Formulation And Evaluation Of Colour Changing Glycerine Soap Using Butterfly Pea Flower Extract For Pediatric Use

The skin is the largest and one of the most vital organs of the human body, functioning as the primary protective barrier against environmental pollutants, microorganisms, ultraviolet radiation, and physical injuries. It also plays an important role in maintaining body temperature, preventing water loss, and providing sensory perception [1,2]. Structurally, the skin is composed of three major layers namely the epidermis, dermis, and hypodermis. Depending on its texture and physiological characteristics, skin can be classified into different types such as normal, dry, oily, combination, sensitive, and baby skin. Among these, baby skin is highly delicate, thin, and sensitive, making it more prone to irritation, dryness, and microbial infections. Therefore, the selection of safe and mild skincare products is especially important for pediatric use [3].

Soap is one of the most commonly used cleansing agents for maintaining skin hygiene. However, conventional soaps available in the market often contain synthetic detergents, artificial fragrances, preservatives, and harsh chemicals that may damage the natural skin barrier and cause irritation, especially in infants and children. In recent years, there has been increasing interest in herbal and natural skincare formulations due to their safety, biocompatibility, and eco-friendly nature. Herbal soaps are prepared using plant-derived oils, natural colorants, herbal extracts, and essential oils, which provide therapeutic and cosmetic benefits without causing harmful side effects. These soaps are biodegradable, environmentally friendly, and suitable for sensitive skin types [4,5].

Among various medicinal plants, Clitoria ternatea L., commonly known as Butterfly Pea Flower, has gained considerable attention because of its medicinal, nutritional, and cosmetic applications. It belongs to the family Fabaceae and is widely cultivated in countries such as India, Thailand, Malaysia, Indonesia, and Vietnam. The flower is rich in bioactive phytoconstituents including anthocyanins (ternatins), flavonoids, alkaloids, saponins, and phenolic compounds. Anthocyanins are natural pigments responsible for the characteristic blue color of the flower and exhibit pH-sensitive color-changing properties. These compounds also possess strong antioxidant activity that helps protect the skin from oxidative stress and free radical damage. In addition, Butterfly Pea Flower exhibits anti-inflammatory, antimicrobial, neuroprotective, and antidiabetic properties, making it a promising ingredient for herbal cosmetic formulations [6].

The incorporation of Butterfly Pea Flower extract into glycerine soap offers several advantages for pediatric skincare. Glycerine soap is known for its mild cleansing action, moisturizing effect, and ability to retain skin hydration. The addition of Butterfly Pea Flower extract not only enhances the antioxidant and antimicrobial potential of the soap but also imparts an attractive natural color-changing property due to the presence of anthocyanins. This color transformation occurs in response to changes in pH and can provide an innovative and appealing feature for children, thereby improving user acceptance and encouraging healthy hygiene practices [7].

The present study focuses on the formulation and evaluation of a color-changing glycerine soap using Butterfly Pea Flower extract for pediatric use. The objective of this research is to develop a mild, safe, and skin-friendly herbal soap suitable for delicate baby skin while utilizing the therapeutic benefits of natural ingredients. The formulated soap was evaluated for various physicochemical parameters such as pH, foam stability, hardness, appearance, and skin compatibility to ensure its suitability, safety, and effectiveness for pediatric application.

Experimental:

Materials:

The materials used in the formulation of colour changing glycerine soap using Butterfly Pea Flower extract for pediatric use were selected based on their safety, skin compatibility, moisturizing ability, and therapeutic benefits. All ingredients used in the study were of cosmetic or analytical grade.

Methods:

Preparation of Butterfly Pea Flower Extract

Fresh flowers of Clitoria ternatea (Butterfly Pea Flower) were collected and washed thoroughly with clean water to remove dust and impurities. About 100 mL of distilled water was taken in a beaker and heated to boiling temperature. The cleaned flowers were added to the boiling water and heated for 10–15 minutes to extract the natural blue pigment and phytoconstituents present in the flowers. After extraction, the solution was allowed to cool to room temperature and then filtered using filter paper to remove solid residues. The obtained filtrate containing Butterfly Pea Flower extract was collected and stored in a clean, airtight container for further use in soap formulation [8].

