Praise be to Allah.
It is not permissible to sprinkle vinegar on unripe dates in order to hasten their ripening, for two reasons:
The first reason:
is what that involves of cheating, because the unripe dates that are sprinkled with vinegar lose a lot of their taste and benefits, and the purchaser does not know that they were sprinkled with vinegar. Muslim (102) narrated from Abu Hurayrah that the Messenger of Allah (blessings and peace of Allah be upon him) passed by a pile of foodstuff; he put his hand in it and found that it had got wet. He said, “What is this, O seller of the foodstuff?” He said: It got rained on, O Messenger of Allah. He said: “Why don’t you put it [the wet part] on top of the food so that people can see it? Whoever deceives [people] does not belong to me.”
Ibn Hajr al-Haytami (may Allah have mercy on him) said: The guideline on cheating that is haram is that the one who has the product, whether he is the seller or the purchaser, knows that there is some issue with it which, if the one who wants to buy it were to find out about it, he would not buy it for that price. In that case, the seller must inform the purchaser of it, so that he will buy it knowing exactly what it is. End quote from az-Zawajir ‘an Iqtiraf al-Kaba’ir (1/396).
The second reason:
is what that causes of harm.
Dr. Ahmad Kamil, Professor of Nutrition at Helwan University, said: Dates have a high nutritional value. The date is a summer fruit that contains iron and calcium, and is very rich in essential nutrients that humans need. One kilogram of dates gives the same number of calories as meat, or three times the calories of a kilogram of fish. Dates contain vitamin A, which is present at high levels that are equivalent to the ratio of the same vitamin in fish oil and yoghurt.
But using vinegar to make the dates ripen has many negative effects on human health, because vinegar is an organic substance that absorbs fats and liquids from the body. Moreover, it detracts from the nutritional value of the dates, leaving them with the taste only. It is also harmful to the liver, because the acetic acid from which vinegar is made causes damage to the liver.
Dr. Hassan ad-Dasuqi, a consultant gastroenterologist at Ain Shams Hospital said: … Sprinkling vinegar on [dates] takes away all their benefits and has a deleterious impact on the digestive system and the liver.
And Allah knows best.