Soy sauce desalting by electrodialysis

In this work, microfiltered samples of a traditional soy sauce containing 15.1 ± 0.3% (w/v) of sodium chloride were desalted using a laboratory-scale electrodialyser equipped with a stack composed of nine cation- and eight anion-exchange membranes so as to minimise the health risks associated with the consumption of high-salt foods, as well as to allow its full freezing at the current industrial freezing temperatures and accurate dosage in the formulation of multi-component ready-to-serve frozen meals.Whatever the electric current applied in the range of 2.5–6.5 A, the recovery of total acids and amino nitrogen in desalted soy sauce was (80 ± 4)% and (70 ± 3)%, respectively. Moreover, the final concentrations of chloride ions and total solids or electric conductivity were (14 ± 2)%, (73 ± 6)%, or (25 ± 1)% of the corresponding initial ones, respectively. A series of sensory tests proved that the ED-desalted soy sauce kept a good soy sauce aroma without salty aftertaste and its taste did not differ significantly from that of raw soy sauce.

► Microfiltered soy sauce (∼15% w/v NaCl) was desalted in a lab-scale electrodialyser. ► Under constant electric current (6.5 A), 75% desalting was achieved in 128 min. ► The corresponding specific energy consumption was 0.65 W h g−1. ► About 70% of amino nitrogen was recovered in desalted soy sauce. ► The ED-desalted soy sauce kept a good soy sauce aroma without salty aftertaste.