With time fast running out, food and drink retailers and manufacturers have admitted they still don't have the answers needed to hit the salt and saturated fat reductions targeted in the ­coalition government's Responsibility Deal.

Last month, the Department of Health unveiled key public-health pledges companies would be encouraged to sign up to.

These reiterated the FSA's 2012 salt reduction targets and included a commitment to remove artificial transfats from food by the end of this year.

Future pledges would also focus on calorie reduction, saturated fat replacement and promotions, it said. But ­retailers and suppliers are already struggling to cut salt, satfat and sugar levels further.

Tesco has removed 3,000 tonnes of salt and 2,500 tonnes of saturated fat from its products since 2005. But speaking at the Biscuit, Cake, Chocolate and Confectionery annual conference last week, Tesco nutritionist Karen Tonks said while it was 70% of the way towards the deal's 2012 salt targets, this didn't mean it was close to completing the task.

"We will need to do more work on a further 25% of our ranges," she said. "About 5% of products will require some really significant work and we don't currently know what the answer is, so we're investigating alternative solutions. In order to meet targets on bacon, for example, we may have to reduce shelf life."

She also said that saturated fat and sugar reductions would be equally tough.

More industry collaboration with food researchers was required to squeeze out the extra reductions necessary, said Tonks, with Tesco in discussion with the Food and Drink Federation and the British Retail Consortium about creating a working group to engage with these researchers. "Lots of universities are doing great work. Whoever has the ingredients that might provide a solution should come and talk to us."

PepsiCo Europe nutrition director Sue Gatenby said her company still had a way to go to hit the salt targets, which companies have until the end of next year to meet, and innovation around sodium reduction was required.

Commitments on salt, saturated fat and sugar published in PepsiCo's 2010 Health Report were proving a "massive challenge", she added. "I wouldn't be surprised if we don't manage to achieve them all despite our best efforts, but that's an indicator of just how stretching they are."

United Biscuits fats and oils development manager Simon Roulston said the reformulation efforts would cost the industry millions and would involve a big technical undertaking. "Saturated fat reductions are not easy. For some of the products we're looking at we would need technological advancements they just won't withstand some of the changes."

Read more
What the Big Society means for grocery (26 March 2011)
Saturday Essay: Why the Responsibility Deal is a no-brainer (26 March 2011)
Big deal? The pledges that might make Brits healthier (19 March 2011)