When the Israelites arrived at Mount Sinai to receive the Torah on Shavuos, they had not yet been given the laws pertaining to kosher meat. Unable to properly slaughter animals, they consumed only dairy foods. In commemoration, many Jews follow the tradition to include dairy foods in the festive meals of Shavuos.
Cheese is a dairy staple that contains its unique set of kosher rules. There are numerous hurdles to leap in producing kosher cheese.
The cheese-making process is fascinating, yet most people are unaware of its intricacies. All dairy products are spinoffs of milk in one form or another. cheese-making begins by taking milk and coagulating it to get curds. The milk must first be pasteurized to kill harmful bacteria, including those that may interfere with the cheese-making. Pasteurization is accomplished by heating the milk to 72° Celsius, or 161° Fahrenheit, for 15 seconds. Subsequently the milk is cooled to a temperature that will not damage the starter culture or the rennet.
 Adding rennet to the vat. Photo courtesy of Chr. Hansen, Inc. |
In the direct set method, a concentrated form of the starter culture is put directly into the milk vat. The culture, which is frozen at a temperature well below zero, is constituted solely of bacteria that were isolated from milk many years ago.
In the bulk set process, the cheese maker takes milk or milk powder, mixes it with water and culture media (sugars and nutrients such as yeast), and sterilizes it. He cools the mixture and then adds a small can of not concentrated bacteria to make a larger amount of liquid culture.
Of concern to the kosher consumer is the source of the culture. It may come from milk, from wine, or from a meat source. If the culture emanates from one of the latter two, we may have a kashrus problem. If the culture originated in wine, we face the problem of stam yainam, wine not made by Jews. If it emanated from an animal, the prohibitions of non-kosher meat and the mixing of meat and milk are involved. However, the likelihood is that the culture comes from milk.
The larger issue with which we deal here is that of chalav Yisrael cheese, cheese made by Jews. It is simple enough to make chalav Yisrael milk, since all that is required is Jewish supervision of the milking. Yet the cultures used in cheese-making are many years old, and did not start as chalav Yisrael, but as chalav stam. Making new cultures is not a simple task; is it possible to somehow use the old, non-chalav Yisrael cultures?
The Ba'er Heteiv rules (Shulchan Aruch Yoreh Deah 115:25, subsection 20) that one can take a culture, dilute it in milk to produce a second-generation culture, then dilute the second culture to produce a third-generation culture. The resultant culture is no longer considered chalav stam. Chalav Yisrael cheeses are made by diluting the original starter culture in this fashion.
The OK certifies both chalav Yisrael and non-chalav Yisrael cheeses. In order to achieve a chalav Yisrael culture, we take a one-milliliter tube, called a cryo, of the old, non-chalav Yisrael culture and add it to 100 milliliters of chalav Yisrael milk. After this 101-milliliter mixture has sat for twenty-four hours, we take one part of it and dilute it further in 100 milliliters of chalav Yisrael milk. Twenty-four hours later, the procedure is repeated yet again. New chalav Yisrael cultures are generally made from one of these already diluted cryos, rather than going back to the original culture and repeating this dilution procedure.
There are additives that may be introduced at various stages. The cheese maker may add calcium chloride before curdling to improve the process. At times potassium nitrate is added, to prevent the occurrence of bacteria. Cheese makers make Swiss cheese by adding propionic culture. This is cooled for thirty days, then warmed. The propionic culture forms gas and the "eyes" in the cheese develop. Some propionic cultures have a chametz media, thus presenting a problem for Pesach.
Very soft, or fresh, cheeses, such as cream, cottage, and farmer, undergo a somewhat different procedure from this point on. We will focus on hard cheeses.
Rennet is now added. The purpose of rennet is to coagulate (ma'amid, in halachic terminology) the milk, so that it separates into two parts: the curd mass that will become the cheese; and a liquid called whey (in halachic terms, mei chalav, the "water of the milk").
The coagulation by rennet is called curdling. As the whey separates from the curd, the curd coagulates. Rennet is extremely potent; one part rennet will coagulate between 10,000 and 15,000 parts milk. Ten percent of the compound will be cheese, while the whey constitutes the remaining ninety percent. The length of time that the rennet sits varies with the type of cheese being produced.
Chymosin, the active ingredient of rennet, is an enzyme that usually is taken from the fourth stomach of baby cows. (Chymosin is not found in adult cows.) Chymosin acts by breaking down casein, a milk protein, to form paracasein. The paracasein then combines with calcium to form calcium paracaseinate. To extract the chymosin, the stomach lining is washed and dried, then cut into pieces and softened in brine or boric acid. This softening takes several days.
As an alternative, the cheese maker can use pepsin, which comes from the fourth stomach of grown calves or heifers. On occasion pepsin is taken from the stomach of pigs.
