CN112915056A - Mild long-acting moisturizing protective cream and preparation method thereof - Google Patents

Abstract

The invention relates to a mild long-acting moisturizing protective cream and a preparation method thereof, wherein the protective cream is prepared from the following raw materials in parts by weight: 5-10 parts of triethanolamine; 5-10 parts of stearic acid; 0.05-0.1 part of polydimethylsiloxane; 3-5 parts of soybean lecithin; 3-5 parts of glycerol; 2-4 parts of hyaluronic acid; 1-2 parts of titanium dioxide; 2-5 parts of lotus root starch processed with vinegar; 5-9 parts of passion fruit peel extract; 15-25 parts of distilled water. The invention has the advantages that the invention can ensure that the polydisiloxane realizes the functions of skin-friendly softness and air permeability under the condition of small content (less than 3wt percent), and ensures that the protective cream has better stability; the effective components contain plant components such as vinegar-processed lotus root starch and passion fruit peel extract, and the vinegar-processed lotus root starch and passion fruit peel extract are mild and non-irritant, have an antiallergic characteristic, and can ensure better and longer-lasting moisturizing performance.

Description

Mild long-acting moisturizing protective cream and preparation method thereof

Technical Field

The invention belongs to the field of skin care products, and particularly relates to mild long-acting moisturizing protective cream and a preparation method thereof.

Background

The skin is the natural coat of human body and is generally divided into three major parts, namely epidermis, dermis and subcutaneous tissue from outside to inside, and the epidermis is further divided into a cuticle layer, a stratum lucidum layer, a stratum granulosum layer, a acanthosphere layer and a stratum basale layer. The stratum corneum, the outermost layer of the skin, plays an important role in the integrity of the skin barrier function. A sebum membrane is formed on the horny layer, and is a semitransparent milky membrane formed by emulsifying sebum, sweat and epidermal cell secretion, and free fatty acid, lactate, urea and uric acid in the sebum membrane are natural moisturizing factors and play a role in moisturizing the skin. The stratum corneum and sebaceous membrane prevent the loss of water from the skin. Normally, the water content of the stratum corneum should be around 10%, below which level, the skin is water-deficient. Dry skin refers to the phenomenon of a lack of moisture in the skin which makes the skin uncomfortable. The symptoms mainly include tight skin, dry and desquamation of individual parts, and itching of the whole body after bathing. Age, climate change, sleep deficiency, fatigue, overheating bath water, strong alkalinity of washing products and the like are all important causes of dry skin.

In the prior art, common moisturizing protective cream usually contains silicone oil or mineral oil components with relatively high proportion in order to improve moisturizing performance and better touch and skin moistening performance, but the problems of influence on the stability of the protective cream product such as phase separation, precipitation and the like often occur due to poor compatibility with other components, and meanwhile, the mineral oil components have the defect of blocking skin pores when in use; in addition, the existing protective cream also usually contains some chemical components which are easy to cause skin allergy, such as sodium dodecyl sulfate, sodium olefin sulfate and the like, and has certain irritation, so that the protective cream is not mild enough, and the use is limited.

Disclosure of Invention

The invention aims to solve the technical problem of providing a mild long-acting moisturizing protective cream and a preparation method thereof, aiming at overcoming the defects that the conventional protective cream in the prior art usually uses silicone oil or mineral oil with relatively high proportion and some irritant components, so that the stability of the protective cream is poor or skin allergy is easy to cause and the mildness is not enough.

The technical scheme for solving the technical problems is as follows: a mild long-acting moisturizing protective cream is composed of the following raw materials in parts by weight: 5-10 parts of triethanolamine; 5-10 parts of stearic acid; 0.05-0.1 part of polydimethylsiloxane; 3-5 parts of soybean lecithin; 3-5 parts of glycerol; 2-4 parts of hyaluronic acid; 1-2 parts of titanium dioxide; 2-5 parts of lotus root starch processed with vinegar; 5-9 parts of passion fruit peel extract; 15-25 parts of distilled water.

On the basis of the technical scheme, the invention can also make the following further specific selection or better selection.

