Confectionary coating using an electrohydrodynamic system (original) (raw)
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Journal of Food Processing and Preservation, 2012
Electrostatic atomization is one way to achieve even coverage of oil soluble flavor, color or nutrients; however, it is sensitive to changes in lecithin content, temperature and voltage. Soybean oil was sprayed on oil sensitive paper with 0-15% lecithin, at 4, 22 and 47C, 0-40 kV, to determine droplet distribution. Lecithin decreased electrical resistivity, increased viscosity, first increased then decreased surface tension and decreased droplet size. Increasing temperature decreased resistivity, viscosity, surface tension and droplet size. Increasing voltage decreased the drop size. Voltage had the greatest effect on the number of droplets followed by lecithin content and temperature. Droplet size range or span decreased with increasing voltage and lecithin content. Thus, 40 kV, 47C and 10% lecithin produced the smallest droplets. PRACTICAL APPLICATIONS Liquid electrostatic coating can produce more uniform and efficient coating than traditional methods in the snack food industry. The loss of high-value additives will be less, costs will be lower, products will have higher quality and products can be made that have less oil sprayed on the surface. Increasing temperature and voltage can be used to lower the amount of lecithin that needs to be added.
Electrohydrodynamic spraying quality of different chocolate formulations
Journal of Electrostatics, 2016
The objective of this research was to determine the effect of ingredients in chocolate (cocoa liquor, cocoa butter, sucrose, milk powder) and tempering on electrohydrodynamic spraying quality. As cocoa butter increased, the droplet size generally decreased, because the viscosity decreased. As cocoa liquor increased, the droplet size and resistivity decreased and then increased, while the viscosity only decreased. Similarly, as sucrose decreased and milk powder correspondingly increased, the droplet size decreased, because the resistivity decreased, but the viscosity did not change. The droplet size and viscosity of chocolate increased during tempering, but the resistivity did not change.
Droplet impact and spreading on lecithinated anhydrous milkfat surfaces
Journal of Food Engineering, 2009
Droplet impact and spreading is an important phenomenon that contributes to the quality of the coatings applied to food powders in air-suspension coating operations. This work investigates the dynamics of spreading 2.8 mm droplets containing maltodextrin DE5 at 20 wt% and 40 wt% in water, at an impact velocity of 2.6 m s À1 . The impact surface was anhydrous milkfat which was treated with three food-grade lecithin products to alter the surface hydrophobicity. Results were analysed with respect to the maximum spread diameter achieved $2 ms after impact and the final spread diameter achieved 2-4 s later. Lecithination of the surface did not affect the maximum spread diameter but resulted in greater final spread diameters. This is because lecithination reduces the equilibrium contact angle of the droplet on the surface. However, addition of lecithin to the droplet produced the same final spread diameters regardless of the surface treatment. This has the processing advantage where only the coating formulation need be manipulated to obtain the best spreading characteristics and avoid the extra processing step to modify the chemical characteristics of the substrate surface.
Optimization of liquid electrostatic coating
Journal of Electrostatics, 2008
Soybean oil with emulsifiers was atomized by electrohydrodynamic spraying. The relationships between voltage (20-40 kV), flow rate (28-88 g/s), emulsifier content (10-15%), apparent viscosity (45-53 mPa-s), conductivity (0.1-0.2 mS/m) and surface tension (43.1-46.0 mN/m) and both coating reproducibility and efficiency were mapped utilizing Response Surface Methodology. Voltage had the most significant effect on reproducibility, followed closely by conductivity, and then flow rate. Viscosity had the least significant effect on coating reproducibility and was only significant through interaction with other factors. Surface tension was not a significant effect. Reproducibility was increased by increasing charge concentration, which decreased droplet size. This was achieved at intermediate voltage, low conductivity, high viscosity and low flow rate. Flow rate had the most significant effect on efficiency followed by voltage and emulsifier content. Efficiency increased at low flow rate and voltage. Optimum conditions produce an optimum charge concentration, resulting in the most reproducible and efficient coating.
