1 kg of fresh root mustard tuber and freeze it at -18±2℃ for 25±1 h;

[0086] (2) Thawing: Thaw at room temperature;

[0087] (3) Juice preparation: Grind the mustard tuber into a pulp, filter to remove residue, and obtain mustard tuber juice;

[0088] (4) Heating: Heat the mustard juice at 75℃~80℃ with stirring. When the juice turns from light yellow to red, continue stirring and heating for 60~80 minutes to fully dissolve the red color; then boil at 92℃~95℃ for 8~10 minutes with stirring to denature and precipitate the protein.

[0089] (5) Centrifuge to remove impurities, then pass through an ultrafiltration membrane to cut off the molecular weight of 8000Da to 10000Da, filter out pectin and other high molecular weight carbohydrates, and then use a precision filter membrane with a pore size of 0.22 to 0.45μm to remove microorganisms and other impurities.

[0090] (6) Vacuum concentration was carried out until the optical density OD520nm≥2.5, and 250g of red slurry was obtained.

[0091] (7) UHT sterilization: 118℃, 20S ultra-high temperature instantaneous sterilization followed by aseptic filling.

[0092] Step S3: Preparation of a red colorant containing isothiocyanate:

[0093] Weigh each component according to the component ratio. Mix the isothiocyanate-containing mustard extract with the emulsifier (mono- and diglyceride fatty acid esters: polyglyceride fatty acid esters = 2:1) until homogeneous. Dissolve the red refined mustard pulp, citric acid, tea polyphenols, glycerol, and 95% alcohol by slow stirring. Then mix the two parts and emulsify by shearing at 5000±200r / min for 1.5±0.5min. Seal and package.

[0094] Measurement method:

[0095] (1) Determination of isothiocyanate: chromatographic column parameters: FFAP (polyethylene glycol capillary column, length 30m × inner diameter 0.32mm × film thickness 0.25μm), instrument settings: injection volume 1μL, split ratio 5:1, carrier gas flow rate 1.0mL / min, temperature program: first hold at 100℃ for 10min, then increase to 200℃ at a rate of 10℃ / min, hold for 2min, injection port temperature and detector temperature are 220℃ and 230℃ respectively.

[0096] (2) The liquid chromatography parameters for the red pigment were: C18 column, methanol:0.2% glacial acetic acid solution = 80:20 (v / v) as mobile phase, flow rate 1.0 ml / min, column temperature 25℃. Structural identification revealed that the main component of the red pigment was peonidin. The ultraviolet detection wavelength was 530 nm, injection volume 10 μL / sample, and the standard was 3-glucoside paeoniflorin.

[0097] Table 1. Effects of sonication-promoted enzymes and voltage-regulated enzymes on isothiocyanate content in mustard extract.

[0098]

[0099]

[0100] Table 1 shows the effects of sonication-promoted enzymes and pressure-regulated enzymes on the isothiocyanate content in mustard extract.

[0101] Gas chromatogram of isothiocyanate standard solution as shown in the figure. Figure 1 The figure shows the chromatographic peaks and retention times of each isothiocyanate in a 0.1 mg / mL mixed standard solution. Qualitative analysis was performed using retention time, as the retention times of each isothiocyanate in the sample solution were consistent with those in the standard solution. Quantification was performed using the internal standard method.

[0102] Germinated mustard seedlings obtained from germination of mustard seeds can accumulate glucosinolates, a precursor substance in sprouts, which can increase the activity of endogenous myrosinase in mature vegetables and sprouts, thereby enriching the enzymatic hydrolysis product isothiocyanate.

[0103] By referencing enzyme-catalyzed groups 1 to 4, the temperature and time parameters of ultrasonic enzymatic hydrolysis were optimized to provide the best hydrolysis environment for myrosinase, allowing glucosinolates and myrosinase to come into full contact.

