The talmudic paradigm for a concept that is blatantly obvious is Keveiasa Bechuscha, the issue is as clear as the permissibility of mixing eggs into dairy products. However, things are not always as simple as they may seem, and just as the Ba’alei HoTosfos in Maseches Eiruvin discuss how less than “obvious” this concept may be, the production and use of eggs in modern food production pose questions whose answers are far from being considered obvious. The purpose of this article is to discuss some of the issues that confront modern kashrus supervision as they relate to egg production.

Eggs are not just for breakfast anymore. They are critical to the production of many foods. In addition to the flavor they impart, the chemical properties which they possess provide important functions in many foods. Whole eggs, yolks and whites are sold as liquid, powder or frozen. Other ingredients, such as oil, can be added to suit customers’ needs. Technology has even been developed to remove cholesterol from egg yolks, or give egg whites which have no cholesterol some of the functional characteristics of whole eggs. But you can’t make an omelet without cracking a few eggs.

The use of eggs in kosher food production historically began with cracking the egg into a glass, inspecting the egg for blood spots and separating the whites and yolks as necessary. Demands of modern food production, however, have made it impractical to amass an army of egg crackers in each food factory. The egg industry has recognized this challenge and has devised a means of not only providing prodigious amounts of liquid egg products to industry sans shell, but also methods of processing to allow for the shipment, storage and use of eggs in ways undreamed of by food processors of previous generations.

In order to process the huge volumes of eggs needed, eggs are removed from crates and placed on large conveyor belts, washed, and then passed over a bright light source. This process is called candling. Usually blood, if present, can be observed and the egg is removed by attendants. Electronic sensing equipment has recently been developed to detect blood spots. The clean eggs are then automatically placed into an egg-cracking machine. Such a machine consists of a series of individual egg holders that crack the egg, separate the yolk and white, and dump each component into a separate pipe. Such a machine can process thousands of eggs an hour, and operators typically monitor the machine to detect eggs which do not separate properly or contain blood spots. When such a discrepancy is noted, they operate controls that direct the egg to an appropriate stream or it is discarded. The fluid egg produced by such a system can be either whole egg or separated yolks and whites.

An interesting point to note is that the United States Department of Agriculture (USDA) maintains a very strict oversight for egg processing plants. A full-time USDA inspector is assigned to every egg plant, similar to the supervision required for meat packing facilities. Such a presence, while not taking the place of a mashgiach, serves as a useful adjunct to a hashgacha.

Halachic Concerns
Eggs processed for industrial use pose several halachic concerns. The first issue involves the status of the eggs themselves. Only the eggs of kosher species of birds are considered kosher. Also, they must not have been laid by a bird that was a Treifa, defective, or removed from a Nevaila, the carcass of a dead chicken. The Talmud discusses the means by which one can verify the kosher origin of an egg. However, the Shulchan Aruch rules that since eggs of non- kosher birds are not common, one may accept whole chicken eggs in the shell without any special investigation. One is also permitted to follow the Rov that most eggs are not from Nevailos and Treifos. Eggs which had been cracked and sold as a liquid, however, have been the subject of discussion by many early halachic authorities. The Bais Yosef quotes the Rabeinu Yerucham who states that the status of liquid eggs is dependent upon two opinions in the Gemara. The Sha”ch quotes the Toras Chatas that even though one is permitted to eat Pas Palter made with eggs (since eggs commonly available are always kosher) one should nevertheless refrain from using liquid eggs unless they have been supervised to assure that they came from a kosher source.

Liquid Eggs
While this discussion may not have been terribly significant in the past when eggs were routinely cracked by the food producer, the issue is of major concern in modern food production. The Minchas Yitzchak discusses at length the acceptability of liquid and powdered eggs and concludes that in situations where only kosher eggs are processed, one Me’ikar Hadin may accept liquid eggs as kosher even where a mashgiach does not check the eggs. This is especially true where the government has established standards and requirements for such productions, and all the more so where a government inspector is present to enforce such rules. While the Minchas Yitzchak is less than sanguine about such a Heter in his time, the consensus of virtually all halachic authorities today is that given the rigid governmental control and total absence of any foreign eggs, fluid eggs produced by the modern egg industry may be accepted Lechatchila.