Specifically, the vinegar-processed lotus root starch is prepared by the following method: adding distilled water 6-10 times the weight of lotus root starch into lotus root starch, stirring to form emulsion, controlling the temperature at 30-35 ℃, dropwise adding acetic anhydride 0.05-0.12 times the weight of lotus root starch into the emulsion under the stirring condition, controlling the pH value at 6.5-7.2, continuously reacting for 0.5-1h after dropwise adding is finished, and naturally drying or vacuum drying and grinding into powder to obtain vinegar-processed lotus root starch (during natural drying, the vinegar-processed lotus root starch can be spread in a container with a large surface similar to a watch glass to accelerate the natural drying speed).

Specifically, the pH control is realized by adding an aqueous solution of sodium carbonate or sodium bicarbonate.

Specifically, the passion fruit peel extract is prepared by the following method: cleaning fresh passion fruit peel, drying in the shade, grinding into powder after primary crushing, and leaching powder with 30-45 vol% ethanol solution, wherein the material-liquid ratio is 1: 6-9g/mL, adjusting the pH of the leaching mixed solution to 5-6 with hydrochloric acid, controlling the temperature at 18-25 ℃, ultrasonically leaching for 0.5-1.2h, then performing suction filtration, washing a filter cake with distilled water, merging filtrate, and concentrating by using a rotary evaporator at 46-50 ℃ until no ethanol taste exists, thus obtaining the passion fruit peel extract.

Specifically, the particle size of the powder obtained by grinding the passion fruit peel dried in the shade into powder is 50-100 meshes.

In addition, the invention also provides a preparation method of the mild long-acting moisturizing protective cream, which comprises the following steps:

s1, adding stearic acid, polydimethylsiloxane, soybean lecithin and hyaluronic acid in corresponding parts by weight into an oil phase kettle, and uniformly stirring and dispersing at 65-75 ℃ to obtain an oil phase;

s2, adding distilled water in a corresponding weight part into an emulsifying pot, adding triethanolamine and glycerol, and stirring and dissolving at 65-75 ℃ to obtain a water phase;

s3, controlling the temperature to be 65-75 ℃, adding the oil phase into the water phase under the stirring condition, uniformly stirring, keeping the temperature for 20-30min, then cooling to 30-40 ℃, continuously adding the titanium dioxide, the vinegar-processed lotus root starch and the passion fruit peel extract according to the corresponding weight parts under the stirring condition, and fully and uniformly stirring to obtain the pigment.

Compared with the prior art, the invention has the beneficial effects that:

1) the protective cream has the beneficial effects that the effective ingredients comprise triethanolamine and stearic acid, the saponification reaction of the triethanolamine and the stearic acid forms an easy-to-form film-forming ingredient, so that a protective film for preventing the water loss of skin can be rapidly formed on the surface of the skin when the protective cream is used, the moisturizing effect is achieved, meanwhile, the film-forming ingredient has good compatibility with vinegar-processed lotus root starch and passion fruit peel extracts, the respective special plant nutrient ingredients are kept as far as possible when the film-forming ingredient and the vinegar-processed lotus root starch and passion fruit peel extracts are prepared, and the film-forming ingredient is coated on the surface of the skin, so that the necessary trace;

2) the protective cream comprises active ingredients containing polydisiloxane and soybean lecithin, and when the two ingredients are used according to a certain proportion, the polydisiloxane can be ensured to realize the functions under the condition of small content (less than 3wt per thousand), so that a protective film formed on the surface of skin by the protective cream has good skin-friendly flexibility and certain air permeability, the problems that the product stability of the protective cream is influenced and potential stimulation is caused to eyes due to the fact that the protective cream is not easy to stir uniformly and phase separation and the like caused by the high content of the polydisiloxane can be effectively avoided, and meanwhile, the soybean lecithin is phospholipid forming a biological film, is easy to absorb and can promote the permeation of other nutrient substances;

3) the lotus root starch prepared by vinegar modifies part of starch in the lotus root starch, so that the solubility and the dispersibility of the lotus root starch are improved after the modification, the lotus root starch is ensured to have better compatibility with other components in the protective cream, the compatibility is enhanced, and the polydimethylsiloxane component is also used in the protective cream without stability problem; the passion fruit peel extract contains a large amount of micromolecule pectin and anthocyanin, the former has a strong water-retaining effect, the latter has the effects of eliminating free radicals and blocking allergen transfer, and meanwhile, the passion fruit peel extract and vinegar-processed lotus root starch have a certain synergistic effect on enhancing the mild anti-allergic effect of the protective cream; in addition, the glycerin, the titanium dioxide and the hyaluronic acid have certain physical or chemical moisturizing effects, and the combination of the glycerin, the titanium dioxide and the hyaluronic acid can ensure the mild and long-acting moisturizing effect of the protective cream.

