Oil-soluble beet red pigment, and preparation method and application thereof

Abstract

The application belongs to the field of natural pigment modification, and particularly relates to oil-soluble beet red pigment as well as a preparation method and application thereof. An aqueous solution containing beet red pigment and phospholipid is added into an aqueous solution containing water-soluble protein and / or water-soluble polypeptide, and then dried to obtain oil-soluble beet red pigment composite powder. Then, the powder is subjected to low-temperature ultrafine grinding to obtain oil-soluble beet red pigment ultrafine powder. Then, the oil-soluble beet red pigment ultrafine powder is added into vegetable oil, and subjected to circulation treatment by a ball mill-colloid mill to obtain oil-soluble beet red pigment. The oil-soluble beet red pigment prepared by the application does not need chemical modification, does not add synthetic emulsifiers and other components, and uses natural and safe materials. The light stability and thermal stability of the beet red pigment are improved, the application range of the beet red pigment is expanded, and the oil-soluble pigment synthesized by industry can be replaced.

Description

Technical Field

[0001] This invention belongs to the field of natural pigment modification, specifically relating to an oil-soluble beet red pigment and its preparation method and application. Background Technology

[0002] Beetroot red, also known as beetroot red pigment, is a natural pigment produced from edible red beets through extraction, separation, concentration, and drying. Its main components are betaine anthocyanins and betaine xanthocyanins. Beetroot red is a reddish-purple to dark purple liquid, in lumps, powder, or paste form. It has an unpleasant odor, is readily soluble in water, sparingly soluble in anhydrous ethanol, propylene glycol, and acetic acid, and insoluble in organic solvents such as ether, acetone, chloroform, benzene, glycerol, and oils. Its aqueous solution is red to purplish-red, with a bright color and good dyeing properties, but it has poor heat resistance, and its degradation rate increases with temperature.

[0003] The United States permitted the use of concentrated red beet juice or dehydrated red beet powder as a food coloring agent as early as 1960, and included it in the "Exempt from Safety Certificates" list to this day. In 1978, the Joint FAO / WHO Expert Committee on Food Additives reiterated that its provisional Admission Limit (ADI) was "not required." Betaine is pharmacologically inert and as safe as edible beets. Food additive hygiene standards stipulate that beet red can be used in fruit-flavored beverages (liquid and solid), fruit juice beverages, soft drinks, formulated wines, candies, pastry colorings, candied fruit peels, canned goods, concentrated fruit juice, plums, ice cream, popsicles, sweet jellies, biscuits, and fillings, etc., in amounts required for normal production.

[0004] Because beetroot red pigment is easily soluble in water but insoluble in oil, its application range is greatly limited. Based on this, researchers have conducted extensive research to improve the oil solubility of beetroot red pigment, including:

[0005] Chinese patent CN201911001462.4 discloses a strain of Candida vesicatoria and its use in the preparation of oil-soluble beet red pigment. The oil-soluble beet red pigment is prepared by mixing the biosurfactant produced by fermentation of Candida vesicatoria with oil and beet red pigment. The beet red color is evenly distributed and no precipitation occurs. However, the cost of the strain used is too high, making it difficult to achieve large-scale production. In addition, there is a lack of relevant standards for the biosurfactant.

[0006] Chinese patent CN201711092553.4 discloses an emulsification process for beet red pigment. The process involves mixing beet red pigment powder with an oil-phase dispersion, grinding the mixture, adding an emulsifier, and then vacuum emulsifying it to obtain oil-soluble beet red. The process relies on the emulsifier to emulsify and disperse the beet red pigment particles. However, beet red is not lipophilic, and the potential energy of the solid-liquid interface formed between it and oil is difficult to maintain a stable state using an emulsifier. This can easily lead to stratification and precipitation, affecting product quality and usability.

[0007] Chinese patent CN202210880227.4 discloses a method for preparing modified betalain, which involves reacting betalain with a carboxylic acid compound to obtain modified betalain, thus solving the problem of betalain's hydrophilicity and oleophobicity, allowing its application in oil-soluble systems. However, this method requires the use of large amounts of toxic solvents, limiting the application of betalain in the food industry.

[0008] While the aforementioned processes can improve the hydrophilicity and oleophobicity of beet red pigment to some extent, they still have certain drawbacks and shortcomings: most processes are complex and costly, some require the use of toxic solvents, raising concerns about food safety, and the final product suffers from low stability, failing to meet market demands. Therefore, it is necessary to provide a novel oil-soluble beet red pigment and its preparation method to overcome these shortcomings. Summary of the Invention

[0009] In order to overcome the shortcomings and disadvantages of the prior art, the primary objective of this invention is to provide a method for preparing oil-soluble beet red pigment. This method does not use organic solvents, does not require chemical modification of beet red, does not add synthetically derived emulsifiers, and uses natural and safe materials. The beet red can be uniformly and stably dispersed in oils, expanding the application range of beet red from water-soluble to oil-soluble, and also improving its stability.

[0010] Another object of the present invention is to provide an oil-soluble beet red pigment prepared by the above preparation method.

