Food Science Packaging – James P. Cox, R. W. Duffy Cox, Jeanne M. Cox, NATIONAL PASTEURIZED EGGS LLC, National Pasteurized Eggs Inc
Abstract for “Methods to process poultry shell eggs”
“Time at Temperature methods for treating whole eggs that make them safer to consume without affecting their functionality or organoleptic qualities. This improves the egg’s quality.
Background for “Methods to process poultry shell eggs”
The United States Department of Agriculture has been enforcing minimum food safety processing standards since many years. Although food safety standards for shell eggs have been in place for a long time, they are not applicable to liquid whole eggs or egg products of many varieties. They are based on minimum standards for pasteurization. As a result, the prior art reviewed in this specification shows that there is no technology available for pasteurizing shell eggs to acceptable standards. This means that the standards are not comparable to the USDA guidelines for other egg products.
“Shell eggs are a valuable commodity that offers many nutritional benefits unmatched by any other food product. These benefits include low costs per nutritional unit, ease of preparation, gastronomic enjoyment, culinary utility, and availability.
“It is well-known that shell eggs can contain Salmonella, which is a major concern from a food safety perspective. There have been several proposals for ways to improve the food safety of eggs by eliminating these harmful microorganisms. None of these techniques, except for those that are effective for external sanitation have been proven to be successful. In an attempt to reduce the severity of the problem indirectly, we have focused on egg processing and handling.
“Awareness and concern regarding infectious organisms within the yolk of a shell egg has been slow to develop. Both awareness and concern have increased over the past decade due to numerous cases of food poisoning that can be irrefutably attributed to yolk-associated organisms.
“Foodborne diseases are now more common in the modern world thanks to medical care and social programs. The most at risk are the significant segments of society with longer lives or who have compromised immune systems due to immunosuppression therapy, organ transplants or diseases like AIDS.
“Increasing concerns about the safety of eggs as food highlight the problem of transovarian infections that develop deep within the egg during its formation in the oviduct. Infectious organisms can also penetrate eggshells and possibly the vitelline membranes, contaminating the yolks with deeper proteins. For unknown reasons, it is now well-known that diseased hens can secrete microorganisms within the egg. Salmonella enteritis (S.) is the microorganism responsible for this problem. enteritis).”
“Salmonella are small, gram negative, nonsporing rods. Under the microscope, or using ordinary nutrient media, they are not easily distinguished from Escherichia coli. All strains and species are considered to be potentially pathogenic for humans at the moment.
Salmonella is a disease organism that can cause a wide range of illnesses, depending on its species. S. Typhimurium, which means “Salmonella From Typhus Mary”, is the only explanation. Enteric fever is caused by S. typhi. S. paratyphi types A and B can cause a syndrome that is similar to, but milder than, typhus.
“Reported cases involving severe gastroenteritis (stomachflu) have also implicated S. bareilly and S. newport. The victim’s age and general state of health are the main factors that determine their mortality. S. choleraesuis, with a 21% mortality rate, has the highest reported death rate.
“Altogether, more than 2,000 Salmonella species are known.” Each year, the number of Salmonella species increases.
Eggs are one of the most common vectors for Salmonella-related food poisoning. The widespread publicity about the illnesses and deaths caused by Salmonella enteritis-contaminated eggs in Europe in recent years has led to a decrease in egg consumption. The reduction in egg consumption has been as high as 50% in some marketing areas. In the United States, as well as Europe, this problem is seen to be a serious public health issue. However, the United States still consumes approximately 240,000,000 eggs annually.
“A recent article in the Nutrition Health Letter, Volume 18, Number 6, July/August 1991 edition, by the Center for Science in the Public Interest (“NAME YOUR FOOD (POISON) POISON”) describes a growing concern. According to the article, around 9,000 people die each year from food poisoning. This is in addition to several billions in health care costs.
“The article asserts that dairy products, eggs and poultry are the primary causative foods.
The article states that 1 in 10,000 eggs may be contaminated by Salmonella enteritis. An average American eats 200 eggs annually. Your chances of eating an egg contaminated by Salmonella are 1 in 50 if you eat an average amount of eggs.
The article suggests that people over 65 who have a disease like cancer or AIDS should not eat raw eggs. They also shouldn’t drink eggnog. All eggs should be cooked thoroughly, yolk and solid white included.
The improper handling of eggs in institutional or home settings only adds to the problem. The all-too frequent observation that eggs are left at room temperature for extended periods of time in institutional kitchens is a common reason. Unknowledgeable treatment can promote bacterial growth in fresh eggs.
“Little information is available about the egg’s virology. Some people still believe that shell eggs are sterile within the shell. This belief has been held for a long time. When cultured, needle puncture samples of the egg’s interior including yolk and white are usually negative. However, it is known that eggs broken in large quantities can quickly show significant gross populations infectious microorganisms. Even though the egg shells are clean and free of filth, it is not uncommon to see plate counts that range from hundreds to thousands. It is well-documented that S. enteritis can be found in shell eggs.
“Eggshells contain many pores that allow the egg to breathe. This is one source of infection. The size of pores varies. These pores come in contact with organic waste when the egg is laid. Most likely, some microbes that come into contact with the egg may be of a size that allows them to pass through the pores. The microbes once inside the egg are not evenly distributed. They are instead retained in small areas on the inner membrane of the egg, which has smaller pores than the shell.
“Washing spreads microbes better, increasing contamination by greater surface contact with egg shell entry pores. The shell membranes of cracked eggs can be torn and ripped. The eggs can be stuffed with the stored inoculum, as well as airborne bacteria, after they are cracked.
