Coconut oil handmade soap and preparation method thereof

Abstract

The invention discloses coconut oil handmade soap and a preparation method thereof, the coconut oil handmade soap is prepared from food-grade raw materials, and the food-grade raw materials comprise the following components by weight: 30-50% of coconut oil; 20-35% of olive oil; 15 to 25% of palm oil; 0.5-5% of a functional additive, wherein the functional additive is selected from at least one of a lithospermum extract, honey, bitter camellia oil, grape seed oil and glycerol; the weight ratio of the food-grade sodium hydroxide to the deionized water in the food-grade aqueous alkali is 1: (2.8-3.2). Through a composite grease system of the coconut oil, the olive oil and the palm oil, powerful cleaning is guaranteed (the coconut oil provides soft foam), excessive degreasing is avoided (the olive oil forms a moisturizing film), meanwhile, the hardness of a soap body (the palm oil) is improved, the problem that a traditional soap is tight, dry or softened and deformed is solved, the hardness is moderate (35-39 Shore A), and the durability is good.

Description

Technical Field

[0001] This invention relates to the field of natural cleaning and care products technology, specifically to a coconut oil handmade soap and its preparation method. Background Technology

[0002] Handmade soaps, as natural cleansing and care products, have received widespread attention due to the naturalness of their raw materials and their potential skincare value. However, current technology has several shortcomings, making it difficult to meet consumers' comprehensive needs for cleansing power, moisturizing feel, targeted efficacy, and stability during use. Specific deficiencies are as follows: I. Imbalance in the basic oil system, highlighting the conflict between cleaning and maintenance. Traditional handmade soaps often rely on a single or improperly proportioned oil formula, leading to a contradiction in their core performance characteristics. Imbalance between cleansing power and moisturizing effect: If the proportion of coconut oil is too high (>50%), the short-chain fatty acids will be excessively degreased after saponification, damaging the skin barrier and causing tightness and dryness (e.g., the commercially available control group with 60% coconut oil and 30% palm oil had an irritation score of 2.2); if the proportion of olive oil is too high (>35%), although it is moisturizing, the soap body will soften and be easily deformed, and the cleansing power will be diluted; if the proportion of palm oil is too high (>25%), the soap body will become harder but the amount of foam will decrease and the skin will feel dry.

[0003] Insufficient soap stability: The soap is prone to softening when exposed to water due to the presence of a single oil or an imbalance in the proportion of oils (such as palm oil <15%), resulting in a short service life (such as the control group 1 having a hardness of only 34 Shore A).

[0004] II. Significant gaps exist in meeting specific skin needs, with a lack of targeted efficacy. Existing products struggle to meet the specific cleansing and skincare needs of different skin types: 1. Sensitive and red skin: Traditional soaps are either too strong and irritate the skin (e.g., control group 2 pH 7.5, free alkali 0.12%), or they only focus on moisturizing and lack barrier repair ability, and cannot take into account "gentle cleansing + soothing repair".

[0005] 2. Sensitive, red, and inflamed / post-operative repaired skin: Lacking active ingredients that can directly inhibit histamine release and relieve inflammation (such as shikonin), traditional products tend to aggravate redness, swelling, and itching, and there are no safe and suitable options during the post-operative repair period.

[0006] 3. Dry and oil-deficient skin: Single or three-element additives (such as glycerin alone) cannot solve the complex problems of "dryness and flaking + oil imbalance + fragile barrier", and lack an integrated care solution of "repair-protection-soothing-moisturizing".

[0007] III. Inappropriate application of functional additives and insufficient synergistic effects. Traditional additives have two major drawbacks: Limitations of using only one type of oil: Glycerin alone is prone to dependence on external moisture, and camellia oil alone provides short-lasting hydration and cannot meet the complex needs of the skin. Improper combination: Imbalanced ratios lead to synergistic failure (e.g., excessive honey causes soap crystallization, excessive oily components reduce hardness), or the concentration does not reach the effective threshold (e.g., when the concentration of comfrey extract is <0.5%, the anti-inflammatory effect is only 35.7%).

[0008] IV. Improper preparation of alkaline solutions compromises safety and efficacy. Raw material safety: Some products use non-food grade alkali, which poses potential health risks; Imbalanced ratio: an alkali-to-water ratio <1:2.8 (high concentration) results in excessive free alkali residue (e.g., 0.12% free alkali in control group 1) and skin irritation; a ratio >1:3.2 (low concentration) results in slow saponification and softening of the soap (e.g., hardness of control group 2 is only 32 Shore A). Process out of control: Adding sodium hydroxide once can cause a sudden rise in temperature (such as to 35°C), which destroys the antioxidant components of grape seed oil (DPPH scavenging rate is only 55.2%), the water-locking ability of glycerin, and other functional activities. Summary of the Invention

[0009] In order to overcome the shortcomings of the existing technology, the purpose of this invention is to provide a coconut oil handmade soap and its preparation method, which solves the technical problems of imbalance in the basic oil system, gap in specific skin needs, unreasonable application of functional additives, and non-standard preparation of alkaline solution in existing handmade soaps.

[0010] To solve the above problems, the technical solution adopted by the present invention is as follows: A coconut oil handmade soap, made from food-grade raw materials, wherein the food-grade raw materials comprise the following components by weight percentage: Coconut oil: 30-50%; Olive oil: 20-35%; Palm oil: 15-25%; Functional additives: 0.5-5%, wherein the functional additives are selected from at least one of the following: comfrey extract, honey, bitter camellia oil, grape seed oil, and glycerin; Food-grade alkaline aqueous solution: balance, wherein the weight ratio of food-grade sodium hydroxide to deionized water in the food-grade alkaline aqueous solution is 1:(2.8-3.2).

[0011] Preferably, the functional additive is a ternary combination of camellia oil, grape seed oil, and glycerin, wherein the weight percentage of each component is: Bitter camellia oil: 1-2%, grapeseed oil: 0.5-1%, glycerin: 0.5-1%.

[0012] Preferably, the food-grade raw material comprises the following components by weight percentage: Coconut oil: 30-50%; Olive oil: 20-35%; Palm oil: 15-25%; Bitter camellia oil: 1.5%, grapeseed oil: 0.8%, glycerin: 0.7%; Food-grade alkaline solution: balance.

[0013] Preferably, the functional additive is a binary combination of honey and bitter camellia oil, with the following weight percentages: honey: 1-2% and bitter camellia oil: 1-1.5%.

[0014] Preferably, the food-grade raw material comprises the following components by weight percentage: Coconut oil: 40%; Olive oil: 25%; Palm oil: 18%; Honey: 1.2%, Bitter Camellia Oil: 1.3%; Food-grade alkaline solution: balance.

[0015] Preferably, the functional additive is comfrey extract, with a weight percentage of 0.5-1%.

[0016] Preferably, the food-grade raw material comprises the following components by weight percentage: Coconut oil: 38%; Olive oil: 30%; Palm oil: 19%; Comfrey extract: 0.8%; Food-grade alkaline solution: balance.

[0017] Preferably, the functional additive is a quaternary combination of bitter camellia oil, grape seed oil, glycerin and honey, with the following weight percentages for each component: bitter camellia oil 1-1.5%, grape seed oil 0.5-1%, glycerin 0.5-1%, and honey 0.5-1%.

[0018] Preferably, the food-grade raw material comprises the following components by weight percentage: Coconut oil: 32%; Olive oil: 32%; Palm oil: 21%; Bitter camellia oil 1.2%, grapeseed oil 0.6%, glycerin 0.6%, honey 0.6%; Food-grade alkaline solution: balance.

[0019] A method for preparing coconut oil handmade soap includes the following steps: S1: Mix coconut oil, olive oil, and palm oil, and heat to 40-50℃ until completely melted to obtain a mixed oil mixture; S2: Add food-grade alkaline aqueous solution to the mixed oils and stir until trace is reached to obtain soap solution mixture; S3: Add functional additives to the soap liquid mixture and stir evenly to obtain a functional soap liquid mixture; S4: Pour the functional soap liquid mixture into a mold and let it stand for 24-48 hours at 20-25℃ and 40-60% relative humidity to solidify; S5: After unmolding, place in a ventilated and dry place to cure for 2-4 weeks to obtain the coconut oil handmade soap; The method for preparing the food-grade alkaline aqueous solution is as follows: Food-grade sodium hydroxide was slowly added to deionized water at 20-22℃ in three portions, stirring until completely dissolved after each addition, and the solution temperature was controlled not to exceed 28℃ during each stirring. The final food-grade alkaline solution was kept at 25-27℃.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) Balances cleansing and moisturizing, improving stability during use. By using a compound oil system of coconut oil (30-50%), olive oil (20-35%), and palm oil (15-25%), it ensures powerful cleaning (coconut oil provides rich foam) while avoiding excessive degreasing (olive oil forms a moisturizing film). At the same time, it increases the hardness of the soap (palm oil), solving the problems of "tight and dry" or "softening and deformation" of traditional soaps. It has a moderate hardness (35-39 Shore A) and good durability.

[0021] (2) Targeted and effective, covering diverse skin needs For sensitive, reddened skin: the combination of honey and bitter camellia oil inhibited histamine release (45.2%), reduced transepidermal water loss (TEWL) by 32.8%, and achieved an irritation score of only 0.5. Postoperative repair / inflammatory skin: The anti-inflammatory effect of comfrey extract reached 42.3%, and its pH value was close to that of the skin (6.3), with no irritation; Dry, oil-deficient skin: The four-element combination (bitter camellia oil + grapeseed oil + glycerin + honey) achieves a closed loop of "repair → protection → moisture retention", with a 4-hour moisturizing rate of 31.2% and a DPPH free radical scavenging rate of 70.2%, effectively improving dryness, flaking and skin barrier fragility.

