The butterfly pea flower (Clitoria ternatea
) originates from subtropical regions and is widely distributed in Africa, Asia, Australia, North America, South America, and the Northwest, Central South, and Southwest Pacific. Butterfly pea, like vine plants, is a perennial climbing plant or herbaceous plant. It is self-pollinated and spreads by seeds. It prefers moist and neutral soil (pH 5.5 to 8.9). Butterfly pea flower is an axillary, solitary, or twin flower. It is harvested in summer. The most apparent feature of the butterfly pea flower is its dark blue petals with a yellow mark. According to Zakaria et al. [1
], the flavonoids found in the butterfly pea flowers can reduce infections in the upper respiratory tract. They have been proven to be anti-inflammatory in animal tests and have antioxidative power. Butterfly pea flowers contain about 0.9 mg ash, 8.94 mg soluble minerals, 41.27 mg crude protein, and 29.18 mg soluble carbohydrate per 100 g of dry weight. Terahara et al. [2
] used reversed-phase High Pressure Liquid Chromatography (HPLC) to isolate five major structures of anthocyanins, which are delphinidin derivatives that are highly acylated.
Tantituvanont et al. [3
] pointed out that the anthocyanins in butterfly pea flowers are mainly delphinidin-glucosides. Anthocyanins are water-soluble macromolecular substances that give orange, red, or blue-violet colour to fruits, vegetables, flowers, leaves, or stems. Saptarini et al. [4
] showed that the anthocyanins in butterfly pea flowers appear blue at pH 4, green at pH 9, and yellow at pH 12, making it an acid-base titration indicator. Anthocyanins are susceptible to environmental and chemical influences, including pH variation, ambient temperature, light, oxidation, and enzymes, making their application in the food industry difficult (Mohamed et al. [5
]). Tantituvanont et al. [3
] and Mohamed et al. [5
] found that the anthocyanins in butterfly pea flower are more stable at low temperatures, and the flowers are purplish red in acidic environments and blue in an alkaline environment. Compared with alkaline environments, the stability and antioxidative activity of the anthocyanins are higher in weakly acidic environments. Rabeta et al. [6
] pointed out that the blue flowers of butterfly peas have good free radical scavenging activity and have potential as antioxidants. Rajamanickam et al. [7
] suggested that the antioxidative power of the methanol extract of butterfly pea flowers is equivalent to that of L-ascorbic acid.
The butterfly pea flower contains anthocyanins and thus, is a natural antioxidant that can delay the aging of the skin and is good for the skin. Therefore, in this study, butterfly pea flowers extracted by cold water extraction and hot water extraction were analyzed for their total phenolics, flavonoids, and ascorbic acid content as well as their antioxidative power. Fermentation solution from lactic acid bacteria contains lactic acid, peptides, and polysaccharides, which are excellent for skin whitening effects. In this study, butterfly pea flowers were fermented by the lactic acid bacteria in a safe and pollution-free environment. The performance of the fermentation solution was evaluated for its whitening and moisture retention effects in order to determine the value of using a butterfly pea flower fermentation solution in cosmetic applications.
The total phenolics were 185.3 mg/100 g and 239.6 mg/100 g in butterfly pea flower extract for the cold water extraction and hot water extraction, respectively. The flavonoid concentration was 106.9 mg/100 g and 128.3 mg/100 g in butterfly pea flower extract in the cold water extraction and hot water extraction, respectively. The ascorbic acid content was 10.36 mg/100 g in the butterfly pea flower cold water extraction. Because hot water destroys ascorbic acid, the ascorbic acid content was not measured for the hot water extraction, and thus was indicated as “not detected” (N.D., see Table 2
). The results showed that hot water can extract more total phenolics and flavonoids. However, ascorbic acid is susceptible to high temperatures, so it cannot be extracted by hot water.