“Also as egg temperatures change, there is an active and ongoing gas-vapor exchange between yolk and white via vitelline membrane, white and inside of shell via outer and inner membranes, and shell and outside environment via the outer shell membranes.” These mechanisms can allow airborne microorganisms to reach the egg’s interior.
“Finally as we have discussed, transovarian infections can cause eggs to be, and often are, contaminated. It is not yet known how severe this problem is. Even if harmful microorganisms are not transported from the egg’s exterior to the interior, eggs may still be unsafe to consume. Worse, both the egg-infecting mechanisms pore penetration and transovarian infections are at work.
The USDA standards require that liquid eggs be processed for no less than 30 minutes. This ensures that the eggs are safe to eat, as all particles have been exposed RPT. However, liquid eggs can still retain some functionality and other valuable properties if they are properly handled. There is no standard for shell eggs because there has never been a reliable temperature method for making them safe to eat. There is no known process that can be used to process whole eggs according to the requirements for liquid eggs. This means that the entire egg, which includes the shell, outer shell and egg membranes as well as the egg white and chalaza, along with the yolk, are exposed to temperatures that allow for the safe killing of any harmful organisms.
“Other researchers have concentrated their attention on temperature and time treatments for devitalization vital shell eggs. Pasteurization of shell eggs to increase food safety quality was also considered.
The growth of food poisoning in external foods is possible in certain TPT/temperature ranges that are favorable influenced in the outermost layer of the shell egg. External food poisoning will get worse in many other temperature ranges. Temperatures near or at the egg yolk centre will never reach the temperature necessary to kill large numbers of infectious microorganisms.
“On the contrary, because internal temperatures at the yolk’s center are not high enough for Salmonella or other infectious microorganisms to be killed, prior art techniques cannot be used. They can only reach yolk temperatures within the suggested times that are in a range that will result in significant increases in food poisoning. Processed eggs can become infected if they are within a narrow range of these parameters. If a yolk infection is minor and non-lethal, the egg can be contaminated with such methods. The egg could then deteriorate rapidly, becoming a serious health risk or even toxic.
Funk did not consider the possibility that Salmonella can be found in eggs throughout the egg. Funk’s primary concern is to deviate the egg egg embryo. He also cares about destroying any bacteriological organisms that may have entered the egg shell. . . Extended as far as the yolk . . . Funk claims that the majority of the conditions he uses to process eggs do not improve any existing infectious conditions and, at worst, increase food poisoning risks. Funk’s claims for a shell egg cannot be applied to the USDA minimum processing standards (see FIG. 2) for liquid eggs products. Other time/temperature combinations not covered by the Funk patent, which also do not meet the minimum processing standards, can result in whites of eggs visible being cooked (see FIG. 8).”
“The Funk process parameters include temperature and TPT. This is the time that a shell egg is kept in a pasteurization medium at a specific temperature. This is very different from the critical TPT. It is the portion of TPT where all particles, including those in the yolk, are at an effective pasteurization temperature. EqT is the point at which the egg’s mass is at this temperature. Funk did not recognize or appreciate the importance of RPT and TPT. Funk would have probably not made the distinction if he did. TPT and RPT are identical for the purpose of devitiating an embryo.
For this purpose, “Lethal thermal injury to any part of an embryo (even just at its surface) is sufficient.” Infections are made up of many micro-entities, which is different from embryos in vital eggs. The ability to cause death at any point in this multifarious environment is not sufficient to kill the infection. This is unlike an embryo that can be killed if only a small portion is heated to a sufficient temperature. In order to be effective against infections that are spread throughout a substrate, the temperature must be high enough to kill many infectious organisms. This means that eggs containing microorganisms must have the right pasteurization temperature. This is why RPT and TPT are different in this instance. The distinction becomes more important as the egg’s potential infection rate increases.
“Funk’s preferred temperature and process times for pasteurization are not the worst. His patent suggests that one of ordinary skill is the best in the art. When many of the Funk temperatures and times for pasteurization, sterilization and devitalization (of vital egg embryos) are used to pasteurize shell eggs in order to improve food safety quality, the results of tests show that they are not consistent with this objective. Furthermore, eggs that were processed under the most favorable conditions, measured at the yolk cannot meet the USDA Protracted Whole Egg Standard For Liquid Whole Eggs (see FIG. 1), or the USDA minimum standards for liquid whole eggs (see FIG. 2).”
The Funk process almost always results in eggs that are capable of reliably eliminating a living embryo. Funk’s method is not likely to cause infected eggs that are visible at the outer layers and remain or become more dangerous to consumers. It was developed to improve food safety and to increase the safety of shell eggs.
“New strains of infectious organisms are constantly being discovered. Food poisoning is on the rise due to increased production, mass handling, widespread distribution, and increased risk of contamination. Egg poisonings are common and likely to increase. Nearly all food products are subject to strict standards for processing that ensure food safety. Only shell eggs are subject to pasteurization standards in relation to eggs and other egg products. This lack of food safety pasteurization standards for eggs and other egg products can be attributed to a lack of knowledge about an efficient process to make shell eggs safe to eat. Funk’s proposed process is ineffective and fails to deliver any significant benefits. They are also highly likely to produce products that pose a significantly increased risk of food poisoning.
“These novel and practical methods for temperature- and time-pasteurization of shell eggs throughout their entire mass have been discovered and disclosed. They are more effective than or equal to USDA’s minimum and protracted standards for whole eggs. This reduces the risk of food poisoning. This is typically a serious illness that can cause gastroenteritis and fever for several days. It can also be deadly if the egg is eaten by someone in any of the above categories. These novel methods for pasteurizing shell eggs do not compromise their integrity, functionality, and quality.