Detailed Description

The present invention is described in further detail below with reference to specific examples, which are provided for illustration only and are not intended to limit the scope of the present invention.

For the sake of brevity, the drugs used in the following examples are all commercially available products unless otherwise specified, and the methods used are conventional methods unless otherwise specified.

The vinegar-processed lotus root starch and passion fruit peel extract used in the following examples or comparative examples were obtained by the following methods:

preparing lotus root starch with vinegar: selecting natural West lake pure lotus root starch without any addition, adding distilled water with the mass of 6-10 times of the lotus root starch into the lotus root starch, stirring to form emulsion, controlling the temperature at 30-35 ℃, then dropwise adding acetic anhydride with the mass of 0.05-0.12 time of the lotus root starch into the emulsion under the stirring condition, controlling the pH to be 6.5-7.2 in the process (realized by a pH monitor and dropwise adding a sodium carbonate aqueous solution in a matching way), continuously reacting for 0.5-1h after dropwise adding is finished, naturally air-drying or vacuum-drying, and grinding into powder (the particle size is more than 100 meshes) to obtain the vinegar-prepared lotus root starch.

The passion fruit peel extract: cleaning fresh passion fruit peel, drying in the shade, grinding into powder after primary crushing, and leaching powder with 30-45 vol% ethanol solution, wherein the material-liquid ratio is 1: 6-9g/mL, adjusting the pH of the leaching mixed solution to 5-6 with hydrochloric acid, controlling the temperature at 18-25 ℃, ultrasonically leaching for 0.5-1.2h, then performing suction filtration, washing a filter cake with distilled water, merging filtrate, and concentrating by using a rotary evaporator at 46-50 ℃ until no ethanol taste exists, thus obtaining the passion fruit peel extract.

Example 1

A mild long-acting moisturizing protective cream is composed of the following raw materials in parts by weight: 5 parts of triethanolamine; 5 parts of stearic acid; 0.05 part of polydimethylsiloxane; 3 parts of soybean lecithin; 3 parts of glycerol; 2 parts of hyaluronic acid; 1 part of titanium dioxide; 2 parts of lotus root starch processed with vinegar; 5 parts of passion fruit peel extract; and 15 parts of distilled water.

The preparation method of the moisturizing protective cream comprises the following steps:

s1, adding stearic acid, polydimethylsiloxane, soybean lecithin and hyaluronic acid in corresponding parts by weight into an oil phase kettle, and uniformly stirring and dispersing at 65-75 ℃ to obtain an oil phase;

s2, adding distilled water in a corresponding weight part into an emulsifying pot, adding triethanolamine and glycerol, and stirring and dissolving at 65-75 ℃ to obtain a water phase;

s3, controlling the temperature to be 65-75 ℃, adding the oil phase into the water phase under the stirring condition, uniformly stirring, keeping the temperature for 20-30min, then cooling to 30-40 ℃, continuously adding the titanium dioxide, the vinegar-processed lotus root starch and the passion fruit peel extract according to the corresponding weight parts under the stirring condition, and fully and uniformly stirring to obtain the pigment.

Example 2

A mild long-acting moisturizing protective cream is composed of the following raw materials in parts by weight: 10 parts of triethanolamine; 10 parts of stearic acid; 0.1 part of polydimethylsiloxane; 5 parts of soybean lecithin; 5 parts of glycerol; 4 parts of hyaluronic acid; 2 parts of titanium dioxide; 5 parts of lotus root starch processed with vinegar; 9 parts of passion fruit peel extract; and 25 parts of distilled water.

The preparation method of the moisturizing protective cream comprises the following steps:

s1, adding stearic acid, polydimethylsiloxane, soybean lecithin and hyaluronic acid in corresponding parts by weight into an oil phase kettle, and uniformly stirring and dispersing at 65-75 ℃ to obtain an oil phase;

s2, adding distilled water in a corresponding weight part into an emulsifying pot, adding triethanolamine and glycerol, and stirring and dissolving at 65-75 ℃ to obtain a water phase;

s3, controlling the temperature to be 65-75 ℃, adding the oil phase into the water phase under the stirring condition, uniformly stirring, keeping the temperature for 20-30min, then cooling to 30-40 ℃, continuously adding the titanium dioxide, the vinegar-processed lotus root starch and the passion fruit peel extract according to the corresponding weight parts under the stirring condition, and fully and uniformly stirring to obtain the pigment.