Ova
A second issue involves ova, the term used for eggs which are harvested from slaughtered chickens. Depending on the level of development of these eggs, they would be considered fleishig, meat, if recovered from kosher slaughtered chickens. If the chickens were not kosher slaughtered, they would have the same halachic status as the non-kosher chicken. One of the largest egg producers in the United States formerly processed ova which therefore required a full time mashgiach for kosher productions. Fortunately, from a kosher perspective, the processing of ova has declined to the point where it is practically non-existent in United States egg processing plants. Nevertheless, the USDA has developed a “Kosher Statement”, which it will append to its certification of egg productions at the request of the manufacturer. This statement vouches for the fact that a particular lot of eggs contains no ova or blood-spotted eggs (see below). Given the USDA’s strict control of egg processing plants, such a guarantee has relevance in halacha.

Blood Spots
The next kashrus issue involves blood spots that are occasionally found in eggs. The Gemara Chulin discusses the status of eggs in which blood is found. A blood spot was typically considered by Chazal as an indication that the egg had been fertilized, and any resulting embryo that had formed would be prohibited. There is a significant discussion amongst the Rishonim concerning distinctions as to the location of the blood spot and whether the entire egg must be discarded or only the blood spot is prohibited. The Ram”a quotes the minhag that, in order to follow all opinions, the entire egg should be discarded regardless of where the blood spot was found. This is indeed the custom in kosher households. Were this to be the requirement for industrial eggs, however, it would be impossible to guarantee that such eggs are free of blood spots. The processing of eggs is monitored by factory workers, not the mashgiach, and with thousands of eggs being processed every hour, it is impossible to guarantee absolutely no blood, despite the USDA “Kosher”statement. Indeed, new egg processing equipment is being designed that eliminates human oversight entirely. Fortunately, such a rigorous oversight is not halachically required.

The Mechaber states explicitly that roasted eggs may be eaten even though it is impossible to check them for blood spots, and the Ram”a explains that the rationale for this is based upon the right to rely on the majority of eggs that have no blood spots. The Ram”a notes, however, that the minhag is to check eggs during the daytime when it is possible – but clearly allows the use of unchecked eggs at night since the option of checking them is not available. Concern over blood spotted eggs today is further mitigated by the fact that the vast majority of eggs sold for food are derived from hens that have never been near a male in their lives. Hens are segregated in huge coops at times containing up to a million birds at a time – for the sole purpose of converting chicken feed into eggs. Such eggs are referred to in the Gemara as Safna Me’ar’ah, and the blood found in such eggs would never prohibit the entire egg. The Iggros Moshe, Yoreh De’ah: 36 discusses the status of blood spotted eggs in countries where such eggs predominate and notes that the Minhag is still to discard the entire egg. However, in cases where a blood spotted egg was cooked in a pot with another egg, there is no basis to be concerned with the status of the other egg or the pot (unless one is aware that it is definitely from a fertilized egg).

Left Overnight
Another concern discussed by both the Minchas Yitzchak and the Iggros Moshe concerns eggs which have been removed from their shell and left to stand overnight. The Gemara states that one who eats a peeled egg that has been left overnight is placing himself in danger. Rav Moshe Feinstein zt”l points out that this statement is not quoted in Shulchan Aruch, and in addition, he opines that the concern does not apply to factory productions. It should be noted, however, that other authorities are much more concerned about this issue. Therefore, many hashgachos at hotels and restaurants that crack their own eggs require the addition of salt to the liquid if the eggs are going to stand overnight.