“Effective pasteurization according to the principles of this invention requires that the preprocessing temperature be known. TPT is determined by this temperature. The TPT process has two components. EqT and RPT are the times it takes for eggs to reach equilibrium temperature with pasteurization medium. This is especially true in the most difficult areas, such as the yolk’s center. RPT is the time spent at a pasteurization temperature that is equivalent to that required for liquid whole eggs. Only once EqT has been achieved, can RPT begin. After the center of a shell egg has reached the desired pasteurization temperature, the egg can be processed at USDA-mandated temperatures with minimum USDA standards. This ensures that the egg remains at the right temperature throughout its entire mass to destroy harmful bacteria.
“Examination (of FIG. “Examination of FIG. Tabularized data of the same data are available in Table 1. The indicated time represents the minimum RPT required to kill harmful microorganisms at the temperature.
“”
The Table 1 pasteurization times and temperatures must be applied to shell eggs. Additional EqT time must also be allotted from the moment the egg is placed into a heat transfer or pasteurization media at the desired pasteurization temp. This will allow the yolk to reach EqT, which is the initial point of RPT. It is the temperature at which the egg reaches temperature stability with the heat transfer medium. After this point is reached, heat must be transferred from the shell egg’s external parts into the yolk. This will ensure that the egg’s temperature has reached equilibrium with its process medium.
“The time it takes for the whole egg to reach equilibrium with the process media or to reach a predetermined process temperature. EqT is added to the actual processing time, RPT as shown in FIGS. The total processing time (TPT) is equal to Table 1 and Table 2.
The egg size, preprocess temperature, and pasteurization temperature are all factors that determine the time it takes to achieve EqT.
One liquid (oil or water, glycol, or the like) can be used to heat the egg’s interior. However, it must be safe. Although it can be used for pasteurization, a gas like air, humidified or mixed with gases such carbon dioxide and nitrogen is not recommended. These gases can be used in the RPT phase or for TPT processes that involve both EqT-RPT phases. Liquids are preferred for RPT steps. These gases are often preferred for tempering. This technique is described in detail below and can be optionally used to ensure egg pasteurization in accordance with the principles of this invention.
“It is not unusual for eggs in a lot to be at different temperatures. Neglecting this important condition could lead to inappropriate EqT, TPT and/or RPT temperatures. These parameters may allow for the pasteurization of eggs at an effective (but not optimal) temperature. However, the egg whites can be cooked at a higher temperature. If the batch of eggs contains eggs at a lower temperature than the recommended minimum RPT, the eggs will not be cooked to the specified pasteurization temperature. 2 and Table 1.
Tempering may be used in accordance with the principles in the present invention when there is a temperature difference in the eggs. Tempering refers to an initial step or pre-processing in which eggs are kept at a subpasteurization temperature for a sufficient time to allow them to reach the same temperature. This ensures consistency in the egg pasteurization, which significantly reduces or eliminates the possibility of eggs with cooked whites or eggs that are not sufficiently pasteurized at the end. Tempering can be used to reduce or eliminate thermal shock cracking in the eggs being processed.
“Tempering can take place in both air and other gases. You can use dry air or humidified air to temper the gas. This is important because it prevents evaporative loss of water from eggs during tempering. If the pasteurization medium is not water, you can add water to it to compensate for evaporative losses. This will restore water that was lost by the egg through evaporation.
“The shortest effective tempering time is preferred.” It is not a good idea to keep eggs at temperatures that favor microorganism growth longer than necessary. Tempering temperature could be one such characteristic.
“There are several important versions of this invention that heat eggs in stages, with one or more heating steps being followed up by a dwell period in which the temperature is equilibrated throughout the egg’s interior.
Pasteurization in stages with significant dwell times between stages is another similar method. To extend shelf life, pasteurization in the same temperature ranges as described above may work together to produce longer shelf lives. Tests have shown this.
“It is impossible to list all the parameters for every option, due to the almost unlimited number of choices available. This is not necessary. The parameters for an option that uses intermittent or discontinuous heating can easily and routinely be determined, as the critical criteria are well known. The pasteurization temperature and RPT should be set so that all eggs in the egg mass have been heated to the temperature required by the USDA Standard for liquid whole eggs (FIGS). 1, 2, and 1.
A baker will notice a slight loss in functionality when pasteurizing liquid whole eggs are processed according to the invention. The difference can be easily made up with small increases in egg quantity. The improved food safety makes up for any potential loss in functionality.
TPT can be decreased by adding turbulence to the pasteurization medium, and/or subjecting the shell eggs mechanical vibration. These two mechanisms, a turbulent pasteurization media and the application vibrational energy to eggs, increase the rate at which heat is transferred from the egg’s interior to the pasteurization medium. Although not necessary, turbulence or vibration can lead to more efficient treatment. If you want to achieve faster, more efficient processing, you should use a turbulent pasteurizing medium or vibrating the egg.
Ultrasonically induced vibrations and other forms of vibration, including those caused by cavitation, may be used to your advantage in microorganism-destroying treatments. This vibration, similar to the mechanical, encourages heat transfer through the egg’s shell and into the egg’s mass. This improves the effectiveness of the process and allows for a more effective reduction in infectious microorganisms.
“Other beneficial process techniques include deliberate overheating of the egg’s initial temperature and the alternation or pulse of the temperature between two levels.
