Oily liquid white pigment and preparation method thereof

Abstract

The invention relates to the technical field of food coloring agents, in particular to an oily liquid white pigment and a preparation method thereof.The oily liquid white pigment is prepared from, by weight, 40-45 parts of vegetable oil, 35-40 parts of food-grade titanium dioxide, 5-10 parts of polyglycerol fatty acid ester and 10-15 parts of a compound; the compound is prepared by modifying lecithin and gelatin. The white pigment prepared by the invention has good dispersibility and stability, and has no side effect on human body.

Description

Technical Field

[0001] The invention relates to the technical field of food colorants, and in particular to an oily liquid white pigment and a preparation method thereof. Background Art

[0002] Pigments are a class of organic or inorganic substances that can absorb and reflect specific wavelengths of light. They are mainly divided into natural pigments and synthetic pigments. Natural pigments come from animals, plants and microorganisms, such as chlorophyll, anthocyanin, lycopene, etc. Synthetic pigments are synthesized by chemical methods, such as sunset yellow, carmine, etc. They give objects color and can be used in different fields. In the food field, they can color beverages, candies, cakes and other foods, which can not only enhance consumers' perception, but also have a certain promoting effect on food quality and storage time. They can also be used in cosmetics such as lipstick, eye shadow, foundation, etc., which are closely related to people's lives, so people have conducted a lot of research on them.

[0003] Patent CN105558765B discloses a carboxymethyl chitosan grafted food pigment and a preparation method, wherein the azo food pigment is purified; the purified pigment is then chlorinated; and then the grafted reaction with the amino group of carboxymethyl chitosan is carried out to obtain the carboxymethyl chitosan grafted food pigment. The invention selects carboxymethyl chitosan as a carrier, which can achieve the purpose of reducing toxicity while retaining the original properties of the pigment, and improves the anti-reduction ability of the food pigment. Patent CN111728124A discloses a food-grade white pigment with higher safety, including calcium carbonate, plant protein and cellulose, calcium carbonate as a matrix, plant protein as a first coating layer, and cellulose as a second coating layer. The invention uses plant protein to coat calcium carbonate particles, which greatly improves the dispersibility of calcium carbonate in food; cellulose is used to coat calcium carbonate particles, so that calcium carbonate does not react with gastric acid in the stomach, reducing indigestion.

[0004] Although the above patents have improved the toxicity and dispersibility of pigments through modification, no further research has been conducted on the stability of the pigments. The stability of pigments has an important impact on the color, quality and consumer perception of food. Therefore, a pigment with good stability is urgently needed on the market. Summary of the invention

[0005] In view of the problems existing in the prior art, the purpose of the present invention is to obtain an oily liquid white pigment with good dispersibility, little side effect on the human body and good stability.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0007] On one hand, the present invention provides an oily liquid white pigment, which comprises the following raw materials, in parts by weight: 40-45 parts of vegetable oil, 35-40 parts of food-grade titanium dioxide, 5-10 parts of polyglycerol fatty acid ester, and 10-15 parts of a complex;

[0008] The complex is prepared by modifying lecithin and gelatin.

[0009] In some embodiments, the method for preparing food-grade titanium dioxide comprises the following steps:

[0010] Under the protection of inert gas, sucralose, titanium dioxide and triethylamine are added to a mixed solvent, stirred at 40-50° C. for 35-37 hours, filtered and washed to obtain food-grade titanium dioxide.

[0011] Preferably, the mixed solvent is ethyl acetate and water, and the volume ratio between the two is 1:(1-2).

