Speaking after chairing the latest meeting of the task force set up to rescue the factory, he said proposals had been put forward to improve the efficiency of the factory and added the management was also looking at ideas for changes to the way meat was processed.
But he said it was “difficult to conceive” that all 1700 jobs could be preserved.
Dutch parent company Vion announced on July 5 it was launching a 90-day consultation on its plan to shut down the plant, which dates back to 1932 and makes a wide variety of products including sausages, haggis and black puddings.
The firm said the plant was making “unsustainable losses” despite “major restructuring exercises”.
West Lothian politicians likened the closure announcement to a pit closure and warned it would have a devastating effect on individuals, families and the wider community. In many cases, several generations of the same family have worked in the factory.
But Vion said the factory was losing £79,000 a day and added a big part of the problem was the inefficient layout of the site.
Yesterday’s meeting of the task force – which brings together the company, unions, government agencies and local politicians – heard a report from the Scottish Manufacturing Advisory Service on how efficiency at the plant could be enhanced.
Mr Swinney said changes had been identified which could improve the performance of the plant.
But he said: “I think it is difficult to conceive that all 1700 jobs could be secured. I think that it’s difficult to conceive given the circumstances that we face.
“But what we will be concentrating on is delivering the best outcome we possibly can do, in partnership with the company, to try to find a way through this that creates a sustainable and a profitable business.”