The treatment of eggs should be performed by heating shell eggs, then storing them at the appropriate temperatures for pasteurization. Rapid cooling or quenching is recommended. The final step ensures that the eggs are quickly cooled to the temperature range that favors bacterial growth. Any remaining harmful bacteria could multiply, negating some or all the benefits of the time at temperature treatment. This is especially true if eggs are left in a temperature zone that favors microbial growth for a significant amount of time. Natural cooling eggs can be used to cool them to ambient temperatures or cold storage to allow for new growth of unkilled microorganisms.
Rapid cooling can lead to serious problems. Microorganisms found in the eggs’ ambient environment can contaminate them and draw them back through the egg shell pores. The faster the cooling is, the cleaner and more sterile the cooling environment.
The egg can be placed in a package, and sealed aseptically after processing but before cooling. Or, the package may be sealed before pasteurization, which is followed by cooling to ambient temperature or a refrigerator. The egg can be processed in its packaging without contaminating it during cooling or handling steps. Packaging eggs in packaging before processing, especially by the dozen, has many benefits. It allows for the use of modified atmosphere gases like carbon dioxide, nitrogen and mixtures to prevent spoilage, reduce breakage during processing, make handling, automation of production and standardization easier. Also, it facilitates the addition and diffusion of process aids into the egg such as citric, lactic and benzoic acids. Individually packaged eggs can be placed in more or less standard egg cartons, while multiple eggs may be packed in cardboard sleeves. This will give the package the expected appearance.
“Packages can be filled with nitrogen, carbon dioxide, or a mixture of carbon dioxide and nitrogen before pasteurization, before cooling, and sealed. The gas will flow through the eggshell and vitelline membranes into the sealed package to stabilize and inhibit deterioration.
“The invention’s important features and advantages will be obvious to the reader through the claims and the appended claims, as well as the detailed description and discussion that follows in conjunction with the accompanying illustrations.”
FIG. FIG. 3 shows a whole uncooked poultry egg 20. Egg 20 is comprised of: (1) an eggshell 22; (2) an outer membrane attached to the inside of the shell 22, including a shell membrane or an egg membrane; (3) viscous layers made of albumen, collectively known as the egg white, and identified by reference characters 26; (4) an egg yolk 28; (5) the vitelline 30 which is thin, relatively strong, and surrounds and envelopes the egg yolk 28. The AVIAN EGG CHEMISTRY AND BIOLOGY, Burley et al., John Wiley & Sons, Inc., New York, N.Y. 1989, contains additional information about the structure and functions of poultry egg components, as well as their attributes, which can be referred to by readers if necessary.
“The time and temperature pasteurization methods for poultry eggs that have been proposed focus almost exclusively on the elimination of superficial infections 32 and 34 on egg shell 22. Funk U.S. Pat. is an exception. No. No. 2,423,233, which claims to disclose but does not document temperature pasteurization processes that are capable of eliminating infections in poultry eggs’ whites. There is no information available that can reveal the time and temperature of pasteurization processes capable to destroy infections in the yolk of poultry eggs. 3. If a shell egg is infected in its entire mass or primarily in its egg, then all of the known pasteurization methods for shell eggs are ineffective. They either accomplish nothing or produce conditions that are conducive to the growth of food poisoning in the egg.
“Infections of the eggshell may occur in three ways: (1) they are concentrated near the eggshell/egg white interface due to migration through the pores. (2) they are indigenous and scattered throughout egg mass. (3) They are indigenous and concentrated in the middle and other parts of the yolk. Transovarian infection of eggs, through-the pore contamination and generalized infections can all lead to indigenous infections. Although it’s easy to think of Salmonella as being symbiotic with eggs and poultry products, it is likely that eggs can also be used as rich hosts for all kinds of infectious organisms under certain circumstances.
“”
“Holding a egg at the right temperature and time can help you achieve minimum USDA liquid egg pasteurization standards. It can also reduce, if not completely eliminate, the risk of infection and still produce a good shell egg for your consumer.”
“It is important that the pasteurization time and temperature are set to a minimum USDA requirement for liquid eggs. This applies regardless of size, egg thickness, freshness, heat transfer medium, or any other characteristics of the egg.
“The eggs can be processed according to the principles of this invention in any gaseous fluid or fluid, food-grade heat transfer medium, including oil, a glycol or water.”
FIG. 9 and 10. 9, and 10. It also included a Blue M. MAGNAWHIRL precision bath water bath 38, which allowed for temperature adjustments (not shown). The 40th batch of eggs was filled into the tank 41 of the Blue M apparatus. It was usually in 13 batches as illustrated in FIG. 10. To eliminate temperature gradients, gentle (laminar flow), circulation of water 41 in tank 42 was used to ensure that all eggs in the body were pasteurized water in the same way.
“The temperature in the middle of the yolk of that 46-oz egg was measured using a Type K thermocouple 48. To measure the temperature of the pasteurization medium, a reference thermocouple 50 was placed in the tank 42’s body of water 41. The uniform pasteurization conditions led to the assumption that the center-of-yolk temperature of eggs remaining in a batch 40 was the same as thermocouple 48.
The thermocouple 48 was made by puncturing egg 46’s shell, outer membranes and vitelline membrane with a hypodermic needle. The progress of the thermocouple 48 was observed through a candling hole. This allowed the egg to be stopped exactly when the temperature sensor tip reached the yolk center. To seal the egg’s shell, epoxy resin was applied.
“The temperature at the center of yolk 46 and bath temperature were continuously measured using a 52-bit Quick Log PC software from Strawberry Tree of Sunnyvale (Calif.) and Tegam K. J&T single input thermometers 54, 56.”
