Episode 7 µBrews covers one of the more common – and important – questions in the brewery: whether a yeast pitch is healthy enough to use on brewday. This question can be answered by staining the yeast with dyes that indicate whether the yeast are alive (viability staining) and which assess the energy stores available to the yeast (vitality staining).
In this video I demonstrate how to perform viability and vitality staining. Trypan blue is used for viability staining. This is a dye which is excluded from living cells, but which can enter and accumulate in dead cells, thus staining these cells a deep blue. Iodine is used for vitality staining. Iodine stains glycogen – the primary energy store of yeast – a dark brown, allowing a brewer to assess the energy stores available prior to pitching the yeast.