[0012] Titanium dioxide has excellent whiteness and brightness, can enhance and brighten the color of white food, and can be added to food as a pigment, but the amount added is usually very small, and it is difficult to mix evenly in oily liquids, resulting in poor stability of oily liquid pigments, such as uneven dispersion, rapid sedimentation, stratification, viscosity changes, etc. The present invention provides an oily liquid white pigment, which not only has good stability, but is also easy to mix evenly with other substances, thereby enhancing the color of food. The possible reason is that by grafting sucralose on the surface of titanium dioxide, on the one hand, the antioxidant property of the food is enhanced, which is beneficial to the food. It can preserve the freshness of food and increase the compatibility of titanium dioxide in vegetable oil, making it less likely to stratify or precipitate. During food processing, it can penetrate into other food ingredients together with vegetable oil. In addition, titanium dioxide and sucralose are connected by a certain amount of ether bonds, which enhances the shelf life of the oily liquid white pigment. It can also reduce the surface tension of the system, increase the suspension of titanium dioxide, and reduce the electrostatic effect between titanium dioxide particles, synergistically increase the dispersibility of titanium dioxide, and enable titanium dioxide to be evenly dispersed in vegetable oil, further enhancing the stability of the oily liquid white pigment.

[0013] In some embodiments, the mass ratio of sucralose to titanium dioxide is (0.1-0.4):1.

[0014] The present invention limits the mass ratio of sucralose to titanium dioxide so that part of the hydroxyl groups on titanium dioxide react with sucralose, while not reducing the whitening effect of titanium dioxide and improving the dispersibility of titanium dioxide to avoid the problem of reduced stability of titanium dioxide in oily liquids.

[0015] In some embodiments, the method for preparing the complex comprises the following steps:

[0016] 1) adding lecithin, hydrogen peroxide and acetic acid into ethanol, reacting at 60-70° C. for 2-3 hours, washing and drying to obtain hydroxylated lecithin;

[0017] 2) Add the hydroxylated lecithin, gelatin and sodium hydroxide obtained in step 1) into n-hexane, react at 70-80° C. for 3-4 hours, wash and dry to obtain.

[0018] Titanium dioxide entering the human body may have an impact on the intestinal microbial flora, thereby affecting intestinal health. The present invention uses lecithin and gelatin to prepare a composite material, which can reduce the contact between titanium dioxide and the gastrointestinal tract, reduce the gastrointestinal burden, and reduce the side effects of titanium dioxide. The possible reason is that lecithin has good affinity with the body, gelatin has a certain viscosity and can adhere to the gastrointestinal tract, which can block the direct contact between titanium dioxide and the gastrointestinal tract and reduce irritation. In addition, an appropriate amount of gelatin entering the human body can provide the human body with certain amino acids and proteins, which is beneficial to the repair of the damaged gastrointestinal tract and regulate the intestinal flora. Lecithin promotes intestinal peristalsis, accelerates the excretion of titanium dioxide from the body, and reduces accumulation in the body.

[0019] In some embodiments, the mass ratio of the hydroxylated lecithin to gelatin in step 2) is (0.5-1):1.

[0020] The invention enhances the affinity of gelatin to the gastrointestinal tract by limiting the mass ratio of hydroxylated lecithin to gelatin, accelerates intestinal peristalsis, reduces titanium dioxide accumulation, and avoids excessive increase in liver burden.

[0021] In some embodiments, the vegetable oil is corn germ oil.

[0022] The second aspect of the present invention provides a method for preparing an oily liquid white pigment, comprising the following steps:

[0023] S1, mixing the vegetable oil, polyglycerol fatty acid ester and the complex to obtain a mixed solution;

[0024] S2. Add food-grade titanium dioxide to the mixed solution obtained in step S1 and stir to obtain an oily liquid white pigment.

[0025] In some embodiments, the stirring temperature in step S1 is 50-60° C., and the stirring time is 1-2 h.

[0026] In some embodiments, the stirring temperature in step S2 is 40-50° C., the stirring time is 3-4 h, and the rotation speed is 300-400 rpm.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] (1) The present invention prepares food-grade titanium dioxide and a composite, and then adds vegetable oil and polyglycerol fatty acid ester to obtain an oily liquid white pigment, which has good dispersibility and stability, good compatibility with other substances, is beneficial to food preservation, and can reduce the accumulation of pigments in the human body.