“In many cases, eggs were inoculated by an infectious organism in several of the examples.” The example lists the number of organisms per gram of eggweight.
“EXAMPLE I”
“TEST 1”
“Method”
“Results”
“Comments”
Summary for “Methods to process poultry shell eggs”
The United States Department of Agriculture has been enforcing minimum food safety processing standards since many years. Although food safety standards for shell eggs have been in place for a long time, they are not applicable to liquid whole eggs or egg products of many varieties. They are based on minimum standards for pasteurization. As a result, the prior art reviewed in this specification shows that there is no technology available for pasteurizing shell eggs to acceptable standards. This means that the standards are not comparable to the USDA guidelines for other egg products.
“Shell eggs are a valuable commodity that offers many nutritional benefits unmatched by any other food product. These benefits include low costs per nutritional unit, ease of preparation, gastronomic enjoyment, culinary utility, and availability.
“It is well-known that shell eggs can contain Salmonella, which is a major concern from a food safety perspective. There have been several proposals for ways to improve the food safety of eggs by eliminating these harmful microorganisms. None of these techniques, except for those that are effective for external sanitation have been proven to be successful. In an attempt to reduce the severity of the problem indirectly, we have focused on egg processing and handling.
“Awareness and concern regarding infectious organisms within the yolk of a shell egg has been slow to develop. Both awareness and concern have increased over the past decade due to numerous cases of food poisoning that can be irrefutably attributed to yolk-associated organisms.
“Foodborne diseases are now more common in the modern world thanks to medical care and social programs. The most at risk are the significant segments of society with longer lives or who have compromised immune systems due to immunosuppression therapy, organ transplants or diseases like AIDS.
“Increasing concerns about the safety of eggs as food highlight the problem of transovarian infections that develop deep within the egg during its formation in the oviduct. Infectious organisms can also penetrate eggshells and possibly the vitelline membranes, contaminating the yolks with deeper proteins. For unknown reasons, it is now well-known that diseased hens can secrete microorganisms within the egg. Salmonella enteritis (S.) is the microorganism responsible for this problem. enteritis).”
“Salmonella are small, gram negative, nonsporing rods. Under the microscope, or using ordinary nutrient media, they are not easily distinguished from Escherichia coli. All strains and species are considered to be potentially pathogenic for humans at the moment.
Salmonella is a disease organism that can cause a wide range of illnesses, depending on its species. S. Typhimurium, which means “Salmonella From Typhus Mary”, is the only explanation. Enteric fever is caused by S. typhi. S. paratyphi types A and B can cause a syndrome that is similar to, but milder than, typhus.
“Reported cases involving severe gastroenteritis (stomachflu) have also implicated S. bareilly and S. newport. The victim’s age and general state of health are the main factors that determine their mortality. S. choleraesuis, with a 21% mortality rate, has the highest reported death rate.
“Altogether, more than 2,000 Salmonella species are known.” Each year, the number of Salmonella species increases.
Eggs are one of the most common vectors for Salmonella-related food poisoning. The widespread publicity about the illnesses and deaths caused by Salmonella enteritis-contaminated eggs in Europe in recent years has led to a decrease in egg consumption. The reduction in egg consumption has been as high as 50% in some marketing areas. In the United States, as well as Europe, this problem is seen to be a serious public health issue. However, the United States still consumes approximately 240,000,000 eggs annually.
“A recent article in the Nutrition Health Letter, Volume 18, Number 6, July/August 1991 edition, by the Center for Science in the Public Interest (“NAME YOUR FOOD (POISON) POISON”) describes a growing concern. According to the article, around 9,000 people die each year from food poisoning. This is in addition to several billions in health care costs.
“The article asserts that dairy products, eggs and poultry are the primary causative foods.
The article states that 1 in 10,000 eggs may be contaminated by Salmonella enteritis. An average American eats 200 eggs annually. Your chances of eating an egg contaminated by Salmonella are 1 in 50 if you eat an average amount of eggs.
The article suggests that people over 65 who have a disease like cancer or AIDS should not eat raw eggs. They also shouldn’t drink eggnog. All eggs should be cooked thoroughly, yolk and solid white included.
The improper handling of eggs in institutional or home settings only adds to the problem. The all-too frequent observation that eggs are left at room temperature for extended periods of time in institutional kitchens is a common reason. Unknowledgeable treatment can promote bacterial growth in fresh eggs.
“Little information is available about the egg’s virology. Some people still believe that shell eggs are sterile within the shell. This belief has been held for a long time. When cultured, needle puncture samples of the egg’s interior including yolk and white are usually negative. However, it is known that eggs broken in large quantities can quickly show significant gross populations infectious microorganisms. Even though the egg shells are clean and free of filth, it is not uncommon to see plate counts that range from hundreds to thousands. It is well-documented that S. enteritis can be found in shell eggs.
“Eggshells contain many pores that allow the egg to breathe. This is one source of infection. The size of pores varies. These pores come in contact with organic waste when the egg is laid. Most likely, some microbes that come into contact with the egg may be of a size that allows them to pass through the pores. The microbes once inside the egg are not evenly distributed. They are instead retained in small areas on the inner membrane of the egg, which has smaller pores than the shell.
“Washing spreads microbes better, increasing contamination by greater surface contact with egg shell entry pores. The shell membranes of cracked eggs can be torn and ripped. The eggs can be stuffed with the stored inoculum, as well as airborne bacteria, after they are cracked.
“Also as egg temperatures change, there is an active and ongoing gas-vapor exchange between yolk and white via vitelline membrane, white and inside of shell via outer and inner membranes, and shell and outside environment via the outer shell membranes.” These mechanisms can allow airborne microorganisms to reach the egg’s interior.