3.1. DPPH Free Radical Scavenging Ability of the Butterfly Pea Flower Extract
DPPH free radicals are stable free radicals containing an odd number of electrons. When they are combined with other free radicals or reduced by antioxidants, DPPH free radicals are scavenged (DPPH +AH→DPPH-H + A), and their color changes from purple to light yellow, which, in turn, reduces their absorbance. The lower the absorbance is, the stronger a sample’s DPPH scavenging ability is and the stronger its antioxidation ability is. DPPH ethanol solution has very strong absorbance at 517 nm visible light. Figure 2
shows the DPPH free radical scavenging ability of the butterfly pea flower cold water extraction and hot water extraction. In terms of antioxidative power, the DPPH free radical scavenging ability of the 1 mg/mL butterfly pea flower hot water extraction was about 6.79% and that of the 10 mg/mL extract was about 65.23%. When the concentration of the butterfly pea flower hot water extraction increased to 100 mg/mL, the DPPH free radical scavenging ability increased to 75.69%, which is equivalent to 76% of 1 mg/mL BHT. As for the butterfly pea flower cold water extraction, the DPPH free radical scavenging ability was about 5.39% and 58.23% for 1 mg/mL and 10 mg/mL of extract, respectively. When the concentration of the cold butterfly pea flower extract was increased to 100 mg/mL, the DPPH free radical scavenging ability increased to 63.25%, which is equivalent to 64% of 1 mg/mL BHT. The results showed that the butterfly pea flower hot water extraction had a better DPPH free radical scavenging ability than the cold water extraction. When the concentration of the butterfly pea flower extracts increased from 1 mg/mL to 10 mg/mL, the DPPH free radical scavenging ability increased. This was true for the butterfly pea flower cold water extraction and hot water extraction. However, when the concentration was higher than 10 mg/mL, the DPPH free radical scavenging ability did not increase linearly, indicating that the DPPH free radical scavenging abilities of the butterfly pea flower extracts were about 60% to 70% of 1 mg/mL BHT (Figure 2
3.2. Reducing Power of the Butterfly Pea Flower Extracts
The higher the OD700
absorbance is, the better the reducing power is. In this study, 1 mg/mL, 10 mg/mL, 25 mg/mL, 50 mg/mL, and 100 mg/mL butterfly pea flower cold water and hot water extractions were used to determine the reducing power of butterfly pea flower extract, and this was compared with the standard BHT. The results showed that the OD700 values of the butterfly pea flower hot water extraction were about 0.5–2.3, and those of the butterfly pea flower cold water extraction were about 0.4–2.0, indicating that the butterfly pea flower hot water extraction had a higher reducing power. At the concentration of 100 mg/mL, the reducing power of the butterfly pea flower hot water extraction was about 96% of the standard BHT. However, that of the butterfly pea flower cold water extraction was only about 83% of the standard BHT (Figure 3
3.3. Moisturizing Effect of the Butterfly Pea Flower Fermentation Solution
The butterfly pea flowers were fermented by lactic acid bacteria. The fermentation solution was diluted with distilled water to 1.0%, 2.5%, 5.0%, 7.5% and 10.0% diluents. The diluents were the experimental group, whereas distilled water was the control group. After the assessment by the moisture instrument, the moisture improvement rates after 14 days were 7.87% for the 1.0% diluent, 11.20% for the 2.5% diluent, 15.15% for the 5.0% diluent, 17.91% for the 7.5% diluent, and 18.11% for the 10.0% diluent. The moisture improvement rates after 28 days were 10.20% for the 1.0% diluent, 14.28% for the 2.5% diluent, 15.91% for the 5.0% diluent, 19.63% for the 7.5% diluent, and 20.32% for the10.0% diluent (see Table 3
and Figure 4
3.4. Whitening Effect of the Butterfly Pea Flower Fermentation Solution
The whitening improvement rate after 28 days was 7.99% for the 1.0% diluent; 10.53% for the 2.5% diluent; 18.50% for the 5.0% diluent; 22.21% for the 7.5% diluent; and 29.97% for the 10.0% diluent (see Table 4
and Figure 5
3.5. Formula Design and Product Development
With the rise in environmental awareness, many people have started to pay attention to the safety of skincare products. We have all heard about the serious pollution and damage imposed upon the environment by skincare products made of chemical raw materials, such as environmental hormones. Such skincare products also harm the human body to various degrees. Therefore, natural and environmentally-friendly products have become preferred by consumers.
The above experiments confirmed that the butterfly pea flower fermentation solution has whitening, moisture retention, and anti-aging effects. It is suitable for use as a raw material in skin care products. Therefore, we have preliminarily designed a mask formula containing sodium bicarbonate, hot spring water, and butterfly pea fermentation solution, and have looked for a manufacturer to develop the product through industry–academia collaboration.
Good essence is the soul of a skin care product. Exquisite ingredients produce remarkable effects. From design to material selection, we failed more than 10 times before coming up with the mask formula presented in Table 5
. After 30 days of use, the hot spring mask containing 6% butterfly pea flower fermentation solution can improve moisture retention by 20.35% (Table 6
) and enhance the whitening effect by 18.34% (Table 7
). With respect to skin irritation, there was no irritation after 24 h of patch testing. In an accelerated aging test, there was no deterioration after the sample was tested in a thermostat chamber at 40 ± 2 °C with a relative humidity of 75 ± 5%.
The experimental data show that the organic butterfly pea flower extract or fermentation solution not only did not cause redness, itching, allergy, or irritation to the skin but also improved moisture retention and had whitening effects, and these effects increased as its concentration increased. As a result, the butterfly pea flower fermentation solution can be added to cosmetic formulas as a natural raw material of skin care products. The outcome of the industry–academia collaboration can be added to teaching materials of various courses, such as cosmetics preparation, projects, and on-campus internships, and can enhance the students′ interests and skills in cosmetics preparation and achieve the effects of diverse learning. The teachers and students will also fulfill their local social responsibility, assist in the innovation and development of the local industry, and be pioneers of the University Social Responsibility (USR) Project. The university can also reuse the resources and make green living a reality in order to develop a green economy, implement ecological concepts, and make life full of joy and blessing.