Food or edible material: processes – compositions – and products – Surface coating of a solid food with a liquid
Reexamination Certificate
2001-08-30
2004-04-20
Paden, Carolyn (Department: 1761)
Food or edible material: processes, compositions, and products
Surface coating of a solid food with a liquid
C426S303000, C427S002140, C427S002150
Reexamination Certificate
active
06723363
ABSTRACT:
FIELD OF INVENTION
The present invention relates to a process of preparing a sprayable liquid coating composition wherein gaseous carbon dioxide is utilized to reduce the viscosity of a concentrated solution comprising an edible polymer and a solvent. The addition of the gaseous carbon dioxide in the concentrated solution permits a sprayable composition to be produced using a significantly reduced level of solvent in the edible polymer/solvent solution. Typical solvents used in the process have been deemed to be volatile organic compounds (VOCs). Thus, by reducing the amount of solvent used in the solution, the level of VOC emission during the coating process also is reduced. Either supercritical carbon dioxide or subcritical carbon dioxide can be used as the gaseous carbon dioxide in the present invention.
BACKGROUND OF THE INVENTION
It is well known to coat pharmaceutical and food products with an edible polymer in order to prevent degradation of the edible product, particularly degradation by moisture and/or oxidation. A number of edible polymers have been used in the prior art including for example shellac, cellulose derivatives, terpene resins and synthetic carboxylic polymers. These edible polymers are dispersed in a carrier or solvent and applied to the edible product by various means, such as panning, spraying, brushing or curtain coating.
The use of shellac as an edible polymer coating has increased in recent years.
Shellac is a naturally occurring resin of animal origin, derived from the seedlac of the tiny scale insect
Laccifer lacca
. Although the precise chemical nature of shellac has yet to be determined, it is the only known commercial resin of animal origin. Shellac's continued use as a resinous coating is due to its water resistant and lustrous finishing properties. Shellac can be manufactured by a solvent process to produce three types of shellac: dewaxed, dewaxed decolorized and wax-containing. For the wax-containing grade, raw seedlac and solvent, typically ethyl alcohol, are charged into a dissolving tank at a ratio of 1:4 by weight, refluxed and filtered. The wax content of these shellacs can be controlled using different proof alcohol to dissolve the lac. Dewaxed shellacs are made by dissolving seedlac in either (a) cooled alcohol of high proof or (b) weaker proof alcohol at slightly elevated temperature. Dewaxed decolorized shellac is produced in the same manner as the dewaxed shellacs followed by a treatment with activated carbon to remove the darker coloring material. Another type of shellac is bleached shellac which is produced from seedlac of Indian or Thailand origin. The seedlac is dissolved in an aqueous alkali solution, such as sodium carbonate, at a high temperature, and processed to remove impurities.
The versatility of shellac in coating compositions is demonstrated in its varied applications. It has been applied to wood, metal, glass fibers, foil, plastics, paper, ceramics, leather, rubber, hair, fruits, candy and tablet. In addition, shellac can be applied by any number of techniques, including brushing, rolling, doctoring, tumbling and spraying (Martin, J. W. “
Shellac
”, Bradshaw-Praeger & Co. Chicago, Ill., p. 442-476). The viscosity of the shellac must be reduced in order to use it in a coating composition. Shellac generally is not water soluble, tending to form a colloidal dispersion. Thus, shellac typically is dissolved in a solvent, such as an alcohol, in order to reduce its viscosity. Current practices include dissolving from about 5 to 10 wt. % (Merl, J. A. and Stock, K. W., “
Silesia Confiserie Manual No.
