has value specification starting optical density measured process variable A precision fermentation measured process variable that indicates the initial optical density (OD) of the fermentation culture from a bioreactor or fermentation system during a fermentation process. precision fermentation starting optical density measured process variable starting OD measured process variable precision_fermentation The starting OD measurement is either measured (by taking a sample after inoculation and measuring the cell density spectophotometrically at 600nm or 900nm wavelength) or calculated (by knowing the final OD of the seed culture, volume inoculated and final cultivation volume). PREFER:0000034 optical density base method variable unit of optical density precision fermentation measured process variable