What are the required conditions for food or its derivatives given as expiation (Kaffarah)?

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The item given as expiation must be free from defects. Specifically, grain must not be worm-eaten, its taste must not be altered, and it must not contain cockle or dirt requiring sifting. This applies equally to flour and bread made from it. This ruling applies because the expiation is a right owed to God that has become obligatory upon the individual, similar to the requirement for the animal given in Zakat to be free from defects.