Biofilm and dairy fouling detection in flexible tubing using low-field NMR

Biofilm and dairy fouling formation is difficult to study non-invasively in closed systems such as flexible tubing. Nuclear magnetic resonance (NMR) is considered as a promising non-invasive detection method for different deposits. This study aimed to investigate three deposit models: (1) Paenibacillus polymyxa biofilm, (2) dairy biofouling, and (3) dairy fouling, in different experimental set-ups by low-field ¹H NMR. The transverse relaxation time T₂ of each component in samples of experimental set-ups was studied. The results show that low-field NMR offers the possibility of qualitatively measuring the selected deposit models and differentiating non-destructively between the tubing and each deposit. The samples in each experimental set-up showed characteristic relaxation behavior of flexible tubing, deposit, and liquid. For the P. polymyxa biofilm, longer relaxation times T₂ of about 100 ms were detected, while relaxation times T₂ for dairy biofouling and dairy fouling were in range of 50–60 ms. It was thus concluded that low-field NMR has a great potential for non-invasive detection of deposit formation at practical industrial scales.