Brewmaster is the MoreBeer wholesale brand. A while back I found this entry on the Brewmaster site: “Cellar Science takes the best winemaking and brewing products from across the world, and packages them in convenient sizes for you. Our yeast is packaged in a dedicated, state of the art room with HEPA filtration. Chemicals and additives are packed in convenient sizes for 6 gallon or 60 gallon batches of wine, or efficient bulk sizes. We use custom designed oxygen, light, and moisture barrier bags for the best quality and shelf life.”
However, they seem to have edited that statement lately.
They do this with grain under the Brewmaster name and hops under the Artisan name as well as other product lines. The Cellar Science brand is for yeast, enzymes, yeast nutrients, and additives.
Though I cannot confirm from their site and emails from the company give no clarity, I believe Mangrove Jacks uses the same business model.