[0104] Referring to enzyme-catalyzed groups 5 and 6, a pressure-controlled catalytic approach was adopted to reduce the thermal stability of myrosinase. However, under certain conditions, polyhydroxy alcohols can provide effective protection. Maltitol was added to promote the catalytic reaction process of myrosinase. The promoting effect was more significant under high pressure than under normal pressure, improving the binding ability of the substrate to myrosinase. Compared with the system of enzyme-catalyzed group 2, after dilution with alcohol at a 2:1 ratio, the isothiocyanate content was (1186*2) / 3 = 791 (μg / g), while the isothiocyanate content of enzyme-catalyzed group 6, after pressure adjustment with methanol, was 866 (μg / g), a significant increase compared to enzyme-catalyzed group 2.

[0105] Compared with the blank enzyme-catalyzed group, after dilution with alcohol at a ratio of 2:1, the isothiocyanate content was (918*2) / 3=612 (μg / g), while after methanol pressure adjustment, the isothiocyanate content of enzyme-catalyzed group 5 was 673 (μg / g), which is an increase compared with the blank enzyme-catalyzed group.

[0106] In summary, compared with the enzymatic control group, ultrasonic temperature and time, as well as pressure adjustment, can fully hydrolyze glucosinolates into isothiocyanates, which has a positive effect on the enzymatic hydrolysis of isothiocyanates and can improve the quality of mustard extract.

[0107] Example 2: Preparation process parameters of red refined mustard pulp

[0108] In this embodiment, the preparation method of the red colorant containing isothiocyanate is the same as in Example 1, except that the heating parameters of the red refined pulp of mustard tuber are different.

[0109] Table 2. Effects of heating parameters on the quality of red refined mustard pulp.

[0110]

[0111] (1) Color stability test, using pigment retention rate as the indicator: The sample was placed in direct sunlight at 20-25℃ for 24 hours. The absorbance at 530nm wavelength before and after treatment was measured using a UV-Vis spectrophotometer, and the pigment retention rate was calculated. Pigment retention rate: A(%) = Ax / A0 × 100%. Where: Ax is the absorbance after sample treatment, and A0 is the absorbance before sample treatment. Soluble solids are the percentage of soluble solids by mass in a liquid, in units of Bx. The soluble solids content is read directly from the refractometer.

[0112] (2) Color value is the absorbance of a unit mass sample at a 1% concentration, measured by a spectrophotometer at its maximum absorption peak using a 1cm cuvette. The absorbance of the extract was measured at 400-620nm; at pH 3, the maximum absorption wavelength was 530nm. 25mg of sample was weighed into a 25ml volumetric flask and diluted to 25ml with 50% ethanol. Then, 2.5ml was transferred to a 100ml volumetric flask, and 80ml of buffer solution was added for ultrasonic dissolution. After cooling, the solution was diluted to 100ml with pH 3.0 buffer solution and mixed thoroughly. The reference solution was prepared using pH 3.0 buffer solution as a blank. The absorbance was measured at 530nm using a 1cm wide cuvette. According to the Chinese definition of color value, it is equal to the absorbance of a unit mass (g) of solution with a liquid layer thickness of 1cm in 100ml. E 1％ 1cm = (1%A) / (CL), where: C is the concentration, L is the thickness of the cuvette (1 cm), and A is the absorbance.

[0113] Table 2 shows the effect of heating parameters on the quality of refined red mustard pulp. Two heating processes were used, employing a segmented heating process: heating at 75℃~80℃ with stirring and holding for 60-80 min to fully dissolve the red pigment; then boiling at 92℃~95℃ for 8-10 min with stirring to denature and precipitate the protein. The soluble solids content of the two heating processes was 61 Bx. Structural identification revealed that the main component of the red pigment was peonidin. The degree of red pigment dissolution and protein denaturation / precipitation in the segmented heating process affects the color value and pigment loss rate of the refined red pulp.

[0114] Example 3: Preparation ratio and process parameters of red colorant

[0115] In this embodiment, the preparation method of the red colorant containing isothiocyanate is the same as in Example 1, except that the ratio and process parameters of the red colorant containing isothiocyanate are different.

[0116] Table 3. Formulation of red colorants containing isothiocyanates

[0117]

[0118]

[0119] Table 4. Effects of different mixing ratios on the quality of red inkjet pigment for inkjet printing.

