Beer giant Carlton & United Breweries has been grilled over an entry in a manager's diary that outlines a strategy to "win the war" against union workers protesting job cuts.

In a Senate inquiry on Thursday, CUB brewery manager Sebastian Siccita was presented with a page from his diary describing a strategy to overcome a six-month protest line outside the Abbotsford brewery gates, including to "shoot the shit out them" and "cut their supply lines and starve them out - through legal fees and defamation".

Trade unions said they were "shocked and appalled" at the emergence of notes kept by management during the dispute, which was sparked last year over the termination of the brewery's entire maintenance workforce.

Mr Siccita was taken by surprise when the Senate committee chairman, Labor's Gavin Marshall, showed him the copy of the document and began questioning him on what he meant by the comments from September last year.