[0022] (3) Safe and gentle, retaining active ingredients Using food-grade raw materials and an alkali-water ratio of 1:(2.8-3.2), the alkaline solution is prepared in three controlled temperature steps, with free alkali residue as low as 0.03% and a pH value of 5.5-6.5, making it suitable for sensitive skin. Functional ingredients are added when the soap solution reaches trace to maximize their activity (e.g., grape seed oil DPPH removal rate is increased to 70.5%) and avoid damage from strong alkalis.

[0023] (4) The preparation method is scientific and the product quality is controllable. Temperature control (40-50℃ for melting oils, 25-27℃ for alkaline solutions) and time control (24-48 hours for static curing, 2-4 weeks for maturation) are implemented at each step to ensure uniform saponification, stable structure, no cracks or roughness, and consistent quality between batches.

[0024] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments. Attached Figure Description

[0025] Figure 1 This is a step diagram illustrating the preparation method of coconut oil handmade soap according to an embodiment of the present invention. Detailed Implementation

[0026] The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the scope of this application and its application or use.

[0027] Example 1: This invention provides a coconut oil handmade soap, made from food-grade raw materials, which include the following components by weight percentage: Coconut oil: 30-50%; Olive oil: 20-35%; Palm oil: 15-25%; Functional additives: 0.5-5%, the functional additives are selected from at least one of the following: comfrey extract, honey, bitter camellia oil, grape seed oil, and glycerin; Food-grade alkaline solution: balance. The food-grade alkaline solution is composed of food-grade alkali and deionized water.

[0028] In this embodiment of the invention, it should be further explained that the above-mentioned handmade soap uses a compound oil system of coconut oil, olive oil, and palm oil, which achieve a balance between "cleansing power and moisturizing sensation" through complementary effects. (1) Coconut oil (30-50%): balances cleansing power and gentleness Raw material characteristics: Rich in short-chain saturated fatty acids such as lauric acid and myristic acid, the sodium fatty acid produced after saponification has strong surface activity, which can quickly emulsify oils and dust and produce dense foam.

[0029] Saponification requirements: As a core cleansing ingredient, it needs to provide sufficient degreasing power to achieve effective cleansing, but excessive use can damage the skin barrier (overly strong degreasing).

[0030] Formulating guidelines: Below 30%: Insufficient cleansing power, little foam, unable to thoroughly remove dirt; Above 50%: Short-chain fatty acids have excessive degreasing power after saponification, which can easily damage the skin's lipid barrier, leading to tightness and dryness after cleansing; 30-50%: Ensures powerful cleansing while avoiding excessive degreasing, maintaining the skin's basic moisture.

[0031] (2) Olive oil (20-35%): balances moisturizing sensation and soap stability Raw material characteristics: Mainly composed of oleic acid (monounsaturated fatty acid), containing active substances such as vitamin E. After saponification, it is gentle and skin-friendly, and can form a breathable protective film on the skin surface to reduce moisture loss.

[0032] Saponification requirements: Relieves tightness after cleansing and provides long-lasting moisturization, but excessive use will reduce the hardness of the soap.

[0033] Formulating guidelines: Below 20%: Insufficient moisturizing, skin may feel tight and flaky after cleansing; Above 35%: Olive oil is a liquid oil, and its low hardness after saponification makes the soap easy to soften and deform, and the cleaning power is diluted (oleic acid has weaker surface activity than short-chain fatty acids); 20-35%: Maintains the basic hardness of the soap while ensuring moisturizing effect, without interfering with the overall cleaning power.

[0034] (3) Palm oil (15-25%): balances the hardness of the soap and the feel of the soap. Raw material characteristics: Contains a high proportion of stearic acid (long-chain saturated fatty acid), which improves the stability of the soap structure after saponification and prevents it from melting too quickly.

[0035] Saponification requirements: to increase the hardness of the soap and extend its service life, but excessive use will reduce the amount of foam and the moisturizing effect.

[0036] Formulating guidelines: Below 15%: The soap body is not hard enough, it is easy to soften and deform when exposed to water, and its service life is short; Above 25%: The amount of foam is reduced after the saponification of stearic acid, and the moisturizing effect of long-chain fatty acids is weaker than that of olive oil, resulting in a dry feeling on the skin after cleansing; 15-25%: While improving the hardness of the soap body, it does not affect the richness of foam and the moisturizing feeling, achieving a balance of "stable durability + comfortable use".

[0037] (4) Functional additives (0.5-5%): to ensure efficacy and saponification compatibility. Raw material characteristics: The functional additives are selected from comfrey extract, honey, bitter camellia oil, grape seed oil, and glycerin. When used alone or in combination, the active ingredients complement each other to achieve specific skin care effects. Comfrey extract: Contains shikonin, which relieves inflammatory reactions such as redness and itching of the skin by inhibiting the release of inflammatory mediators such as histamine. It is suitable for sensitive, red skin or skin in the postoperative recovery period.

[0038] Honey: Natural polysaccharides (fructose, glucose) have hygroscopic and moisturizing properties, while enzymes and amino acids can soothe the skin and strengthen its barrier function.

[0039] Bitter camellia oil: Rich in unsaturated fatty acids such as linoleic acid and linolenic acid, as well as tea polyphenols, it penetrates the stratum corneum to repair the damaged lipid barrier and relieve dryness and sensitivity.

[0040] Grape seed oil: Contains antioxidants such as proanthocyanidins and vitamin E, which can eliminate free radicals, delay oxidative damage to the skin, and protect the skin barrier.

[0041] Glycerin: A small molecule humectant that absorbs moisture from the air and locks in moisture on the skin's surface, forming a moisturizing film and enhancing long-lasting hydration.

[0042] Saponification requirements: The active ingredients must remain stable during the saponification process and not interfere with the reaction between the oils and the alkali.

[0043] Formulating guidelines: Lower limit 0.5%: Active ingredients must reach the minimum effective concentration (e.g., shikonin in comfrey extract needs to be ≥0.5% to exert anti-inflammatory effects); Upper limit 5%: Excessive addition may interfere with the saponification reaction (e.g., the sugar in honey may cause soap crystallization, and excessive oily additives may reduce the hardness of the soap), or the high concentration of active ingredients may irritate the skin (e.g., excessive glycerin may cause stickiness); 0.5-5%: While ensuring specific skin care effects (e.g., soothing, moisturizing, and anti-oxidation), the soap structure and stability must not be damaged.

[0044] (5) Remaining alkaline aqueous solution: to meet the metering requirements of the saponification reaction and control the reaction conditions. Raw material characteristics: Composed of food-grade NaOH and deionized water.

[0045] Saponification requirements: (1) Stoichiometric balance: The total amount of alkali must match the total weight of the oil (calculated based on the saponification value) to ensure complete saponification of the oil (without any free oil residue) while avoiding excessive free alkali (which can irritate the skin). (2) Reaction rate control: The proportion of water affects the saponification reaction rate. An appropriate proportion can make the reaction rate moderate, which can ensure that the soap solidifies evenly and stably, while retaining the activity of functional additives (such as the proanthocyanidins of grape seed oil and the water-locking ability of glycerin).

[0046] Formulary basis: The balance is the "precise replenishment amount" required for complete saponification of oils. Combined with the control of the water ratio, it achieves the dual goals of "safe saponification + efficacy preservation".

[0047] The percentage of each component is set around a four-dimensional balance of "cleansing power - moisturizing feel - soap stability - efficacy". Through complementary raw material characteristics and precise measurement control, the handmade soap can ultimately achieve gentle cleansing, long-lasting moisturizing and specific skin care effects.

[0048] The experimental data are as follows: I. Experimental Grouping and Component Design Five experimental groups (corresponding to different combinations of functional additives) and two control groups were designed, with the specific components as follows:

[0049] II. Testing Methods pH value: Dissolve 10g of soap sample in 100mL of deionized water and measure the pH value of the solution at 25℃ using a pH meter; Soap hardness: The surface hardness of the soap was tested using a Shore hardness tester (Type A) (after standing for 7 days); Moisturizing rate: After cleansing the forearms of 20 volunteers with dry skin, the skin moisture values ​​were measured before cleansing and 1 hour and 4 hours after cleansing using a skin moisture meter (Corneometer CM825). The moisturizing rate was calculated as ((moisture after cleansing - moisture before cleansing) / moisture before cleansing × 100%). Irritation: 20 volunteers with sensitive skin underwent a patch test (24h) and were scored according to the degree of redness / itching (0=none, 1=mild, 2=moderate, 3=severe). Anti-inflammatory effect: For experimental group 3, a mouse ear swelling model (xylene-induced inflammation) was used to calculate the ear swelling reduction rate ((model group swelling degree - experimental group swelling degree) / model group swelling degree × 100%).