“Finally as we have discussed, transovarian infections can cause eggs to be, and often are, contaminated. It is not yet known how severe this problem is. Even if harmful microorganisms are not transported from the egg’s exterior to the interior, eggs may still be unsafe to consume. Worse, both the egg-infecting mechanisms pore penetration and transovarian infections are at work.
The USDA standards require that liquid eggs be processed for no less than 30 minutes. This ensures that the eggs are safe to eat, as all particles have been exposed RPT. However, liquid eggs can still retain some functionality and other valuable properties if they are properly handled. There is no standard for shell eggs because there has never been a reliable temperature method for making them safe to eat. There is no known process that can be used to process whole eggs according to the requirements for liquid eggs. This means that the entire egg, which includes the shell, outer shell and egg membranes as well as the egg white and chalaza, along with the yolk, are exposed to temperatures that allow for the safe killing of any harmful organisms.
“Other researchers have concentrated their attention on temperature and time treatments for devitalization vital shell eggs. Pasteurization of shell eggs to increase food safety quality was also considered.
The growth of food poisoning in external foods is possible in certain TPT/temperature ranges that are favorable influenced in the outermost layer of the shell egg. External food poisoning will get worse in many other temperature ranges. Temperatures near or at the egg yolk centre will never reach the temperature necessary to kill large numbers of infectious microorganisms.
“On the contrary, because internal temperatures at the yolk’s center are not high enough for Salmonella or other infectious microorganisms to be killed, prior art techniques cannot be used. They can only reach yolk temperatures within the suggested times that are in a range that will result in significant increases in food poisoning. Processed eggs can become infected if they are within a narrow range of these parameters. If a yolk infection is minor and non-lethal, the egg can be contaminated with such methods. The egg could then deteriorate rapidly, becoming a serious health risk or even toxic.
Funk did not consider the possibility that Salmonella can be found in eggs throughout the egg. Funk’s primary concern is to deviate the egg egg embryo. He also cares about destroying any bacteriological organisms that may have entered the egg shell. . . Extended as far as the yolk . . . Funk claims that the majority of the conditions he uses to process eggs do not improve any existing infectious conditions and, at worst, increase food poisoning risks. Funk’s claims for a shell egg cannot be applied to the USDA minimum processing standards (see FIG. 2) for liquid eggs products. Other time/temperature combinations not covered by the Funk patent, which also do not meet the minimum processing standards, can result in whites of eggs visible being cooked (see FIG. 8).”
“The Funk process parameters include temperature and TPT. This is the time that a shell egg is kept in a pasteurization medium at a specific temperature. This is very different from the critical TPT. It is the portion of TPT where all particles, including those in the yolk, are at an effective pasteurization temperature. EqT is the point at which the egg’s mass is at this temperature. Funk did not recognize or appreciate the importance of RPT and TPT. Funk would have probably not made the distinction if he did. TPT and RPT are identical for the purpose of devitiating an embryo.
For this purpose, “Lethal thermal injury to any part of an embryo (even just at its surface) is sufficient.” Infections are made up of many micro-entities, which is different from embryos in vital eggs. The ability to cause death at any point in this multifarious environment is not sufficient to kill the infection. This is unlike an embryo that can be killed if only a small portion is heated to a sufficient temperature. In order to be effective against infections that are spread throughout a substrate, the temperature must be high enough to kill many infectious organisms. This means that eggs containing microorganisms must have the right pasteurization temperature. This is why RPT and TPT are different in this instance. The distinction becomes more important as the egg’s potential infection rate increases.
“Funk’s preferred temperature and process times for pasteurization are not the worst. His patent suggests that one of ordinary skill is the best in the art. When many of the Funk temperatures and times for pasteurization, sterilization and devitalization (of vital egg embryos) are used to pasteurize shell eggs in order to improve food safety quality, the results of tests show that they are not consistent with this objective. Furthermore, eggs that were processed under the most favorable conditions, measured at the yolk cannot meet the USDA Protracted Whole Egg Standard For Liquid Whole Eggs (see FIG. 1), or the USDA minimum standards for liquid whole eggs (see FIG. 2).”
The Funk process almost always results in eggs that are capable of reliably eliminating a living embryo. Funk’s method is not likely to cause infected eggs that are visible at the outer layers and remain or become more dangerous to consumers. It was developed to improve food safety and to increase the safety of shell eggs.
“New strains of infectious organisms are constantly being discovered. Food poisoning is on the rise due to increased production, mass handling, widespread distribution, and increased risk of contamination. Egg poisonings are common and likely to increase. Nearly all food products are subject to strict standards for processing that ensure food safety. Only shell eggs are subject to pasteurization standards in relation to eggs and other egg products. This lack of food safety pasteurization standards for eggs and other egg products can be attributed to a lack of knowledge about an efficient process to make shell eggs safe to eat. Funk’s proposed process is ineffective and fails to deliver any significant benefits. They are also highly likely to produce products that pose a significantly increased risk of food poisoning.
“These novel and practical methods for temperature- and time-pasteurization of shell eggs throughout their entire mass have been discovered and disclosed. They are more effective than or equal to USDA’s minimum and protracted standards for whole eggs. This reduces the risk of food poisoning. This is typically a serious illness that can cause gastroenteritis and fever for several days. It can also be deadly if the egg is eaten by someone in any of the above categories. These novel methods for pasteurizing shell eggs do not compromise their integrity, functionality, and quality.
