The source identifies raw, unprocessed Arwa Chawal for Rasiya and Kasar, distinguishing it from Usna Chawal. Its purity explanation is presented as a ceremonial interpretation rather than a classification related to food safety.
The Rule of Arwa Chawal
While preparing Prasad for Chhath Puja—particularly the Rasiya (Kheer) on Kharna and the Kasar laddus—devotees adhere strictly to using Arwa Chawal (raw, unparboiled rice).
Why Parboiled Rice is Banned
Parboiled rice (Usna Chawal) is boiled and steamed at mills prior to husking. Since it is processed and managed by outside parties in large quantities, it is regarded as ceremonially impure (Jootha) for sacred offerings. Arwa Chawal, which is milled straight from the raw paddy, maintains complete sattvic purity, making it the sole rice suitable for Chhathi Maiya.