Generally speaking, eating pineapple and having a sore mouth is caused by the bromelain enzyme in pineapple that irritates the mucous membranes of the mouth and lips.
Pineapple is a tropical fruit, rich in vitamin C and organic acids, including malic acid and citric acid. At the same time contains an enzyme called pineapple enzyme, the enzyme can break down proteins, usually stimulate the oral mucosa and lips, direct consumption of pineapple part of the population will appear mouth pain discomfort.
However, if you consume pineapple soaked in salt water, because the salt water reduces the activity of pineapple enzyme, generally will not appear after consumption of mouth pain phenomenon.
-Pineapple is high in sugar, so diabetics need to limit their intake. Ordinary people can consume it in moderation.