Kosher in the Dairy Case

From genetically engineered microbial rennet to ‘Rocky Road’ ice cream, the dairy industry presents new challenges to the kosher kitchen.

As with many other food products, modern food technology has created new concerns for the kosher consumer. All dairy products, by definition, begin with milk, and milk from a kosher species of animal is inherently kosher.
Nevertheless. during the time of the Mishnah, our sages promulgated a number of special rules regarding kosher to address specific issues, one of which concerned the milk supply. Given the small number of animals owned by a farmer in the Middle East at that time, it was common for kosher cow ‘s and sheep’s milk to be mixed with milk from non-kosher species and sold on the open market as kosher milk. The sages were faced with the task of guaranteeing the integrity of the milk supply, and a special gezerah was issued to the effect that unless milk were supervised by a religious Jew from the time of milking, there was no guarantee that the milk was not adulterated, and the milk is to be considered completely non-kosher. The supervised milk is referred to as chalav yisrael.
This halachah is mentioned in the Mishnah, Gemara, and Shulchan Aruch, and the requirement that milk be supervised is binding halachah to this day.
In the United States today, the government guarantees the integrity and wholesomeness of the milk supply. It assures that all regular milk sold comes only from cows. With this vigilant supervision on the part of the USDA of the American milk supply, the question was posed as to whether, as a matter of halachah, we have the right to rely on such supervision to fulfill the requirement for chalav yisrael. This question was most recently addressed by Rabbi Moshe Feinstein, zt“l, who ruled that all milk sold in the United States, as well as in any country where milk is as strictly controlled, is permitted as a matter of halachah, and equivalent to chalav yisrael. Rav Moshe bases his ruling on the concept of anan sahadi: that given the nature of governmental control of the milk supply, we are considered to have direct knowledge of the status of the milk1. In addition, other rabbis are of the opinion that the requirement of Chazal for Jewish supervision of milk was limited to locations where adulteration was prevalent, or that non-kosher milk is widely used. According to both of these opinions, regular milk sold in the United States is kosher2. This position has been accepted by the OU as well as most major kosher certifying agencies in the United States. All references to the kosher status of milk in this article are based on this policy.
Chalav yisrael that is certified by the OU is marked specifically as chalav yisrael. Otherwise, regular milk bearing the OU indicates that there is a rabbinic supervision on the vitamins and other ingredients added to the milk. Traditionally, vitamin D is added to milk to ensure proper absorption of calcium, and vitamin A is added to low-fat milk to replace this vitamin normally found in the milk fat. Although the amounts of both of these vitamins are minuscule, they can be of non-kosher origin. Even though they can be considered batul – insignificant in terms of Jewish law – a kosher product should not rely on bitul on a regular basis. A reliable hashgachah guarantees the kosher status of all such ingredients. Chocolate milk can contain a number of questionable ingredients, such as flavorings and emulsifiers, and here again a hashgachah is necessary to ensure that these issues have been properly addressed.
Kosher issues regarding most milk products, therefore, are similar to those affecting other food products. Other than the milk itself, all other ingredients and the equipment on which it is processed must be kosher.
A recent trend in the dairy industry has been to address the use of milk products by those people who are lactose intolerant.
Lactose, or milk sugar, is a complex sugar that requires a specific enzyme (lactase) to enable a person to digest it. Many people stop producing lactase after childhood, and are unable to digest milk as adults. The industry has addressed this problem in two ways. The first is by inoculating milk with a bacteria which breaks the lactose into component sugars, allowing for easier digestion. The second is to add a lactase enzyme directly to the milk to yield the same result. Both of these additives can pose kosher issues, and again rabbinic supervision guarantees that these additives are kosher.
Milk is a very perishable commodity, and historically the only way to preserve milk was to ferment it and curdle it into cheese. In the olden days, naturally occurring bacteria would sour the milk, and rennet – an extract from a calf’s stomach rich in the enzyme rennin – was added to the milk to cause the casein protein to curdle. This curd was pressed into cheese, and the liquid that did not curdle was separated as whey. Each area where cheese was made had naturally occurring bacteria peculiar to that area – hence “Swiss” cheese came from Switzerland, “Gouda” from the Netherlands, etc. Today, these
bacteria have been isolated and stored for the cheese maker, so these cheeses are made throughout the world. Similarly, rennet is prepared from the stomach of calves and purified, so that this preparation is available on a commercial basis. Since kosher cheese requires the use of kosher rennet, production of such rennet was always difficult and in short supply3. One of the innovations in the cheese industry has been the development of so-called “microbial” rennets. Rennin (a protease enzyme, the active enzyme in rennet) is a protein produced in the stomach of a calf which breaks the casein molecule in a particular fashion to produce a soft curd. Within the past forty years, scientists have learned how to grow certain naturally occurring fungi in a manner in which they secrete a protease which closely mimics the action of natural calf rennet.
These proteases are now widely used to make cheese throughout the world. They are less expensive than natural rennet and have been refined to produce a very good cheese. However, they are not true rennets, and there is a perceptible difference between these rennets and the animal product, both in functionality and finished product. The kosher status of these enzymes is primarily contingent upon the media on which the organisms are grown. All kosher cheese made today uses microbial rennet.
