The goal of this workpackage will be the realisation of a shoe-box sized demonstrator PTS and/or QEPAS sensor capable of monitoring the quality of foods. As target gas analytes, basic amines (in particular ammonia) as an indicator for food degradation (fish) as well as diacetyl as a quality parameter for brewing have been chosen. These analytes were selected because of i) their real-world relevance as indicated by the needs of the industrial partners and ii) because different modulation techniques need to be developed for measuring ammonia (resolved and thus sharp ro-vibrational lines) and diacetyl (non-resolved and thus broad absorption bands), respectively. The demonstrator shall be validated using spiked samples as well as appropriate reference analytics (gas and ion chromatography).
Concerning liquid phase analysis, a PTS system based on a Mach-Zehnder interferometer will be developed and applied for measuring different proteins in aqueous solutions like milk samples. The mid-IR spectra of proteins and especially the amide I band related to the C=O bond are indicative for the secondary structure of a protein. OPTAPHI will investigate the possibility to quantify up to three proteins simultaneously and compare the results obtained using the PTS technique with data recorded using direct spectroscopy using broadly tunable external cavity QCLs.