[0120]

[0121] Measurement method:

[0122] The antibacterial performance test was conducted using the inhibition zone method. The negative control was physiological saline. Multiple sterile culture dishes were prepared, and 50 μL of 10⁸ CFU / mL bacterial suspensions of Staphylococcus aureus, Escherichia coli, and Salmonella were evenly spread onto sterile bacterial nutrient agar plates. 10 μL of each sample was then added to LB plates. The plates were numbered and labeled with the bacterial strains on the bottom. The dishes were incubated at 37°C for 16–18 hours. The diameter of the inhibition zone was measured using calipers. Staphylococcus aureus was incubated for 16–18 hours, while Escherichia coli and Salmonella were incubated for 24–48 hours. A larger inhibition zone diameter indicates better antibacterial performance.

[0123] The experimental results are shown in Table 4. The product of this invention has good antibacterial properties against Staphylococcus aureus, Escherichia coli and Salmonella. It can inhibit the growth and toxin production of bacteria and prevent or alleviate food spoilage caused by Staphylococcus aureus, Escherichia coli and Salmonella.

[0124] Table 4 shows the effect of different formulation ratios on the quality of red inkjet colorant for inkjet printing. In formulation comparison 1, because deionized water was used instead of isothiocyanate-containing mustard extract, the isothiocyanate content was 0. Formulation 2, however, added 12% mustard extract, resulting in an isothiocyanate content of 282 μg / g. In other formulations and comparison groups that added isothiocyanate-containing mustard extract, the diameter of the inhibition zone was significantly increased, indicating that the addition of isothiocyanate has an effective antibacterial effect. In formulation 1, the amount of isothiocyanate-containing mustard extract added was less than 10%, so its bactericidal effect was weaker. It should be noted that compared to formulation 2, the use of deionized water instead of refined red mustard pulp in comparison 2 mainly affected the color depth, with minimal impact on indicators such as sterilization, viscosity, and drying time.

[0125] Furthermore, the color value of formulation 2 is 15.3, suitable for red coloring. In this formulation, glycerol effectively reduces water activity and inhibits isothiocyanate hydrolysis while maintaining the fluidity of the inkjet pigment, thus helping to stabilize the quality of the red colorant. Citric acid and tea polyphenols have color-protecting effects on red pigments. A 2:1 ratio of mono- and diglyceride fatty acid esters to polyglycerol fatty acid esters acts as an emulsifier for isothiocyanates, stabilizing the liquid pigment. Without an emulsifier, sedimentation and stratification will occur after standing for 5 minutes.

[0126] Compared with other formulations, the isothiocyanate-containing mustard extract and refined mustard red pulp simultaneously affect the viscosity of the colorant, which in turn affects the smoothness of the colorant in the inkjet printing pipeline; the isothiocyanate-containing mustard extract will shorten the drying time and improve the efficiency of the inkjet printing process.

[0127] In summary, the selection of the formulation of red colorants containing isothiocyanates requires comprehensive consideration of the balance between antibacterial properties, viscosity, and drying time. Formulation 2 is the preferred ratio: the proportions of mustard extract, refined red mustard pulp, (mono- and diglyceride fatty acid esters: polyglyceride fatty acid esters = 2:1), citric acid, tea polyphenols, glycerol, and 95% alcohol are 12%, 13.5%, 0.6%, 0.2%, 1.2%, 40%, and 32.5%, respectively. This ratio achieves the optimal balance between antibacterial properties, viscosity, and drying time in the red colorant containing isothiocyanates.

[0128] Furthermore, the optimized colorant formulation ratios all enhance the stability of the colorant. In formulation group 2, the physicochemical properties of the colorant were: moisture 28.51±0.05%, water activity 0.885±0.015. The emulsifier and glycerol in the formulation effectively reduced the volatility of isothiocyanate, thereby increasing the residual amount of isothiocyanate in the red colorant and improving the stability of isothiocyanate in the colorant.

[0129] Two groups with the above-mentioned optimal ratios were selected to further study the effect of shear emulsification process on the quality of red colorants containing isothiocyanate. The results are shown in Table 5.

