Why Does Butterfly Pea Powder Change Color?
Butterfly pea powder is used as a natural pigment in the beverage industry. It turns blue when dissolved in water. Its color changes under different pH conditions. Why does butterfly pea powder change color?

Why Does Butterfly Pea Powder Change Color?
Chemical Mechanism: 
The color change of blue matcha butterfly pea flower powder is essentially due to the reversible or irreversible transformation of the anthocyanin molecular structure with changes in environmental pH. The central anthocyanin molecule is a 2-phenylbenzopyran cation (flavylium cation) skeleton, which undergoes a balanced transformation between four main structural forms under different pH conditions.

• pH below 3.0 (Strongly Acidic Conditions)
In the pH range of 2.5–3.0, Blue Butterfly Pea Flower Powder anthocyanins mainly exist in the form of red to purplish-red flavylium cations (AH⁺). In this form, the oxygen atom carries a positive charge, and the conjugated molecular system absorbs light with a wavelength of approximately 520–530 nm, corresponding to a red visual appearance. For beverage systems, carbonated drinks, some fruit and vegetable juices, and acidic dairy beverages are typically within this pH range.

• pH 3.0–5.0 (Weakly Acidic Conditions)
As pH increases, the carbinol pseudo-base (B) loses a proton, transforming into a colorless carbinol pseudo-base or chalcone (C) structure. Within this range, the color rapidly diminishes from reddish-purple, appearing temporarily colorless or very pale pink. This region is a warning for beverage developers: if the pH of the final product falls within this range, the color intensity of butterfly pea powder may decrease significantly.

• pH 5.0–7.0 (Near-Neutral to Neutral Conditions)
In the pH range of approximately 5.5–6.5, the carbinol pseudo-base further deprotonates to form a quinoidal base (A). The absorption spectrum of the quinoidal base exhibits a blue shift, with the main absorption peak shifting to around 560–580 nm, displaying a blue to bluish-purple color. The advantages of butterfly pea anthocyanins compared to other plant sources are fully demonstrated in this range: most fruit anthocyanins rapidly degrade or turn grayish-blue under neutral conditions, while blue butterfly pea tea powder quinoidal bases exhibit better stability.

• pH 7.0–9.0 (Weakly Alkaline Conditions)
When the pH rises above 7.5, quinone bases continue to deprotonate to form anionic quinone bases, and intermolecular or intramolecular co-coloring may occur. The absorption wavelength further blue-shifts to 590–620 nm, exhibiting green, blue-green, and even yellow-green hues. At pH greater than 9, irreversible degradation begins, producing benzoic acid derivatives, and the color turns yellowish-brown.

Therefore, butterfly pea blossom powder exhibits a continuous color change across the entire pH range from acidic to alkaline: reddish-purple → light pink/colorless → bluedish-purple → blue → green → yellowish-green → brown. The most commonly used color change ranges in the beverage industry are pH 2.5–3.5 (red series) and pH 5.5–7.0 (blue series).

Physicochemical Factors
Besides pH as the dominant factor, the following factors also significantly affect the actual color change effect and color stability of Blue Butterfly Pea Flower Powder in beverages.

• Temperature: 
Anthocyanin degradation follows first-order reaction kinetics. Under heating conditions above 60°C, the thermal degradation rate constant of butterfly pea anthocyanins increases significantly. For hot-filled beverages (85–95°C), even after cooling to a suitable pH, some pigment structures undergo irreversible degradation, resulting in a final color that is yellowish or grayish. Cold filling (≤25°C) or rapid cooling after ultra-high temperature sterilization (UHT, 135–140°C, 4–5 seconds) is the recommended process for preserving the color development properties of butterfly pea powder.

• Light: 
Anthocyanin molecules can undergo photo-oxidation and ring-opening reactions after absorbing ultraviolet light (280–400 nm). If beverages packaged in transparent PET bottles are exposed to sunlight or commercial lighting, the color of powdered butterfly pea flower may change from blue to grayish-green or even colorless within several weeks. Using UV-barrier packaging (such as PET or aluminum foil composites with added UV absorbers) can significantly extend the color stability of the product over its shelf life. 3. Metal Ions

• Metal ions
Fe³⁺, Al³⁺, Sn²⁺, and other metal ions can undergo complexation reactions with the ortho- and tho-hydroxyl groups of anthocyanins. Fe³⁺ complexes range in color from grayish-purple to black, negatively impacting the appearance of blue beverages. This problem may occur if the iron content in the beverage production water exceeds 0.5 ppm. Al³⁺ complexation can produce a brighter blue, but it is rarely actively added in actual beverage production. It is recommended to use reverse osmosis water treatment and control the materials of pipes and containers (preferably 316L stainless steel or food-grade plastic).