[0050] III. Experimental Results

[0051] IV. Results Analysis pH value: The pH values ​​of all experimental groups were in the range of 5.5-6.5 (close to the skin pH), which was significantly better than that of control group 1 (6.8) and control group 2 (7.5), indicating that the formula of the experimental group was milder; Hardness: The experimental group had moderate hardness (35-39), balancing stability and usability, while the control group 2 had higher hardness (42) but strong degreasing properties. Moisturizing rate: The moisturizing rate of the experimental group (20.3%-31.2%) was much higher than that of the control group (10.3%-15.7%). Among them, the quaternary combination (experimental group 4) had the best moisturizing effect, which verified the synergistic water-locking effect of functional additives. Irritation: The irritation scores of the experimental group were all ≤1.0, which is friendly to sensitive skin, while the control group had a score of 2.2 (which is likely to cause discomfort). Anti-inflammatory effect: The regression rate of experimental group 3 reached 42.3%, proving the targeted anti-inflammatory effect of comfrey extract and filling the gap in special care scenarios.

[0052] Conclusion: The coconut oil handmade soap formula in this embodiment, through the synergy of a complex oil system and functional additives, is significantly superior to traditional formulas and commercially available products in terms of gentleness, moisturizing, stability, and targeted efficacy, thus verifying its technological advantages.

[0053] Background Description: Traditional handmade soaps often face limitations in terms of skincare efficacy due to their singular focus: relying solely on a single moisturizing ingredient (such as a single plant oil) often fails to achieve long-lasting hydration; focusing only on moisturizing (such as glycerin alone) may lack the ability to repair the skin barrier and provide antioxidant protection, thus failing to meet the dual needs of "instant hydration" and "long-lasting moisturization." Based on this: In one possible embodiment, the functional additive is a ternary combination of camellia oil, grapeseed oil, and glycerin, wherein the weight percentage of each component is: Bitter camellia oil: 1-2%, grapeseed oil: 0.5-1%, glycerin: 0.5-1%.

[0054] In this embodiment of the invention, it is necessary to further explain that this ternary combination achieves an integrated skincare effect of "moisturizing and repairing - anti-oxidative protection - water-locking and hydrating" through the complementarity and synergy between the ingredients, solving the problem that a single additive cannot simultaneously provide immediate moisturization and long-lasting hydration. The specific principle is as follows: 1. Bitter Camellia Oil (1-2%): Deeply moisturizes and repairs the skin barrier. Bitter camellia oil is rich in unsaturated fatty acids such as linoleic acid and linolenic acid, as well as tea polyphenols. Its molecules can penetrate into the stratum corneum to replenish the lipid components lost by dry and oil-deficient skin and repair the damaged skin barrier. Tea polyphenols can also soothe the sensitivity and redness caused by dryness and provide basic moisturizing and repair support for the skin.

[0055] 2. Grape seed oil (0.5-1%): Antioxidant protection and barrier maintenance Grape seed oil contains high concentrations of proanthocyanidins, vitamin E, and other antioxidants, which can remove free radicals from the skin surface and delay the damage of oxidative damage to the repaired skin barrier. At the same time, its antioxidant properties can resist the erosion of the skin by external environmental factors (such as ultraviolet rays and pollutants) and prolong the duration of the healthy state of the skin barrier.

[0056] 3. Glycerin (0.5-1%): Provides long-lasting hydration and enhances moisturization. Glycerin, as a small molecule humectant, can absorb moisture from the air and form a breathable moisturizing film on the skin surface, locking in the moisture retained after the camellia oil repairs the skin barrier and preventing rapid moisture loss after cleansing. Its water-locking effect complements the moisturizing and repairing properties of camellia oil, solving both immediate dryness and long-lasting hydration.

[0057] 4. Synergistic effect The three elements work synergistically through a progressive process of "repair-protection-moisture retention": Bitter camellia oil repairs the skin barrier (basic) → grape seed oil provides antioxidant protection for the skin barrier (maintenance) → glycerin locks in moisture and strengthens hydration (long-lasting). Avoiding the limitations of single ingredients (such as glycerin alone being too dependent on external moisture, or camellia oil alone having a short moisturizing effect), this method ultimately enhances the moisturizing and oil-balancing properties of handmade soaps, making them especially suitable for dry and oil-deficient skin.

[0058] 5. Basis for proportioning: This formulation range ensures that each ingredient reaches the minimum effective concentration (e.g., the antioxidant components of grape seed oil need to be ≥0.5% to be effective), while avoiding excessive addition that could interfere with the saponification reaction (e.g., excessive glycerin can make the soap sticky, and too much oil can reduce the hardness of the soap), thus balancing efficacy and soap stability.

[0059] This combination significantly enhances the moisturizing, repairing, and long-lasting hydrating capabilities of handmade soaps through the synergistic effect of their ingredients, filling a gap in the efficacy of cleansing products for dry and oil-deficient skin.

[0060] In one possible embodiment, the functional additives, based on the weight percentage of the above components, are further limited by the following weight percentages of food-grade raw materials: Coconut oil: 30-50%; Olive oil: 20-35%; Palm oil: 15-25%; Bitter camellia oil: 1.5%, grapeseed oil: 0.8%, glycerin: 0.7%; Food-grade alkaline solution: balance.

[0061] In this embodiment of the invention, it is necessary to further explain that the principle of this embodiment is based on the balanced synergy of the basic oil system and the ternary synergistic effect of functional additives, as detailed below: I. The Balance Logic of the Basic Oil System It uses a compound oil system of coconut oil (30-50%), olive oil (20-35%), and palm oil (15-25%), which achieves a three-dimensional balance of cleansing power, moisturizing feel, and soap stability through complementary effects. (1) Coconut oil (30-50%): Provides core cleaning power. Its rich short-chain saturated fatty acids produce dense foam after saponification, effectively emulsifying dirt. The 30-50% ratio ensures powerful cleaning while avoiding excessive degreasing that could damage the skin barrier.

[0062] (2) Olive oil (20-35%): mainly composed of oleic acid, which forms a breathable protective film after saponification, relieving the tightness after cleansing; the 20-35% ratio moisturizes the skin while maintaining the basic hardness of the soap and preventing the soap from softening and deforming.

[0063] (3) Palm oil (15-25%): contains a high proportion of stearic acid, which improves the stability of the soap structure and extends its service life; the 15-25% ratio enhances hardness without affecting the richness of foam and moisturizing feel.

[0064] The three components work together to achieve gentle and effective cleansing while ensuring skin hydration and soap durability.

[0065] II. The ternary synergistic effect of functional additives This embodiment uses a ternary combination of bitter camellia oil (1.5%), grapeseed oil (0.8%), and glycerin (0.7%) to address the cleansing and care issues of dry, dehydrated skin through a progressive and synergistic approach. (1) Bitter Camellia Oil (1.5%): Rich in unsaturated fatty acids and tea polyphenols, it penetrates the stratum corneum to repair the damaged lipid barrier of dry skin, laying the foundation for subsequent care; the 1.5% ratio achieves an effective repair concentration and does not interfere with the saponification reaction.

[0066] (2) Grape seed oil (0.8%): Contains proanthocyanidins and vitamin E, which can eliminate free radicals, provide antioxidant protection and repair the skin barrier, and resist damage to the barrier from external environment (such as ultraviolet rays and pollutants); the 0.8% ratio ensures antioxidant effect while avoiding excessive reduction of soap hardness.

[0067] (3) Glycerin (0.7%): a small molecule humectant that absorbs moisture from the air and locks in moisture on the skin surface, consolidating the moisturizing effect of camellia oil after repair and preventing rapid loss of moisture after cleansing; the 0.7% ratio achieves long-lasting water retention and is non-sticky.

[0068] The three ingredients work together to form a progressive chain of action: "repair → protection → moisture retention": bitter camellia oil repairs the skin barrier → grapeseed oil maintains the health of the skin barrier → glycerin consolidates moisturization. This not only solves the immediate moisturizing needs of dry skin, but also achieves long-lasting moisture retention, significantly enhancing the moisturizing, repairing and oil-balancing effects of handmade soap, making it especially suitable for dry and oil-deficient skin.

[0069] III. The rationality of the overall proportion The proportions of each component in this embodiment are designed around "efficacy + stability": the proportion of base oils balances cleansing, moisturizing and soap durability; the concentration of the ternary combination of functional additives is within the effective range and does not interfere with the saponification reaction or damage the soap structure, ultimately achieving the effect of integrated cleaning and maintenance.

[0070] In summary, this embodiment, through the complementary balance of base oils and the synergistic effect of functional additives, not only ensures the cleansing power and stability of handmade soap, but also specifically addresses the issues of moisturizing, repairing, and providing long-lasting hydration for dry and oil-deficient skin.

[0071] The experimental data are as follows: I. Experimental Design Experimental objective: To verify whether this specific ratio of ternary combination (1.5% bitter camellia oil + 0.8% grapeseed oil + 0.7% glycerin) is superior to other combinations of the same ingredients in different proportions. The core test indicators cover five dimensions: moisturizing and repairing, antioxidant protection, water-locking and moisturizing, soap stability, and gentleness.

[0072] Experimental Groups: All groups used the same basic oil system (40% coconut oil + 25% olive oil + 18% palm oil + balance alkaline solution), differing only in the proportion of functional additives.

[0073] Test metrics: 4-hour moisturizing rate (water-locking ability, skin moisture tester). DPPH free radical scavenging rate (antioxidant capacity, representing the efficacy of grapeseed oil); Transdermal water loss (TEWL) reduction rate (barrier repair ability, representing the efficacy of bitter camellia oil). Soap hardness (Shore A hardness tester, after standing for 7 days); Irritation rating (sensitive skin patch test, 0 = no irritation, 3 = severe irritation).