[0029] (2) The present invention grafts sucralose on the surface of titanium dioxide, which, on the one hand, enhances the antioxidant property of food and is beneficial to food preservation. On the other hand, it increases the compatibility of titanium dioxide in vegetable oil, making it less likely to be stratified or precipitated. During food processing, it can penetrate into other food ingredients together with vegetable oil. In addition, titanium dioxide and sucralose are connected by a certain amount of ether bonds, which enhances the shelf life of the oily liquid white pigment. It can also reduce the surface tension of the system, increase the suspension of titanium dioxide, and reduce the electrostatic interaction between titanium dioxide particles, thereby synergistically increasing the dispersibility of titanium dioxide, so that titanium dioxide can be evenly dispersed in vegetable oil, further enhancing the stability of the oily liquid white pigment.

[0030] (3) The present invention uses lecithin and gelatin to prepare a complex. Lecithin has good affinity with the body, and gelatin has a certain viscosity and can adhere to the gastrointestinal tract, which can block direct contact between titanium dioxide and the gastrointestinal tract and reduce irritation. In addition, an appropriate amount of gelatin entering the human body can provide the human body with certain amino acids and proteins, which is beneficial to the repair of damaged gastrointestinal tract and regulate intestinal flora. Lecithin promotes intestinal peristalsis, accelerates the excretion of titanium dioxide from the body, and reduces accumulation in the body. DETAILED DESCRIPTION

[0031] The present invention will be described below in conjunction with specific embodiments. It should be noted that the following embodiments are examples of the present invention and are only used to illustrate the present invention, but not to limit the present invention. Other combinations and various modifications within the concept of the present invention may be performed without departing from the spirit or scope of the present invention.

[0032] In the following examples and comparative examples, the compounds and related reagents used can be purchased from the market, among which egg yolk lecithin is food grade purchased from Shandong Aicai Biotechnology Co., Ltd.; gelatin is food grade purchased from Jiangxi Fumeitai Biotechnology Co., Ltd.; titanium dioxide is food grade, model R-996, purchased from Jiangsu Caiwei Biotechnology Co., Ltd.

[0033] Unless otherwise specified, the post-processing steps such as "rotary evaporation", "filtration", "washing" and "drying" used below are routine operations of those skilled in the art and can be selected according to actual operations.

[0034] Preparation Example 1

[0035] The preparation method of food-grade titanium dioxide-1 comprises the following steps:

[0036] Under nitrogen protection, 3 g of sucralose, 10 g of titanium dioxide and 0.5 g of triethylamine were added to a mixed solvent of 40 ml of ethyl acetate and 40 ml of deionized water, stirred at 45° C. for 36 h, filtered and washed to obtain food-grade titanium dioxide-1.

[0037] Preparation Example 2

[0038] The preparation method of food-grade titanium dioxide-2 is the same as that of Preparation Example 1, except that the amount of sucralose added is 6 g.

[0039] Preparation Example 3

[0040] The preparation method of the complex-1 comprises the following steps:

[0041] 1) Add 10 g of egg yolk lecithin, 3 g of hydrogen peroxide and 0.5 g of acetic acid to 50 g of anhydrous ethanol, react at 65° C. for 2.5 h, wash and dry to obtain hydroxylated egg yolk lecithin;

[0042] 2) Add 8 g of hydroxylated egg yolk lecithin obtained in step 1), 10 g of gelatin and 0.1 g of sodium hydroxide into 100 ml of n-hexane, react at 75° C. for 3.5 h, wash and dry to obtain the product.

[0043] Preparation Example 4

[0044] The preparation method of complex-2 is the same as that of preparation example 4, except that the amount of hydroxylated egg yolk lecithin added is 13 g.