[0011] Another object of the present invention is to provide the application of the above-mentioned oil-soluble beet red pigment.

[0012] The objective of this invention is achieved through the following technical solution:

[0013] A method for preparing an oil-soluble beet red pigment includes the following steps:

[0014] (1) Add an aqueous solution containing beet red pigment and phospholipids to an aqueous solution containing water-soluble protein and / or water-soluble peptides to obtain a beet red pigment-phospholipid-protein / peptide mixture;

[0015] (2) The beet red pigment-phospholipid-protein / peptide mixture obtained in step (1) is dried to obtain oil-soluble beet red pigment composite powder.

[0016] The method for preparing the oil-soluble beet red pigment preferably further includes the following steps:

[0017] (3) The oil-soluble beet red pigment composite powder obtained in step (2) is subjected to low-temperature ultrafine grinding to obtain oil-soluble beet red pigment ultrafine powder.

[0018] The method for preparing the oil-soluble beet red pigment preferably further includes the following steps:

[0019] (4) Add the oil-soluble beet red pigment ultrafine powder obtained in step (3) to vegetable oil, grind and disperse to obtain oil-soluble beet red pigment;

[0020] In step (1), the mass ratio of beet red pigment to phospholipid is 1:(0.05~30.0), preferably 1:

[0021] (0.05~20.0);

[0022] The mass fraction of the aqueous solution containing water-soluble protein and / or water-soluble polypeptide in step (1) is 5-45%, preferably 5-25%;

[0023] In step (1), the total amount of water-soluble protein and water-soluble polypeptide in the beet red-phospholipid-protein / peptide mixture is in the mass ratio of beet red to water-soluble protein (0.01-13.0):1, preferably (0.01-10.0):1.

[0024] The phospholipid mentioned in step (1) is at least one of lecithin, modified soybean phospholipid, and enzymatically hydrolyzed soybean phospholipid;

[0025] The phospholipids mentioned in step (1) are preferably at least one of modified soybean phospholipids and enzymatically hydrolyzed soybean phospholipids;

[0026] The aqueous solution containing beetroot red pigment and phospholipids mentioned in step (1) is preferably prepared by the following method:

[0027] Mix beet red pigment and phospholipids and dissolve them in water to obtain a homogeneous solution, which is an aqueous solution containing beet red pigment and phospholipids;

[0028] The water-soluble protein mentioned in step (1) is at least one of collagen, soy protein isolate, and sodium caseinate;

[0029] The polypeptide mentioned in step (1) is a soybean oligopeptide;

[0030] The aqueous solution containing water-soluble protein and / or water-soluble polypeptide in step (1) preferably contains at least one of soy protein isolate, sodium caseinate and soy oligopeptides.

[0031] The aqueous solution containing beet red pigment and phospholipids mentioned in step (1) is preferably slowly added to the aqueous solution containing water-soluble protein and / or water-soluble peptide and sheared to mix, so as to obtain a beet red pigment-phospholipid-protein / peptide mixture.

[0032] The drying process described in step (2) is preferably spray drying; wherein, the oil-soluble beet red pigment composite powder obtained by spray drying has a relatively small particle size (up to 100 mesh or less), which is beneficial to improving the efficiency of ultrafine grinding.

[0033] The spray drying described in step (2) is preferably at least one of pressure spray drying and centrifugal spray drying;

[0034] The beet red pigment-phospholipid-protein / peptide mixture described in step (2) is preferably homogenized before drying;

[0035] The preferred temperature for the low temperature mentioned in step (3) is 0–10°C;

[0036] The particle size of the oil-soluble beetroot ultrafine powder mentioned in step (3) is 100-300 mesh, preferably 200-300 mesh;

[0037] The beetroot ultrafine powder mentioned in step (4) has a mass fraction of 10-50% in vegetable oil, preferably 10-30%;

[0038] The vegetable oil mentioned in step (4) is at least one of olive oil, corn oil, sunflower seed oil, safflower seed oil and soybean oil;

[0039] The vegetable oil mentioned in step (4) is preferably at least one of olive oil, corn oil and sunflower seed oil;

[0040] The grinding and dispersion process described in step (4) is preferably a ball mill-colloid mill cycle process;

[0041] The grinding and dispersion process described in step (4) is preferably performed until the D90 of the beet red pigment is <0.5 μm;

[0042] The grinding and dispersion time in step (4) is preferably not less than 240 min;

[0043] The principle of this invention:

[0044] First, in an aqueous solution, the hydrophilic -OH terminal of phospholipid molecules and the =O terminal of beetroot red pigment molecules can bind together via hydrogen bonding in a 1:1 ratio, meaning one phospholipid molecule is bonded to one beetroot red pigment molecule. Therefore, this invention provides lipophilicity to beetroot red through phospholipids. Furthermore, an aqueous solution containing beetroot red pigment and phospholipids is slowly added to an aqueous solution containing water-soluble proteins and / or water-soluble peptides. The water-soluble proteins or peptides can assist phospholipids in imparting lipophilicity to beetroot red, thereby further improving the stability of beetroot red pigment in oils.