• Ascorbic Acid (Vitamin C)
Ascorbic acid can decompose under oxygen-containing conditions to produce hydrogen peroxide and furfural, which can condense or degrade with anthocyanins, accelerating fading. If vitamin C needs to be added to the beverage formula, it is recommended to use microencapsulated vitamin C or sodium isoascorbate as a substitute, and strictly control the dissolved oxygen content (<1 ppm). 
• Sugars and Sweeteners 
Sucrose, high-fructose corn syrup, and other sweeteners can stabilize anthocyanin structures to some extent by reducing water activity and increasing system viscosity at high concentrations (>30°Brix). High-intensity sweeteners (such as sucralose and steviol glycosides) have virtually no effect on discoloration behavior due to their extremely low dosage. It doesn’t effect the butterfly pea flower powder flavor taste.

How To Use Butterfly Flower Powder In Drink?
For different beverage types, the following application parameters are recommended.
Beverage Types    Target pH    Recommended dosage（w/w）    Result
Carbonated Beverages    2.8–3.2    0.02%–0.05%    Pink to reddish-purple
Flavored Water (Containing Citric Acid)    3.0–3.5    0.03%–0.08%    Purple-red
Neutral Tea Beverages    5.5–6.5    0.01%–0.03%    Blue
High-Protein Plant-Based Beverages    7.0–7.5    0.02%–0.04%    Teal green
Alcoholic Beverages (Premixed Drinks)    3.5–4.5    0.01%–0.02%    Light purple to blue gradient

Conclusion:
The color-changing mechanism of pea blossom powder originates from the structural interconversion of anthocyanin molecules at different pH levels, involving flavonoid cations, methanol pseudobases, and quinone bases, resulting in a continuous shift in visible light absorption wavelength within the 520–620 nm range. The beverage industry can utilize this property to produce products with natural hues ranging from reddish-purple to green, particularly filling the market gap for natural blue pigments. Temperature, light, metal ions, vitamin C, and dissolved oxygen are the main process parameters affecting color stability in actual production. By precisely controlling pH, selecting appropriate sterilization and packaging methods, and optimizing water quality and formulation, beverage developers can fully realize the color-changing potential of butterfly pea powder.

Guanjie Biotech as a professional bulk butterfly pea powder supplier, provides end-to-end quality, serving food and beverage companies in over 100 countries worldwide. For technical information, samples, or customized products, please contact: info@gybiotech.com.

References: 
References
[1] Hasanah, N. N., Azman, E. M., Rozzamri, A., Abedin, N. H. Z., & Ismail-Fitry, M. R. (2023). A systematic review of butterfly pea flower (Clitoria ternatea L.): Extraction and application as a food freshness pH-indicator for polymer-based intelligent packaging. Polymers, 15(11), 2541. https://doi.org/10.3390/polym15112541 
[2] Handayani, L., Aprilia, S., Arahman, N., & Bilad, M. R. (2024). Anthocyanin extraction and pH-modulated color alterations in butterfly pea flower (Clitoria ternatea L.). IOP Conference Series: Earth and Environmental Science, 1359(1), 012087. https://doi.org/10.1088/1755-1315/1359/1/012087 
[3] Fu, X., Wu, Q., Wang, J., Chen, Y., Zhu, G., & Zhu, Z. (2021). Spectral characteristic, storage stability and antioxidant properties of anthocyanin extracts from flowers of butterfly pea (Clitoria ternatea L.). Molecules, 26(22), 7000. https://doi.org/10.3390/molecules26227000 
[4] Saputri, D., Listyadevi, Y. L., Adiwibowo, M. T., & Damayanti. (2023). The effect of acidity condition (pH) on the color change of anthocyanin compound from butterfly pea flower extract (Clitoria ternatea). Communication in Food Science and Technology, 2(2), 54. 
[5] Mohd Idris, A. A., Asman, S., Abu Mohammad, A. S., Amirullah, A. F., & Tasyrif, H. M. (2024). Determination of anthocyanin at different pH from Clitoria ternatea sp. using maceration method. Enhanced Knowledge in Sciences and Technology, 4(1), 223–228.