4”, Silisia Gerhard Hanke KG, Abt., Neuss Germany, 1996, p. 84) to up to about 45 wt. % (Martin, J. W. “
Shellac
”, Bradshaw-Praeger & Co. Chicago, Ill., p. 466-470) shellac in the solvent. More commonly, about 30 wt. % of shellac is dissolved in the solvent (Mitchell, N. E. “
The Clean Air Act Its Effect on Panning Candies
”, Manufacturing Confectioner, October 1999, p. 41-44). Edible film coating compositions comprising an edible shellac dissolved in an alcohol-based solvent are described in U.S. Pat. No. 4,661,359 to Seaborne et al, issued Mar. 7, 1989, U.S. Pat. No. 4,710,228 to Seaborne, issued Oct. 16, 1985 and U.S. Pat. No. 4,810,534, issued Mar. 7, 1989.
One conventional process for coating edible products is panning. Panning involves tumbling the edible product (such as tablets, candies, etc.) in a revolving drum. As the product is tumbled, the edible shellac/alcohol solution is sprayed or ladled into the drum. Drying air is introduced to the pan in order to evaporate the alcohol, and the alcohol is exhausted into the air handling system and out of the factory. An example of such a process is disclosed in U.S. Pat. No. 3,949,096 to Johnson et al., issued Apr. 6, 1976, which describes an edible surface coating dispersion comprising an edible coating material and a fugitive solvent, wherein the solvent is volatized in a heating zone to leave a dry surface coating.
Ethyl and isopropyl alcohol are classified as a volatile organic compounds (VOCs) or volatile organic materials (VOMs). Volatile organic compounds are one cause of pollution, mostly in the form of ground level ozone, which is a highly reactive gas that can be harmful to the public and contribute to smog. Consequently, a serious drawback to the use of the shellac/alcohol coating solution is the emission of volatile organic compounds (VOCs). For example, a 55-gallon drum (about 400 pounds), of which 70% is ethanol, yields about 280 pounds of VOC fugitive emissions (Giesecke, A., “
Volatile Organic Compounds
(
VOCs
) ”, Manufacturing Confectioner, October 1998, p. 77-78).
The Environmental Protection Agency (EPA) has designated certain areas as “non-attainment areas” in order to regulate the amount of permissible VOC production for a given facility. There are several types of “non-attainment areas” including moderate, serious, severe and extreme; different rules regarding the level of permissible VOC emissions have been imposed for each area. For example, Chicago is classified as a severe non-attainment area. Chicago-area confectionary companies produce a significant portion of all panned candies sold in the United States. The process of pan-polishing of candies generally utilizes ethyl alcohol as the main solvent in the glaze, the ethyl alcohol being emitted into the atmosphere as a VOC in the absence of any controls. EPA restrictions now limit the VOC content of a glazing mixture to 3.5 lbs/gallon. If this limit cannot be achieved, control of at least 81% of the overall VOC emissions must be established. However, the currently available glazing systems and non-compliant glazing mixtures generate more than 5 lbs of potential VOCs/gallon (Mitchell, N. E. “
The Clean Air Act Its Effect on Panning Candies
”, Manufacturing Confectioner, October 1999, p. 41-44).
Thus, in panning techniques where the solvent levels are too high, systems for capturing the solvent must be utilized. However, conventional panning emissions are fugitive VOC emissions that are not readily addressed by typical stack controls such as catalytic or thermal oxidizers or other available VOC reduction technologies (Potter, C., “
VOC Emission Limitations from Candy Manufacturing Facilities in California
”, Memorandum to Stephanie Smith, National Confectioner's Association, Mar. 22, 2000). Therefore, “scrubbing” the exhaust stream in order to contain the VOCs is required, but it also is very cost prohibitive. As a result, there have been attempts to replace the alcohol with a substitute solvent, such as water or acetone. While acetone is legal in all states except California, the volatility of acetone as a substitute solvent makes it dangerous for use in panning operations. Water-soluble glazes also have been used as a substitute coating solution, but the production time is increased substantially due to increased drying time. In addition, the water-borne coatings are often susceptible to problems with humidity, such that the products begin to stick together.
Carbon dioxide specifically i
Frank Matthew C.
Wysk Richard A.
Ziegler Gregory R.
DeLaurentis PA Anthony J.
Paden Carolyn
The Penn State Research Foundation
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