The preferred provider is Compass Group, and Health Benefits Ltd is running the process, even though that organisation is to be axed.
A board spokesman referred the Otago Daily Times to HBL for further comment.
Some food will be brought to the South pre-cooked, but there was scant detail yesterday.
No staff will lose jobs.
The move was subject to formal consultation with staff, and the board wants more information before signing the contract, chairman Joe Butterfield said in a statement yesterday.
''We recognise the impact implementation of this decision may have on affected staff and local suppliers and Southern DHB will not enter into a contract until we are completely satisfied with its benefits,'' he said.
Staff were told yesterday their jobs were safe, which came after about two years of delay and uncertainty.
Board members decided to opt into the national food service after a last-ditch plea from a Service and Food Workers Union delegation to the board meeting yesterday in Dunedin failed.
It is expected to save $870,000 in its first year.
About 100 kitchen workers would know more detail next February, and yesterday union organisers criticised the lack of information.
SFWU organiser Anna Huffstutler, of Southland, said staff were angry and upset by the decision.
They had been ''waiting around'' for two years for the decision.
Miss Huffstutler said members were ''passionate'' about staying employed by the health board, and did not want to be contracted out.
''They feel like they're providing a public service.
''At the end of the day, I think everyone kind of knew it was going to be made in the financial ... because the DHB's in trouble, and if there's an opportunity to save money, they're going to try to take that opportunity.''
Miss Huffstutler believed the process was overly secretive.
Given the preferred provider was chosen, there should be more information.
''We've got too many questions, and they've got no answers,'' Southland SFWU delegate Karena Kelland said.
Health Minister Jonathan Coleman announced last month HBL will be wound up by the middle of next year and responsibility for cost-cutting will switch to health boards.
