Thorntons is kicking off its centenary year with an expanded chocolate Easter range although cost pressure on card not cocoa could shape future innovation.

Over the course of 2011, the upmarket chocolatier will commemorate its 100-year birthday by introducing special on-pack flashes across its portfolio. It will also launch a raft of centenary-inspired new products and marketing activities through the year.

First up is its 15-strong Easter range, which boasts two more lines than last year's and rolls out this week with new-look packaging. Thorntons said it expected sales to exceed last year's £5.9m and revealed that the two new lines were an impulse-sized Melts Treat Egg (rsp: 59p) and a Bramble Bunny chocolate model (rsp: £1.99). A Cheeky Devil model is also being launched (rsp: £1.99) alongside the Easter range, targeting the Valentine's Day market.

Peter Lawson, head of ­commercial at Thorntons, said that the two models had been packaged in ribbon-tied ­cellophane packaging to showcase the "intricate craftsmanship of the chocolatier" compared with the foil-wrapped seasonal lines from rival brands.

"If this clear packaging works well, we will roll it out to other small products," he said. "Packaging has been a key focus area for Thorntons over the past year especially as it is the inflation on cardboard rather than cocoa that is now the biggest cost pressure."

Last year, Thorntons packaged its small Classic egg and Moments egg in pyramid-shaped packaging. The alternative packs will not be returning.