A TVNZ spokeswoman said producers did not want to discuss overseas filming so any surprises were not spoiled for viewers.
The series of the reality cooking show has been expanded after the success of the first two series.
Episodes have been increased from 13 to 17, and filmed in locations including Hawke's Bay and Taupo.
Contestants are staying at the same North Shore mansion as in previous series.
The show will return to TV One early next year.
Meanwhile, former MasterChef contestant Cameron Petley has been giving celebrity chef Rick Stein tips on how to catch local delicacies.
Petley, a former Herald on Sunday columnist, took Stein eeling in the Waikato ahead of their appearance at Auckland's Taste of New Zealand festival.