The first thought that might come to your mind is that this is a miracle of God! It is not just food but the Prasad of the Gods and that's why, it is a divine blessing that the prasad does not go to waste. But that's not entirely true and I am not mocking or trying to hurt anybody's sentiments here. I am just sharing what happens behind the scenes and why the prasad is never wasted, as told to me by a priest and observed with my own eyes.
In recent times, I have had the opportunity to visit the Jagannath Temple in Puri in January 2018 and December 2019. During my second visit, I chose to have the prasad that is offered. The prices are extorbitant, by the way! The temple committee has a rate chart starting from 500 rupees for which you get two sweets only and all the way to 1 lakh rupees. I opted for the 1,500 rupees Prasad in which only one person can have the very basic Prasad consisting of rice, dal and two types of sabzi.
They are collecting funds for the temple in the name of Prasad, but let's leave that aside. My priest-cum-guide told me two interesting things. He told me that the food in the temple is cooked in three earthern pots, one kept above the other and the food on the topmost pot gets cooked first followed by the middle one and then the last. People consider it the blessing of God, but Class 7 Physics taught me the principles of convection and this was expected.
What he told me next was that no matter the number of devotees coming to the temple, which ranges between 5,000 to 50,000 per day, the prasad never goes to waste. This made me curious and I asked how they manage to budget the food every day, to which I was told that they cook on a batch system by checking the number of devotees paying for the prasad. You pay for the prasad first, then go for darshan, which takes at least an hour on average and after coming out of the main shrine, one gets the prasad. Since the food is cooked on the basis of pre-payment of the meals, they never end up over-preparing. And if there is still a surplus, that is distributed among the poor outside the temple premises.