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Whey Protein Isolate Coatings as Replacements for Shellac in the Confectionery Industry
By,
K. L. DANGARAN, S-Y Lee and J.M. Krochta
Department of Food Science and Technology
University of California, Davis
In the confectionery industry, the final process of candy manufacture is providing products with a glossy, moisture-barrier glaze. Currently, the most commonly used glazing agent is edible shellac dissolved in ethanol, a volatile organic compound (VOC). Use of ethanol and other VOCs creates explosion hazards in the work place. Moreover, increased regulations of VOC emissions into the atmosphere with a goal of zero discharge have made water-based alternatives to shellac coatings a necessity. Previous studies found that water-based whey protein isolate (WPI) coatings provided the same gloss as alcohol-based shellac coatings on model surfaces. We hypothesized whey protein coatings could be applied to chocolates and provide similar gloss levels as shellac.
Our objective was to compare four different WPI/plasticizer systems to determine which provided the most gloss and which was most stable. The four plasticizers studied were glycerol, polyethylene glycol (PEG), propylene glycol (PG) and sucrose, all in a 1:1 ratio with WPI.
The formulations were applied to chocolate-covered almonds, and gloss stability was determined by measuring gloss fade over time and by visually monitoring coatings for cracking or peeling. Gloss measurements were taken with a Tricor Gloss Analysis System model 801.
Our results showed that initially the WPI/sucrose coating provided chocolates with the most gloss. Moreover, after seven days, the gloss from the glycerol, PEG, and PG formulations had significantly faded. Within two weeks, the PG coating developed significant cracking. Gloss measurements continue to be taken, but after three months the gloss from sucrose formulation has experienced minimal fading.
These results show that WPI/sucrose coatings provide the highest and most stable gloss. With optimization, water-based WPI/sucrose coatings could replace alcohol-based shellac coatings in the confectionery industry.
For more information on Dr. Krochta’s work and the Food Science and Technology Department at UC Davis, please visit Dr. Krochta's Web site - http://foodscience.ucdavis.edu/fst/faculty/KrochtaWeb/index.htm.