[0130] Table 5. Effect of colorant shear emulsification process on the quality of isothiocyanate-containing red colorants

[0131]

[0132] Measurement method:

[0133] Settling stability was monitored using a settling rate test: 25 ml of sample was poured into a stoppered colorimetric tube (50 ml), left for 24 hours, and then visually observed under natural light. Results showing no agglomeration or turbidity were used for stability testing. The sample was then centrifuged at 4000 rpm for 3 minutes at room temperature, and the presence and percentage of phase separation were observed.

[0134] Table 5 shows the effect of different shear emulsification processes on the quality of red inkjet printers. Compared to unsheared emulsification, liquid red inkjet printers produced by shear emulsification have a more uniform liquid state, are less prone to stratification and sedimentation, and have better flowability, making them less likely to clog the small diameter of the inkjet printer nozzles.

[0135] While shear emulsification group 3 offers good stability and smoothness, and won't clog the printer's pipes, the excessive foaming caused by high-speed shearing can lead to interrupted blank sections in the print. Therefore, shear emulsification group 2 is the preferred shear emulsification process: shear emulsification at 5000±200 r / min for 1.5±0.5 min, resulting in a colorant that is well-matched to the printing process.

[0136] Example 4: Application of isothiocyanate-containing red coloring agents in the production of cold-processed deep ultraviolet sterilized shaped bread

[0137] In this embodiment, the red colorant containing isothiocyanate prepared in Example 1 is applied to the production of cold-processed deep ultraviolet sterilized figurative bread.

[0138] Specifically, the following steps are included:

[0139] (1) Prepare the colorant: Install the red colorant containing isothiocyanate prepared in Example 1 into the inkjet printer for later use;

[0140] (2) Preparation of figurative bread slices: Weigh each ingredient of the three-color dough according to the known bread weight proportions, and after mixing, dividing, rolling, shaping, putting into molds, fermenting, baking, cooling, and slicing, uncolored figurative bread slices are obtained.

[0141] (3) Coloring the pictographic bread slice: Place the pictographic bread slice under the nozzle of the inkjet printer and outline and color it according to the pictographic trajectory to obtain the colored pictographic bread slice;

[0142] (4) Deep ultraviolet sterilization: The colored pictographic bread slices are placed in a deep ultraviolet sterilization device. The parameters are set as follows: the wavelength range of the sterilization lamp is 200-300nm, the half-width is <15nm, the total emissivity is >100mW, the sterilization temperature and humidity is 45-55% and 22-28℃, the sterilization distance is 6-10cm, and the sterilization conveyor belt speed is 20-30cm / s. The sterilized cold-processed pictographic bread slices are obtained.

[0143] (5) Packaging: The sterilized cold-processed shaped bread slices are passed through an inner packaging machine, and nitrogen is simultaneously filled and oxygen absorber is added to obtain the cold-processed shaped bread.

[0144] Table 6. The impact of deep ultraviolet sterilization process on the quality of shaped bread.

[0145]

[0146] Measurement method:

[0147] Microbiological monitoring methods shall comply with GB 4789; limit values ​​for the following indicators: Staphylococcus aureus—n=5, c=1, m=100, M=1000; coliforms—n=5, c=2, m=10, M=10 2 Total bacterial count—n=5, c=2, m=10 4 M=10 5 .

[0148] Pigment Retention Rate: The shaped bread was treated in a deep ultraviolet sterilization device. The absorbance at 530 nm wavelength before and after treatment was measured using a UV-Vis spectrophotometer, and the pigment retention rate was calculated to evaluate color stability. Pigment Retention Rate: A(%) = Ax / A0 × 100%. Where: A0 is the absorbance of the sample before treatment; Ax is the absorbance of the sample after treatment.

[0149] The test results of each embodiment are shown in Table 6, which illustrates the effect of different deep ultraviolet sterilization processes on the quality of shaped bread.

[0150] The control group, which did not undergo deep ultraviolet (UV) sterilization, had a very high pigment retention rate, but a higher number of microorganisms. Comparing group 1 (UV sterilization control group) and groups 1 and 2 (UV sterilization comparison groups), group 1 had more reasonable temperature and humidity settings. Although its pigment retention rate was slightly lower than groups 1 and 2, its sterilization effect was better. Considering both sterilization effect and pigment retention rate, the parameter settings for group 1 (UV sterilization control group) were relatively more suitable, and the taste did not change significantly after the UV sterilization process.

