Design and evaluation of an in-line system for gas sensing in flow-packed products

A method for the in-line application of Tunable Diode Laser Absorption Spectroscopy (TDLAS) for headspace oxygen sensing in flow-packed products is presented. This is one of the first automated, industrial application on food packaging samples of a well known spectroscopic technique.The developed instrument is discussed starting from its sensor design with details on the optical working principles to point out the peculiarities and application issues linked with this particular technique. A production line implementation of the sensor is then presented, based on a conveyor belt for automatic sampling. This device was also integrated with line automation in order to enable measurement on the full production. Both in-line and off-line instruments were validated against traditional, industry-standard invasive measurement techniques. The accuracy of the measurement applied to regular samples from production line was found better than 0.4% vol. O2.