Integrating on-site wine yeast propagation into vintage procedures can be difficult. Specialized equipment and a dedicated staff are required to successfully utilize yeast propagation on a large scale. The larger the facility and the faster the pace of fruit intake, the more demanding a program like this becomes. I have worked at facilities that had a winemaker dedicated solely to managing propagation and fermentation procedures, with several cellar staff members dedicated to this alone.
A winery needs to allocate adequate equipment for yeast propagation. What equipment exactly will be based of factors such as the batch/tank volumes to be inoculated, the total volume of juice/must to be inoculated within a certain time frame, and the number of yeast strains to be propagated simultaneously.
The most important equipment required for yeast propagation are tanks. There are specialized tanks for sale specifically manufactured for yeast propagation, but it is relatively easy to modify typical wine tanks for propagation. The primary requirements for propagation tanks are:
- Full temperature control of the tanks. Most wineries have existing tank cool systems, but far less have the ability to heat tanks. It is also beneficial if propagation tanks are fully jacketed to maintain temperature control regardless of culture size.
- Constant oxygen sparging. Specialized propagation tanks have this built in, but it is easy enough to use a mobile sparging unit. We are not talking about micro-oxygenation, propagation requires a good flow rate.
- Tank size will be dependent on the size of cultures, but keep in mind that yeast starters tend to need a decent amount of head space.
Tanks are not the only cellar equipment required for yeast propagation. The remaining equipment does not necessarily have to be dedicated solely to a yeast propagation program, but I would recommend doing so due to the time sensitivity of procedures and the sanitation requirements.
- Vessels for rehydrating yeast when creating yeast starters.
- A pump able to handle solids and rather gaseous liquid gently. A mono-pump is pretty ideal because it can be run dry (without liquid) and move small volumes against head pressure.
- A set of hoses that are long enough to reach any point inoculation will be required.
Accurately analyzing and tracking yeast propagation programs is essential. Timing and calculating required additions for the yeast starter itself to determining inoculum volumes to get accurate inoculation rates require well-coordinated laboratory staff.
Basic analysis of juice/must typically desired prior to fermentation is all necessary when operating a yeast propagation program: temperature, brix, pH, TA, free and total SO2, VA, and YAN.
The primary requirement is the ability to accurately measure yeast population. There are plenty of basic cell count methods that are sufficiently accurate. A note of caution: if using yeast rehydration nutrients during propagation procedures, viability testing will be inaccurate since yeast rehydration nutrients are composed largely of autolyzed yeast cells.