Tapioca starch, NaCl (28, 135, and 378 μm), corn starch, cocoa powder, soy protein isolate, cheese powder, wheat protein, modified starch, nacho cheese, and sugar were coated at 0 kV for nonelectrostatic and at 25 kV for electrostatic coating onto metal, wood, unoiled paper, oiled paper, unoiled plastic, oiled plastic, fresh bread, and dry bread. Powders and targets were allowed to naturally tribocharge, or all charge was removed before coating. Powder particle size, flowability, resistivity, and target resistivity were reported. Electrostatic coating produced the same or better wrap around, or percent side coverage as nonelectrostatic coating for every powder and target. The greatest electrostatic improvement was found when using powders that had the worst nonelectrostatic side coverage: large particle size (>135 μm), low resistivity, and low cohesiveness, especially on targets that had high-surface resistivity (2 x 105 Ωm). Tribocharging had a similar effect as electrostatic coating. In both nonelectrostatic and electrostatic coating, percent side coverage increased as powder particle size decreased, cohesiveness increased, or target resistivity decreased. In electrostatic coating, percent side coverage increased as powder resistivity increased; however, in nonelectrostatic coating, as powder resistivity increased, percent side coverage increased on only oiled plastic and dry bread.
Salts were coated on a variety of thick targets. The best transfer efficiency, adhesion (> 70%), and percent side coverage (100%) was obtained when small (< 200 µm) and cohesive (Hausner ratio > 1.20) salt was used with electrostatic coating on targets with high water activity (> 0.7), low resistivity (< 9 x 108 Ωm), and short charge decay time (< 3.8 sec). The shape of salt particles also affected the coating performance; porous cube provided significantly better transfer efficiency and adhesion than flake salt on some targets. There was no significant effect of KCl content on coating performance.
Hot break, cold break and commercially canned tomato juice was concentrated by vacuum concentration and solid-liquid separation (SLS). Tomato products from vacuum concentration had higher soluble solids than those from SLS because of loss of soluble solids into the filtrate. Most volatile levels in vacuum concentration greatly decreased initially then remained constant during further concentration. In SLS, volatile levels linearly decreased with increasing concentration so SLS had greater retention of volatile compounds than vacuum concentration. Viscosity of the rediluted samples decreased with concentration, except in the hot break and commercial samples from SLS, which maintained the same viscosity. Samples from SLS were close to the original color while samples from vacuum concentration were redder due to heat induced Maillard browning. Vitamin C decreased during concentration with greater loss during SLS than vacuum concentration. SLS consumed 45 times less electric power energy than vacuum concentration, which also needed water for creating vacuum conditions.