Lord Shiva is the deity of the universe, on which only by offering a lotta water, you get freedom from all the sufferings of life. Lord Shiva is also considered a destroyer. It is believed that Lord Brahma is the creator of the universe, Vishnu is a patron and Shiva is a destroyer.

Whenever we worship the deities in Hinduism, we also offer some food etc. After worship, we receive it as offerings. It is believed that the offerings offered to the gods and goddesses are like nectar, but this is not the case with Lord Shiva. It is said in the scriptures that it is forbidden to receive any offerings offered on the Shivling.

What is recognition?
It is believed that whenever a offerings are made to a goddess or deity, a part of it goes to that deity itself, but the Prasad offered on the Shivling becomes the property of Chandeshwar Swami. It is believed that Chandeshwar Swami, who is the king of ghosts and demons, appeared from the mouth of Lord Shiva. For this reason, he has authority over the offerings to be offered on Shivling. If a person receives this offerings, then he has to face the anger of Chandeshwar Swami. This leads to sorrow and poverty in that person's life.

It is also mentioned in the Puranas.
Should not receive offerings offered to Shiva. It is also mentioned in the Puranas.

1. According to Shiva Mahapuran,

“Neither prasad is accepted, nor flowers, nor they are accepted.”
“Linguchenan Devendra: Greatness of heaven.”

Meaning: Naivedya (enjoyment), flowers etc. offered on Shivling should not be eaten. The person who does this, his virtue is destroyed and he is deprived of the pleasures of heaven.

2. According to Skanda Purana,

“That is, the fruit of sexual intercourse is water.”
“I imagine that the gods will punish me for my sins.”

Meaning: Fruits, water or other offerings offered on Shivling should not be taken again, as they are particularly dedicated to Lord Shiva and are not for human consumption.

3. According to Linga Mahapuran,

“Also, even if it is given, it is not eaten again.”
“A sinful animal is a malevolent of Shiva.”

Meaning: Whatever is offered to Lord Shiva, it should not be eaten again. If someone does this, he feels a sin and he is called Shivdrohi.

4. According to the Padma Purana,

“Worshiping Shivalinga does not get money back.”
“This is why Bhujit imagines hell.”

Meaning: A person who eats prasad offered on Shivling becomes a part of sin and has to go to hell.

According to the shlokas written in these Puranas, the offerings offered on the Shivling are not considered to be edible.

Not everyone gets recognition.
According to the experts of the scriptures, the offerings made on Shivling made of ordinary stones, soil and ceramic should not be received. They should be drove in a river or reservoir and flowers and leaves should be placed under a tree. Also, offerings made of metal (gold, silver, copper) or offered on Parad Shivling can be received. There is no harm by eating this offerings. Along with this, the offerings offered on the idol of Lord Shankar can also be received.

What is a scientific reason?
Talking about the scientific reason behind this, along with offering water and milk on the Shivling, poisonous materials like Dhatura are also offered. Along with this, alcoholic things like cannabis etc. are also offered to Lord Shiva. People who come in contact with them are prone to infection by eating prasad. Along with this, physical health also has a negative effect.