Seven appliances from around Dunedin were called to battle the blaze in the Forth St factory just before 10am.
Workers were evacuated and part of the street closed.
The plant's third and fourth floors were filled with smoke, and smoke could be
seen pouring from the building.
Despite the dramatic sight and the resources needed to fight it, Cerebos Gregg's logistics manager Philip McLennan said the building was undamaged and workers were able to return to the plant and continue production once the site was cleared by firefighters.
``We have two roasters here, so we are able to continue operations,'' he said.
``There's no damage. We have just got to work through the process and conduct an investigation into the cause.''
The fire was in the roaster's ducting, not the roaster itself, Mr McLennan said. It appeared the roaster was undamaged.
No-one was injured.
Firefighters left the scene just after noon.
``There was nothing suspicious at all. It's now in the hands of the owner,'' a fire spokesman said.
Seven appliances from Dunedin Central, Roslyn, Lookout Point, St Kilda, Willowbank, Port Chalmers and Ravensbourne were called to the scene, while Mosgiel transferred to Lookout
Point and was placed on standby.
Senior station officer Kerry McNamara said the fire was under control by 11am.
``We have got a couple of hot spots in the pipe work, so we don't want it to spread outside that.''
The Fire Service received many calls reporting smoke and flames coming from the factory and a fire on the third or fourth floor.
``Crews encountered heavy smoke in these areas,'' he said.
Cerebos Gregg's completed a $20million upgrade of the plant in November.