[0045] A higher proportion of phospholipids provides stronger lipophilicity to betalains, but excessive phospholipids can make the betalain powder too soft, making it difficult to further break down during ball milling. Therefore, considering production costs and the susceptibility of proteins to various environmental influences such as denaturation, spoilage, and pathogen growth, the ratio of betalains, phospholipids, and proteins / peptides in this invention is crucial.

[0046] Furthermore, regarding the order of raw material addition, due to the high polarity of phospholipids, if proteins are added first, the proteins will dominate the dispersed phase. If phospholipids are added at this point, the phospholipid molecules, influenced by the larger molecular weight of the proteins, will preferentially bind to the proteins, forming random aggregates. This isolates the beet red pigment molecules, resulting in beet red ultrafine powder that is almost identical to ordinary powder after further drying and pulverization. Adding water-soluble proteins and / or water-soluble peptides to an aqueous solution containing beet red pigment and phospholipids may cause spatial folding of the protein or peptide molecular structure, leading to protein or peptide denaturation, aggregation, and clumping, which will affect the lipophilicity and stability of beet red.

[0047] Secondly, this invention directly mixes oil-soluble beet red pigment ultrafine powder with vegetable oil. The beet red pigment is suspended in the oil in the form of particles. Through repeated grinding with a ball mill and colloid mill, the ultrafine powder is further pulverized. The smaller the particles, the larger the specific surface area, and the stronger the lipophilic effect of phospholipids. This can drag beet red molecules to make them stably dispersed in the oil. After grinding, the beet red particles are further refined to a particle size of less than 0.5μm. With its high specific surface area and lipophilic effect of phospholipids, it can maintain the long-term stability of the emulsion.

[0048] Animal fats have a higher calorie content than vegetable oils and contain large amounts of saturated fatty acids and cholesterol. Excessive consumption can easily lead to hypertension, arteriosclerosis, coronary heart disease, and hyperlipidemia, which are detrimental to human health. In addition, animal fats have a higher freezing point, are prone to solidification at low temperatures, are generally more viscous than vegetable oils, and have a distinctive animal odor, all of which greatly affect the taste and aroma of the final product. Therefore, this invention selects to mix beetroot red pigment ultrafine powder with vegetable oil.

[0049] The present invention has the following advantages and effects compared with the prior art:

[0050] (1) The equipment used in this invention is a general-purpose equipment in the industry.

[0051] (2) The preparation method of the present invention does not involve high-temperature operation, does not use organic solvents in the entire process, does not undergo chemical modification, and does not add synthetically derived emulsifiers or other components. The process and raw materials are green and environmentally friendly, which is more conducive to food safety.

[0052] (3) The oil-soluble beet red pigment prepared by the present invention can be stored for a long time without layering or precipitation. In chocolate application tests, the chocolate color is uniform and there are no pigment particles.

[0053] (4) The oil-soluble beet red pigment composite powder and oil-soluble red pigment ultrafine powder prepared by the present invention can also be marketed as separate products, and their stability is higher than that of ordinary beet red pigment.

[0054] (5) The oil-soluble beet red pigment prepared by the present invention can be flexibly adjusted in terms of its dyeing intensity to adapt to different usage environments.

[0055] (6) This invention improves the photostability and thermal stability of beet red pigment, expands the application range of beet red pigment, and can replace industrially synthesized oil-soluble pigments. Attached Figure Description

[0056] Figure 1 The images show the appearance of the emulsions made from the oil-soluble beet red pigment obtained in Examples 1-7 after being placed in natural light at 25°C for 12 months.

[0057] Figure 2 These are images showing the appearance of chocolates made from the oil-soluble beetroot red pigment obtained in Examples 1-7.

[0058] Figure 3 This is an image showing the appearance of the emulsions prepared from oil-soluble beet red pigments (control samples 1-8) in Comparative Example 1 after being placed under natural light at 25°C for 12 months.

[0059] Figure 4 This is an image showing the appearance of chocolates made from oil-soluble beet red pigment, numbered 1-8 in Comparative Example 1.

[0060] Figure 5 This is an image showing the appearance of the emulsions made from oil-soluble beet red pigments (control samples 9-16) in Comparative Example 2 after being placed under natural light at 25°C for 12 months.

[0061] Figure 6 This is an image showing the appearance of chocolates made from oil-soluble beet red pigment, numbered 9-16 in Comparative Example 2.

[0062] Figure 7This is an image showing the appearance of the emulsions made from oil-soluble beet red pigments (control samples 17-24) in Comparative Example 3 after being placed under natural light at 25°C for 12 months.

[0063] Figure 8 This is an image showing the appearance of chocolates made from oil-soluble beetroot red pigment, which are control samples 17-24 in Comparative Example 3.

[0064] Figure 9 The images show the appearance of emulsions made from oil-soluble beet red pigment in proportions 4 and 5 after being left in natural light at 25°C for 12 months, as well as the appearance of chocolate. Detailed Implementation

[0065] The present invention will be further described in detail below with reference to the embodiments and accompanying drawings, but the embodiments of the present invention are not limited thereto.

