The Muggle New Year began on January 1st of the solar calendar, determined by the Earth completing one orbit around the Sun, while the wizarding New Year began on Halloween.
It marked the official end of summer and the beginning of winter. The King of the Forest changed from oak to holly, while the souls of the departed returned to their former homes on this day to celebrate the autumn harvest with the living.
In the past, Halloween customarily consisted only of a feast, with the occasional choir performance. Once everyone had eaten and drunk their fill, they returned to their dormitories to sleep. But after Harry Potter enrolled, the tradition changed again.
In the first year, a Troll entered the school, and Quirrell shouted in the Great Hall while the children screamed in fright.
In the second year, there were bloody words on the wall and a petrified Mrs Norris.
The third year brought Sirius Black. Even without a performance by the Skeleton Song-and-Dance Troupe, the holiday had been quite "eventful."
Then came Halloween of the fourth year, which happened to be the day the Triwizard Tournament "champions" were selected. Under normal circumstances, once the contestants had been chosen, it would be time for the feast. Who could have expected a fourth "champion" to appear? No one had the heart to eat the feast prepared by the kitchens, but the dishes were not thrown away.
Four dragons were coming to Hogwarts, and the dragon handlers and Aurors responsible for transporting them had come from afar. The food was just what they needed to replenish their spent strength.
The purpose of preserving food was to extend its shelf life, though the process also happened to give it a flavor different from fresh food. Food spoiled because of microorganisms and enzymatic