Which pigment compound in fruits and vegetables is the least affected by changes in pH?

The least affected pigment compound by changes in pH among fruits and vegetables is carotenoids. Carotenoids, which include pigments like beta-carotene and lutein, are known for their stability across a range of pH levels. They maintain their color and structural integrity when exposed to acidic or alkaline conditions, making them reliable markers for ripeness and quality in fruits and vegetables. This stability is crucial in food processing and storage, where pH levels can fluctuate.

In contrast, flavonoids can change color based on pH; for example, anthocyanins, a type of flavonoid, shift from red to blue depending on whether the environment is acidic or alkaline. Pheophytin, which is a derivative of chlorophyll, can also be affected by pH changes, leading to a dull brown color in the presence of acids. Chlorophyll, while it does have some stability, can degrade or undergo changes in color with varying pH conditions. Thus, carotenoids are recognized for their resilience to these shifts, making them the correct choice in this context.