[0066] Unless otherwise specified, all experimental methods used are conventional methods, and all materials used (modified soybean lecithin, enzymatically hydrolyzed soybean lecithin, sodium caseinate, soy protein isolate, soybean oligopeptides, etc.) can be purchased commercially.

[0067] (1) The method for preparing beet red pigment in the embodiment is as follows: beet root is used as raw material and is obtained by crushing, water extraction, filtration, refining and drying according to conventional methods;

[0068] (2) The chocolate application experiment method described in the example is as follows: 0.1g of oil-soluble beet red pigment is added to 10g of white chocolate that has been heated and completely liquefied. The mixture is stirred evenly and then poured into a mold to cool and solidify. The shape of the mold is not limited, as long as it is easy to observe. Under natural light, the best result is when the chocolate has a uniform color and no pigment seepage. Otherwise, it proves that the beet red has not reached the oil-soluble dispersion state.

[0069] (3) The color intensity detection method described in the example is as follows: Weigh 0.1g of sample (accurate to 0.0002g), extract and separate beet red pigment from oil using 10ml of acetate-sodium acetate buffer (pH 5.4), repeat the operation 3 to 4 times, combine the buffer and make up to 100ml, use the buffer as a reference, use a spectrophotometer with a 1cm cuvette to measure the absorbance of the sample solution at 535nm, which is the color intensity.

[0070]

[0071] In the formula: A—absorbance at 535 nm; c—concentration of beetroot red solution.

[0072] (4) The deposition rate mentioned in the examples refers to the precipitation and accumulation of beet red pigment under centrifugation. The deposition rate reflects the stability of beet red in oil. The higher the deposition rate, the less stable the oil-soluble beet red. A deposition rate of less than 10% indicates that the beet red is stable in oil and meets the shelf life requirements. The detection method is as follows: Take 5.0g of oil-soluble beet red pigment, centrifuge at 25℃ and 6000 rpm for 10min, pour off the supernatant, and obtain xg of oil layer. The deposition rate α is calculated as follows:

[0073] α = (5-x) / 5 × 100%

[0074] Example 1

[0075] (1) Add 100g beet red pigment (color value 150) and 50g modified soybean lecithin to 3500ml of water and stir until completely dissolved to obtain an aqueous solution containing beet red pigment and lecithin; dissolve 350g sodium caseinate in 4650ml of water to obtain a sodium caseinate aqueous solution with a mass fraction of 7%.

[0076] (2) The aqueous solution containing beet red pigment and phospholipids obtained in step (1) is slowly added to the sodium caseinate aqueous solution at a rate of 10 ml / s, and the solution is sheared for 10 min at a linear speed of 20 m / s using a high-speed shearing machine to obtain a beet red-phospholipid-sodium caseinate mixture.

[0077] (3) The beet red-phospholipid-sodium caseinate mixture obtained in step (2) was homogenized at 45 MPa and then spray-dried into dry powder to obtain beet red pigment composite powder.

[0078] (4) The beet red pigment composite powder obtained in step (3) is pulverized at 12,000 rpm and passed through a 200-mesh sieve in a drying environment of 0-10℃ to obtain beet red pigment ultrafine powder.

[0079] (5) Take 200g of the beet red pigment ultrafine powder obtained in step (4) and add it to 1800ml of olive oil. After grinding in a ball mill and pulverizing in a colloid mill for 120min, oil-soluble beet red pigment is obtained with a particle size D90 = 0.788μm, a coloring strength of 3.0 and a deposition rate of 12.3%. The chocolate should have a uniform color and no beet red pigment particles.

[0080] Example 2

[0081] (1) Add 100g of beet red pigment (color value 150) and 150g of modified soybean lecithin to 2600ml of water and stir until completely dissolved to obtain an aqueous solution containing beet red pigment and lecithin; dissolve 500g of soy protein isolate in 4500ml of water to obtain a soy protein isolate aqueous solution with a mass fraction of 10%.

[0082] (2) The aqueous solution containing beet red pigment and phospholipids obtained in step (1) is slowly added to the aqueous solution of soy protein isolate at a rate of 10 ml / s, and the solution is sheared at a linear speed of 20 m / s for 20 min using a high-speed shearing machine to obtain a beet red-phospholipid-soy protein isolate mixture.

[0083] (3) The beet red-phospholipid-soy protein isolate mixture obtained in step (2) is homogenized at 45 MPa and then spray-dried into dry powder to obtain beet red pigment composite powder.

[0084] (4) The beet red pigment composite powder obtained in step (3) is subjected to ultra-high temperature pulverization at 12000 rpm and passed through a 260-mesh sieve in a drying environment of 0-10℃ to obtain beet red pigment ultrafine powder.

[0085] (5) Take 200g of the beet red pigment ultrafine powder obtained in step (4) and add it to 1800ml of olive oil. After grinding in a ball mill and pulverizing in a colloid mill for 120min, oil-soluble beet red pigment is obtained with a particle size D90 = 0.609μm, a coloring strength of 2.0 and a deposition rate of 8.5%. The chocolate should have a uniform color and no beet red pigment particles.

