Three relative unknowns – chefs Jock Zonfrillo and Andy Allen and food writer Melissa Leong – have been cast as the new judges on Channel Ten’s popular reality show MasterChef Australia.

The trio of younger, more diverse and considerably cheaper reality TV judges will replace the household names Matt Preston, Gary Mehigan and George Calombaris, who announced suddenly in July that they were leaving. Ten said at the time it could not meet the demands of the three former judges.

Today’s announcement surprised many who believed well-known personalities such as Poh Ling Yeow, Kylie Kwong, Adam Liaw or Maggie Beer may be cast in the roles.

Zonfrillo is the owner and chef of the three-hatted restaurant Orana and Bistro Blackwood in Adelaide and has hosted television shows including Nomad Chef and Restaurant Revolution.

“When I think of MasterChef Australia, I think of discovering new talented cooks with fresh ideas and creativity,” Zonfrillo said. “There hasn’t been a season yet where I haven’t been surprised by just how talented some of the undiscovered cooks are, so much so that many of them have worked in my kitchen over the years. I can’t wait to get in that kitchen.”

The first female judge on MasterChef Australia, Leong, is a first-generation Singaporean Australian. She is a writer and broadcaster who has hosted a cooking show on SBS. “It came as a huge surprise for me, and is without a doubt the opportunity of a lifetime,” she said. “I am really looking forward to getting stuck in!”

Allen is well known to MasterChef viewers after winning the title in 2012. When his Rosebery restaurant, Three Blue Ducks, was awarded a chef’s hat, Allen became the first MasterChef Australia contestant to take out the culinary honour.

“I entered this competition as a contestant in 2012, somehow I won it, and then I went out into the big, bad wide world of hospitality,” he said. “To be asked to be a judge, and to come full circle back to MasterChef Australia, is really flattering and really special. I’m stoked because it means that I’ve done the hard work to be here. You don’t ask Joe Blow to be a judge on MasterChef Australia.”

Network 10’s chief content officer, Beverley McGarvey, said the new judges would be joined by the better known guest judges Gordon Ramsay, Heston Blumenthal and Curtis Stone for the new series in 2020: MasterChef Australia – Back To Win.

“Their combined culinary credentials coupled with their passion and sheer joy for food, and their relentless enthusiasm to explore ingredients, preparation and cooking methods ensures we are in for a real treat,” McGarvey said.

The resignation of the three judges in July followed revelations that Calombaris’s companies had underpaid staff at his restaurants by nearly $8m.