About Kosher Laws
Jewish Involvement in Kosher Food Preparation
Thousands of years ago, the rabbis of old recognized that Jewish identity is the key to the survival of the Jewish people. To this end, they enacted three sets of food laws to limit assimilation: Bishul Yisrael, Pat Yisrael, and Stam Yeinam (cooked food, bread, and wine prepared by non-Jews, respectively).
These enactments were based on the realization that bonds of friendship are established by eating together, and breaking bread with a stranger is the first step to developing a closer relationship.
Throughout thousands of years of exile, the biblical and rabbinic laws of kashrut have formed a fortress that protected the Jewish people from assimilating into the many different cultures of the world and helped keep their Jewish identity and communities intact.
On this page:
2. Pat Yisrael
3. Stam Yeinam
More than two thousand years ago, the rabbis prohibited eating certain foods cooked fully by non-Jews in order to limit socialization that might lead to intermarriage. This prohibition is known as bishul akum. Food that has a bishul akum status, meaning that it was fully cooked by a non-Jew, is no more kosher than a sandwich of cold roast beef and cheese: it is not kosher even though the ingredients used to prepare the food were initially kosher in and of themselves.
There is a dispute among the Rishonim (the Sages of the Medieval period) as to whether the prohibition against bishul akum is obviated when a Sabbath-observant Jew contributes to the cooking process by lighting the fire before a non-Jew places a pot of food on the stove. The major codifiers of Jewish law argue this point as well.
Rav Yosef Caro (1488-1575), author of the Shulchan Aruch (the Code of Jewish Law), subscribes to the stringent opinion, and this is the custom practiced by Sephardic Jewry. According to this view, a Sabbath-observant Jew must place the pot on a burning fire in order for the food be considered bishul Yisrael (“Jewish cooked”). Alternatively, a Jew may turn on the fire after a non-Jew has placed the pot on the cold stove.
Rema (Rabbi Moshe Isserles, 1520-1572) follows the lenient opinion and allows a non-Jew to place raw food on a fire that was lit by a Jew. Since the Jew has a share in the overall process, the food is not considered to be bishul akum.
Rema goes one step further, and writes that if a Jew has even a partial role in preparing the fire, bishul akum does not apply. For example, if a Jew added a wood chip or any other fuel to the fire, or if a non-Jew lit a fire from another fire that was originally lit by a Jew, there is no restriction of bishul akum. In both of these instances, the fire is considered aish Yisrael (fire of a Jew) because of the involvement of the Jew.
Jews of Ashkenazic descent follow this ruling and, accordingly, a non-Jew may turn on a gas burner that is ignited from a pilot light that was lit by a Jew. However, since stoves with pilot lights are no longer common, it is important that observant Jews realize the serious kashrut concerns associated with meals prepared by non-Jewish domestic employees.
Baked items made from the five grains (What are the five grains?) usually fall into the category of bread and as such are not subject to the prohibition of bishul akum (which applies to cooked foods only).
The Mishna in Avoda Zara (35b) tells us that Chazal forbade pat akum (bread baked fully by a non-Jew). The Gemara explains that this was done as a precaution to avoid intermarriage (Avoda Zara 36b). However a later Beit Din removed this prohibition (Tosafot A.Z. 35b s.v. Michlal).
The exact extent of this retraction is a disagreement between the author of the Shulchan Aruch and Rema. While all agree that bread baked by an akum for personal use is still forbidden, there are differing opinions as to how careful one must be to avoid eating pat palter, bread baked by a non-Jew for the purpose of selling. There is a machloket (disagreement) between the author of the Shulchan Aruch and Rema as to whether one may eat pat palter when pat Yisrael is available.
Rema (Torat Chatat 75:1; Darchei Moshe (O.C. 242) says that the general custom is to permit pat palter even if pat Yisrael is readily available (except during the Aseret Yemei Teshuva, Shabbat, and Yom Tov, when one should try to be as strict as possible). However, the Shulchan Aruch (Y.D. 112:2) says that one may only be lenient to purchase pat palter if pat Yisrael is unavailable or of inferior quality. Sephardim follow the opinion of the Shulchan Aruch while Ashkenazim follow Rema.
For bread to be considered pat Yisrael, a Jew must have some involvement in the baking of it. Therefore it is considered pat Yisrael:
If a Jew places the bread into the oven
If a Jew turns on the oven
If a Jew raises the temperature of the oven, causing more gas to flow, even if he subsequently lowers it.
The pat palter leniency only applies to breads or pat haba b’kisnin (cakes, cookies, etc…). Pastries that are cooked or fried, even though the blessing made on them is Mezonot (such as blintzes and cannolis), may be subject to the halachot of bishul akum.
Although the Taz (Y.D. 112:7) says that the leniency of pat palter does not apply to Jewish-owned bakeries in which a non-Jew bakes the breads without involvement of a Jew. Iggrot Moshe (Y.D. I:45) explains that this is only applicable to small bakeries in which the bread could have been baked by the Jew without the need for hiring employees. In an industrial bakery that has many employees this rule does not apply.