Example 3

A mild long-acting moisturizing protective cream is composed of the following raw materials in parts by weight: 5 parts of triethanolamine; 10 parts of stearic acid; 0.05 part of polydimethylsiloxane; 5 parts of soybean lecithin; 3 parts of glycerol; 4 parts of hyaluronic acid; 1 part of titanium dioxide; 5 parts of lotus root starch processed with vinegar; 5 parts of passion fruit peel extract; and 25 parts of distilled water.

The preparation method of the moisturizing protective cream comprises the following steps:

s1, adding stearic acid, polydimethylsiloxane, soybean lecithin and hyaluronic acid in corresponding parts by weight into an oil phase kettle, and uniformly stirring and dispersing at 65-75 ℃ to obtain an oil phase;

s2, adding distilled water in a corresponding weight part into an emulsifying pot, adding triethanolamine and glycerol, and stirring and dissolving at 65-75 ℃ to obtain a water phase;

s3, controlling the temperature to be 65-75 ℃, adding the oil phase into the water phase under the stirring condition, uniformly stirring, keeping the temperature for 20-30min, then cooling to 30-40 ℃, continuously adding the titanium dioxide, the vinegar-processed lotus root starch and the passion fruit peel extract according to the corresponding weight parts under the stirring condition, and fully and uniformly stirring to obtain the pigment.

Example 4

A mild long-acting moisturizing protective cream is composed of the following raw materials in parts by weight: 7 parts of triethanolamine; 6 parts of stearic acid; 0.08 part of polydimethylsiloxane; 4 parts of soybean lecithin; 4 parts of glycerol; 3 parts of hyaluronic acid; 1.5 parts of titanium dioxide; 3 parts of lotus root starch processed with vinegar; 7 parts of passion fruit peel extract; and 20 parts of distilled water.

The preparation method of the moisturizing protective cream comprises the following steps:

s1, adding stearic acid, polydimethylsiloxane, soybean lecithin and hyaluronic acid in corresponding parts by weight into an oil phase kettle, and uniformly stirring and dispersing at 65-75 ℃ to obtain an oil phase;

s2, adding distilled water in a corresponding weight part into an emulsifying pot, adding triethanolamine and glycerol, and stirring and dissolving at 65-75 ℃ to obtain a water phase;

s3, controlling the temperature to be 65-75 ℃, adding the oil phase into the water phase under the stirring condition, uniformly stirring, keeping the temperature for 20-30min, then cooling to 30-40 ℃, continuously adding the titanium dioxide, the vinegar-processed lotus root starch and the passion fruit peel extract according to the corresponding weight parts under the stirring condition, and fully and uniformly stirring to obtain the pigment.

Comparative example 1

In contrast to example 4, the protective cream of this comparative example lacks polydimethylsiloxane.

Comparative example 2

In contrast to example 4, the protective cream of this comparative example lacks soy lecithin.

Comparative example 3

Compared with example 4, the protective cream of the comparative example lacks vinegar-processed lotus root starch.

Comparative example 4

Compared with example 4, the protective cream of the comparative example lacks the passion fruit peel extract.

The protective creams obtained in the embodiments 1 to 4 and the comparative examples 1 to 4 are subjected to performance detection, and specific detection comprises basic character observation, a mild test, moisturizing capability detection, stability detection and the like.

The properties of the protective cream prepared in each example and comparative example are directly observed and smeared, and the protective cream is found to be a slight pink cream, fine, uniform and light-fragrance except for the slight yellow of the comparative example 4.

