New products should only be judged a success if they make it past the two-year mark, according to a food innovation expert speaking at Food & Drink Expo.

Criticising the tendency to heap praise on new products, often just months after their launch, chairman of the Food and Drink Innovation Network Jeffrey Hyman said longevity was the only measure of success.

"I am against a panel of experts looking at products that have been launched and awarding them prizes for innovation just because they stand out," he said during a seminar on NPD best practice.

"If you're still on the shelf 24 months down the line you may have a good new product with a long shelf life on your hands."

Coke Zero, odour neutraliser Oust and Walkers Baked crisps are among the products launched two years ago that have established themselves as long-term brands.

Coming up with a successful new product was as tough as ever, said Hyman, former director of innovation at RHM Foods.

"Category managers are not afraid to chuck out underperforming products because they haven't reached their hurdle rates," he said, adding that the criteria for successful innovation were constantly evolving.

Where health, taste and convenience were once the cornerstones of innovation, green and ethical considerations were now top of the consumer agenda.

Clear insight into what consumers wanted was critical to the success of new products, as was efficient replenishment of stock, effective marketing and promotional activity, he said.

NPD was too important a process to be left to brand managers and required the input of everybody in the organisation from board level down, he added.

Own label was stealing a march on branded in NPD, said Hyman, describing Marks & Spencer and Waitrose as best in class.