也许是雪碧里面的防腐剂苯甲酸钠起了作用

"Sprite — like most other non-cola sodas — is caffeine-free. The main ingredients in Sprite are water, high-fructose corn syrup, and natural lemon and lime flavors. It also contains citric acid, sodium citrate, and sodium benzoate, which act as preservatives (1)."