[0086] Example 3

[0087] (1) Add 500g of beet red pigment (color value 150) and 250g of enzymatically hydrolyzed soybean lecithin to 3500ml of water and stir until completely dissolved to obtain an aqueous solution containing beet red pigment and lecithin; dissolve 600g of sodium caseinate in 3400ml of water to obtain a sodium caseinate aqueous solution with a mass fraction of 15%.

[0088] (2) The aqueous solution containing beet red pigment and phospholipids obtained in step (1) is slowly added to the aqueous solution of soy protein isolate at a rate of 10 ml / s, and the solution is sheared at a linear speed of 20 m / s for 10 min using a high-speed shearing machine to obtain a beet red-phospholipid-sodium caseinate mixture.

[0089] (3) The beet red-phospholipid-sodium caseinate mixture obtained in step (2) was homogenized at 45 MPa and then spray-dried into dry powder to obtain beet red pigment composite powder.

[0090] (4) The beet red pigment composite powder obtained in step (3) is subjected to ultra-high temperature pulverization at 12000 rpm and passed through a 300-mesh sieve in a drying environment of 0-10℃ to obtain beet red pigment ultrafine powder.

[0091] (5) Take 400g of the beet red pigment ultrafine powder obtained in step (4) and add it to 1600ml of corn oil. Grind it in a ball mill and then pulverize it in a colloid mill for 240min until the beet red particle size D90 < 0.5μm. Oil-soluble beet red pigment with D90 = 0.430μm, coloring strength of 11.1 and deposition rate of 6.9% is obtained. The chocolate should have a uniform color and no beet red pigment particles.

[0092] Example 4

[0093] (1) Add 500g of beet red pigment (color value 150) and 700g of enzymatically hydrolyzed soybean lecithin to 6300ml of water and stir until completely dissolved to obtain an aqueous solution containing beet red pigment and lecithin; dissolve 300g of soy protein isolate in 2700ml of water to obtain a 10% soy protein isolate aqueous solution.

[0094] (2) The aqueous solution containing beet red pigment and phospholipids obtained in step (1) is slowly added to the aqueous solution of soy protein isolate at a rate of 10 ml / s, and the solution is sheared for 10 min at a linear speed of 20 m / s using a high-speed shearing machine to obtain a beet red-phospholipid-soy protein isolate mixture.

[0095] (3) The beet red-phospholipid-soy protein isolate mixture obtained in step (2) is homogenized at 45 MPa and then spray-dried into dry powder to obtain beet red pigment composite powder.

[0096] (4) The beet red pigment composite powder obtained in step (3) is subjected to ultra-high temperature pulverization at 12000 rpm and passed through a 260-mesh sieve in a drying environment of 0-10℃ to obtain beet red pigment ultrafine powder.

[0097] (5) Take 400g of the beet red pigment ultrafine powder obtained in step (4) and add it to 1600ml of corn oil. Grind it in a ball mill and then pulverize it in a colloid mill for 240min until the beet red particle size D90 < 0.5μm. This yields oil-soluble beet red pigment with D90 = 0.481μm, a coloring strength of 10.0, and a deposition rate of 4.7%. The chocolate should have a uniform color and beet red pigment particles.

[0098] Example 5

[0099] (1) Add 800g of beet red pigment (color value 150), 370g of modified soybean lecithin, and 220g of enzymatically hydrolyzed soybean lecithin to 6600ml of water and stir until completely dissolved to obtain an aqueous solution containing beet red pigment and lecithin; dissolve 500g of soy protein isolate in 2000ml of water to obtain a 20% soy protein isolate aqueous solution.

[0100] (2) The aqueous solution containing beet red pigment and phospholipids obtained in step (1) is slowly added to the aqueous solution of soy protein isolate at a rate of 10 ml / s, and the solution is sheared at a linear speed of 20 m / s for 20 min using a high-speed shearing machine to obtain a beet red-phospholipid-soy protein isolate mixture.

[0101] (3) The beet red-phospholipid-soy protein isolate mixture obtained in step (2) is homogenized at 45 MPa and then spray-dried into dry powder to obtain beet red pigment composite powder.

[0102] (4) The beet red pigment composite powder obtained in step (3) is subjected to ultra-high temperature pulverization at 12000 rpm through a 220-mesh sieve in a drying environment of 0-10℃ to obtain beet red pigment ultrafine powder.

[0103] (5) Take 600g of the beet red pigment ultrafine powder obtained in step (4) and add it to 1400ml of sunflower seed oil. Grind it in a ball mill and then pulverize it in a colloid mill for 320min until the beet red particle size D90 < 0.5μm. Oil-soluble beet red pigment with D90 = 0.218μm, coloring strength of 19.0 and deposition rate of 1.87% is obtained. The chocolate should have a uniform color and no beet red pigment particles.

