Study of electrochemically treated walnut emulsion and its stability

Abstract

AbstractThe oil‐containing walnut flour has limited applications since it is easily oxidized and deteriorated. In the present study, walnut cake with a fat content of 16.3% was used as a raw material for by‐products making following an hydraulic process. The walnut cake was crushed to 20 meshes and mixed with water at a ratio of 1:4. The mixtures were ground and filtered. Then, the filtrates were homogenized at 80 MPa pressure. The walnut emulsions were pumped into the solid polymer electrochemical reaction chamber at a speed of 35 mL/min, the temperature was controlled at 60 °C, the current density of the direct current was 0.08 A/cm2, and the time of cycle reaction was 90 min. After electrochemical treatment, the iodine values of fats in walnut emulsions were reduced from 140 to 92 g I2/100 g oil. The nitrogen solubility index of walnut emulsion has improved by 4.6% at 30 °C. Storing the oil‐containing walnut flour for 24 weeks, the peroxide value was reduced to 5.64 meq O2/kg oil compared to the nonelectrochemical treated oil (10.52 meq O2/kg oil). These results indicate that the electrochemical treatment enhances the stability of the oil‐containing walnut flour.Practical applicationsIn the present study, fats from walnut cake were used for by‐products making following a hydraulic process. The electrochemical hydrogenation reduced the iodine values of fats in walnut emulsions. Based on the current funding, the oxidation stability of oil‐containing walnut flour was improved significantly. The trans fatty acids of electrochemical‐treated oil‐containing walnut flour was only 1.6%. A portion of the protein was electrolytically reduced. The nitrogen solubility index of oil‐containing walnut flour increased and improved the quality of the final products. The electrochemical hydrogenation improved significantly the stability of oil‐containing walnut flour and can be further applied for industrial purposes.