[0045] Example 1

[0046] An oily liquid white pigment comprises the following raw materials, measured in parts by weight: 43 parts of corn germ oil, 38 parts of food-grade titanium dioxide-1, 7 parts of food-grade polyglycerol monostearate, and 13 parts of complex-1.

[0047] The preparation method of the oily liquid white pigment of this embodiment comprises the following steps:

[0048] S1, mixing corn germ oil, food grade polyglycerol monostearate and complex-1 at 55° C. for 1.5 h to obtain a mixed solution;

[0049] S2. Add food-grade titanium dioxide-1 to the mixed solution obtained in step S1, stir at 45° C. for 3.5 hours at a rotation speed of 350 rpm to obtain an oily liquid white pigment.

[0050] Example 2

[0051] An oily liquid white pigment comprises the following raw materials, measured in parts by weight: 40 parts of corn germ oil, 35 parts of food-grade titanium dioxide-1, 5 parts of food-grade polyglycerol monostearate, and 10 parts of complex-1.

[0052] The preparation method of the oily liquid white pigment of this embodiment comprises the following steps:

[0053] S1, mixing corn germ oil, food grade polyglycerol monostearate and complex-1 at 50° C. for 2 h to obtain a mixed solution;

[0054] S2. Add food-grade titanium dioxide-1 to the mixed solution obtained in step S1, stir at 40° C. for 4 hours at a rotation speed of 300 rpm to obtain an oily liquid white pigment.

[0055] Example 3

[0056] An oily liquid white pigment comprises the following raw materials, measured in parts by weight: 45 parts of corn germ oil, 40 parts of food-grade titanium dioxide-1, 10 parts of food-grade polyglycerol monostearate, and 15 parts of complex-1.

[0057] The preparation method of the oily liquid white pigment of this embodiment comprises the following steps:

[0058] S1. Mix corn germ oil, food-grade polyglycerol monostearate and complex-1 at 60° C. and stir for 1 h to obtain a mixed solution;

[0059] S2. Add food-grade titanium dioxide-1 to the mixed solution obtained in step S1, stir at 50° C. for 3 h at a rotation speed of 350 rpm to obtain an oily liquid white pigment.

[0060] Example 4

[0061] An oily liquid white pigment and a preparation method thereof, wherein the specific implementation manner is the same as that of Example 1, except that an equal amount of food-grade titanium dioxide-1 is replaced by food-grade titanium dioxide-2.

[0062] Example 5

[0063] An oily liquid white pigment and a preparation method thereof, wherein the specific implementation manner is the same as that of Example 1, except that an equal amount of complex-1 is replaced by complex-2.

[0064] Comparative Example 1

[0065] An oily liquid white pigment and a preparation method thereof, wherein the specific implementation manner is the same as that of Example 1, except that an equal amount of food-grade titanium dioxide-1 is replaced by titanium dioxide.

[0066] Performance Testing

[0067] The oily liquid white pigment obtained in the above embodiments and comparative examples was subjected to the following tests:

[0068] 1. Suspension and stability

[0069] Suspension property: Take the oily liquid white pigment prepared in the above embodiments and comparative examples to test the viscosity (25°C), then place it in a centrifuge and centrifuge it at 3000 rpm for 15 minutes to observe whether a white precipitate appears at the bottom;

[0070] Stability: After the oily liquid white pigment prepared in the above embodiments and comparative examples was placed at room temperature for 1 month, the viscosity (25°C) was tested to observe whether the appearance color was uniform and whether white precipitation appeared at the bottom.

[0071] The test results are shown in Table 1:

[0072] Table 1

[0073]

[0074] From the comparison of the experimental data of Examples 1-3 in Table 1, it can be seen that the white pigment obtained by the present invention has good suspension and stability; from the comparison of Example 4 and Example 1, it can be seen that the suspension and stability of the oily liquid white pigment are reduced by changing the ratio of sucralose to titanium dioxide; from the comparison of Example 5 and Example 1, it can be seen that the suspension and stability of the oily liquid white pigment are reduced by changing the ratio of hydroxylated lecithin to gelatin; from the comparison of Comparative Example 1 and Example 1, it can be seen that the suspension and stability of the white pigment are reduced by directly using titanium dioxide.