During the past five years, however, scientists have used the art of genetic engineering to alter the genetic makeup of certain microorganisms (bacteria, fungi, and yeasts) with the same genetic coding a calf follows to produce true rennet. The new “microbial rennets” are virtually identical to natural calf rennet, yet since they are derived from innocuous microorganisms, their kosher status is the same as other microbial rennets.
Cheese makers now the have the best of both worlds -a kosher and uniform source of true rennet without relying on extraction from calf stomachs.
Since cheese making historically required the use of an animal derivative which would only be kosher if the animal were slaughtered by shechitah (and for a number of other reasons), Chazal made a special prohibition against cheese made by a non-Jew at the same time as the ruling for chalav yisrael was promulgated. However, there is a major difference between these gezerot, in that the prohibition against cheese applies even if all of the ingredients are known to be kosher.
This rule is referred to as gevinat akum. In order for cheese to he considered kosher – gevinat yisrael – it must use only kosher ingredients and be made by a religious Jew, the act of making cheese being defined as adding the coagulant, the rennet.
The only cheese products excluded from this requirement are those referred to in halachah as “soft cheeses.” The cheeses with which we have been dealing are known as “hard cheeses,” or “rennet-set cheeses” by the cheese industry. These include Muenster, Mozzarella, Swiss, Brie and Cheddar. There is another entire class of cheeses which are known as “acid-set cheeses.” Milk can be curdled in a number of ways, such as the addition of a strong acid or strong bacterial fermentation, and do not require the use of rennet. These cheeses include cream, cottage, and neufchatel cheese. The OU follows the rabbinic ruling that these products are merely fermented milk, and not true cheeses at all. As such, they are not subject to the rules of gevinat akum, and can be produced without the constant presence of a mashgiach, as long as all ingredients are kosher.
A hashgachah is still critical, since various cultures, flavors, emulsifiers, and stabilizers which can pose serious kosher concerns, are used in these cheeses. These products can indeed be produced by major companies as part of their kosher programs with no material impact on their cost of production.
Another popular product on the dairy shelf is yogurt. Yogurt is milk which has been fermented by a particular yogurt culture and is usually flavored with flavoring or fruit mixture. Unfortunately, many yogurts also contain non-kosher gelatin, and the flavorings can pose other kosher ingredient issues. Even the fruit preparations contain flavorings to enhance their “fruity” properties. It is therefore important to assure that yogurt be properly certified as kosher.
Another look through the dairy case will yield one of the great ironies of American labeling law – “non-dairy” milk products. The government requires that products containing casein – as opposed to milk – be labeled as “Non-Dairy.’ Casein is that portion of fluid milk which coagulates in the presence of rennet or strong acid, and is produced in a number of foreign countries from surplus milk. There is no question that according to halachah this product is milchig (dairy), regardless of domestic political considerations, This is a classic reason for the insistence of the OU that dairy products be labeled OU-D, even if labeled “Non-Dairy,” You will find this ingredient, or its caseinate salts, in coffee creamers, aerosol whipped toppings, and many baked goods. (See the Kosher column in Jewish Action, Summer 1992, “To ‘D’ or Not to ‘D’ for a fuller explanation of OU policy on OU-D labeling.)
Another dairy ingredient in common use is whey, the liquid that does not coagulate during the manufacture of cheese. Although a derivative of cheese manufacture, it may not be subject to the rules of gevinat akum. The rules regarding the kosher status of whey are dependent upon the manner by which it is produced and the ingredients used, and requires a reliable kosher certification. Whey and whey protein concentrate are important ingredients in ice cream and baked goods.
Speaking of ice cream, a reliable kosher certification is imperative. Certain emulsifiers and stabilizers are used which could be of animal derivation. Gelatin has been a major stabilizer used for this purpose, and is an ingredient in most marshmallow-type flavor such as “Rocky Road.” The flavorings used must likewise be verified as kosher. The public’s fascination with new ice cream flavors also yields new kosher problems. For example, the recently popular “cookies ‘n’ cream” flavor typically uses a cookie with lard as its shortening!
Not only does this invalidate the kosher status of those ice creams – its use also causes major problems for the kosher status of the entire dairy where it is produced. (Please note that there are a number of kosher versions of “cookies ‘n’ cream” ice creams. Check for a reliable hashgachah.) The complexity of the dairy industry today demands constant updating for rabbinic supervisors and certifying agencies. The next time you are in the market for “real” dairy products, make sure to look for a “real” hashgachah to ensure the integrity of your kosher kitchen.

1 1t is important to note however, that while Rabbi Feinstein’s position has substantial precedent, it is not universally accepted and he himself considered it proper to be more stringent and use chalav yisrael where possible. On the other hand, even according to the more stringent authorities, there is substantial disagreement as to the need for separate dishes between chalav yisrael and non.chalav yisrael, as well as the need for chalav yisrael in cheese, powdered milk and whey.

2 Travelers beware: The heter (permission) to use non-supervised milk applies only in countries where the government maintains strict controls on the milk supply. There are a number of countries where governmental control is weak, and effective enforcement of food regulations is non-existent. In addition, non-kosher milk such as mare’s milk is a staple in certain parts of the world, and its availability could compromise any general assumptions as to the kashruth of the milk supply. A rabbi should be consulted regarding the use of milk in such areas.

3 Even if the rennet were derived from a properly slaughtered calf, would there not still be a problem of bassar b’chalav – mixing meat and milk? This issue is indeed dealt with extensively in halachic literature.

OU Kosher Staff