[0104] Example 6

[0105] (1) Add 800g of beet red pigment (color value 80), 300g of modified soybean lecithin, and 520g of enzymatically hydrolyzed soybean lecithin to 7600ml of water and stir until completely dissolved to obtain an aqueous solution containing beet red pigment and lecithin; dissolve 600g of soy protein isolate and 150g of sodium caseinate in 3000ml of water to obtain a mixed protein aqueous solution with a mass fraction of 20%;

[0106] (2) The aqueous solution containing beet red pigment and phospholipids obtained in step (1) is slowly added to the mixed protein aqueous solution at a rate of 10 ml / s, and the solution is sheared at a linear speed of 20 m / s for 20 min using a high-speed shearing machine to obtain a beet red-phospholipid-mixed protein mixture.

[0107] (3) The beet red-phospholipid-mixed protein mixture obtained in step (2) is homogenized at 45 MPa and then spray-dried into dry powder to obtain beet red pigment composite powder.

[0108] (4) The beet red pigment composite powder obtained in step (3) is subjected to ultra-high temperature pulverization at 12000 rpm and passed through a 300-mesh sieve in a drying environment of 0-10℃ to obtain beet red pigment ultrafine powder.

[0109] (5) Take 600g of the beet red pigment ultrafine powder obtained in step (4) and add it to 1400ml of sunflower seed oil. Grind it in a ball mill and then pulverize it in a colloid mill for 320min until the beet red particle size D90 < 0.5μm. This yields oil-soluble beet red pigment with D90 = 0.198μm, a coloring strength of 8.1, and a deposition rate of 0.94%. Chocolate should be uniform in color and free of beet red pigment particles.

[0110] Example 7

[0111] (1) Add 500g beet red pigment (color value 80), 150g modified soybean lecithin, and 350g enzymatically hydrolyzed soybean lecithin to 8000ml of water and stir until completely dissolved to obtain an aqueous solution containing beet red pigment and lecithin; dissolve 300g soybean oligopeptides and 150g sodium caseinate in 2197ml of water to obtain a mixed protein aqueous solution with a mass fraction of 17%;

[0112] (2) The aqueous solution containing beet red pigment and phospholipids obtained in step (1) is slowly added to the mixed protein aqueous solution at a rate of 10 ml / s, and the solution is sheared at a linear speed of 20 m / s for 20 min using a high-speed shearing machine to obtain a beet red-phospholipid-mixed protein mixture.

[0113] (3) The beet red-phospholipid-mixed protein mixture obtained in step (2) is homogenized at 45 MPa and then spray-dried into dry powder to obtain beet red pigment composite powder.

[0114] (4) The beet red pigment composite powder obtained in step (3) is subjected to ultra-high temperature pulverization at 12000 rpm through a 240-mesh sieve in a drying environment of 0-10℃ to obtain beet red pigment ultrafine powder.

[0115] (5) Take 450g of the beet red pigment ultrafine powder obtained in step (4) and add it to 1550ml of sunflower seed oil. Grind it in a ball mill and then pulverize it in a colloid mill for 300min until the beet red particle size D90 < 0.5μm. Oil-soluble beet red pigment with D90 = 0.375μm, coloring strength of 6.1 and deposition rate of 2.94% is obtained. The chocolate should have a uniform color and no beet red pigment particles.

[0116] Comparative Example 1

[0117] This example is a comparative example, aimed at comparing the effects of directly mixing ordinary beet red powder (containing dextrin) with emulsifiers and oils to prepare oil-soluble beet red pigment. The specific method is as follows:

[0118] The beetroot red pigment ultrafine powder in step (5) of Example 1 was replaced with ordinary beetroot red powder (containing dextrin) of the same color value and mass, and the emulsifier in Table 1 was added to olive oil. The proportion of emulsifier was the same as that of phospholipid in Example 1. All experiments were conducted under the same experimental conditions as in step (5) of Example 1 to prepare oil-soluble beetroot red pigment. The obtained oil-soluble beetroot red pigment was analyzed for chocolate appearance and emulsion appearance after being stored for 12 months.

[0119] Table 1. Types and proportions of emulsifiers and final product appearance of each control sample in Comparative Example 1

[0120]

[0121] Comparative Example 2

[0122] This example is a comparative example, aimed at comparing the effects of directly mixing ordinary beet red powder (containing dextrin) with emulsifiers and oils to prepare oil-soluble beet red pigment. The specific method is as follows:

[0123] The beetroot red pigment ultrafine powder in step (5) of Example 4 was replaced with ordinary beetroot red powder (containing dextrin) of the same color value and mass, and the emulsifier in Table 2 was added to olive oil. The proportion of emulsifier was the same as that of phospholipid in Example 4. All experiments were conducted under the same experimental conditions as in step (5) of Example 4 to prepare oil-soluble beetroot red pigment. The obtained oil-soluble beetroot red pigment was analyzed for chocolate appearance and emulsion appearance after being stored for 12 months.

