Question:Why do we keep curtains/doors of altar closed when Lord is taking prasadam or when we are taking prasadam in front of altar?
Answer by Romapada Swami: According to Bhakti Rasamrta Sindhu (Nectar of Devotion), it is an offense to offer food that has been seen by animals or uninitiated persons.In addition, others should not directly see the bhoga prior to its being offered to the deity because we may lustfully consider enjoying that which is meant for Krishna, even within our minds, and thus an offense is commited. Consider, for example, how Madhavendra Puri felt when he saw the sweet rice offered to Gopinath in Remuna, prior to the offering being completed; he felt that a GREAT offense had been commited, due to his simply thinking of getting an opportunity to taste the sweet rice in order to learn how to prepare a similar preparation for his deity Gopal. You will find this entire narrative in Caitanya Caritamrita Madhya Lila Chapter 4.Thus, the training given by our Founder-acarya is that we cover the tray of not-yet-offered food preparations from the kitchen to the altar with a cloth, and we offer bhoga with the altar curtain (or door) closed to the public. Sometimes a half-curtain if utilized for this purpose, such that the deity can be seen but the unoffered food items cannot be seen until the offering is completed.The act of our eating is not a clean activity; thus we cleanse the area fully wherever eating has taken place after eating, and we do not eat in front of the deity.