“Effective pasteurization according to the principles of this invention requires that the preprocessing temperature be known. TPT is determined by this temperature. The TPT process has two components. EqT and RPT are the times it takes for eggs to reach equilibrium temperature with pasteurization medium. This is especially true in the most difficult areas, such as the yolk’s center. RPT is the time spent at a pasteurization temperature that is equivalent to that required for liquid whole eggs. Only once EqT has been achieved, can RPT begin. After the center of a shell egg has reached the desired pasteurization temperature, the egg can be processed at USDA-mandated temperatures with minimum USDA standards. This ensures that the egg remains at the right temperature throughout its entire mass to destroy harmful bacteria.
“Examination (of FIG. “Examination of FIG. Tabularized data of the same data are available in Table 1. The indicated time represents the minimum RPT required to kill harmful microorganisms at the temperature.
“”
The Table 1 pasteurization times and temperatures must be applied to shell eggs. Additional EqT time must also be allotted from the moment the egg is placed into a heat transfer or pasteurization media at the desired pasteurization temp. This will allow the yolk to reach EqT, which is the initial point of RPT. It is the temperature at which the egg reaches temperature stability with the heat transfer medium. After this point is reached, heat must be transferred from the shell egg’s external parts into the yolk. This will ensure that the egg’s temperature has reached equilibrium with its process medium.
“The time it takes for the whole egg to reach equilibrium with the process media or to reach a predetermined process temperature. EqT is added to the actual processing time, RPT as shown in FIGS. The total processing time (TPT) is equal to Table 1 and Table 2.
The egg size, preprocess temperature, and pasteurization temperature are all factors that determine the time it takes to achieve EqT.
One liquid (oil or water, glycol, or the like) can be used to heat the egg’s interior. However, it must be safe. Although it can be used for pasteurization, a gas like air, humidified or mixed with gases such carbon dioxide and nitrogen is not recommended. These gases can be used in the RPT phase or for TPT processes that involve both EqT-RPT phases. Liquids are preferred for RPT steps. These gases are often preferred for tempering. This technique is described in detail below and can be optionally used to ensure egg pasteurization in accordance with the principles of this invention.
“It is not unusual for eggs in a lot to be at different temperatures. Neglecting this important condition could lead to inappropriate EqT, TPT and/or RPT temperatures. These parameters may allow for the pasteurization of eggs at an effective (but not optimal) temperature. However, the egg whites can be cooked at a higher temperature. If the batch of eggs contains eggs at a lower temperature than the recommended minimum RPT, the eggs will not be cooked to the specified pasteurization temperature. 2 and Table 1.
Tempering may be used in accordance with the principles in the present invention when there is a temperature difference in the eggs. Tempering refers to an initial step or pre-processing in which eggs are kept at a subpasteurization temperature for a sufficient time to allow them to reach the same temperature. This ensures consistency in the egg pasteurization, which significantly reduces or eliminates the possibility of eggs with cooked whites or eggs that are not sufficiently pasteurized at the end. Tempering can be used to reduce or eliminate thermal shock cracking in the eggs being processed.
“Tempering can take place in both air and other gases. You can use dry air or humidified air to temper the gas. This is important because it prevents evaporative loss of water from eggs during tempering. If the pasteurization medium is not water, you can add water to it to compensate for evaporative losses. This will restore water that was lost by the egg through evaporation.
“The shortest effective tempering time is preferred.” It is not a good idea to keep eggs at temperatures that favor microorganism growth longer than necessary. Tempering temperature could be one such characteristic.
“There are several important versions of this invention that heat eggs in stages, with one or more heating steps being followed up by a dwell period in which the temperature is equilibrated throughout the egg’s interior.
Pasteurization in stages with significant dwell times between stages is another similar method. To extend shelf life, pasteurization in the same temperature ranges as described above may work together to produce longer shelf lives. Tests have shown this.
“It is impossible to list all the parameters for every option, due to the almost unlimited number of choices available. This is not necessary. The parameters for an option that uses intermittent or discontinuous heating can easily and routinely be determined, as the critical criteria are well known. The pasteurization temperature and RPT should be set so that all eggs in the egg mass have been heated to the temperature required by the USDA Standard for liquid whole eggs (FIGS). 1, 2, and 1.
A baker will notice a slight loss in functionality when pasteurizing liquid whole eggs are processed according to the invention. The difference can be easily made up with small increases in egg quantity. The improved food safety makes up for any potential loss in functionality.
TPT can be decreased by adding turbulence to the pasteurization medium, and/or subjecting the shell eggs mechanical vibration. These two mechanisms, a turbulent pasteurization media and the application vibrational energy to eggs, increase the rate at which heat is transferred from the egg’s interior to the pasteurization medium. Although not necessary, turbulence or vibration can lead to more efficient treatment. If you want to achieve faster, more efficient processing, you should use a turbulent pasteurizing medium or vibrating the egg.
Ultrasonically induced vibrations and other forms of vibration, including those caused by cavitation, may be used to your advantage in microorganism-destroying treatments. This vibration, similar to the mechanical, encourages heat transfer through the egg’s shell and into the egg’s mass. This improves the effectiveness of the process and allows for a more effective reduction in infectious microorganisms.
“Other beneficial process techniques include deliberate overheating of the egg’s initial temperature and the alternation or pulse of the temperature between two levels.
The treatment of eggs should be performed by heating shell eggs, then storing them at the appropriate temperatures for pasteurization. Rapid cooling or quenching is recommended. The final step ensures that the eggs are quickly cooled to the temperature range that favors bacterial growth. Any remaining harmful bacteria could multiply, negating some or all the benefits of the time at temperature treatment. This is especially true if eggs are left in a temperature zone that favors microbial growth for a significant amount of time. Natural cooling eggs can be used to cool them to ambient temperatures or cold storage to allow for new growth of unkilled microorganisms.
