The IDF itself has indicated that they prevent the entry of certain items due to their potential dual-use. While the examples they provide may not include food items, this confirms the existence of a policy that is likely being interpreted arbitrarily.
On this note, according to more than two dozen humanitarian and government officials interviewed by CNN, Israel has imposed arbitrary and contradictory criteria for aid entry. The prohibited items include anesthetics and anesthesia machines, oxygen cylinders, ventilators, and water filtration systems. Other items stuck in bureaucratic limbo include dates, sleeping bags, cancer medications, water purification tablets, and maternity kits.