Warm ice cream is the holy grail for scientists at Unilever, owner of the Magnum and Ben & Jerry’s brands, which is developing a “low-carbon” product to be sold at room temperature and frozen at home.

Unilever hopes that a product sold at room temperature will help to reduce greenhouse gas emissions. Ice cream is one of the company’s more energy-intensive products because of the need to keep it frozen during transport and storage.

The company, the world’s largest producer of ice cream, sells €5 billion (£4.3 billion) a year worldwide of brands that also include Wall’s, Cornetto, Feast, Viennetta and Solero. The UK ice cream market is worth £789 million a year, it says.

A spokesman for Unilever said that warm, or so-called ambient, ice cream was a “very interesting idea” but one that posed tough challenges that its scientists were trying to solve. “The key question which has yet to be fully answered is: how do you ensure that, when the ambient ice cream is frozen at home it will have the right microstructure to produce a fantastic consumer experience?”

The research programme is being undertaken in Unilever’s own laboratories with help from academics at Cambridge University.

Gavin Neath, Unilever’s senior vice-president for sustainability, said: “We have to look at a really radical solution.” He said that the ice cream programme was part of a review that Unilever was undertaking to minimise the environmental impact of its products.

Unilever is trying to reduce the emissions from its ice cream operation by improving the energy efficiency of factories in Gloucester, Heppenheim in Germany, Caivano in Italy and Saint-Dizier in France. It is also upgrading two million refrigerated cabinets that it supplies to retailers in 40 countries. Mr Neath said that 400,000 of these refrigerators had been replaced with a propane-powered cabinet that was 15 per cent more energy efficient.

He said, however, that while Unilever’s global operations, including its factories, offices, research laboratories, lorries and staff travel, probably emitted nearly four million tonnes of carbon per year, those from the full life cycle of its products, including energy to run dishwashers and washing machines, or to refrigerate and cook food, were about 400 million tonnes.

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