The Bourtreehill Supermarket in Irvine has collected more than 3000 two litre bottles of the original drink.
The stock grab comes ahead of the introduction of a new recipe of the fizzy drink at the end of this month that contains 50 per cent less sugar.
Some devoted fans of the beloved Scottish drink have voiced their opposition to the recipte change, which has coincided with the introduction of the so-called “sugar tax” in April.
“Irn-Bru original recipe production has officially stopped,” store owner Imran Ali told STV.
“Fear not Bourtreehill.
“We have over 3000 two litre bottles of original Irn-Bru in stock. From end of January Irn-Bru will have up to 50 per cent less sugar.
“Some people don’t mind the less sugar but some aren’t happy.
“We like to look after our customers and go extra mile to cater for their needs.”
The amount of sugar in every can of Irn-Bru is being cut from 8.5 teaspoons to four, going from just under 140 calories to about 65 calories.
A test of the new and old Irn-Bru recipes carried out by staff at The Scotsman found little difference between the two in a blind tasting.
Reporter James Delaney added: “I was a little bit sceptical when I heard they were changing the recipe, but trying it for the first time it is almost impossible to tell the difference. It still tastes like the Irn-Bru we all know and love.”