I was told before Pesach that flour in a closed package (a regular 1 kilo sack) is not chametz and to throw it out is ba’al tashchis. I put 2 sacks in a cupboard with kitniyos (I do not sell real chametz) that was locked over Pesach. I have not yet got a psak on the status of the flour. Should I throw it out?
There is no need to throw it out.
Some prefer not to keep flour over Pesach, for fear that the processing before packaging will cause it to be chametz. However, this is only a slight concern for chametz, and therefore there is no need for stringency concerning the prohibition of chametz after Pesach.