To sterilize grain spawn properly, you need to consider factors like grain type and bag weight. If you're using millet mushroom spawn or rye berries, the method stays consistent - pressure cooking. The rule of thumb is to run the pressure cooker for 90 - 180 minutes at around 15-18 psi to reach the sterile core temperatures necessary for successful inoculation G2G transfer. Regardless of how you choose to sterilize rye grain or other types, remember to ensure that grains are on the dry side when preparing no soak grain spawn, and before bagging them up (spawn bag tek). This prevents excess moisture from causing bacterial issues – maintaining the best temperature conditions for grain spawn growth is paramount here. As a spawn supplement tip, adding quarters or pint jars at the bottom helps maintain balance during sterilization.