baby food waste

Soooo i asked my dr about giving prunes to my 4 month old so he can have easier bowel movements and he said its okay. I bought organic happy baby stage 1 prune pouch. I came home and read that its only good for 24 hours after opening. Its a 3.5 oz of prune purée for 4+ month olds. How is my 4 month old supposed to finish all that in a day??? I found it sooo soo stupid for them to make it that big. Any baby who finishes the whole pouch clearly would not stop having bowel movements for the next 24 hours and be very very very uncomfortable. Of course im not about to give my baby more than a teaspoon of prunes but cmon WHAT A WASTE!!!!