Recent phone conversation with a devotee about rules concerning how to deal with prasāda –
Advaitadās: “When the offering comes off the altar you should not throw the Prasād back in the cooking pot. If the contents of the cooking pot have gone cold you can warm it up again separately. Put the mahā-prasāda in the eating plates of the devotees and add the contents of the cooking pots to it. kṛṣṇa prasāda militair iha bhoja-peyaiḥ - Vilāpa Kusumāñjali (49) shows the principle of making food prasādī – “The food and drink (bhoja-peya) have joined (milita) Kṛṣṇa’s prasāda.” Not everything is considered prasāda just because an offering has been done. Then all the huge tons of wheat, sugar and semolina in the kitchen of a large temple would already all be offered after the first offering from them? Instead one must and can add prasāda to unoffered food and make it prasād through association or touch – kṛṣṇa prasāda militair iha bhoja-peyaiḥ. The rest of the wheat and sugar in the kitchen in the huge containers are then not considered offered. Suppose I buy 10 bananas and 1 pack of soy milk and I live alone. It means I will just eat 2 bananas per meal and offering. The other 8 bananas can then be offered the next time. It is not that they are now offered too because I offered 2 bananas from them. For a single person it would otherwise mean he would either have to eat 10 bananas at once or go shopping for 2 bananas every day. No, 8 bananas can be offered the next time (except when they are touched by the prasādī bananas). The same thing could be done with an excess of subji cooked in the morning. Unless eaten from or touched with prasāda it COULD be offered again the next evening (though personally I don’t think that it is the most devotional thing to do). For the pack of soy milk – one small cup is offered and some more is added to my own drinking cup (thus making the contents of the whole drinking cup prasādī) but it is not that then the entire 1 liter-pack of soy milk is then also offered. Another sample is taken from it in the evening for the next offering, etc. - this is the most sane, practical and also devotional way of doing it. I cannot drink a whole liter of soy milk at once because a small sample was offered in the morning!
Look at Govinda Līlāmṛta, chapter 20 (64-66):
athāhūyāha jaṭilā viśākhāṁ mat suto gataḥ;
gośālāṁ śayituṁ bhuktvā bhoktum āhvaya me snuṣām (64)
sāha sāste gṛhe suptā śrāntāraṇya parikramāt;
tatraivātsyati dehyannaṁ satemanam (65)
sāpi hṛṣṭā tadānīya cādhāya bhojanālaye;
śrī rādhām etya tasyai tad vārtām āvedayan mudā (66)
"Jaṭilā then called Viśākhā and said: "My son went out—tell Rādhā to come and eat. Her husband will sleep in the barn tonight after his meal." Viśākhā said: "Rādhā is tired of walking around in the forest and fell asleep. Please give me the rice and vegetables, I will give them to Her." Viśākhikā happily took the meal and kept it in a corner of the dining hall. Then she went to Rādhā and happily told Her what had happened."
Śrī Rādhikā never eats anything unmixed with Kṛṣṇa’s Prasāda.
Food for a Vaiṣṇava has one of three statuses – amanīya (unoffered), jhuṭā (already eaten and thus polluted by saliva) and prasādī (a status of being offered, and objects that touch prasāda also become prasādī and need to be washed or at least sprinkled if they are to be offered still.)