[0151] During the shelf life of bread, the isothiocyanate-containing red colorant of this invention remained stable under light-protected storage conditions. It can be used for food coloring and the spraying of shaped bread, resulting in vivid and lifelike designs. Within the shelf life, the levels of Staphylococcus aureus, coliform bacteria, and total bacterial count met food safety standards.

[0152] To further illustrate the various embodiments, the present invention provides accompanying drawings. These drawings are primarily used to illustrate the embodiments and can be used in conjunction with the relevant descriptions in the specification to explain the operating principles of the embodiments. With reference to these drawings, those skilled in the art should be able to understand other possible implementations and the advantages of the present invention. Furthermore, the front, rear, left, and right directions mentioned in this embodiment are merely references and do not represent actual locations in practical application. In addition, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0153] The above description is only a preferred embodiment of the present invention and is not intended to limit the design of this case. All equivalent changes made based on the key design features of this case shall fall within the protection scope of this case.

Claims

1. A process for the preparation of an isothiocyanate-containing red colorant, characterized by: The method comprises the following steps: S1: preparing isothiocyanate-containing mustard extract: obtaining sprouted mustard seedlings and blanched mustard stem and leaf, freezing, homogenizing, ultrasonic-assisted enzymatic hydrolysis, pressure-assisted enzymatic hydrolysis, impurity removal and distillation to obtain isothiocyanate-containing mustard extract; S2: preparing red mustard head refined juice: taking root mustard head, freezing, thawing, slurry preparation, residue filtration, heating and stirring, centrifugation and ultrafiltration, refined filtration, UHT sterilization and aseptic filling to obtain red mustard head refined juice; S3: preparing isothiocyanate-containing red colorant: emulsifying mustard extract, emulsifier, red mustard head refined juice, citric acid, tea polyphenol, glycerol and alcohol to obtain isothiocyanate-containing red colorant.

2. A process for the preparation of an isothiocyanate-containing red colorant as claimed in claim 1, characterized in that: In step S1, the preparation method of the isothiocyanate-containing mustard extract is as follows: (1) After the mustard seeds are selected, disinfected, soaked and water-absorbed, they are cultured in a 27±2℃ incubator for 4-8 days, and 25mmol / L MgSO4 solution is sprayed on the second day of the culture to obtain sprouted mustard seedlings, which are screened, de-rooted and cleaned, and then transferred to clean ice to spread out and cool down rapidly in 75±10℃ hot water; (2) The mustard stem and leaf are steamed and blanched for 200±10 seconds, and then transferred to clean ice to spread out and cool down rapidly; (3) The cooled sprouted mustard seedlings and mustard stem and leaf are sealed in bags and frozen in a-18℃ refrigerator for 24 hours; (4) The frozen mustard is ground into slurry at a ratio of 1:1.2 w / v to distilled water; (5) Ultrasonic water bath enzymatic hydrolysis is performed at a temperature of 30-35℃ for 1-2 hours; (6) Maltitol is added, and the mass ratio of the enzymatic hydrolysis solution to maltitol is 2:1, and then the mixture is transferred to a clean polypropylene packaging bag, vacuum sealed at-100KPa, pressurized to 200MPa at a speed of 1MPa / s, maintained for 10 minutes, and then depressurized; (7) After centrifugation for solid-liquid separation, resin adsorption is performed, and after adsorption, 4 times the volume of deionized water and 4 times the volume of ethanol solution are used to elute impurities, wherein the volume percentage of ethanol in the ethanol solution is 20%, and then 6 times the volume of ethanol solution is used for elution, wherein the volume percentage of ethanol in the ethanol solution is 75%, and the eluent is distilled under reduced pressure to recover ethanol, thereby obtaining the isothiocyanate-containing mustard extract.

