Mashing and Fermenting

Mash Sampler, Waterloo, Ontario; circa 1980; stainless steel; 91.15.2.

Once the grain was ground into meal, it was transported to a tub and mixed with water. The mixture, or mash, was heated with steam until the starch gelatinized. This mixture was then cooled to 63 degrees Celsius and malted barley was added to help convert the starch to fermentable sugar. The mash was then cooled and pumped to fermenting tanks where yeast was added to convert the sugar to alcohol. Jack Petrie, who worked as a yeast room operator in the 1960s, was responsible for adding the yeast culture which was produced on site at that time: "The lab would make the [yeast] culture and you took up a couple of flasks of culture and you started off the yeast in small tanks. Then you heated [the mixture] to a certain degree, then cooled it down and then you'd ... pump the yeast over to the larger [fermenting tanks]. You'd have a stick in your yeast tub, with measurements on it, once it went down so far, you'd shut the bottom of your yeast tub off ... and you'd add water to it. In the fermenting room ... we'd have to go down and take samples ... when it was working [fermenting] there were bubbles on it and then in forty-eight hours or so it was dead, nothing on top. Then the guys from the lab, they'd want their test so we'd take a sample down to the lab."