Separation of Powder Mixtures during Electrostatic and Nonelectrostatic Coating

Powder separation causes uneven flavor and color on coated food products. Understanding the basis behind separation is needed to decrease separation. NaCl , starch, protein, sugar and mixtures of pairs of those powders were coated nonelectrostatically and electrostatically. Separation occurred in most mixtures. Individual targeting loss and adhesion loss caused separation while interactions between powders decreased both of these losses and separation during mixture coating. The difference in individual targeting loss was the greatest cause of separation. During nonelectrostatic coating, when NaCl was one of the powders in the mixture, there were a greater number of locations both where separation actually occurred and where it was predicted to occur. During electrostatic coating, the individual targeting loss of all powders during electrostatic coating was lower than in nonelectrostatic coating and the difference in individual targeting loss was also lower. Electrostatic coating generally decreased separation in the mixtures without NaCl . Practical Applications Using mixtures with similar size powders has been shown to reduce separation during powder coating. However, even if the powders are the same size, separation still occurs because different powders have different properties. Increasing the amount of salt in a mixture may decrease separation because salt has greater targeting loss than other powders. Minimizing differences in individual targeting loss decreases separation, as does mixing powders together. Electrostatic coating can be used to decrease losses and separation in mixtures without salt.