Hibiscus tea turns blue because its color pigments, called anthocyanins, change hue in response to the pH level of the liquid.
The natural vibrant red color of hibiscus tea comes from these anthocyanins. These same pigments are found in other red-colored plants like red cabbage. The reference states that the color of hibiscus tea depends on the pH and contains anthocyanins.
The key factor is how anthocyanins react to different pH environments:
- Low pH (Acidic): Anthocyanins appear red. Hibiscus tea is naturally acidic, which is why it is typically red in color.
- Higher pH (Neutral or Alkaline): Anthocyanins shift towards green and blue colors.
According to the reference: "At low pH the tea will be red while it is green to blue at higher values". This means that if you add something that increases the pH of the naturally acidic hibiscus tea (making it less acidic or even alkaline), the anthocyanins will change from red to green or blue.
The Role of pH in Hibiscus Tea Color
Think of pH as a scale measuring how acidic or alkaline a substance is.
| pH Level | Acidity/Alkalinity | Anthocyanin Color | Hibiscus Tea Color (Potential) |
|---|---|---|---|
| Low pH (<7) | Acidic | Red | Naturally Red |
| Higher pH (>7) | Alkaline | Blue / Green | Turns Blue / Green |
Adding substances that are alkaline, such as baking soda, can increase the pH of the tea, causing the color to shift from red to blue. This demonstrates the pH-sensitive nature of the anthocyanin pigments present in the tea.
