Confectionary coating using an electrohydrodynamic system (original) (raw)

In the chocolate coating industry, cocoa butter is a high value ingredient. Due to high cost, shortage of supply and blooming, hard butters are frequently used as cocoa butter replacers. An electrohydrodynamic system (EHD), which forms fine droplets with a relatively narrow size distribution, may be beneficial in confectionary coating to reduce cost and to increase quality because complete and even coverage can be achieved. The objective of this research is to optimize the use of EHD by altering the resistivity and viscosity of different types of confectionery coating using different levels of lecithin. Non-EHD and EHD coating systems using confectionary coating made of cocoa butter equivalent, lauric cocoa butter or cocoa butter with different percentages of lecithin were analyzed. Droplet size, width of coating area, thickness, and minimum flow rate to produce complete coverage was measured. The voltage supplied for EHD coating system was 25kV. As lecithin content decreased, resistivity of all samples decreased. Viscosity of the sample is affected by the interaction of lecithin and fat when they are mixed together. The minimum viscosity was at 0.5% lecithin. EHD coating was more efficient than non-EHD as smaller droplet size and thinner coating was formed. Due to repulsive forces between the like-charges on the droplets during EHD, it spread over wider areas which lead to higher minimum flow rate to get complete coverage. Under EHD, the effect of resistivity dominated the droplet size. The droplet size for all samples significantly increased at the highest resistivity with 0 and 0.05% lecithin addition. There was no trend between resistivity and droplet sizes for any of the fats under non-EHD since electrical resistivity should not be important because there are no electrical charges applied during the coating. The lowest coating thickness was observed at the minimum viscosity with 0.5% lecithin addition. The fit for minimum flow rate to viscosity is better than resistivity because viscosity affects how well products flow. Under both EHD and non-EHD system, at low lecithin content with higher viscosity, the minimum flow rate to get complete coverage was always low.