Enhancement of Salt Uptake with the Application of Rotary Magnetic Field in Brining Cucumber

Abstract

An experimental system by use of magnetic and hydrodynamic force was established to accelerate mass transport and thus to shorten the salting equilibrium time in salting of fresh-cut cucumbers. The cucumbers were brined with flowing 3% NaCl solution under rotary magnetic field at 22 ºC. During brining period, salt contents of the cucumbers at varying Reynolds number of flowing brine, rotary frequency, and magnetic flux density of magnetic field were separately investigated and the salt uptake kinetics was also analyzed. Results showed that flowing brine disturbed the salt diffusion into cucumber tissues without the application of magnetic field. Consequently, the salt uptake rate decreased compared to the conventional brining. No significant difference in salt content of cucumbers was observed between the conventional brining and static-magnetic-field-assisted brining. The salt uptake rate was improved by the combination of rotary magnetic field and flowing brine. The increment of salt uptake rate during this combined treatment got larger with the increase of magnetic flux density. Salt uptake rate of cucumber increased with the increase of rotational frequency of the magnetic field and Reynolds number of the flowing brine, up to a critical value. A 170% increment in salt uptake rate constant could be achieved at magnetic flux density 0.13 T, rotational frequency 5 Hz and Reynolds number 1127. Thus, an intergrated technique based upon rotary magnetic field and flowing brine is provided for brining of porous agricultural products.