Effect of rotating magnetic field and flowing Ca2+ solution on calcium uptake rate of fresh-cut apple

- Negative exponential model sufficiently described the calcium uptake.
- Magnetic field combined with flowing Ca2+ solution accelerated ionic diffusion.
- Higher magnetic flux field could increase the calcium uptake rate.
- Threshold f and Re value existed for promoting ionic diffusion.

The combination of a rotating perpendicular magnetic field and a flowing Ca2+ solution accelerated the calcium uptake of fresh-cut apple cubes and shortened the time needed for calcium equilibration between the Ca2+ solution and samples. The influence of operational parameters (Reynolds number of the flowing Ca2+ solution, magnetic flux density of the magnetic field, rotating frequency of the magnetic field, and temperature) on the calcium uptake rate were investigated. Negative exponential models were used to sufficiently describe the calcium uptake rate of samples. Magnetic flux density and temperature positively affected the calcium uptake rate. Higher Reynolds number and rotating frequency both accelerated the calcium diffusion, but excessively high levels (turbulent flowing at Re = 4134 or rotating frequency at 10 Hz) decreased the calcium content. Neither the flowing Ca2+ solution alone, nor the magnetic field alone, accelerated the calcium diffusion. This study provides an alternative methodology for the mineral fortification of fresh-cut fruits under the joint action of a rotating magnetic field and a flowing electrolyte solution.