Detection of P. polymyxa biofilm, dairy biofouling and CIP-cleaning agents using low-field NMR

The accumulation of unwanted deposits in food-processing equipment may cause significant production downtime, add to expenses for cleaning agents and wastewater disposal, as well as food contamination. Nuclear magnetic resonance (NMR) is considered as a promising non-invasive tool for the monitoring of processes in food industry. In this work, two deposit models and cleaning agents are investigated by low-field 1H NMR: (1) Paenibacillus polymyxa biofilm, (2) dairy biofouling and (3) clean-in-place (CIP) cleaning agents. The transverse relaxation times T2 obtained by inverse Laplace transform as well as diffusion coefficients DS of the samples are studied. The obtained results reveal that low-field NMR can be used for the detection and identification of selected deposit models and CIP-cleaning agents. Transverse relaxation times T2 demonstrate characteristic relaxation behavior of flexible tubing, differently structured deposits, and liquid phases. Moreover, with increasing biofouling thickness (up to 406.2 mg/cm2), transverse relaxation times T2 shift toward slower relaxation rates up to T2 111.9 ms. In addition, significant differences in the diffusion behavior of water are noted in each sample group of the deposit models and CIP-cleaning agents. The diffusion coefficient of water in dairy biofouling and in microbial biofilm matrix corresponds to approximately 65% and 75% of the value in pure water, respectively. In addition to the NMR results, the biofilm and biofouling identification is validated through microbiological methods and by microscope images.