Diced tomatoes are commonly dipped in calcium solutions to increase their firmness and drained weight. Electrostatic powder coating could be an alternative method to evenly apply calcium without wastewater production. Calcium has been shown to preserve texture against mechanical damage in tomatoes. The objectives of this study were to determine if electrostatic powder coating would be as effective as liquid dipping for applying calcium to dices and to determine when the addition of calcium best inhibits bruising. Tomato dices were dipped in a calcium solution for 0-240 sec or powder coated electrostatically with 0-1100 mg/kg calcium. Batches were treated with calcium before or after bruising for 0-240 sec in a rotary drum. The drained weight and firmness increased with dip time and calcium addition for both methods. The raw dices were significantly firmer than the canned dices. Dices that were powder coated electrostatically with calcium were firmer than those obtained by liquid dipping for the same final calcium content. For the tumbled samples, the drained weight and firmness did not depend on whether calcium was added before or after agitation. However, the measured calcium content increased when calcium was added before agitation. Sensory evaluation of the tumbled samples showed that panelists preferred the samples calcified before agitation.
Electrostatic powder coating could be used in the tomato processing industry to produce optimum firmness at lower calcium concentrations compared to liquid dipping.