Selecting 20 subjects with sensitive skin and age of 25-45 years who have used cosmetic allergy to the facial skin, sequentially trying any one of common protective cream sold on the market, and the protective cream corresponding to example 4, comparative example 3 and comparative example 4 in four stages, uniformly smearing 2.5g of samples on the face of the subject in the morning, the noon and the evening respectively, not using any other cosmetics in the period, stopping using the protective cream if obvious uncomfortable symptoms such as burning, stabbing and itching of the facial skin occur, or continuously using the protective cream until a trial period of 7 days is up, and performing trial again in the next stage after a recovery period of at least 30 days after each stage of trial use (only washing the face with water and not smearing any skin care product in the period). The test results are shown in the following table:

the above table shows that the protective cream provided by the invention is mild and non-irritant, is friendly to allergic skin, and the vinegar-processed lotus root starch (containing various trace elements and tannins) and passion fruit peel extract (containing various anthocyanidins and pectins) have obvious positive significance in improving the mild and anti-allergic performance of the protective cream. In addition, in order to further strengthen and verify the synergistic effect of the two components on the anti-allergic property in the protective cream, on the basis of the formula of the comparative example 4 (namely in the absence of the passion fruit peel extract), a plurality of protective creams are obtained by increasing or reducing the amount of the vinegar-processed lotus root starch to different degrees in the preparation process, then sensitivity tests are carried out on each protective cream in the same way, and a plurality of tests show that, more or less subjects with obvious discomfort symptoms all the time, and the number of the subjects with discomfort each time is more than 2, to a certain extent, the passion fruit peel extract is the main effective component for resisting allergy, and the lotus root starch processed by vinegar is indispensable, and the best antiallergic effect can be obtained only when the vinegar-processed lotus root starch and the passion fruit peel extract are used at the same time according to a certain proportion, and the lotus root starch and the passion fruit peel extract have the effect of synergistically enhancing the antiallergic capability.

In addition, 10 female consumers (with the age of 25-45 years) who have a habit of using the moisturizing protective cream at ordinary times are selected, the protective creams of the embodiment 4, the comparative example 1 and the comparative example 2 are tried, the skin-friendly performance and the air permeability of the protective cream after being smeared are evaluated, and feedback results show that the samples corresponding to the embodiment 4 and the comparative example 2 are easy to spread when being smeared and have good skin-friendly performance and air permeability, and the protective cream corresponding to the comparative example 1 has obviously poor skin-friendly performance and air permeability.

When the moisturizing capability of the protective cream corresponding to each example and comparative example is tested, 135 subjects with dry hand skin (obviously white marks after the nails are lightly scratched) and even cracked are selected and divided into 9 groups, one group corresponding to each example and comparative example is used for testing for 10 days by using any one of the common protective creams sold on the market, the subjects are required not to engage in activities or work irritating to the hand skin (not to contact detergents or other chemical substances obviously irritating to the skin) during the testing period, the subjects take 2g of samples respectively in the morning, the noon and the evening and uniformly smear the samples on the back of the hands, and the subjects who are statistically cured, effective and ineffective after 10 days. Effect determination criteria: 1) and (3) healing: the hand cracks disappear, the nails have no white marks after being scratched, and the skin is fine and smooth; 2) the method has the following advantages: the hand cracks disappear, but slight white marks still exist when the fingernails are scratched; 3) and (4) invalidation: the hand crack is not improved or even aggravated. The results are shown in the following table:

from the results in the table above, it can be basically seen that the protective cream provided by the present invention has significantly better effects in terms of improvement and moisture retention of hand skin chapping, at least, compared to the comparative examples and the commercially available protective creams; the data in the table also show that the polydimethylsiloxane, the soybean lecithin, the vinegar-processed lotus root starch and the passion fruit peel extract in the protective cream provided by the invention are all indispensable, and the moisturizing protective effect of the protective cream on hand skin chap is reduced to a certain extent due to the lack of any component.

The long-acting moisturizing effect of the protective cream provided by the invention is tested as follows (refer to QB/T4256-2011 cosmetic moisturizing efficacy evaluation guidelines): taking the common moisturizing cream product of example 4 and any one of the commercially available common moisturizing cream products as a sample, resting for one hour at a relative humidity of 50 +/-5% under a constant temperature environment (22 +/-1 ℃), and keeping the humidity at (2.0 +/-0.1) mg/cm²The amount was applied to the inner forearm of the left hand and the inner right forearm (4 cm. times.4 cm) of the subject, and the uncoated blank was tested simultaneously. The hydration status of the skin was tested at 2h, 4h, 6h and 8h after application of the samples, respectively, with 24 subjects aged between 25-45. The evaluation results are expressed as the average value of the degree of hydration, as shown in the following table:

as can be seen from the above table, the protective cream provided by the invention has better and longer-lasting moisturizing effect.