[0074] II. Experimental Results

[0075] III. Results Analysis The key reason why this specific ratio is superior to other combinations lies in the precise matching of the effective threshold of each component ratio and the maximization of synergistic effects: (1) 1.5% bitter camellia oil: It can fully penetrate the stratum corneum to replenish lipids and repair the dry skin barrier (TEWL reduction rate of 35.2% was significantly higher than that of control group 3, which was 28.7%). The amount was not excessive (e.g., 2% in control group 4 was close to the upper limit), to avoid interfering with the hardness of the soap (the hardness of the experimental group was 38, which was better than that of control group 4, 35).

[0076] (2) Grape seed oil 0.8% The activity of proanthocyanidins and vitamin E was maximized (DPPH clearance rate of 68.5%, higher than 55.8% in control group 4, while grape seed oil in control group 4 had only 0.5%, close to the lower limit). The amount was not exceeded (e.g., 1.2% in control group 5 exceeded the upper limit), thus avoiding a decrease in soap stability (the hardness of the experimental group was 38, which was better than that of control group 5, which was 37).

[0077] (3) Glycerin 0.7% It can absorb moisture to form a moisturizing film (4-hour moisturizing rate of 29.1%, higher than 25.3% of control group 3), and it is not sticky (control group 3 has 1% glycerin, which is slightly above the range, and the irritation score of 0.9 is higher than 0.7 of experimental group).

[0078] Synergistic effect: The three components form a complete progressive chain of "repair (bitter camellia oil) → protection (grape seed oil) → water locking (glycerin)," with the component concentration in each link being in the optimal range. The synergistic effect is significantly better than other ratios (such as the equal distribution of each component in control group 3, which resulted in no outstanding advantage; control group 4, which had insufficient antioxidant capacity; and control group 5, which had weak repair ability).

[0079] IV. Conclusion The formula of "1.5% bitter camellia oil + 0.8% grapeseed oil + 0.7% glycerin" precisely controls the effective concentration of each ingredient, ensuring the maximum efficacy of each individual ingredient while achieving synergistic effects among the three. It performs optimally in moisturizing and repairing, anti-oxidative protection, water-locking and moisturizing, soap stability and gentleness, making it an ideal formula for a three-element combination.

[0080] Background: Traditional handmade soaps have significant shortcomings in cleansing and caring for sensitive, reddened skin. Most products either focus on cleansing power but contain highly irritating ingredients, easily exacerbating redness, itching, or barrier damage in sensitive skin; or they only add moisturizing ingredients, making it difficult to simultaneously meet the dual needs of gentle cleansing and soothing repair. Therefore: In one possible embodiment, the functional additive is a binary combination of honey and bitter camellia oil, with the following weight percentages: honey: 1-2% and bitter camellia oil: 1-1.5%.

[0081] In this embodiment of the invention, it is necessary to further explain that this embodiment addresses the shortcomings of traditional handmade soaps in cleansing and caring for sensitive and reddened skin (irritation aggravates sensitivity or insufficient moisturization). It achieves a dual effect of gentle cleansing and soothing repair through the synergistic effect of two ingredients. The specific principle is as follows: 1. The core function of honey Honey is rich in natural polysaccharides (fructose, glucose), enzymes, and amino acids. Moisture absorption and moisturizing: Polysaccharides have good moisture absorption properties, which can absorb moisture from the air and form a moisturizing film on the skin surface, relieving the dryness of sensitive skin after cleansing; Soothe and strengthen the skin barrier: Enzymes and amino acids can soothe skin discomfort, help strengthen the damaged skin barrier, and reduce the impact of external stimuli on sensitive skin.

[0082] 2. The core function of bitter camellia oil Bitter camellia oil contains unsaturated fatty acids such as linoleic acid and linolenic acid, as well as tea polyphenols. Repairing a damaged skin barrier: Unsaturated fatty acids can penetrate into the stratum corneum, replenishing the lipid components lacking in sensitive skin and repairing redness and itching caused by a damaged skin barrier. Soothing and anti-inflammatory: Tea polyphenols can relieve skin sensitivity and reduce redness and discomfort.

[0083] 3. Synergistic Efficiency Mechanism The moisturizing and soothing components of honey work synergistically with the repairing and soothing components of bitter camellia oil: With the basic oil system (coconut oil, olive oil, palm oil) providing gentle cleansing power, the two work together to avoid the irritation of traditional soaps and solve the problem that a single moisturizing ingredient cannot simultaneously provide repair. It achieves the effect of "non-irritating during cleansing and soothing and repairing after cleansing", effectively improving the cleansing experience of sensitive and red skin and filling the gap in the market for cleansing soaps specifically for sensitive skin.

[0084] 4. Rationality of the formula Honey (1-2%): This concentration ensures that the polysaccharides reach the effective moisturizing and soothing threshold, while avoiding excessive sugar interfering with the saponification reaction (such as causing soap crystallization). Bitter camellia oil (1-1.5%): This concentration ensures that there are enough unsaturated fatty acids to repair the skin barrier, and will not reduce the hardness of the soap or affect its cleaning power due to excessive oily components; The ratio of the two achieves a balance between efficacy and soap stability, and is compatible with the cleansing and moisturizing balance of the base oil system.

[0085] In summary, this dual-component combination addresses the cleansing challenges of sensitive, reddened skin through complementary and synergistic ingredients, achieving a holistic effect of gentle cleansing and soothing repair.

[0086] In one possible embodiment, the functional additives, based on the weight percentage of the above components, are further limited by the following weight percentages of food-grade raw materials: Coconut oil: 40%; Olive oil: 25%; Palm oil: 18%; Honey: 1.2%, Bitter Camellia Oil: 1.3%; Food-grade alkaline solution: balance.

[0087] In this embodiment of the invention, it is necessary to further explain that this embodiment addresses the cleansing and care needs of sensitive and reddened skin by achieving an integrated effect of "gentle cleansing + soothing repair" through the gentle balance of the basic oil system and the synergistic effect of functional additives. The principle is as follows: I. The Mild Balance Logic of the Basic Oil System The soap uses a blend of coconut oil (40%), olive oil (25%), and palm oil (18%) to achieve a precise balance between cleansing power, moisturizing feel, and soap stability. 1. Coconut oil (40%): It provides sufficient cleaning power (emulsifies dirt and produces rich foam) through short-chain saturated fatty acids, while avoiding excessive degreasing (protecting the sensitive skin barrier from damage). 2. Olive oil (25%): The main component, oleic acid, forms a breathable protective film after saponification, which relieves the tightness after cleaning and maintains the basic hardness of the soap (without softening or deforming). 3. Palm oil (18%): Stearic acid enhances the stability of the soap structure (extending its service life) without affecting the richness of foam and moisturizing feel.

[0088] The three elements work together to ensure that the handmade soap retains the skin's essential lipids while gently cleansing, avoiding irritation and redness to sensitive skin.

[0089] II. The dual synergistic effect of functional additives The combination of honey (1.2%) and bitter camellia oil (1.3%) provides complementary repair for the core pain points of sensitive skin (damaged barrier, redness and itching): 1. Honey (1.2%): Natural polysaccharides (fructose, glucose) absorb moisture from the air, forming a moisturizing film on the skin surface to relieve dryness after cleansing; Enzymes and amino acids soothe skin discomfort, strengthen the damaged barrier, and reduce the impact of external stimuli on sensitive skin; The ratio is within the effective range of 1-2%, which ensures both moisturizing and soothing effects while avoiding excessive sugar content from interfering with the saponification reaction.

[0090] 2. Bitter camellia oil (1.3%): Unsaturated fatty acids such as linoleic acid and alpha-linolenic acid penetrate the stratum corneum, replenish the lipids lost by sensitive skin, and repair the skin barrier. Tea polyphenols have anti-inflammatory and soothing properties, reducing redness and itching; The ratio is within the effective range of 1-1.5% to ensure repair efficacy without reducing the hardness of the soap.

[0091] Synergistic Mechanism: The moisturizing and soothing effects of honey and the barrier-repairing effects of bitter camellia oil work synergistically. Honey provides immediate relief from dryness, while bitter camellia oil deeply repairs the skin barrier. Together, they address the shortcomings of traditional handmade soaps that "cleanse but irritate sensitive skin," achieving a dual effect of gentle cleansing and soothing repair.

[0092] III. The rationality of the overall proportion The component ratios in this embodiment are designed around the principles of "sensitive skin friendly + stable efficacy": The proportion of base oils balances cleansing power, moisturizing feel, and soap durability, making it suitable for the gentle needs of sensitive skin. The concentration of functional additives is within the effective threshold and does not interfere with the saponification reaction or damage the soap structure; The overall system fills the gap in cleansing products for sensitive and red skin, ensuring both effective cleansing and targeted solutions to the repair needs of sensitive skin.

[0093] In summary, this embodiment achieves the core goal of "cleansing without irritation and effectively repairing" sensitive and reddened skin through the gentle balance of basic oils and the synergistic effect of functional ingredients.

[0094] The experimental data are as follows: I. Experimental Design Experimental objective: To verify whether the binary combination of "1.2% honey + 1.3% bitter camellia oil" is superior to other combinations of the same ingredients in different proportions. The core indicators cover four dimensions: soothing and repairing sensitive and red skin, moisturizing, gentleness, and soap stability.

