Why Are Ants Suddenly Attracted To My Saliva?

Why are ants suddenly attracted to my saliva? I drink water from a satchet and I m hardly ever able to drink it all in one sitting. I ve always been able to leave it on my desk and return to drink it later. But for the past few days, when I leave a satchet out and return to it, ants are all over the area my mouth touched. Please what s the reason for this?