- Email: [email protected]
Detection of Cracked Eggs
Detection of Cracked Eggs J. A. DICKENS,1 W. A. MOATS,2 and J. E. THOMSON1 United States Department ofAgriculture, Agricultural Research Service, Richard B. Russell Agricultural Research Center, P.O. Box 5677, Athens, Georgia 30613 and
(Received for publication June 14, 1984) ABSTRACT An automated system was developed for applying a starch-iodine stain to detect checked eggs under commercial conditions. The stain solution was sprayed onto previously candled eggs and then rinsed off. Checks not detectable by standard candling methods were visible as blue lines on the shell membrane upon recandling. Commercial use of this system would significantly reduce the number of cracked eggs that reach the consumer, decrease the risk of egg contamination, and retain higher egg quality. (Key words: eggs, checks, stains) 1985 Poultry Science 64:414-416 INTRODUCTION
In the past few years concern has been expressed about the quality of eggs reaching the consumer, but this is not a recent problem. In 1925, the first steps were taken to ensure quality standards for individual eggs (US Department of Agriculture, 1981). Then in 1948, the first consumer grades were issued by the US Department of Agriculture (US Department of Agriculture, 1981). In 1967, standards for consumer grades at origin and destination were issued to allow for damage due to handling and transportation (US Department of Agriculture, 1981). The physical characteristics of egg shells and currently accepted handling procedures during marketing predispose eggs to breakage. The latest standards issued by the Agricultural Marketing Service and Food Safety and Inspection Service of USDA specify the number of checks (an individual egg with broken or cracked shell, but with shell membranes intact and content not leaking) allowed in packaged eggs both at the origin and final destination. Currently, many small "hairline" checks are not visible to the operators of the candling station; thus, the number of checks packaged by automatic equipment may increase. To
1 2
Richard B. Russell Agricultural Research Center. Beltsville Agricultural Research Center.
improve and ensure high product quality, new approaches or techniques are needed to aid in detecting checked eggs with higher proficiency than at present. A process to increase the detection of checks by candling personnel consists of applying a special stain to the shells (Moats, 1982). The stain penetrates checks in the shell, staining the shell membrane blue, which is readily visible to the candling personnel. The stain then fades rapidly and leaves no residue. The stain is a starch iodine solution; iodine is permitted as a sanitizing agent for shell eggs and elsewhere in the food industry. The purpose of this experiment was to design and fabricate a mechanical system that would have in-line application in egg packing plants to apply stain properly to improve efficiency of checked egg detection.
MATERIALS AND METHODS
A commercial egg conveyor was modified by adding a stain spraying system and a fresh water rinse manifold. The modifications were designed to operate at commercial line speeds. The modified conveyor consisted of two sections, divided by stainless steel cowlings and plastic flaps, which prevented the overspray from each section entering the other (Fig. 1). In the first section, the stain solution was applied to the eggs and the overflow was recycled. A manifold with four 3/8 GG 15
414
Downloaded from http://ps.oxfordjournals.org/ at Uniwersytet Warszawski Biblioteka Uniwersytecka on April 29, 2015
United States Department of Agriculture, Agricultural Research Service, Meat Science Research Laboratory, Beltsville Agricultural Research Center, Beltsville, Maryland 20705
RESEARCH NOTE
Spraying Systems full jet nozzles was placed over the conveyor (Fig. 2). A 3/4 hp centrifugal pump delivered the stain to the manifold. Two 2.54-cm (1-in) gate valves, one in the delivery line and the other in the overflow line, were installed to regulate the pressure in the manifold. The overflow line directed the staining solution back into the supply tank. A pressure gauge was mounted in the manifold delivery line to monitor the incoming pressure. The 189-liter (50-gal) stainless steel supply tank, mounted to the mainframe below the conveyor, was equipped with a two-piece lid to allow quick access for cleaning (Fig. 1). A 1.9-cm (3/4-inch) drain plug was installed in the bottom of the tank to facilitate draining and cleaning. Two 7.62-cm (3-inch) holes in the lid accommodated the overflow line from the pump and the overflow from the drain pan. In the second section, the stain solution was rinsed from the eggs (Fig. 1). A manifold with four 3/8 GG 9.5 Spraying Systems full jet nozzles was installed over the conveyor; these nozzles, smaller than in the first section, conserved water during the rinsing. The rinse water manifold was coupled directly to the facility cold water supply and was equipped with a pressure-reducing valve and a pressure gauge (Fig. 1). The used rinse water was piped to a facility disposal drain.
3 Mention of specific brand names does not imply endorsement by the authors or institutions at which they are employed to the exclusion of others not mentioned.