[0095] Experimental Groups: All groups used the same basic oil system (40% coconut oil + 25% olive oil + 18% palm oil + balance alkaline solution), differing only in the proportion of functional additives (total addition was 2.5% for all groups to ensure fairness):

[0096] Test metrics: Histamine release inhibition rate (anti-inflammatory effect, representing the efficacy of bitter camellia oil): In vitro cell experiments tested its ability to inhibit histamine release; TEWL decline rate (barrier repair capacity): a transepidermal water loss test that reflects the degree of barrier repair. 4-hour moisturizing rate (moisturizing effect, representing the efficacy of honey): The skin moisture tester measures the moisture retention rate 4 hours after cleansing; Irritation rating (sensitive skin affinity): Patch test on 20 volunteers with sensitive skin, rating range 0 (no irritation) to 3 (severe irritation); Soap hardness (Shore A hardness tester, after standing for 7 days): reflects the stability and durability of the soap.

[0097] II. Experimental Results

[0098] III. Results Analysis The key reason why this specific formula (1.2% honey + 1.3% bitter camellia oil) is superior to other combinations lies in the precise matching of ingredient ratios to the needs of sensitive skin and the maximization of synergistic effects: (1) Honey 1.2% Natural polysaccharides (fructose, glucose) reach the optimal moisture absorption and moisturizing threshold, ensuring that the moisturizing rate 4 hours after cleansing (26.5%) is significantly higher than that of the control group 8 (22.1%), while avoiding excessive sugar content that could lead to soap crystallization or irritation (irritation score of only 0.5). Enzymes and amino acids play a full role in soothing and helping bitter camellia oil repair the skin barrier.

[0099] (2) 1.3% bitter camellia oil: Unsaturated fatty acids (linoleic acid, linolenic acid) penetrate the stratum corneum to replenish lipids, and the TEWL reduction rate (32.8%) is higher than that of the control group (28.6%), indicating stronger barrier repair ability; Tea polyphenols inhibited histamine release (45.2%) and relieved sensitive redness, with better results than the control group 6 (40.1%). The amount was not excessive (e.g., 1.7% in control group 8), to avoid a decrease in soap hardness (the hardness of the experimental group was 36, which was better than that of control group 8, 33).

[0100] Synergistic effect: The moisturizing and soothing properties of honey complement the anti-inflammatory and repairing properties of camellia oil, simultaneously relieving redness and itching of sensitive skin during the cleansing process (high histamine inhibition rate) and repairing the damaged barrier (high TEWL reduction rate), while maintaining soap stability (moderate hardness) and gentleness (lowest irritation score).

[0101] In summary, this formula achieves an optimal balance of anti-inflammatory repair, moisturizing, gentleness, and soap stability for sensitive skin through precise control of ingredient concentration, which is significantly superior to other combinations of the same ingredients in different proportions.

[0102] Background Description: Traditional handmade soaps have a significant gap in specific skincare scenarios: for the daily cleansing needs of sensitive, red, and inflammatory skin (such as redness and itching, mild inflammation caused by a damaged skin barrier) or skin during post-operative recovery, existing products struggle to simultaneously address the dual goals of "gentle cleansing" and "targeted anti-inflammatory." Most products are either too strong, easily irritating fragile skin and exacerbating inflammation; or they focus solely on moisturizing, lacking active ingredients that can directly alleviate inflammation. This results in a lack of safe and suitable options for this specific skin type in their daily cleansing routine. Therefore: In one possible embodiment, the functional additive is comfrey extract, at a weight percentage of 0.5-1%.

[0103] In this embodiment of the invention, it is necessary to further explain that the core active ingredient in the comfrey extract, shikonin, directly acts on the mechanism of skin inflammation by inhibiting the release of inflammatory mediators such as histamine: histamine is a key mediator that causes inflammatory symptoms such as redness, swelling and itching of the skin. Shikonin can block its release pathway, thereby reducing or alleviating the inflammatory response of sensitive and red skin, as well as the mild inflammation that may exist in the skin during the postoperative repair period.

[0104] This handmade soap is tailored to specific skin needs through a combination of gentle cleansing and targeted anti-inflammatory benefits. Gentle Cleansing Base: The base oil system (such as 38% coconut oil, 30% olive oil, and 19% palm oil in the examples) achieves a balance between cleansing power and gentleness. Coconut oil provides moderate cleansing power without excessive degreasing, olive oil forms a breathable protective film on the skin surface to reduce moisture loss, and palm oil ensures the soap is stable and durable, avoiding the burden on fragile skin caused by traditional cleansing products due to irritation or excessive degreasing. Targeted anti-inflammatory: Shikonin's anti-inflammatory effect directly soothes these types of skin inflammation problems. While completing daily cleansing, it will not irritate the skin. On the contrary, it can help relieve discomfort such as redness, swelling and itching, making it suitable for the special care needs of sensitive, red skin or skin in the post-operative recovery period.

[0105] Traditional handmade soaps have significant shortcomings in daily cleansing scenarios for "sensitive, red, and inflammatory skin" or "skin in the post-operative recovery period": most products are either too strong in their cleansing power, which can easily irritate fragile skin and aggravate inflammation; or they only focus on moisturizing and lack active ingredients that can directly relieve inflammation.

[0106] Handmade soaps containing comfrey extract offer a safe and suitable daily cleansing option for this special skin group through their dual benefits of "gentle cleansing + targeted anti-inflammatory," filling the gap in existing products for this specific skin care scenario.

[0107] In summary, the addition of comfrey extract makes handmade soaps both gentle on sensitive, red, and post-operatively repaired skin, and also specifically address inflammation issues, making it an effective solution for this specific scenario.

[0108] In one possible embodiment, the functional additives, based on the weight percentage of the above components, are further limited by the following weight percentages of food-grade raw materials: Coconut oil: 38%; Olive oil: 30%; Palm oil: 19%; Comfrey extract: 0.8%; Food-grade alkaline solution: balance.

[0109] In this embodiment of the invention, it is necessary to further explain that this embodiment addresses the daily cleansing needs of sensitive, red, and inflammatory skin, or skin in the post-operative recovery period. Through the synergistic design of a gentle cleansing base system and targeted anti-inflammatory effects, it fills the gap in traditional handmade soaps for this specific skincare scenario. The specific principle is as follows: I. The Mild Balance Logic of the Basic Oil System The blend of coconut oil (38%), olive oil (30%), and palm oil (19%) achieves a three-dimensional balance of cleansing power, gentleness, and soap stability, providing a non-irritating cleansing foundation for delicate skin. 1. Coconut oil 38%: Rich in short-chain saturated fatty acids, it provides moderate cleansing power (emulsifies dirt and produces rich foam) while avoiding excessive degreasing that could damage the skin barrier, making it suitable for the cleansing needs of delicate skin. 2. Olive oil 30%: mainly composed of oleic acid (monounsaturated fatty acid), after saponification, it forms a breathable protective film on the skin surface, reducing moisture loss and relieving the tightness after cleansing; 3. Palm oil 19%: Contains a high proportion of stearic acid, which improves the stability of the soap structure (prevents softening and deformation), extends the service life, and does not affect the richness of foam and moisturizing feel.

[0110] The three elements work together to ensure that the handmade soap effectively cleanses without aggravating the inflammatory burden on delicate skin.

[0111] II. Targeted anti-inflammatory effects of functional additives The core function of comfrey extract (0.8%) is to directly relieve skin inflammation: 1. Mechanism of active ingredients: Shikonin, as the core active substance, inhibits the release of inflammatory mediators such as histamine, blocks the path of inflammatory symptoms such as redness, swelling and itching, and specifically soothes the inflammatory problems of sensitive and red skin, or assists in the reduction of mild inflammation of the skin during the postoperative repair period. 2. Reasonable concentration: 0.8% can ensure anti-inflammatory effects (reaching the minimum threshold for shikonin to exert its effects) without interfering with the saponification reaction or irritating fragile skin.

[0112] III. Overall Synergistic Effect This embodiment achieves precise adaptation to special skin types through a combination of "gentle cleansing foundation + targeted anti-inflammatory treatment": The basic oil system provides a safe and non-irritating cleansing experience, avoiding the exacerbation of inflammation caused by excessive degreasing or irritation from traditional products; The anti-inflammatory properties of comfrey extract work simultaneously during the cleansing process to help relieve skin discomfort; The overall formula balances efficacy and stability, providing a safe and suitable daily cleansing option for sensitive, red, or post-operative skin during the recovery period, filling a gap in existing products for this specific scenario.

[0113] In summary, this embodiment, through the synergistic design of the ingredients, not only meets the gentle cleansing needs of special skin types but also addresses their inflammatory issues in a targeted manner, making it an effective solution for this specific skincare scenario.

[0114] The experimental data are as follows: I. Experimental Design Experimental objective: To verify whether a 0.8% concentration of comfrey extract is superior to other combinations of the same ingredients at different concentrations, with key indicators covering anti-inflammatory efficacy, barrier repair, gentleness, and soap stability.

[0115] Experimental groups: All groups had the same basic oil system (38% coconut oil + 30% olive oil + 19% palm oil + balance alkaline solution), with the only difference being the amount of comfrey extract added.

[0116] Test metrics: Histamine release inhibition rate (in vitro cell experiment, reflecting anti-inflammatory effect); TEWL decline rate (transdermal water loss, reflecting barrier repair capacity); Improvement rate of skin redness (visual scores of 20 volunteers with sensitive redness after 1 week of use); Irritation rating (sensitive skin patch test, 0 = no irritation, 3 = severe irritation); Soap hardness (Shore A hardness tester, standing for 7 days, reflecting stability).

[0117] II. Experimental Results

[0118] III. Results Analysis The core reason why the 0.8% ratio is optimal: 1. Maximizing efficacy: The concentration of shikonin reached the optimal threshold for anti-inflammatory and repair effects. The histamine inhibition rate (48.2%), TEWL reduction rate (35.1%), and redness improvement rate (40.3%) were significantly higher than those of other groups, proving that it can most effectively relieve the inflammatory response of sensitive and red skin and repair the skin barrier.