Rapid cooling can lead to serious problems. Microorganisms found in the eggs’ ambient environment can contaminate them and draw them back through the egg shell pores. The faster the cooling is, the cleaner and more sterile the cooling environment.
The egg can be placed in a package, and sealed aseptically after processing but before cooling. Or, the package may be sealed before pasteurization, which is followed by cooling to ambient temperature or a refrigerator. The egg can be processed in its packaging without contaminating it during cooling or handling steps. Packaging eggs in packaging before processing, especially by the dozen, has many benefits. It allows for the use of modified atmosphere gases like carbon dioxide, nitrogen and mixtures to prevent spoilage, reduce breakage during processing, make handling, automation of production and standardization easier. Also, it facilitates the addition and diffusion of process aids into the egg such as citric, lactic and benzoic acids. Individually packaged eggs can be placed in more or less standard egg cartons, while multiple eggs may be packed in cardboard sleeves. This will give the package the expected appearance.
“Packages can be filled with nitrogen, carbon dioxide, or a mixture of carbon dioxide and nitrogen before pasteurization, before cooling, and sealed. The gas will flow through the eggshell and vitelline membranes into the sealed package to stabilize and inhibit deterioration.
“The invention’s important features and advantages will be obvious to the reader through the claims and the appended claims, as well as the detailed description and discussion that follows in conjunction with the accompanying illustrations.”
FIG. FIG. 3 shows a whole uncooked poultry egg 20. Egg 20 is comprised of: (1) an eggshell 22; (2) an outer membrane attached to the inside of the shell 22, including a shell membrane or an egg membrane; (3) viscous layers made of albumen, collectively known as the egg white, and identified by reference characters 26; (4) an egg yolk 28; (5) the vitelline 30 which is thin, relatively strong, and surrounds and envelopes the egg yolk 28. The AVIAN EGG CHEMISTRY AND BIOLOGY, Burley et al., John Wiley & Sons, Inc., New York, N.Y. 1989, contains additional information about the structure and functions of poultry egg components, as well as their attributes, which can be referred to by readers if necessary.
“The time and temperature pasteurization methods for poultry eggs that have been proposed focus almost exclusively on the elimination of superficial infections 32 and 34 on egg shell 22. Funk U.S. Pat. is an exception. No. No. 2,423,233, which claims to disclose but does not document temperature pasteurization processes that are capable of eliminating infections in poultry eggs’ whites. There is no information available that can reveal the time and temperature of pasteurization processes capable to destroy infections in the yolk of poultry eggs. 3. If a shell egg is infected in its entire mass or primarily in its egg, then all of the known pasteurization methods for shell eggs are ineffective. They either accomplish nothing or produce conditions that are conducive to the growth of food poisoning in the egg.
“Infections of the eggshell may occur in three ways: (1) they are concentrated near the eggshell/egg white interface due to migration through the pores. (2) they are indigenous and scattered throughout egg mass. (3) They are indigenous and concentrated in the middle and other parts of the yolk. Transovarian infection of eggs, through-the pore contamination and generalized infections can all lead to indigenous infections. Although it’s easy to think of Salmonella as being symbiotic with eggs and poultry products, it is likely that eggs can also be used as rich hosts for all kinds of infectious organisms under certain circumstances.
“”
“Holding a egg at the right temperature and time can help you achieve minimum USDA liquid egg pasteurization standards. It can also reduce, if not completely eliminate, the risk of infection and still produce a good shell egg for your consumer.”
“It is important that the pasteurization time and temperature are set to a minimum USDA requirement for liquid eggs. This applies regardless of size, egg thickness, freshness, heat transfer medium, or any other characteristics of the egg.
“The eggs can be processed according to the principles of this invention in any gaseous fluid or fluid, food-grade heat transfer medium, including oil, a glycol or water.”
FIG. 9 and 10. 9, and 10. It also included a Blue M. MAGNAWHIRL precision bath water bath 38, which allowed for temperature adjustments (not shown). The 40th batch of eggs was filled into the tank 41 of the Blue M apparatus. It was usually in 13 batches as illustrated in FIG. 10. To eliminate temperature gradients, gentle (laminar flow), circulation of water 41 in tank 42 was used to ensure that all eggs in the body were pasteurized water in the same way.
“The temperature in the middle of the yolk of that 46-oz egg was measured using a Type K thermocouple 48. To measure the temperature of the pasteurization medium, a reference thermocouple 50 was placed in the tank 42’s body of water 41. The uniform pasteurization conditions led to the assumption that the center-of-yolk temperature of eggs remaining in a batch 40 was the same as thermocouple 48.
The thermocouple 48 was made by puncturing egg 46’s shell, outer membranes and vitelline membrane with a hypodermic needle. The progress of the thermocouple 48 was observed through a candling hole. This allowed the egg to be stopped exactly when the temperature sensor tip reached the yolk center. To seal the egg’s shell, epoxy resin was applied.
“The temperature at the center of yolk 46 and bath temperature were continuously measured using a 52-bit Quick Log PC software from Strawberry Tree of Sunnyvale (Calif.) and Tegam K. J&T single input thermometers 54, 56.”
“In many cases, eggs were inoculated by an infectious organism in several of the examples.” The example lists the number of organisms per gram of eggweight.
“EXAMPLE I”
“TEST 1”
“Method”
“Results”
“Comments”
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