NMR assessment of mix and ice cream. Effect of formulation on liquid water and ice

The overall quality of ice creams is often related to the state of water and fat either in liquid or solid state. This work investigates the capacity of low-field NMR spectrometry in characterizing the different behaviours of water protons in mix and in ice cream. Meanwhile, different formulations (types of protein, fat or emulsifier) were tested. The factor which most affected the T2 and T1 relaxation time of the liquid water and ice protons was the protein type. Although this effect is well-known on the NMR behaviour of liquid water protons, it has been observed on the solid water protons for the first time. Assessing the behaviour of liquid water already gave new elements for better understanding the mechanisms responsible for the formation and aging of mix and ice cream. The corresponding relaxation time showed no correlation with rheological properties of mixes, indicating that interactions between molecules in suspension (e.g. proteins) and water protons are not involved in. Its changes during cold storage were relevant of a “non-equilibrium” behaviour, which is further discussed in the paper.