[0124] Table 2. Types and proportions of emulsifiers and final product appearance of each control sample in Comparative Example 2

[0125]

[0126] Comparative Example 3

[0127] This example is a comparative example, aimed at comparing the effects of directly mixing ordinary beet red powder (containing dextrin) with emulsifiers and oils to prepare oil-soluble beet red pigment. The specific method is as follows:

[0128] The beetroot red pigment ultrafine powder in step (5) of Example 6 was replaced with ordinary beetroot red powder (containing dextrin) of the same color value and mass, and the emulsifier in Table 3 was added to olive oil. The proportion of emulsifier was the same as that of phospholipid in Example 6. All experiments were conducted under the same experimental conditions as in step (5) of Example 6 to prepare oil-soluble beetroot red pigment. The obtained oil-soluble beetroot red pigment was analyzed for chocolate appearance and emulsion appearance after being stored for 12 months.

[0129] Table 3. Types and proportions of emulsifiers and final product appearance of each control sample in Comparative Example 3

[0130]

[0131]

[0132] Comparative Example 4 had an excessively high phospholipid ratio.

[0133] (1) Add 50g of beet red pigment (color value 150) and 1800g of enzymatically hydrolyzed soybean lecithin to 13.950L of water and stir until completely dissolved to obtain an aqueous solution containing beet red pigment and lecithin; dissolve 350g of sodium caseinate in 4650ml of water to obtain a sodium caseinate aqueous solution with a mass fraction of 7%.

[0134] (2) The aqueous solution containing beet red pigment and phospholipids obtained in step (1) is slowly added to the mixed protein aqueous solution at a rate of 10 ml / s, and the solution is sheared at a linear speed of 20 m / s for 10 min using a high-speed shearing machine to obtain a beet red-phospholipid-mixed protein mixture.

[0135] (3) The beet red-phospholipid-mixed protein mixture obtained in step (2) is homogenized at 45 MPa and then pressure spray dried into dry powder to obtain beet red pigment composite powder. Due to the high phospholipid ratio, the composite powder is highly viscous and has poor flowability. During drying, it sticks to the machine severely, and a thick layer of beet red powder adheres to the inner wall of the equipment.

[0136] (4) The beet red pigment composite powder obtained in step (3) was subjected to superheated grinding at 12,000 rpm in a drying environment of 0-10℃. Due to the high viscosity of the powder, it adhered to the pin of the grinder and was difficult to sieve. Even when the temperature was lowered to -10℃-0℃, the grinding effect could not be improved.

[0137] (5) Take 200g of the beet red pigment ultrafine powder obtained in step (4) and add it to 1800ml of olive oil. After grinding in a ball mill and pulverizing in a colloid mill for 120min, oil-soluble beet red pigment is obtained with a particle size D90 = 15.388μm. Due to the presence of a large amount of insoluble matter during testing, its coloring intensity could not be measured. When used in chocolate, the pigment could not be mixed with the chocolate for coloring. During the circulation process, the ball mill and colloid mill were blocked multiple times. The blockage was cleared as irregular small lumps of paste. The reason for this was that the beet red powder had high viscosity and agglomerated under mechanical action.

[0138] Comparative Example 5

[0139] (1) Add 800g of beet red pigment (color value 150), 370g of modified soybean lecithin, and 220g of enzymatically hydrolyzed soybean lecithin to 6600ml of water and stir until completely dissolved to obtain an aqueous solution containing beet red pigment and lecithin; dissolve 500g of soy protein isolate in 2000ml of water to obtain a 20% soy protein isolate aqueous solution.

[0140] (2) The soy protein isolate aqueous solution obtained in step (1) was slowly added to the aqueous solution containing beet red pigment and phospholipids at a rate of 10 ml / s. As the protein aqueous solution was added, solid particles were gradually observed on the surface of the liquid and their number increased. The solution was sheared at a linear speed of 20 m / s for 20 min using a high-speed shearing machine and filtered through a 100-mesh filter to obtain a beet red-phospholipid-mixed protein mixture. The filter screen contained a large amount of pigment-containing insoluble matter, which was determined to be caused by the denaturation of the protein in the strong polar environment of the beet red-phospholipid solution.

[0141] (3) The beet red-phospholipid-mixed protein mixture obtained by filtering in step (2) is homogenized at 45 MPa and spray-dried under pressure to obtain beet red pigment composite powder.

[0142] (4) The beet red pigment composite powder obtained in step (3) is subjected to ultra-high temperature pulverization at 12000 rpm through a 220-mesh sieve in a drying environment of 0-10℃ to obtain beet red pigment ultrafine powder.

[0143] (5) Take 600g of the beet red pigment ultrafine powder obtained in step (4) and add it to 1400ml of sunflower seed oil. After passing through a ball mill-colloid mill for 320min, oil-soluble beet red pigment is obtained with a particle size D90 = 1.884μm, a coloring strength of 9.2, and a deposition rate of 23.94%. The chocolate application is uneven in color and contains beet red pigment particles.

[0144] The results of comparative examples 1-3 show that adding emulsifier can improve the stability of oil-soluble beet red, but the improvement is very limited. The main reason is that beet red pigment molecules are not lipophilic. Although emulsifiers contain hydrophilic groups, there is no water in the oil-soluble environment. The hydrophilic groups of the emulsifier and beet red molecules are only maintained by intermolecular forces, which are far from enough to overcome the gravity of beet red itself. During the shelf life, it is very easy to aggregate and precipitate, affecting the use of the product.

