This is a very nice description of the transcendental nature of Krsna prasadam taken from the translations and purports of the Sri Caitanya Caritamrta Antya Lila 16th Chapter. Enjoy!
VERSES 81-97
One day, when Sri Caitanya Mahaprabhu went to visit the temple of Lord Jagannatha, the gatekeeper at Simha-dvara approached Him and offered respectful obeisances. The Lord asked him, "Where is Krsna, My life and soul? Please show Me Krsna." Saying this, He caught the doorkeeper's hand. The doorkeeper replied, "The son of Maharaja Nanda is here; please come along with me, and I shall show You." Lord Caitanya said to the doorman, "You are My friend. Please show Me where the Lord of My heart is." After the Lord said this, they both went to the place known as Jagamohana, where everyone views Lord Jagannatha. "Just see!" the doorkeeper said. "Here is the best of the Personalities of Godhead. From here You may see the Lord to the full satisfaction of Your eyes." Sri Caitanya Mahaprabhu stayed behind the huge column called the Garuda-stambha and looked upon Lord Jagannatha, but as He looked He saw that Lord Jagannatha had become Lord Krsna, with His flute to His mouth. In his book known as Gauranga-stava-kalpavrksa, Raghunatha dasa Gosvami has described this incident very nicely." 'My dear friend the doorkeeper, where is Krsna, the Lord of My heart? Kindly show Him to Me quickly.' With these words, Lord Sri Caitanya Mahaprabhu addressed the doorkeeper like a madman. The doorkeeper grasped His hand and replied very hastily,'Come, see Your beloved!' May that Lord Sri Caitanya Mahaprabhu rise within my heart and thus make me mad also."The offering of food known as gopala-vallabha-bhoga was then given to Lord Jagannatha, and arati was performed with the sound of the conch and the ringing of bells. When the arati finished, the prasada was taken out, and the servants of Lord Jagannatha came to offer some to Sri Caitanya Mahaprabhu. The servants of Lord Jagannatha first garlanded Sri Caitanya Mahaprabhu and then offered Him Lord Jagannatha's prasada. The prasada was so nice that its aroma alone, to say nothing of its taste, would drive the mind mad. The prasada was made of very valuable ingredients. Therefore the servant wanted to feed Sri Caitanya Mahaprabhu a portion of it. Sri Caitanya Mahaprabhu tasted a portion of the prasada. Govinda took the rest and bound it in the end of his wrapper. To Sri Caitanya Mahaprabhu the prasada tasted millions upon millions of times better than nectar, and thus He was fully satisfied. The hair all over His body stood on end, and incessant tears flowed from His eyes. Sri Caitanya Mahaprabhu considered, "Where has such a taste in this prasada come from? Certainly it is due to its having been touched by the nectar of Krsna's lips." Understanding this, Sri Caitanya Mahaprabhu felt an emotion of ecstatic love for Krsna, but upon seeing the servants of Lord Jagannatha, He restrained Himself. The Lord said again and again, "Only by great fortune may one come by a particle of the remnants of food offered to the Lord." The servants of the Jagannatha temple inquired, "What is the meaning of this?"
PURPORT BY SRILA PRABHUPADA
The remnants of Krsna's food are mixed with His saliva. In the Mahabharata and the Skanda Purana it is stated:
maha-prasade govinde
nama-brahmani vaisnave
svalpa-punyavatam rajan
visvaso naiva jayate
"Persons who are not very highly elevated in pious activities cannot believe in the remnants of food [prasada] of the Supreme Personality of Godhead, nor in Govinda, the holy name of the Lord, nor in the Vaisnavas."
VERSES 98-109
Sri Caitanya Mahaprabhu replied, "These are remnants of food that Krsna has eaten and thus turned to nectar with His lips. It surpasses heavenly nectar, and even such demigods as Lord Brahma find it difficult to obtain."Remnants left by Krsna are called phela. Anyone who obtains even a small portion must be considered very fortunate. "One who is only ordinarily fortunate cannot obtain such mercy. Only persons who have the full mercy of Krsna can receive such remnants. "The word 'sukrti' refers to pious activities performed by the mercy of Krsna. One who is fortunate enough to obtain such mercy receives the remnants of the Lord's food and thus becomes glorious." After saying this, Sri Caitanya Mahaprabhu bade farewell to all the servants. After seeing the next offering of food to Lord Jagannatha, a function known as upala-bhoga, He returned to His own quarters. After finishing His noon duties, Sri Caitanya Mahaprabhu ate His lunch, but He constantly remembered the remnants of Krsna's food. Sri Caitanya Mahaprabhu performed His external activities, but His mind was filled with ecstatic love. With great difficulty He tried to restrain His mind, but it would always be overwhelmed by very deep ecstasy.After finishing His evening duties, Sri Caitanya Mahaprabhu sat down with His personal associates in a secluded place and discussed the pastimes of Krsna in great jubilation. Following the indications of Sri Caitanya Mahaprabhu, Govinda brought the prasada of Lord Jagannatha. The Lord sent some to Paramananda Puri and Brahmananda Bharati. Sri Caitanya Mahaprabhu then gave shares of the prasada to Ramananda Raya, Sarvabhauma Bhattacarya, Svarupa Damodara Gosvami and all the other devotees. As they tasted the uncommon sweetness and fragrance of the prasada, everyone's mind was struck with wonder. Sri Caitanya Mahaprabhu said, "These ingredients, such as sugar, camphor, black pepper, cardamom, cloves, butter, spices and licorice, are all material. Everyone has tasted these material substances before.
PURPORT BY SRILA PRABHUPADA
The word prakrta refers to things tasted for the sense gratification of the conditioned soul. Such things are limited by the material laws. Sri Caitanya Mahaprabhu wanted to make the point that material things have already been experienced by materially absorbed persons who are interested only in sense gratification.
VERSES 110-112
"However," the Lord continued, "in these ingredients there are extraordinary tastes and uncommon fragrances. Just taste them and see the difference in the experience. "Apart from the taste, even the fragrance pleases the mind and makes one forget any other sweetness besides its own."Therefore, it is to be understood that the spiritual nectar of Krsna's lips has touched these ordinary ingredients and transferred to them all their spiritual qualities.
PURPORT BY SRILA PRABHUPADA
Since everyone had previously tasted these ingredients, why had they become extraordinary and spiritually tasteful? This was proof that food, prasada, becomes uncommonly flavorful and tasteful by touching Krsna's lips.
VERSES 113-116
"An uncommon, greatly enchanting fragrance and taste that makes one forget all other experiences are attributes of Krsna's lips. "This prasada has been made available only as a result of many pious activities. Now taste it with great faith and devotion." Loudly chanting the holy name of Hari, all of them tasted the prasada. As they tasted it, their minds became mad in the ecstasy of love.