3. A process for the preparation of an isothiocyanate-containing red colorant as claimed in claim 1, characterized in that: In step S2, the preparation method of the red mustard head refined juice is as follows: (1) Freezing: fresh root mustard head is frozen at-18±2℃ for 25±1 hours; (2) Thawing: thawing at room temperature; (3) Juice preparation: grinding, filtering and removing residue to obtain mustard head juice; (4) Heating: heating the mustard head juice at 75-80℃, and the juice changes from light yellow to red, and continues to be heated and stirred for 60-80 minutes to fully dissolve the red color; then boiling at 92-95℃ for 8-10 minutes to denature and precipitate proteins; (5) centrifugal impurity removal, then cross-flow 8000Da-10000Da molecular weight through ultrafiltration membrane, filter out pectin high molecular weight carbohydrates, then remove microorganisms and other impurities through 0.22-0.45μm pore size precision filtration membrane; (6) vacuum concentration to optical density OD520nm≥2.5; (7) UHT sterilization: 118℃, 20s ultra-high temperature instantaneous sterilization, then aseptic filling.

4. The method of preparing an isothiocyanate-containing red colorant of claim 1, wherein: In step S3, the preparation method of the isothiocyanate-containing red colorant is as follows: Each component is weighed according to the component ratio, the isothiocyanate-containing mustard extract and the emulsifier are first stirred uniformly, and then the mustard red refined paste, citric acid, tea polyphenol, glycerol and 95% alcohol are slowly stirred and dissolved, and then the two parts are mixed and sheared and emulsified at 4000-6000 r / min for 1.5±0.5 min, and then sealed and packaged.

5. A process for the preparation of an isothiocyanate-containing red colorant as claimed in claim 4, characterized in that: The component ratio of the isothiocyanate-containing red colorant is as follows: isothiocyanate-containing mustard extract 10%-15%, mustard red refined paste 10%-17%, glycerol 38%-42%, 95% alcohol 31%-34%, tea polyphenol 0.8%-1.5%, citric acid 0.1%-0.4%, and emulsifier 0.5%-0.8%.

6. An isothiocyanate-containing red colorant characterized by: The isothiocyanate-containing red colorant is prepared by the preparation method of the isothiocyanate-containing red colorant according to any one of claims 1-5.

7. Use of the isothiocyanate-containing red colorant according to claim 6 for the production of cold-worked deep-UV sterilized hieroglyphic bread, characterized in that: The method comprises the following steps: Preparation of bread slices, obtaining uncolored hieroglyphic bread slices, outline coloring, deep ultraviolet sterilization using a deep ultraviolet sterilization device, and obtaining cold-processed hieroglyphic bread after inner packaging.

8. Use of the isothiocyanate-containing red colorant according to claim 7 for the production of cold-worked deep-UV sterilized hieroglyphic bread, characterized in that: Specifically comprising the following steps: (1) preparing a colorant: installing the isothiocyanate-containing red colorant on a spray drawing machine and reserving it for use; (2) preparing hieroglyphic bread slices: weighing each ingredient of a three-color dough according to a known bread weight ratio, stirring, dividing, rolling up, shaping, molding, fermenting, baking, cooling, and slicing to obtain uncolored hieroglyphic bread slices; (3) coloring hieroglyphic bread slices: placing the hieroglyphic bread slices under the spray drawing nozzle of the spray drawing machine, and performing outline coloring according to the hieroglyphic track to obtain colored hieroglyphic bread slices; (4) deep ultraviolet sterilization: placing the colored hieroglyphic bread slices in a deep ultraviolet sterilization device, setting the sterilization temperature and humidity, sterilization distance, and sterilization conveyor belt speed to obtain sterilized cold-processed hieroglyphic bread slices; (5) packaging: passing the sterilized cold-processed hieroglyphic bread slices through an inner packaging machine, synchronously charging nitrogen and configuring a deoxidizer to obtain the cold-processed hieroglyphic bread.

9. Use of the isothiocyanate-containing red colorant according to claim 7 for the production of cold-worked deep-UV sterilized hieroglyphic bread, characterized in that: In the deep ultraviolet sterilization device, the sterilization lamp has a wavelength range of 200-300nm, a half-wave width of <15nm, a total radiation rate of >100mW, a sterilization temperature and humidity of 45-55% and 22-28℃, a sterilization distance of 6-10㎝, and a sterilization conveyor belt speed of 20-30㎝ / s.

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