[0119] 2. Mild and balanced: The irritation score is only 0.6, which is much lower than that of control group 10 (1.0%, 0.8 points) and control group 11 (1.2%, 1.0 points), avoiding skin discomfort caused by high concentration.

[0120] 3. Soap stability: The hardness of 37 is moderate, which ensures durability without causing the soap to soften due to excessive addition (for example, the hardness of the control group 11 is only 34).

[0121] Other concentration defects: 0.5%: The concentration is below the effective threshold, and the anti-inflammatory and repair effects are insufficient (histamine inhibition rate is only 35.7%, and redness improvement rate is 25.6%). 1.0%: close to the upper limit, slightly more irritating and slightly less effective than the experimental group; 1.2%: Exceeds the effective range, soap hardness decreases (34), irritation increases significantly (1.0 point), and efficacy decreases (histamine inhibition rate 42.1%).

[0122] In summary, the 0.8% concentration of comfrey extract achieves an optimal balance of anti-inflammatory efficacy, gentleness, and soap stability through precise concentration control, which is superior to other combinations of the same ingredients at other concentrations.

[0123] Background Description: Traditional handmade soaps, while addressing dry, dehydrated skin, utilize a three-element combination (bitter camellia oil, grapeseed oil, and glycerin) through a synergistic mechanism of "moisturizing and repairing - anti-oxidative protection - locking in moisture," overcoming the limitations of single additives in providing both immediate and long-lasting hydration. However, they lack a more comprehensive approach to addressing the complex issues of dryness, oil imbalance, and a weakened skin barrier. This requires both long-lasting hydration and a strengthened skin barrier to regulate sebum secretion, achieving a closed loop from cleansing to deep nourishment. Therefore: In one possible embodiment, the functional additive is a quaternary combination of bitter camellia oil, grape seed oil, glycerin and honey, with the following weight percentages: bitter camellia oil 1-1.5%, grape seed oil 0.5-1%, glycerin 0.5-1%, and honey 0.5-1%.

[0124] In this embodiment of the invention, it is necessary to further explain that the quaternary combination provided in this embodiment addresses the complex problems of dry and oil-deficient skin (dryness, oil imbalance, and fragile skin barrier). Through the synergistic effect of the four ingredients, it achieves integrated care of "moisturizing and repairing - anti-oxidative protection - soothing and strengthening - locking in moisture". The specific principle is as follows: 1. Core functions of each component Bitter Camellia Oil (1-1.5%): Rich in unsaturated fatty acids (linoleic acid, linolenic acid) and tea polyphenols, it penetrates the stratum corneum to replenish the skin's missing lipids, repairs the damaged barrier, soothes sensitivity caused by dryness, and provides deep moisturizing foundation for the skin.

[0125] Grape seed oil (0.5-1%): Contains antioxidants such as proanthocyanidins and vitamin E, which can eliminate free radicals, resist external damage such as ultraviolet rays and pollutants, maintain the healthy state of the repaired skin barrier, and prevent oxidative damage from aggravating skin problems.

[0126] Glycerin (0.5-1%): A small molecule humectant that absorbs moisture from the air and forms a breathable moisturizing film to lock in the moisture of the repaired skin, preventing rapid moisture loss after cleansing and achieving long-lasting hydration.

[0127] Honey (0.5-1%): Natural polysaccharides (fructose, glucose) absorb moisture and keep skin hydrated, while enzymes and amino acids soothe skin discomfort, strengthen the damaged barrier, and further enhance the skin's moisturizing and anti-irritant abilities.

[0128] 2. Synergistic Efficiency Mechanism The four components work synergistically to form a complete maintenance loop: Bitter camellia oil repairs the skin barrier → grapeseed oil provides antioxidant protection → honey soothes and strengthens the skin barrier → glycerin locks in moisture and consolidates hydration. Compared to the three-ingredient combination (bitter camellia oil + grapeseed oil + glycerin), the addition of honey adds a "soothing and strengthening barrier" dimension. It further regulates sebum secretion to address the problem of a fragile skin barrier, solving the complex problems of dry and oil-deficient skin (dryness and flaking, oil imbalance, sensitivity and redness), achieving an integrated effect from cleansing to deep nourishment.

[0129] 3. Rationality of the formula The concentrations of all components are within the effective threshold: Bitter camellia oil 1-1.5%: reaches an effective concentration for repairing the skin barrier without interfering with the saponification reaction; Grapeseed oil 0.5-1%: Ensures antioxidant effects and avoids excessive reduction of soap hardness; Glycerin 0.5-1%: Achieves a water-locking effect without leaving a sticky feeling; Honey 0.5-1%: Provides moisturizing and soothing effects, and avoids excessive sugar content from affecting the stability of the soap.

[0130] The overall formula balances efficacy and soap structure stability, without compromising cleaning power or user experience.

[0131] 4. Final Result This combination offers four benefits, and long-term use can improve dryness, oil imbalance, and a fragile skin barrier in dry, dehydrated skin. It fills the gap in traditional handmade soaps for complex skin care scenarios, achieving a holistic approach to cleansing and nourishing.

[0132] In summary, the quaternary combination provides a more comprehensive cleansing and care solution for dry and oil-deficient skin through the complementary and synergistic effects of its ingredients, addressing complex skin problems that cannot be covered by single or ternary combinations.

[0133] In one possible embodiment, the functional additives, based on the weight percentage of the above components, are further limited by the following weight percentages of food-grade raw materials: Coconut oil: 32%; Olive oil: 32%; Palm oil: 21%; Bitter camellia oil 1.2%, grapeseed oil 0.6%, glycerin 0.6%, honey 0.6%; Food-grade alkaline solution: balance.

[0134] In the embodiments of this invention, it is necessary to further explain, firstly, the balance logic of the basic oil system. This embodiment uses a compound oil system of coconut oil (32%), olive oil (32%), and palm oil (21%). The three oils complement each other to form a foundation for gentle cleaning and stable use. 1. Coconut oil (32%) Core function: Provides moderate cleaning power. Its rich short-chain saturated fatty acids (lauric acid, myristic acid) produce sodium fatty acids with strong surface activity after saponification, which can effectively emulsify dirt and produce dense foam. Formulating principle: To ensure effective cleansing while avoiding excessive degreasing (damaging the skin barrier), and to meet the gentle cleansing needs of dry, oil-deficient skin.

[0135] 2. Olive oil (32%) Core functions: Deeply moisturizes and protects the skin barrier. It is mainly composed of oleic acid (monounsaturated fatty acid). After saponification, it forms a breathable protective film on the skin surface, reducing moisture loss and relieving the tightness after cleansing. Formulating principle: While providing long-lasting moisturization, maintain the basic hardness of the soap (to avoid softening and deformation) and do not dilute the overall cleaning power.

[0136] 3. Palm oil (21%) Core function: Enhances soap stability; contains a high proportion of stearic acid (long-chain saturated fatty acid), which strengthens the soap structure and hardness after saponification, prevents softening upon contact with water, and extends service life. Formulating principle: To enhance the durability of the soap without affecting the richness of the lather or the moisturizing effect.

[0137] Synergistic effect: The three components work together to achieve the basic characteristics of "cleaning without irritation, moisturizing without greasiness, and stable and durable soap body", providing a safe carrier for subsequent functional maintenance.

[0138] II. The Quadrivalent Synergistic Mechanism of Functional Additives The formula incorporates a quaternary combination of bitter camellia oil (1.2%), grapeseed oil (0.6%), glycerin (0.6%), and honey (0.6%), creating a progressive, closed-loop skincare routine to address the complex issues of dry, dehydrated skin. 1. Bitter Camellia Oil (1.2%): Deeply repairs the skin barrier. Key functions: Rich in unsaturated fatty acids such as linoleic acid and alpha-linolenic acid, as well as tea polyphenols, it penetrates the stratum corneum to replenish the skin's missing lipid components, repairs the damaged barrier, and soothes dryness-induced sensitivity and redness. Formulary rationale: to ensure repair efficacy without interfering with the saponification reaction.

[0139] 2. Grape seed oil (0.6%): Antioxidant protection Key functions: Contains antioxidants such as proanthocyanidins and vitamin E, which scavenge free radicals, resist oxidative damage to the repaired barrier caused by ultraviolet rays and pollutants, and maintain the healthy state of the barrier; Formulating criteria: To ensure antioxidant activity and avoid excessive reduction in soap hardness.

[0140] 3. Honey (0.6%): Soothes and strengthens the skin barrier. Key functions: Natural polysaccharides (fructose, glucose) absorb moisture and keep skin hydrated, while enzymes and amino acids soothe skin discomfort, further strengthen the damaged barrier, and regulate sebum secretion; Formulating principle: To achieve a soothing effect without stickiness or soap crystallization.

[0141] 4. Glycerin (0.6%): Long-lasting moisturizing and hydrating. Key function: Small molecule humectant, absorbs moisture from the air and forms a breathable moisturizing film to lock in the moisture of the repaired skin and prevent rapid moisture loss after cleansing; Formula ratio: to ensure effective moisture retention without irritating the skin.

[0142] Synergistic Mechanism: The four components form a progressive chain of action: "repair → protection → soothing and strengthening → moisture retention". Bitter camellia oil repairs the damaged barrier (basic) → grape seed oil provides antioxidant protection for the barrier (maintenance) → honey soothes and strengthens the barrier (regulates oil production) → glycerin locks in moisture and consolidates hydration (long-lasting).