This traditional method of sourcing rennet is not acceptable by kosher standards unless the animal is properly slaughtered. The OK Labs, under the direction of Rabbinic Coordinator Rabbi Dovid Steigman, has produced rennet by this method. Special care must be taken not to use a calf less than eight days old, whose consumption is prohibited by halachah.
Generally, however, kosher cheeses are produced with microbial rennet, that is, rennet made by fermenting certain bacteria — usually Mucor miehei, but also Bacillus subtilis and Bacillus prodigiosum.
An alternate method for creating rennet is cloning. In cloning, the rennet is engineered in the laboratory by introducing the genetic code for chymosin into a micro-organism. The genetic information comes via cells harvested from the calf stomach. The bacteria will subsequently produce chymosin that is a perfect match to the chymosin in calf stomach cells. The micro-organisms into which chymosin has been successfully introduced are Kluyveromyces lactis, a yeast; the fungus Aspergillus niger var awamori, and a strain of the bacteria Escherichia coli.
Microbial or cloned rennet may pose a concern for Pesach, since these can originate from chametz. There is not yet a cloned rennet that can be used to make Kosher for Passover cheese.
 Cutting the curd. |
Finally the cheese needs to mature, so that it reaches the desired flavor. The maturation period varies; Parmesan is matured for nine months, Cheddar for as little as a week or as long as eighteen months. Condiments such as garlic powder and hot pepper are added to certain varieties of cheese, but these do not present a kashrus problem.
What are some of the kashrus issues encountered in cheese production? A concern can arise with traditional Muenster, Romano, Parmesan, and Mozzarella cheeses, since they are put in brine. If the brine tanks were previously used for not kosher cheese, they must be kashered. However, this kashering is very difficult, and the cheese industry has acquired new tanks that are used exclusively for kosher cheese.
Another issue concerns American cheese, which is made by cooking Cheddar and introducing additional ingredients. The cooker has to be kashered, and therefore must sit idle for twenty-four hours, so that it becomes aino ben yomo. Therefore, kosher American cheese is produced on Mondays, since the only time when companies are not using the cooker is over the weekend.
 Stirring out the curds and whey to seperate them. |
Furthermore, the knives that cut the cheese blocks to the desired size need to be kashered before a kosher run. This is achieved by running a stone on them; the stone simultaneously kashers and sharpens the knives. It is also necessary to kasher the pasteurizers, since these were used for non-chalav Yisrael milk. This kashering must be done at 212°. Although there are some parties who have denied the feasibility of 212° kashering of pasteurizers, leading supervision agencies around the world have mastered this proper kashering method. The OK Laboratories remains prepared to demonstrate our method of 212° kashering to anyone who seeks the knowledge. (See "How Halachah Meets Technology," The Jewish Homemaker, February 1996, for a fuller treatment of this subject.)
Finally, the agitation involved in the process of making cheese or whey may lead to the presence of foam. A defoamer is added to settle the foam. Care must be taken to see that the defoamer is kosher. If a Pesach run is being done, the mashgiach must make sure that the defoamer is not chametz.
Ascertaining that the ingredients are kosher and that the equipment is properly kosherized are only part of the difficulty in making kosher cheese. There is an entirely separate halachic issue, the matter of gevinas akum (cheese produced by a non-Jew). Jewish law mandates that even if all the ingredients in cheese are kosher, the cheese production must be overseen (or actively participated in) by a Jew.
The Shulchan Aruch states: "The Sages prohibited cheeses of non-Jews because they are ma'amid (coagulate) them in the skin of the stomach of their slaughtered animals, which are not kosher. And even if they are ma'amid it in grasses, it is prohibited." The Rema comments: "That is the custom, and one cannot abrogate it, except in a place where they have traditionally permitted it. However, if a Jew oversees the cheese-making and the milking, it is permitted, and that is the custom in all our countries."
This stringency is greater than the one of chalav Yisrael. While there are leading rabbis who have ruled that one may be lenient regarding chalav Yisrael if there is certainty that the milk comes from a kosher animal, the same is not true with cheese. Even if we know absolutely that the cheese is made of only kosher ingredients, a Jew must supervise the production, else the cheese is prohibited.
The OK team of rabbis has decades of collective experience in all facets of kosher cheese supervision. Rabbis Avrohom Juravel, Leizer Teitelbaum, and Dovid Steigman, under the guidance of Kashrus Administrator Rabbi Don Yoel Levy, have forged a reputation for expertise in dairy supervision.
As we celebrate Shavuos, we can look proudly back on our traditions, dating to mattan Torah, the giving of the Torah at Mount Sinai. The laws of kashrus have been an anchor of Jewish life for thousands of years; more today than ever, in the face of intermarriage, assimilation, and other weighty challenges to the Jewish community, we reaffirm our commitment to observe these laws.
Rabbi Yitzchok Ort, an OK Rabbinic Coordinator, is an expert on kosher cheese production and has worked extensively in dairy supervision.