I say, and with God's success: It is not permissible; because the essential element in Zakat al-Fitr is the ownership transfer to the poor; as stated in his saying (peace be upon him): 'Pay for every free person and slave' in Sunan al-Daraqutni 2: 150, and the performance is the ownership transfer, which cannot be achieved with permissible food, and with what is not ownership at all. Refer to: Bada'i al-Sana'i 2: 74-75, and God knows best.