Pasteurization
An important health issue addressed by egg processors was concern of bacterial contamination. The producers of the eggs themselves – the chickens – are not noted for living in a particularly hygienic environment, and the eggs are generally a bit dirty when collected from the coop. Although the eggs are washed with antibacterial solutions prior to being sold or processed, salmonella, a bacteria which causes food poisoning, can contaminate the egg while it is still being formed in the chicken. In order to reduce the risk of spreading such contamination, the USDA has mandated that all commercial egg products be pasteurized. As we shall see, heat treating eggs is no easy matter – enough heat has to be used to kill the bacteria without turning them into omelets!

Pasteurization involves heating the liquid to a temperature which reduces dangerous bacteria to very low levels, and is typically accomplished in a machine called a heat exchanger. Liquid egg passes on one side of a metal plate and hot water on the other, allowing the eggs to reach the required temperature for an appropriate period of time. The hot water used for this purpose does not come in direct contact with the eggs, and is reheated and recirculated through the system. The kashrus concerns with this process is due to the fact that many egg plants pasteurize both pure eggs and egg/milk blends. Not only must the pasteurizer itself be kashered from dairy to pareve productions, but the water which has been used to heat a dairy product must be changed before processing a pareve product.

Pasteurization, however, poses additional kashrus concerns. In order for pasteurization to be effective, sufficient heat must be used. Many food products, such as fruit juices and milk, can be pasteurized without significantly degrading the product. When egg proteins are heated they coagulate, changing the physical characteristics of the product. While whole eggs can tolerate a minimal pasteurization temperature, egg whites would solidify under such conditions. In order to enable a lower pasteurization temperature, an oxidizing chemical called hydrogen peroxide is added to the egg whites to aid in the reduction of bacteria. While hydrogen peroxide will indeed address the need to kill bacteria, its presence in the final egg product is not desired – it is unstable in the eggs and will release oxygen gas over time. Hydrogen peroxide can be removed from the eggs by use of an enzyme called catalase. The only problem with this enzyme is that its classical source was non-kosher liver. Although used in infinitesimal amounts, the addition of any non-kosher ingredient ab initio, Lechatchila, is generally not allowed. Fortunately, enzymologists have discovered new ways of making microbial enzymes through fermentation, which can be entirely kosher.

Spray Drying
Liquid egg whites can be spray dried to produce a powder without prior pasteurization. (An older, more specialized process involves spreading the egg whites on a pan and allowing the egg whites to crystallize. Very few companies still use this process, and such product is highly prized by the confectionery industry.) After the egg whites have been dried and packaged, the boxes of finished product are stored in a hot room for over a week. This slow “pasteurization” kills the offending bacteria. A technical problem with this process, however, is caused by the small amount of natural sugar contained in egg whites. When certain sugars are heated with protein, they react in what is termed the Maillard reaction, which causes the product to become brown. However, customers have no desire for brown egg white powder. In order to avoid this problem, the liquid egg whites are desugared prior to drying. This can be done in two ways. The first method is to culture the eggs with a bacteria or yeast. These microorganisms require carbohydrates as food, and therefore consume the sugar. The second method is to employ an enzyme called glucose oxidase, which is also derived from fermentation. This enzyme breaks the sugar into new components, which do not contribute to the Maillard reaction. Both methods raise kashrus concerns in that some of the other nutrients used to grow these microorganisms may be non-kosher. In addition, both the yeasts and enzymes may not be acceptable for Pesach.

Powdered whole egg product is not free of kashrus concerns, either. The USDA distributes free egg “product” as part of its nutrition program both at home and abroad. In order to balance the interests of its competing agricultural constituencies, the USDA mandates that the egg product it purchases must contain both dairy and egg ingredients, and is produced by egg manufacturers on the same equipment as conventional powdered whole egg. Since these companies desire that their regular powdered products be certified as pareve, all equipment used to produce USDA product must be kashered appropriately before the production of pareve powdered eggs.

In the final analysis, the consumer rarely purchases the processed egg products which we have discussed. With the exception of cholesterol-free egg mix, the house-person still buys – and cracks – eggs the old fashioned way. Concern over salmonella, however, have led companies to offer more and more pasteurized liquid egg products. Processed eggs are very much part of many of the foods we eat. The vigilance of the kashrus authorities is critical in this incredible food product.