The staining solution was prepared as follows: .1 g of iodine and .4 g potassium iodide were dissolved in 100 ml of water to make the iodine solution. For the starch suspension, 5 g of commercial starch was slurried in 10 ml of water and added to 1000 ml of boiling water. The starch iodine was prepared by using a ratio of 20 ml iodine solution with 100 ml starch solution until the desired amount was obtained. To begin the operation, the stain solution was formulated and placed in the supply tank. The solution was pumped through the system for a short time to temper and mix it thoroughly. Before eggs were placed on the conveyor, the stain solution was cooled to below 43 C (110 F). Both gate valves in the pump lines were adjusted to obtain a pressure between 83 and 103 Kpa (12 to 15 psig) in the stain solution supply line, and the rinse manifold supply was adjusted to 69 Kpa (10 psig). When the operating parameters were reached, eggs were loaded on the conveyor for testing. A conveyor speed of 100 cases per hour was used for the experimental runs. Ninety dozen eggs obtained from various commercial suppliers were used for the test runs. They were candled by hand using commercial candling equipment by experienced investigators, and eggs with visually detectable checks were removed and counted. The eggs with no visually detectable checks passed through the automated staining system. The eggs were placed by hand on the conveyor two dozen at a time. When the eggs emerged from the system, they were removed and inspected under fluorescent light.
FIG. 2. A) Stain manifold; B) rinse manifold.
Downloaded from http://ps.oxfordjournals.org/ at Uniwersytet Warszawski Biblioteka Uniwersytecka on April 29, 2015
FIG. 1. Stain conveyor: A) stain section; B) rinse section; C) 189—liter tank.
415
416
DICKENS ET AL. RESULTS AND DISCUSSION
the candling station immediately, where eggs showing a blue stain, indicating otherwise undetectable checks or cracks, could be removed. This staining procedure would decrease the required concentration of candling personnel and increase the number of checked eggs removed. ACKNOWLEDGMENTS
The authors thank R. Vaughn for his excellent technical assistance and J. Cornelius for her clerical work. REFERENCES Moats, W. A., 1982. A staining procedure for detecting cracked eggs. Poultry Sci. 61:1007-1008. US Department of Agriculture, 1981. Fed. Reg. 46(149): 39,566-39,573.
Downloaded from http://ps.oxfordjournals.org/ at Uniwersytet Warszawski Biblioteka Uniwersytecka on April 29, 2015
Candling of eggs by the standard method resulted in detection of 78 cracked or checked eggs among the 90 doz eggs from commercial sources. When the eggs that appeared to be sound on first candling were passed through the automated staining system, then recandled, an additional 35 checked eggs were detected. This application system would thus reduce the number of checked eggs reaching the consumer. The packer could more easily meet USDA requirements, and the possibility would be reduced of contamination of packed eggs by microorganisms potentially detrimental to the quality of the eggs or harmful to the consumer. In a commercial plant, this system could be installed on the packing line between the washer and oiler. The eggs could then pass to
(Received for publication June 14, 1984) ABSTRACT An automated system was developed for applying a starch-iodine stain to detect checked eggs under commercial conditions. The stain solution was sprayed onto previously candled eggs and then rinsed off. Checks not detectable by standard candling methods were visible as blue lines on the shell membrane upon recandling. Commercial use of this system would significantly reduce the number of cracked eggs that reach the consumer, decrease the risk of egg contamination, and retain higher egg quality. (Key words: eggs, checks, stains) 1985 Poultry Science 64:414-416 INTRODUCTION
In the past few years concern has been expressed about the quality of eggs reaching the consumer, but this is not a recent problem. In 1925, the first steps were taken to ensure quality standards for individual eggs (US Department of Agriculture, 1981). Then in 1948, the first consumer grades were issued by the US Department of Agriculture (US Department of Agriculture, 1981). In 1967, standards for consumer grades at origin and destination were issued to allow for damage due to handling and transportation (US Department of Agriculture, 1981). The physical characteristics of egg shells and currently accepted handling procedures during marketing predispose eggs to breakage. The latest standards issued by the Agricultural Marketing Service and Food Safety and Inspection Service of USDA specify the number of checks (an individual egg with broken or cracked shell, but with shell membranes intact and content not leaking) allowed in packaged eggs both at the origin and final destination. Currently, many small "hairline" checks are not visible to the operators of the candling station; thus, the number of checks packaged by automatic equipment may increase. To
1 2
Richard B. Russell Agricultural Research Center. Beltsville Agricultural Research Center.
improve and ensure high product quality, new approaches or techniques are needed to aid in detecting checked eggs with higher proficiency than at present. A process to increase the detection of checks by candling personnel consists of applying a special stain to the shells (Moats, 1982). The stain penetrates checks in the shell, staining the shell membrane blue, which is readily visible to the candling personnel. The stain then fades rapidly and leaves no residue. The stain is a starch iodine solution; iodine is permitted as a sanitizing agent for shell eggs and elsewhere in the food industry. The purpose of this experiment was to design and fabricate a mechanical system that would have in-line application in egg packing plants to apply stain properly to improve efficiency of checked egg detection.