Preparation of Herbal Glycerine Soap

Approximately 50 g of glycerine soap base was cut into small pieces to facilitate easy melting. The soap base was then melted using a double boiler method with continuous stirring to obtain a uniform molten mixture. Care was taken to avoid overheating in order to preserve the transparency and quality of the soap base. After complete melting, the herbal ingredients were added gradually with continuous stirring. About 5 mL of Butterfly Pea Flower extract was incorporated as a natural colorant and antioxidant agent. Subsequently, 5 mL of aloe vera gel extract was added to provide moisturizing and soothing effects to the skin. To improve nourishment, cleansing ability, and skin hydration, 10 mL of coconut oil was mixed into the formulation. In addition, 5 mL of glycerin was added to enhance softness and moisture retention properties of the soap.

Further, Vitamin E capsules were cut open and their contents were added as an antioxidant and skin nourishing agent. Approximately 2–3 mL of rose oil was incorporated to provide a mild and pleasant fragrance suitable for pediatric use. The entire mixture was stirred continuously until a homogeneous and uniform solution was obtained, while minimizing bubble formation to maintain a smooth appearance. The prepared liquid soap mixture was then carefully poured into clean and dry soap molds and kept undisturbed at room temperature for proper setting. The soap was allowed to cool and solidify completely for several hours. After complete hardening, the soap bars were gently removed from the molds. Finally, the prepared herbal glycerine soap bars were wrapped in butter paper or aluminum foil and stored in a cool and dry place until further evaluation studies were carried out [9].

Table 1: Formulation Composition of Colour Changing Herbal Glycerine Soap

EVALUTION OF HERBAL BABY SOAP [10]

1. Physical Appearance

The prepared soap was visually examined for: Colour, Shape, Texture, Transparency 

2. pH Determination

Dissolve 1 g of soap in 10 mL distilled water. Measure pH using a pH meter or pH paper.

3. Foam Height Test

Dissolve 1 g soap in 50 mL distilled water in a measuring cylinder. Shake vigorously for 1 minute. Measure foam height immediately.

4. Foam Retention / Stability Test

After foam height measurement, allow the cylinder to stand for 5 minutes. Measure remaining foam height.

5. Hardness Test

Soap hardness was checked manually by pressing with fingers. Hardness tester may

also be used if available.

6. Moisture Content

Weigh a small quantity of soap Dry in hot air oven at 105°C until constant weight obtained.

7. Total Fatty Matter (TFM)

Determined by standard analytical method.

8. Skin Irritation Test

Apply small amount of soap solution on skin.Observe for redness, itching, or irritation for 24 hours.

9. Cleansing Ability

Soap was applied on skin and washed with water. Cleansing effect and ease of washing were observed.

10. Spreadability / Texture

Texture and smoothness were checked manually.

RESULT AND DISCUSSION

Evaluation of Antioxidant-Rich Herbal Baby Soap

Three different formulations (F1, F2, and F3) of colour changing herbal glycerine soap were prepared using varying concentrations of herbal ingredients. The prepared formulations were evaluated for various physicochemical and organoleptic parameters such as appearance, color, odor, homogeneity, irritation, washability, pH, loss on drying (LOD), and rancidity. The formulations showed satisfactory characteristics suitable for pediatric use.

Table 2: Preliminary Phytochemical Screening of Herbal Extracts

Table 3: Organoleptic Characteristics of Prepared Herbal Soap

Table 4: Evaluation Parameters of Prepared Colour Changing Glycerine Soap

The prepared formulations exhibited acceptable physicochemical and organoleptic properties. The color intensity increased with increasing concentration of Butterfly Pea Flower extract due to the presence of anthocyanins. All formulations showed good homogeneity, pleasant odor, smooth texture, and satisfactory washability. The pH values were found to be within the suitable range for pediatric skin, indicating mildness and skin compatibility. No irritation or rancidity was observed in any formulation, confirming the stability and safety of the herbal soap. Preliminary phytochemical screening confirmed the presence of important bioactive compounds such as flavonoids, alkaloids, terpenoids, proteins, and antioxidants, which may contribute to the therapeutic and protective effects of the formulated soap.

Stability Study:

The stability of the formulated herbal soap was evaluated over a period of three months under ICH guidelines at 30˚C ± 2˚C / 75 ± 5% RH. The formulations were stored properly, and samples were analyzed at 0 months (initial) and 3 months for appearance, pH and viscosity to assess any physicochemical changes.

Table 5: Stability Study of Optimized Formulation (F2)