Which pigment remains unchanged in color in acidic or alkaline solutions?

Carotene is the pigment that remains unchanged in color in acidic or alkaline solutions. Carotene is a type of carotenoid, which are pigments found in many plants, responsible for the orange and yellow hues seen in foods like carrots, sweet potatoes, and butternut squash. One of the key characteristics of carotene is its stability across various pH levels, meaning that it retains its color and does not react dramatically with changes in acidity or alkalinity.

In contrast, anthocyanins can change color in response to pH changes, often appearing red in acidic conditions and blue in alkaline environments. Chlorophyll also undergoes significant changes when exposed to acidic conditions, typically turning to a brownish hue. Flavones can change color as well, often showing a shift from yellow to colorless or brown under varying pH levels. Thus, carotene stands out among these pigments for its resistance to such changes in color based on the acidity or alkalinity of its environment.