[0145] Depend on Figure 3-8 It can be seen that the stability of the oil-soluble beetroot red pigment emulsions in Comparative Examples 1-3 is positively correlated with the amount of emulsifier used. However, beetroot red itself has no binding ability with the emulsifier and can only maintain suspension and dispersion by relying on the limited viscosity of the emulsifier. Compared with the preparation method provided by this invention, the stability is significantly different. In the 12-month storage experiment of Examples 1-7, the state of the emulsion did not change, and the appearance of the chocolate was normal. Figure 1-2 In Comparative Example 1, control samples 1-8 showed complete pigment precipitation during the 12-month storage experiment, and the chocolate exhibited a light and uneven color upon application. Figure 3-4 In Comparative Example 2, control samples 9–16 showed complete pigment precipitation during the 12-month storage experiment, although the precipitation rate decreased, and the chocolate's appearance was uneven. Figure 5-6In Comparative Example 3, control samples 17–24 showed complete pigment precipitation during the 12-month storage experiment, with a reduced precipitation rate, resulting in uneven coloring of the chocolate. Figure 7-8 Of these, control sample 23 had less precipitation, but diacetyl tartrate mono- and diglycerides had a strong acetic acid taste, which greatly affected the flavor.

[0146] Furthermore, as can be seen from Examples 1 to 7, the longer the ball mill grinding-colloid mill pulverization cycle treatment time, the smaller the particle size of the oil-soluble beet red pigment, the lower the deposition rate, and the higher the stability.

[0147] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A method for preparing an oil-soluble beet red pigment, characterized in that... Includes the following steps: (1) Add an aqueous solution containing beet red pigment and phospholipids to an aqueous solution containing water-soluble protein and / or water-soluble peptides to obtain a beet red pigment-phospholipid-protein / peptide mixture; (2) The beet red pigment-phospholipid-protein / peptide mixture obtained in step (1) is dried to obtain oil-soluble beet red pigment composite powder. (3) The oil-soluble beet red pigment composite powder obtained in step (2) is subjected to low-temperature ultrafine grinding to obtain oil-soluble beet red pigment ultrafine powder. (4) Add the oil-soluble beet red pigment ultrafine powder obtained in step (3) to vegetable oil, grind and disperse to obtain oil-soluble beet red pigment; The phospholipid mentioned in step (1) is at least one of lecithin, modified soybean phospholipid, and enzymatically hydrolyzed soybean phospholipid; The water-soluble protein mentioned in step (1) is at least one of collagen, soy protein isolate, and sodium caseinate; The polypeptide mentioned in step (1) is a soybean oligopeptide; The mass ratio of beet red pigment to phospholipid in step (1) is 1:(0.05~30.0). The mass fraction of the aqueous solution containing water-soluble proteins and / or water-soluble peptides in step (1) is 5-45%; In step (1), the total amount of water-soluble protein and water-soluble peptide in the beet red-phospholipid-protein / peptide mixture is in the mass ratio of beet red to beet red (0.01~13.0):

1.

2. The method for preparing oil-soluble beet red pigment according to claim 1, characterized in that: The aqueous solution containing beet red pigment and phospholipids described in step (1) is slowly added to the aqueous solution containing water-soluble protein and / or water-soluble peptide and sheared to mix, thereby obtaining a beet red pigment-phospholipid-protein / peptide mixture.

3. The method for preparing oil-soluble beet red pigment according to claim 1, characterized in that: The drying process described in step (2) is spray drying.

4. The method for preparing oil-soluble beet red pigment according to claim 1, characterized in that: The vegetable oil mentioned in step (4) is at least one of olive oil, corn oil, sunflower seed oil, safflower seed oil and soybean oil.

5. The method for preparing oil-soluble beet red pigment according to claim 1, characterized in that: The aqueous solution containing beetroot red pigment and phospholipids mentioned in step (1) was prepared by the following method: Mix beet red pigment and phospholipids and dissolve them in water to obtain a homogeneous solution, which is an aqueous solution containing beet red pigment and phospholipids.

6. The method for preparing oil-soluble beet red pigment according to claim 1, characterized in that: The low temperature mentioned in step (3) is 0~10℃.

7. The method for preparing oil-soluble beet red pigment according to claim 1, characterized in that: The particle size of the oil-soluble beetroot ultrafine powder mentioned in step (3) is 100~300 mesh.

8. The method for preparing oil-soluble beet red pigment according to claim 1, characterized in that: The beetroot red ultrafine powder mentioned in step (4) has a mass fraction of 10-50% in vegetable oil.

9. The method for preparing oil-soluble beet red pigment according to claim 1, characterized in that: The grinding and dispersion described in step (4) is a cycle process of ball mill-colloid mill.

10. The method for preparing oil-soluble beet red pigment according to claim 1, characterized in that: The grinding and dispersion process described in step (4) is performed until the D90 of the beet red pigment is <0.5 μm.

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