On‐line batch fermentation process monitoring (NIR)—introducing ‘biological process time’

On‐line near infrared (NIR) spectroscopy enables detailed monitoring of many important types of industrial fermentation processes to document progress and to ensure comparable end‐product quality. In this work a newly developed modification of multivariate statistical process control (MSPC) charts based on on‐line NIR allows easy and efficient identification of abnormal fermentation runs, even at an early stage of the fermentation, which is critical for industrial production monitoring. This study especially focuses on alignment of cultivations through usage of three different time concepts: absolute time, relative time and ‘biological process time’. For the investigated batch fermentation the absolute time concept for alignment is not acceptable. Using the relative time concept or the ‘biological process time’ concept gave similar possibilities for early warning of abnormal batch runs for completed runs. For on‐line use, however, the relative time concept cannot be used, which is the reason for our development and introduction of a new ‘biological process time’ concept.