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.