Effect of processing conditions on water mobility and cooking quality of gluten-free pasta. A magnetic resonance imaging study

A new approach for producing gluten-free pasta from hydrated (50 °C, 20 min) rice kernels, skipping the grinding step, was explored. Magnetic Resonance Imaging (MRI) was used to study the hydration kinetics of rice, by monitoring the time evolution of both proton density and water transverse-relaxation rate during water diffusion. Results showed that the optimal water diffusion was reached after 180 min, allowing the extrusion of hydrated rice kernels into pasta. MRI analysis also highlighted in cooked pasta gradients of water distribution and mobility, in agreement with the high shear force that was measured using the Kramer cell (1066.5 vs 896.4 N). The high hydration in the external layers of pasta did not negatively affect the cooking quality (cooking loss, compression energy, firmness) of the product. MRI analysis provided experimental evidence for the optimization of early steps in the technological process of grains for the production of gluten-free pasta.