Swelling of food powders: Kinetics measurement and quantification using NMR relaxometry

Quantitative data on powder swelling kinetics is essential to understand phenomena occurring during rehydration, e.g. lump formation. In this study, swelling kinetics of food powders (gelatin powder, soy protein isolate, pea protein concentrate) were quantified by Nuclear Magnetic Resonance (NMR) relaxometry. Using gelatin plates as a model system, it was successfully demonstrated that NMR relaxometry is an efficient, non-destructive method to study swelling kinetics of non-dissolving systems with moderate swelling speeds. For plant-based proteins, high swelling speeds were observed. The obtained maximum water uptake due to swelling was 5.10 ± 0.80 g/g for soy protein isolate and 3.93 ± 0.16 g/g for pea protein isolate, which is in the expected range. Measurement speed was too low to resolve early swelling kinetics (below 84 s), evaluation was more elaborate and results less unambiguous. [Display omitted] •Successful investigation of NMR relaxometry as method to quantify powder swelling.•Water uptake of gelatin quantified with high accuracy using NMR.•Plant-based protein powders swell significantly faster than gelatin powder.•Quantification of water uptake possible for plant-based proteins but more complex.•Method recommended especially for slow and strongly swelling material.