[0075] 2. Acute toxicity test

[0076] 2.1 The food-grade titanium dioxide obtained in Preparation Example 1 was tested in accordance with GB 1886.341-2021 and was found to be in compliance with the national standard for food-grade titanium dioxide.

[0077] 2.2 The oily liquid white pigment obtained in Example 1-3 was subjected to acute toxicity test. The maximum tolerated dose method was adopted. 25 male and female mice aged 6 to 8 weeks (weight 20±2g) were gavaged twice at 15000 mg / kg. The mice were fasted for 16 hours before gavage. There was a 4-hour interval between gavages. All mice were observed for 14 days without any death or abnormal performance. The eating activity and weight gain were normal. After 14 days, the animals were killed and the liver, spleen and kidney were dissected and observed. At the same time, the organ coefficients were measured. No lesions were visible to the naked eye. No abnormalities were found in the pathological sections. The coefficients of each organ were within the normal range. The LD can be determined. 50 ﹥15000mg / kg body weight (mouse, oral), judged as non-toxic according to the oral toxicity classification standard of foreign chemicals in food toxicology of my country.

[0078] The above implementation modes are only for illustrating the technical concept and features of the present invention, and their purpose is to enable people familiar with this technology to understand the content of the present invention and implement it, and they cannot be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be included in the protection scope of the present invention.

Claims

1. An oily liquid white pigment, characterized in that The composition comprises the following raw materials in parts by weight: 40-45 parts of vegetable oil, 35-40 parts of food-grade titanium dioxide, 5-10 parts of polyglycerol fatty acid ester, and 10-15 parts of a compound; The complex is prepared by modifying lecithin and gelatin.

2. The oily liquid white pigment according to claim 1, characterized in that The preparation method of the food-grade titanium dioxide comprises the following steps: Under the protection of inert gas, sucralose, titanium dioxide and triethylamine are added to a mixed solvent, stirred at 40-50° C. for 35-37 hours, filtered and washed to obtain food-grade titanium dioxide.

3. The oily liquid white pigment according to claim 2, characterized in that The mass ratio of sucralose to titanium dioxide is (0.1-0.4):

1.

4. The oily liquid white pigment according to claim 1, characterized in that The polyglycerol fatty acid ester is food grade polyglycerol monostearate.

5. The oily liquid white pigment according to claim 1, characterized in that The preparation method of the composite comprises the following steps: 1) adding lecithin, hydrogen peroxide and acetic acid into ethanol, reacting at 60-70° C. for 2-3 hours, washing and drying to obtain hydroxylated lecithin; 2) Add the hydroxylated lecithin, gelatin and sodium hydroxide obtained in step 1) into n-hexane, react at 70-80° C. for 3-4 hours, wash and dry to obtain.

6. The oily liquid white pigment according to claim 5, characterized in that The mass ratio of the hydroxylated lecithin to gelatin in step 2) is (0.5-1):

1.

7. The oily liquid white pigment according to claim 1, characterized in that The vegetable oil is corn germ oil.

8. A method for preparing the oily liquid white pigment according to any one of claims 1 to 7, characterized in that: The following steps are involved: S1, mixing the vegetable oil, polyglycerol fatty acid ester and the complex to obtain a mixed solution; S2. Add food-grade titanium dioxide to the mixed solution obtained in step S1 and stir to obtain an oily liquid white pigment.

9. The method for preparing the oily liquid white pigment according to claim 8, characterized in that: The stirring temperature in step S1 is 50-60° C., and the stirring time is 1-2 h.

10. The method for preparing the oily liquid white pigment according to claim 8, characterized in that: The stirring temperature in step S2 is 40-50° C., the stirring time is 3-4 h, and the rotation speed is 300-400 rpm.

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