Finally, stability tests are carried out on the protective cream corresponding to each embodiment and comparative example, wherein the stability tests comprise rapid centrifugal detection and long-time standing detection. During rapid centrifugal detection, 2.5g of protective cream corresponding to each embodiment and comparative example is weighed and placed in each corresponding centrifugal tube, and after centrifugation is carried out for 30min at the rotating speed of 2000r/min, whether the layering phenomenon exists is observed; and (3) performing long-time standing detection, namely placing 10g of each sample in a transparent glass tube with the inner diameter of 1cm, standing vertically for 6 months at room temperature, and observing whether the layering phenomenon exists or not. The results are shown in the following table:

the above table shows that the protective cream provided by the invention has better stability, wherein both the soybean lecithin and the lotus root starch processed with vinegar have positive significance for improving the stability of the protective cream. In addition, the protective cream provided by the invention is subjected to freezing resistance and heat resistance stability tests according to a common method, and no obvious oil-water separation phenomenon exists after the protective cream is recovered to room temperature, which shows that the protective cream has good freezing resistance and heat resistance stability.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.

Claims (6)

1. The mild long-acting moisturizing protective cream is characterized by comprising the following raw materials in parts by weight: 5-10 parts of triethanolamine; 5-10 parts of stearic acid; 0.05-0.1 part of polydimethylsiloxane; 3-5 parts of soybean lecithin; 3-5 parts of glycerol; 2-4 parts of hyaluronic acid; 1-2 parts of titanium dioxide; 2-5 parts of lotus root starch processed with vinegar; 5-9 parts of passion fruit peel extract; 15-25 parts of distilled water.

2. The mild long-acting moisturizing cream as claimed in claim 1, wherein the vinegar-processed lotus root starch is prepared by the following method: adding distilled water 6-10 times the weight of lotus root starch into lotus root starch, stirring to form emulsion, controlling the temperature at 30-35 ℃, then dropwise adding acetic anhydride 0.05-0.12 times the weight of lotus root starch into the emulsion under the stirring condition, controlling the pH value between 6.5-7.2, continuously reacting for 0.5-1h after dropwise adding is finished, naturally drying or vacuum drying, and grinding into powder to obtain the vinegar-processed lotus root starch.

3. A mild long-acting moisturizing cream according to claim 2, wherein the pH control is achieved by adding an aqueous solution of sodium carbonate or sodium bicarbonate.

4. The mild long-acting moisturizing cream as claimed in claim 1, wherein the passion fruit peel extract is prepared by the following method: cleaning fresh passion fruit peel, drying in the shade, grinding into powder after primary crushing, and leaching powder with 30-45 vol% ethanol solution, wherein the material-liquid ratio is 1: 6-9g/mL, adjusting the pH of the leaching mixed solution to 5-6 with hydrochloric acid, controlling the temperature at 18-25 ℃, ultrasonically leaching for 0.5-1.2h, then performing suction filtration, washing a filter cake with distilled water, merging filtrate, and concentrating by using a rotary evaporator at 46-50 ℃ until no ethanol taste exists, thus obtaining the passion fruit peel extract.

5. The mild long-acting moisturizing cream as claimed in claim 4, wherein the grain size of the powder of the pulverized passion fruit peel after drying in the shade is 50-100 meshes.

6. A method of making a mild long-lasting moisturizing cream according to any one of claims 1 to 5, comprising the steps of:

s1, adding stearic acid, polydimethylsiloxane, soybean lecithin and hyaluronic acid in corresponding parts by weight into an oil phase kettle, and uniformly stirring and dispersing at 65-75 ℃ to obtain an oil phase;

s2, adding distilled water in a corresponding weight part into an emulsifying pot, adding triethanolamine and glycerol, and stirring and dissolving at 65-75 ℃ to obtain a water phase;

s3, controlling the temperature to be 65-75 ℃, adding the oil phase into the water phase under the stirring condition, uniformly stirring, keeping the temperature for 20-30min, then cooling to 30-40 ℃, continuously adding the titanium dioxide, the vinegar-processed lotus root starch and the passion fruit peel extract according to the corresponding weight parts under the stirring condition, and fully and uniformly stirring to obtain the pigment.