Electrospraying of water in oil emulsions for thin film coating
Journal of Food Engineering, 2013
ABSTRACT Electrospraying of water-in-oil emulsions was investigated to produce thin edible barriers. A reproducible model surface was used, namely cellulose membranes of which permeability is well-established. PGPR-based emulsions were stable during electrospraying and produced a fine stable jet spray; emulsions prepared with lecithin and span80 produced unstable jets and only sporadic sprays. The droplet size decreased to 50 ± 10 μm by the addition of water droplets till 3% but remained constant at higher water volume fractions. On the other hand, the addition of protein and salt influenced the droplet size and radius values up to 200 μm were found. The addition of whey protein isolate (10% w/w) resulted in films with water vapour barrier properties that were at least 70% better than lipid only, therewith showing that addition of protein enhances the integrity of the films.
2014
Many foods, especially snack foods, have powdered seasonings in order to enhance their flavor and increase product variety. Seasonings are generally a mixture of powders but most studies in food powder coating have used only one powder. The objective of this study was to determine the effect of being in a mixture on transfer efficiency, separation and dustiness during nonelectrostatic and electrostatic coating. Fine (51-63 μm) and coarse (244-367 μm) NaCl, KCl, sugar, rice starch and whey protein powders were mixed. The mixtures were coated on a target at 0 and -25 kV at 30-35% relative humidity. During both nonelectrostatic and electrostatic coating, being in a mixture decreased or did not change the transfer efficiency of fine powders, compared to when they were coated individually. Transfer efficiency of coarse powders was generally not affected by being in a mixture during nonelectrostatic or electrostatic coating. Total transfer efficiency of most mixtures did not change when c...
Journal of Food Science, 2003
Hydroxypropyl methylcellulose solutions were used as coating systems in this study and solution concentrations, viscosity, densities, and surface tensions were characterized. Fuji apples were coated by dipping and stored 4 d at room temperature, after which the internal oxygen and carbon dioxide were measured. Results indicated that coating thickness varied with viscosity, concentration, density, and draining time of the biopolymer solution. Coating thickness relates to the square root of viscosity and the inverse square root of draining time, which agrees with the theoretical approach for flat plate dip-coating in low-capillary-number Newtonian liquids. These results indicate the possibility of controlling coating thickness and internal gas composition based on coating solution properties.
Lecithins in oil-continuous emulsions. Fat crystal wetting and interfacial tension
Journal of The American Oil Chemists Society, 1995
Lecithin is a powerful emulsifier widely used in foods, feeds and pharmaceuticals. Several analytical methods have been proposed to characterize lecithins, but they are often inadequate to determine the industrial functionality. The purpose of this study was to find a relationship between the interfacial properties of lecithins (adsorption to oil/water and fat crystal/oil/water interfaces), phospholipid composition and functionality. Results show that all lecithins adsorb to fat crystals at the triglyceride oil/water interface, making their surface more polar (observed as an increase in the contact angle measured through the oil at the interface: fat crystal/oil/water). This adsorption process is quick (less than five minutes) for relatively polar lecithins, such as soybean phosphatidylcholine (PC), and results in highly polar surfaces (contact angle ∼180°). Less polar lecithins give slow adsorption (some hours) and less polar crystals (contact angle ≤90°). The adsorption of different lecithins to the oil/water interface, observed as a decrease in interfacial tension, follows the adsorption pattern to the fat crystals. We found a relation between high-fat crystal polarity and poor lecithin functionality in margarine (margarines spatters during frying), and also between high-fat crystal polarity and a high polar to nonpolar phospholipids [Σ(PI + PA + LPC)/ΣPE; PI, phosphatidylinositol; PA, phosphatidic acid; LPC, lysoPC, PE, phosphatidylethanolamine] ratio in lecithin. The correlations might bevia aggregation properties of lecithin in the oil. We found also that monoolein shifted the adsorption kinetics of lecithin (soybean PC) to fat crystals and the hydrophilicity of adsorbed layers probably due to formation of mixed aggregates between monoolein and soybean PC.