[0143] This closed-loop system addresses the complex issues of dry, oil-deficient skin (dryness and flaking, oil imbalance, sensitivity and redness), achieving an integrated effect from cleansing to deep nourishment.

[0144] This formula, through the balanced complementarity of base oils and the synergistic effect of functional additives, ensures both the cleansing power and stability of handmade soaps, while also specifically addressing multiple issues of dry and dehydrated skin, achieving an integrated "cleansing + care" effect and filling the gap in traditional handmade soaps for complex skin care scenarios.

[0145] In summary, the formulation design of this embodiment revolves around the core of "efficacy + stability," and through precise proportions and synergistic effects of ingredients, it provides a safe and effective daily cleansing and care solution for dry and oil-deficient skin.

[0146] The experimental data are as follows: I. Experimental Objective The study verified whether this specific quaternary ratio is superior to other combinations of the same ingredients in different proportions. The core indicators cover six dimensions: moisturizing and repairing, anti-oxidative protection, water locking and hydration, barrier repair, gentleness, and soap stability, demonstrating the technological advantages of synergistic effects.

[0147] II. Experimental Grouping All groups share the same basic oil system (32% coconut oil + 32% olive oil + 21% palm oil + balance from alkaline solution), differing only in the proportion of functional additives (total addition is 3% for all groups to ensure fairness):

[0148] III. Test Indicators 4-hour hydration rate: The skin moisture retention rate was measured 4 hours after cleansing using a skin moisture meter (Corneometer CM825). DPPH free radical scavenging rate: an in vitro experiment reflecting the antioxidant capacity of grape seed oil; TEWL reduction rate: Transdermal moisture loss tester, reflecting the barrier repair effect of bitter camellia oil; Skin hydration rating: After 1 week of use, 20 volunteers with dry skin were evaluated using a combination of instrumental testing (skin oil content) and subjective ratings (out of 5). Irritation rating: Patch test on 20 volunteers with sensitive skin (0 = no irritation, 3 = severe irritation); Soap hardness: Shore A hardness tester (after standing for 7 days), reflecting the stability of the soap.

[0149] IV. Experimental Results

[0150] V. Conclusion and Analysis The key reason why this specific quaternary ratio (1.2%+0.6%+0.6%+0.6%) is superior to other combinations lies in the precise matching of the effective thresholds of each component and the maximization of synergistic effects: 1. Bitter Camellia Oil 1.2%: Unsaturated fatty acids fully penetrate and repair the skin barrier, and the TEWL reduction rate (38.1%) is significantly higher than that of the control group (30.5%-35.2%). 2. Grape seed oil 0.6%: maximized proanthocyanidin activity, with a DPPH scavenging rate (70.2%) leading the control group (60.3%-65.1%). 3. Glycerin 0.6% + Honey 0.6%: The two work together to lock in moisture, with a 4-hour moisturizing rate (32.5%) that far exceeds that of the control group (26.1%-28.3%), and without any stickiness; 4. Overall Synergy: It forms a closed loop of "repair → protection → water retention → soothing", with the best moisturizing score (4.8) and mildness (0.6 points). The soap hardness (39) balances stability and user experience.

[0151] In summary, this formula, through precise synergy between its ingredients, significantly outperforms other combinations of the same ingredients in core efficacy such as moisturizing and repairing, anti-oxidation, and water-locking, thus verifying its technological superiority.

[0152] Background Description: Traditional handmade soaps face several challenges in the preparation and application of lye solutions: First, some products use non-food-grade lye raw materials, making it difficult to meet safety standards and posing potential risks. Second, improper control of the lye-to-water ratio is problematic. If the lye concentration is too high, the saponification reaction rate is too fast, resulting in uneven soap solidification, a rough texture, and increased free lye residue, which can irritate the skin and cause dryness and discomfort during cleansing. If the concentration is too low, the reaction is too slow, the soap softens and is difficult to shape, affecting the user experience. Third, the lack of temperature control in the preparation of lye solutions can easily destroy the activity of functional additives such as the antioxidant components of grape seed oil and the water-locking components of glycerin, weakening the skincare benefits of handmade soaps. Based on this: In one possible embodiment, the weight ratio of food-grade sodium hydroxide to deionized water in the food-grade alkaline aqueous solution is 1:(2.8-3.2); The preparation method of food-grade alkaline solution is as follows: Food-grade sodium hydroxide was slowly added to deionized water at 20-22℃ in three portions, stirring until completely dissolved after each addition, and the solution temperature was controlled not to exceed 28℃ during each stirring. The final food-grade alkaline solution was kept at 25-27℃.

[0153] In the embodiments of this invention, it is necessary to further explain the principle of the weight ratio of food-grade sodium hydroxide to deionized water as 1:(2.8-3.2). The core design principle of this ratio is to balance reaction safety, saponification efficiency, soap stability, and the activity of functional ingredients, specifically addressing the three major pain points of traditional handmade soap lye solutions: 1. Safety and Compliance: Food-grade sodium hydroxide is used, consistent with the overall food-grade raw material system, avoiding potential safety risks from non-food-grade alkali; 2. Reaction rate control: If the ratio is less than 1:2.8 (too high alkali concentration): the saponification reaction rate is too fast, which can easily lead to uneven solidification of the soap, rough texture, and increased free alkali residue, which can irritate the skin and cause dryness and tightness during cleansing. If the ratio is higher than 1:3.2 (too low alkali concentration): the saponification reaction is too slow, the soap softens and is not easy to shape, affecting the user experience; The ratio of 1:(2.8-3.2) ensures a moderate reaction rate, guaranteeing complete saponification of oils (without any free oil residue) while avoiding excessive free alkali, thus balancing the cleansing gentleness with the stability of the soap structure. 3. Compatible with functional ingredients: The alkaline solution concentration at this ratio will not destroy the activity of functional additives such as the antioxidant components of grape seed oil and the water-locking components of glycerin, thus maximizing their skin care efficacy. 4. Soap quality optimization: Ensure uniform curing and fine texture of the soap, avoid roughness or softening and deformation, and extend service life.

[0154] II. Reasons for adding sodium hydroxide slowly in three stages and controlling the temperature The dissolution of sodium hydroxide in water is a strongly exothermic reaction. The design of adding it in three stages with temperature control (≤28℃ each time, final temperature 25-27℃) aims to protect the active ingredients, ensure reaction uniformity, and maintain soap quality. 1. Preventing the destruction of active ingredients: Traditional preparation methods lack temperature control, which can easily lead to a sudden rise in temperature, destroying the antioxidant components of grape seed oil, the water-locking ability of glycerin, and other functional additives. Adding the ingredients slowly in three batches can disperse the heat release and control the temperature to no more than 28°C, effectively preserving the skin care efficacy of these ingredients. 2. Dissolution uniformity: Stir until completely dissolved after each addition to avoid excessively high local sodium hydroxide concentration, ensure that the saponification reaction proceeds uniformly throughout the system, and prevent local roughness or free alkali residue in the soap. 3. Stabilize the saponification reaction: The final temperature is maintained at 25-27℃, so that the saponification reaction rate is in the optimal range, which ensures that the reaction is complete and that the soap does not solidify unevenly due to the excessively fast rate, thereby improving the overall texture and user experience of the soap. 4. Reduced risk of irritation: Uniform dissolution and temperature control reduce the amount of free alkali residue, further reducing the probability of skin irritation and making it suitable for the needs of special groups such as those with sensitive skin.

[0155] In summary, this alkaline solution preparation method, through precise proportioning and process control, achieves multiple objectives including safety and compliance, stable reaction, and preservation of efficacy, laying the foundation for the cleansing power and skincare benefits of handmade soaps.

[0156] The experimental data are as follows: I. Experimental Objective The preparation scheme of food-grade sodium hydroxide to deionized water weight ratio 1:(2.8-3.2) + slow addition in three parts + temperature control was verified to have advantages in soap mildness, retention of functional components and structural stability compared with other alkali water ratios / preparation methods.

[0157] II. Experimental Grouping All groups share the same basic formula (using a ternary compound formula: 40% coconut oil + 25% olive oil + 18% palm oil + 1.5% camellia oil + 0.8% grapeseed oil + 0.7% glycerin + balance lye), differing only in the lye ratio / preparation method:

[0158] III. Test Indicators and Results

[0159] IV. Results Analysis 1. Advantage of being mild: The experimental group had a pH value (6.2) close to the skin pH (5.5-6.5), and its free alkali content (0.03%) was much lower than that of the control groups 15 (0.12%) and 17 (0.07%). Its irritation score (0.6) was significantly lower than other control groups. Reason: A 1:3.0 ratio controlled the reaction rate; the alkali was added in three stages; and temperature control prevented excessively high local alkali concentrations, thus reducing free alkali residue.

[0160] 2. Retention of functional ingredients: The experimental group showed the highest DPPH scavenging rate (70.5%), indicating that the antioxidant activity of grape seed oil was best preserved. Control group 15, due to its excessively high proportion and lack of temperature control (temperature rose to 35℃), destroyed the proanthocyanidins in the grape seed oil; control group 16, with its excessively low proportion, had a slow reaction, but improper preparation methods still affected its activity; control group 17, with the same proportion but added at a single temperature, resulted in insufficient activity retention.

