1. The antioxidant capacity of red bean soup is obviously lower than that of mung bean soup. The redder the color, the lower the antioxidant capacity, indicating that mung bean soup is better than red bean soup.

2. The color of mung bean soup cooked with different water quality is different. The color of distilled water is the greenest and remains unchanged for a long time. Followed by pure water and mineral water. The color of mung bean soup boiled in tap water changes the fastest, and it darkens obviously almost every minute after touching the air, and soon turns red.

3.pH value will greatly affect the discoloration effect of soup. The color of acidic tap water does not change much after boiling, while the color of slightly alkaline tap water changes very quickly after boiling.