US-based bakery brand Dunkin’ Donuts said that it has developed a new oil in order to create donuts free from trans fats.

The donuts have been served in approximately 400 restaurants throughout the US, as part of a nationwide blind test over a period of four months, said Dunkin’ Donuts in a statement.

The Massachusetts-based company developed the trans- free oil, which can be used as an alternative cooking oil, with the criteria that it works without sacrificing the quality, flavour and taste.

According to the US Food and Drug Administration definition, "zero trans fat" means an oil that contains less than 0.5g of trans fat per serving.

Dunkin’ Donuts tested more than 28 alternative oils and blends and conducted 80 independent tests to find a suitable alternative.

"We are proud to be the first major quick-service outlet to introduce a donut that has zero grams trans fat," said Joe Scafido, chief creative and innovation officer at Dunkin’ Brands.

"We applaud the Dunkin’ Brands research and development and supply chain teams, who have worked behind the scenes for nearly four years to move towards an entirely zero grams trans fat menu."

Dunkin’ Donuts has more than 13,000 franchises in 50 countries worldwide. It said that, by mid-October, all of its bakery products would be trans fat-free, including croissants, muffins, bagels and other bakery products.

The announcement comes as bakery producers are under mounting pressure to help tackle obesity.