Alliance Group manufacturing general manager Willie Wiese became the interim chief executive on Friday.
Group chairman Murray Taggart said the board was working through a process of recruiting a new chief executive.
"Given this may take several months, we wanted to ensure seamless continuity."
Mr Wiese joined Alliance in December 2017 and had led the co-operative’s Manufacturing Excellence Programme, which significantly improved operational performance across the co-operative’s plant network, Mr Taggart said.
The programme included an investment in technology such as primal cutters and warehouse automation, along with gains in yield performance and health and safety.
“Willie and the executive leadership team will ensure our strategic and operational priorities continue to progress until a permanent appointment is made."
In November, the co-operative announced the resignation of chief executive David Surveyor after nearly eight years in the role.
