Question

why oranges,limes and curd have a sour taste

Answer 1

Curd, lemon juice, orange juice and vinegar taste sour. These substances taste sour because they contain acids. The chemical nature of such substances isacidic. The word acid comes from the Latin word acere which means sour.

Acid, Bases 

Answer 2

All the food items mentioned above contain acids like citric acid, lactic acid n so on n the acids are sour in taste. Therefore these food items taste sour.

Hope it helps!!!