[0161] 3. Soap stability: The experimental group had a moderate hardness (38 Shore A), balancing durability and usability. The control group 15 had a high hardness (42) but strong degreasing properties (irritation); the control group 16 had a low hardness (32) and was easily softened and deformed; the control group 17 had a slightly lower hardness (36) and a higher free alkali content.

[0162] 4. Barrier repair effect: The experimental group showed the highest TEWL decrease rate (35.2%), indicating that the bitter camellia oil best preserved its barrier-repairing efficacy. Reason: The mild alkaline environment and temperature-controlled preparation avoided damaging the unsaturated fatty acid structure of the bitter camellia oil.

[0163] V. Conclusion The 1:(2.8-3.2) ratio + three-stage addition + temperature control alkaline solution preparation scheme, through precise control of reaction rate, reduction of free alkali residue, and preservation of functional ingredient activity, is superior to other alkaline solution ratios / preparation methods in terms of soap mildness, efficacy, and stability, verifying its technical advantages.

[0164] Example 2, see Figure 1 The present invention provides a step-by-step method for preparing coconut oil handmade soap. Figure 1 The method for preparing a coconut oil handmade soap, as shown, includes the following steps: S1: Mix coconut oil, olive oil, and palm oil, and heat to 40-50℃ until completely melted to obtain a mixed oil mixture; S2: Add food-grade alkaline solution to the mixed oils and stir until trace is reached to obtain soap solution mixture; S3: Add functional additives to the soap mixture and stir well to obtain a functional soap mixture; S4: Pour the functional soap liquid mixture into the mold and let it stand for 24-48 hours at 20-25℃ and 40-60% relative humidity to cure; S5: After unmolding, place in a well-ventilated and dry place to cure for 2-4 weeks to obtain coconut oil handmade soap. In this embodiment of the invention, it is necessary to further explain that the principle of each step in the coconut oil handmade soap preparation method is based on the chemical characteristics of the saponification reaction, the protection of raw material activity, and the requirements for product stability, as detailed below: S1: Melt the mixed oils by heating (40-50℃) principle: 1. Physical state transformation: Coconut oil (containing a lot of saturated fatty acids, which may be solid at room temperature) and palm oil (solid at room temperature) need to be heated to 40-50℃ to completely melt into liquid, while olive oil (liquid at room temperature) remains stable, ensuring that the three oils are mixed evenly; 2. Prerequisites for saponification reaction: Saponification reaction (oil + alkali → soap + glycerin) needs to be carried out in a liquid environment. Liquid oil can fully contact the alkaline solution to avoid uneven local reaction. 3. Temperature control: 40-50℃ is the suitable temperature for melting oils, which will not destroy the active ingredients in the oils (such as vitamin E in olive oil) nor cause the oils to oxidize and deteriorate due to excessive temperature.

[0165] S2: Add alkaline aqueous solution and stir until trace is reached. principle: 1. Saponification reaction initiation: The alkaline aqueous solution (NaOH + deionized water) reacts with liquid oils to produce sodium fatty acid (the main component of soap) and glycerin; 2. The significance of the trace state: This refers to the state where the soap solution thickens to the point where it can leave stirring marks. This indicates that the reaction has reached the emulsification stage, the oils and lye are fully mixed, and there is no unreacted free lye residue in any area (to avoid skin irritation). 3. Reaction rate control: The ratio of alkali solution (1:2.8-3.2) and temperature (25-27℃) ensure a moderate reaction rate, which will not cause the reaction to be too fast due to excessive alkali concentration (rough soap body, more free alkali) nor too slow due to excessive concentration (soft soap body that is not easy to shape), thus ensuring uniform saponification.

[0166] S3: Add functional ingredients and stir well. principle: 1. Protection of active ingredients: Functional additives (such as enzymes in honey, antioxidants in grape seed oil, and shikonin) are sensitive to strong alkaline environments. If added in the early stages of saponification, their activity will be destroyed. When the soap reaches the trace stage, the activity of the alkali has been partially consumed. Adding it at this time can preserve its skin care effects to the maximum extent. 2. Uniform distribution: Stirring ensures that the functional ingredients are evenly dispersed in the soap solution, so that each bar of soap can exert the same effect (such as soothing and anti-oxidation) after curing. 3. Avoid interfering with saponification: Functional additives (such as bitter camellia oil) are added after trace, which will not affect the process of saponification and ensure the stability of soap structure.

[0167] S4: Mold static curing (20-25℃, humidity 40-60%, 24-48h) principle: 1. Saponification reaction is complete: The saponification reaction continues during the standing process until the oil and lye solution have almost completely reacted (the free lye is reduced to a safe range). 2. Stable structure and molding: Temperature is controlled at 20-25℃ to avoid excessive reaction and uneven heating inside the soap (causing cracks), and humidity is controlled at 40-60% to prevent the surface of the soap from losing water too quickly while the inside is not cured (cracking), ensuring that the soap structure is uniform and without defects; 3. Preliminary shaping: After curing, the soap changes from a liquid to a solid state, making it easier to demold.

[0168] S5: Ventilated and dried for aging (2-4 weeks) principle: 1. Moisture evaporation: Excess moisture in the soap slowly evaporates, increasing the soap's hardness (making it more durable and less prone to melting). 2. Elimination of free alkali: The residual trace amounts of free alkali continue to react with glycerin or unreacted oils, lowering the pH value of the soap (gradually becoming milder and closer to the skin's pH value), thus reducing irritation; 3. Stable efficacy: During the maturation process, the functional ingredients are further integrated with the soap structure, ensuring stable release of efficacy during use (such as the anti-inflammatory effect of shikonin and the moisturizing effect of honey).

[0169] In summary, by precisely controlling temperature, humidity, and reaction timing at each step, the safety of the saponification reaction, the preservation of the activity of functional ingredients, and the stability of the product are achieved, ultimately resulting in a mild, effective, and clearly efficacious handmade soap.

[0170] In conclusion, the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A coconut oil handmade soap, characterized by, Prepared from food-grade raw materials, the food-grade raw materials include the following components by weight percentage: Coconut oil: 30-50%; Olive oil: 20-35%; Palm oil: 15-25%; Functional additives: 0.5-5%, selected from at least one of the following: liquorice root extract, honey, camellia oil, grape seed oil, glycerol; Food-grade aqueous alkali solution: the balance, the weight ratio of food-grade sodium hydroxide to deionized water in the food-grade aqueous alkali solution is 1:(2.8-3.2).

2. The coconut oil handmade soap according to claim 1, characterized by, The functional additives are a ternary combination of camellia oil, grape seed oil and glycerol, and the weight percentage of each component is: Camellia oil: 1-2%, grape seed oil: 0.5-1%, glycerol: 0.5-1%.

3. The coconut oil handmade soap according to claim 2, characterized by, The food-grade raw materials include the following components by weight percentage: Coconut oil: 30-50%; Olive oil: 20-35%; Palm oil: 15-25%; Camellia oil: 1.5%, grape seed oil: 0.8%, glycerol: 0.7%; Food-grade aqueous alkali solution: the balance.

4. The coconut oil handmade soap according to claim 1, characterized by, The functional additives are a binary combination of honey and camellia oil, and the weight percentage is: honey: 1-2%, camellia oil: 1-1.5%.

5. The coconut oil handmade soap according to claim 4, characterized by, The food-grade raw materials include the following components by weight percentage: Coconut oil: 40%; Olive oil: 25%; Palm oil: 18%; Honey: 1.2%, camellia oil: 1.3%; Food-grade aqueous alkali solution: the balance.

6. The coconut oil handmade soap according to claim 1, characterized by, The functional additives are liquorice root extract, and the weight percentage is 0.5-1%.

7. The coconut oil handmade soap according to claim 6, characterized by, The food-grade raw materials include the following components by weight percentage: Coconut oil: 38%; Olive oil: 30%; Palm oil: 19%; Liquorice root extract: 0.8%; Food-grade aqueous alkali solution: the balance.

8. The coconut oil handmade soap according to claim 1, characterized by, The functional additives are a quaternary combination of camellia oil, grape seed oil, glycerol and honey, and the weight percentage of each component is: camellia oil 1-1.5%, grape seed oil 0.5-1%, glycerol 0.5-1%, honey 0.5-1%.

9. The coconut oil handmade soap according to claim 8, characterized by, The food-grade raw materials include the following components by weight percentage: Coconut oil: 32%; Olive oil: 32%; Palm oil: 21%; Camellia oil 1.2%, grape seed oil 0.6%, glycerol 0.6%, honey 0.6%; Food-grade aqueous alkali solution: the balance.

10. A process for the preparation of the coconut oil handmade soap as claimed in claim 1, wherein, The following steps are included: S1: Mix coconut oil, olive oil and palm oil, heat to 40-50℃ to completely melt, and obtain mixed oil; S2: Add food-grade aqueous alkali solution to the mixed oil, stir to trace state, and obtain a soap solution mixture; S3: Add functional additives to the soap solution mixture, stir evenly to obtain a functional soap solution mixture; S4: Pour the functional soap solution mixture into a mold, and stand for 24-48 hours for solidification under the conditions of 20-25℃ and relative humidity of 40-60%; S5: After demolding, place in a well-ventilated and dry place for 2-4 weeks for aging, and obtain the coconut oil handmade soap; The preparation method of the food-grade aqueous alkali solution is: Food grade sodium hydroxide was slowly added in three portions to deionized water at 20-22°C, after each addition the solution was stirred until complete dissolution and the temperature of the solution was controlled not to exceed 28°C during each stirring, the final temperature of the food grade aqueous sodium hydroxide solution was maintained at 25-27°C.

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