Spatiotemporal quantification of sodium concentration in food using magnetic resonance imaging

Quantitative ²³Na MRI presents numerous technical challenges that limit its application in food science - especially in the context of salt reduction. This study aimed to fill this gap by developing a quantitative ²³Na MRI protocol for following the evolution of salt concentration in food samples. By doing so, valuable information on salting processes of real food products can be obtained. The protocol utilizes a 2D interleaved-spiral sequence implemented on a 9.4 T MRI system, enabling the generation of multiple quantitative sodium maps to monitor sodium diffusion over time. The protocol was first validated on a homogeneous gel with a known salt concentration. Subsequently, a theoretical model of salt diffusion was developed using data obtained from boiled carrots salted at the start of the cooking process. Additionally, a visual comparison of salting methods was conducted, contrasting salting at the beginning of cooking with salting after cooking. The results demonstrated that our protocol effectively minimized spatial artifacts caused by coil inhomogeneities in both emission and reception modes. Experimental data collected from salted carrots aligned with expected behavior, confirming the protocol's accuracy. Utilizing the developed model, salt distribution at the extreme ends of the salting process could be extrapolated, providing insights relevant to practical, domestic applications. Moreover, differences between salting methods were identified, emphasizing the significant influence of salting practices on salt distribution, which could positively enhance salt perception.