MATERIALS AND METHODS
A commercial egg conveyor was modified by adding a stain spraying system and a fresh water rinse manifold. The modifications were designed to operate at commercial line speeds. The modified conveyor consisted of two sections, divided by stainless steel cowlings and plastic flaps, which prevented the overspray from each section entering the other (Fig. 1). In the first section, the stain solution was applied to the eggs and the overflow was recycled. A manifold with four 3/8 GG 15
414
Downloaded from http://ps.oxfordjournals.org/ at Uniwersytet Warszawski Biblioteka Uniwersytecka on April 29, 2015
United States Department of Agriculture, Agricultural Research Service, Meat Science Research Laboratory, Beltsville Agricultural Research Center, Beltsville, Maryland 20705
RESEARCH NOTE
Spraying Systems full jet nozzles was placed over the conveyor (Fig. 2). A 3/4 hp centrifugal pump delivered the stain to the manifold. Two 2.54-cm (1-in) gate valves, one in the delivery line and the other in the overflow line, were installed to regulate the pressure in the manifold. The overflow line directed the staining solution back into the supply tank. A pressure gauge was mounted in the manifold delivery line to monitor the incoming pressure. The 189-liter (50-gal) stainless steel supply tank, mounted to the mainframe below the conveyor, was equipped with a two-piece lid to allow quick access for cleaning (Fig. 1). A 1.9-cm (3/4-inch) drain plug was installed in the bottom of the tank to facilitate draining and cleaning. Two 7.62-cm (3-inch) holes in the lid accommodated the overflow line from the pump and the overflow from the drain pan. In the second section, the stain solution was rinsed from the eggs (Fig. 1). A manifold with four 3/8 GG 9.5 Spraying Systems full jet nozzles was installed over the conveyor; these nozzles, smaller than in the first section, conserved water during the rinsing. The rinse water manifold was coupled directly to the facility cold water supply and was equipped with a pressure-reducing valve and a pressure gauge (Fig. 1). The used rinse water was piped to a facility disposal drain.
3 Mention of specific brand names does not imply endorsement by the authors or institutions at which they are employed to the exclusion of others not mentioned.
The staining solution was prepared as follows: .1 g of iodine and .4 g potassium iodide were dissolved in 100 ml of water to make the iodine solution. For the starch suspension, 5 g of commercial starch was slurried in 10 ml of water and added to 1000 ml of boiling water. The starch iodine was prepared by using a ratio of 20 ml iodine solution with 100 ml starch solution until the desired amount was obtained. To begin the operation, the stain solution was formulated and placed in the supply tank. The solution was pumped through the system for a short time to temper and mix it thoroughly. Before eggs were placed on the conveyor, the stain solution was cooled to below 43 C (110 F). Both gate valves in the pump lines were adjusted to obtain a pressure between 83 and 103 Kpa (12 to 15 psig) in the stain solution supply line, and the rinse manifold supply was adjusted to 69 Kpa (10 psig). When the operating parameters were reached, eggs were loaded on the conveyor for testing. A conveyor speed of 100 cases per hour was used for the experimental runs. Ninety dozen eggs obtained from various commercial suppliers were used for the test runs. They were candled by hand using commercial candling equipment by experienced investigators, and eggs with visually detectable checks were removed and counted. The eggs with no visually detectable checks passed through the automated staining system. The eggs were placed by hand on the conveyor two dozen at a time. When the eggs emerged from the system, they were removed and inspected under fluorescent light.
FIG. 2. A) Stain manifold; B) rinse manifold.
Downloaded from http://ps.oxfordjournals.org/ at Uniwersytet Warszawski Biblioteka Uniwersytecka on April 29, 2015
FIG. 1. Stain conveyor: A) stain section; B) rinse section; C) 189—liter tank.
415
416
DICKENS ET AL. RESULTS AND DISCUSSION
the candling station immediately, where eggs showing a blue stain, indicating otherwise undetectable checks or cracks, could be removed. This staining procedure would decrease the required concentration of candling personnel and increase the number of checked eggs removed. ACKNOWLEDGMENTS
The authors thank R. Vaughn for his excellent technical assistance and J. Cornelius for her clerical work. REFERENCES Moats, W. A., 1982. A staining procedure for detecting cracked eggs. Poultry Sci. 61:1007-1008. US Department of Agriculture, 1981. Fed. Reg. 46(149): 39,566-39,573.
Downloaded from http://ps.oxfordjournals.org/ at Uniwersytet Warszawski Biblioteka Uniwersytecka on April 29, 2015
Candling of eggs by the standard method resulted in detection of 78 cracked or checked eggs among the 90 doz eggs from commercial sources. When the eggs that appeared to be sound on first candling were passed through the automated staining system, then recandled, an additional 35 checked eggs were detected. This application system would thus reduce the number of checked eggs reaching the consumer. The packer could more easily meet USDA requirements, and the possibility would be reduced of contamination of packed eggs by microorganisms potentially detrimental to the quality of the eggs or harmful to the consumer. In a commercial plant, this system could be installed on the packing line between the washer and oiler. The eggs could then pass to