1. Rav Belsky, an OU rabbinic authority, has said that if a Jew turns on the fire or raises the temperature, even if the oven is subsequently turned off and turned back on by a non-Jew, the bread baked in the oven can still be considered pat Yisrael, so long as the oven did not cool down to below 176 degrees Fahrenheit (80 degrees Celsius). This is the approximate lowest temperature at which foods will still cook. Since the dough will eventually cook in this oven even without the non-Jew turning back on the fire, it is considered pat Yisrael.
Although one may argue that turning up the thermostat and allowing more gas to flow is simply a gramma and should not be considered a full involvement of a Yisrael, still Rav Belsky explained that since this is the ordinary way in which people bake, for the purpose of pat Yisrael it is adequate.
2. The OU does not accept the use of a light bulb or glow plug in maintaining pat Yisrael, since this will not cause the oven to maintain 176 degrees Fahrenheit. If a heating rod can be installed that will permanently heat the entire oven to 176 degrees Fahrenheit, then this is acceptable.
All grape juice, grape wines or brandies must be prepared under strict Orthodox rabbinic supervision and may not be handled by non-Jews. However, once a kosher wine has been cooked, no restrictions are attached to its handling. Such products are generally labeled "mevushal" (cooked).
What Is the Meaning of Chalav Yisrael?
During the time of the Mishna, our Sages enacted a number of special kashrut rules designed 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 milk from cows and sheep 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. They issued a special enactment to the effect that, unless milk was supervised by a religious Jew from the time of milking, there was no guarantee that the milk was not adulterated and it is to be considered completely non-kosher. Supervised milk is referred to as chalav Yisrael and is kosher.
This law is referenced in the Mishna, the Gemara and the Shulchan Aruch; the requirement that milk be supervised is binding 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 of the American milk supply by the USDA, the question was posed as to whether we are able to rely on such supervision to fulfill the requirement for chalav Yisrael.
This question was most recently addressed by Rabbi Moshe Feinstein (1895-1986), 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 Jewish law and is equivalent to chalav Yisrael (Iggrot Moshe, Yoreh Deah 1:47-49).
Rav Moshe based his ruling on the legal principle that, given the nature of governmental control of the milk supply, we are considered to have direct knowledge of the status of the milk. In addition, other rabbis are of the opinion that the Sages’ requirement for Jewish supervision of milk was limited to locations where adulteration is prevalent, or where non-kosher milk is widely used. According to both of these opinions, regular milk sold in the United States is kosher and is commonly referred to as chalav stam. This position has been accepted by the OU as well as most major kosher certifying agencies in the United States.
You may still see packages bearing the OU symbol, or the symbols of other kosher certifying organizations. It must be noted that any milk which bears an OU-D symbol means that the OU visits the milk facility and assures that the production equipment is either dedicated exclusively to milk or is formally kashered for milk production. Presence of the OU-D symbol on milk also indicates that all vitamins in the milk are kosher. The OU-D symbol does not signify chalav Yisrael status, unless specifically noted on the packaging.
Of all dairy products, kosher certification of cheese is the most difficult. The Mishna (Avodah Zarah 29b, 35a-35b) states that gevinat akum – cheese made by a non-Jew – is rabbinically prohibited. Many reasons are offered in the Gemara (ibid. 35a-b) as to why the Sages forbade gevinat akum. Many prominent authorities, including Rif, Rambam and the Shulchan Aruch, follow the rationale advanced by the Sage Shmuel, who states that the enactment against gevinat akum is due to the use of non-kosher animal rennet by non-Jews in their cheese-making.
Rennet is the enzyme that turns milk into cheese (as will be seen in more detail below) and it originates in calf stomach lining. Since rennet was traditionally derived from the lining of a calf’s stomach, the Sages forbade cheeses not made under onsite rabbinical supervision because of the likelihood that they contained rennet from calves that had not been slaughtered in accordance with Jewish law.
It is important to note that the prohibition against gevinat akum is not at all related to the kosher regulations regarding milk (chalav stam, unsupervised milk, and chalav Yisrael, milk under onsite rabbinical supervision). Even those who consume chalav stam are fully bound to adhere to the prohibition against eating gevinat akum. Gevinat akum is deemed non-kosher under all conditions, rendering the utensils and cookware used in making and serving it non-kosher as well.
How does one manufacture gevinat Yisrael? Rema stipulates that a Jewish presence is required when the cheese is made, and Shach (Rabbi Shabbatai ben Meir HaKohen, 1621–1662) argues, maintaining that a Jew must personally add the enzyme that forms the cheese.
The supervision provided by most kashrut agencies normally fulfills both opinions, such that when the mashgiach (kosher-food supervisor) is present for cheese production (thereby fulfilling Rema’s requirement), he personally adds the rennet enzyme to the milk for each batch of cheese (thereby fulfilling Shach’s requirement).
In the case of many newer cheese factories, which use automated rennet feeders rather than manual incorporation of rennet into cheese vats, the mashgiach activates the rennet feeder for each vat, entering the control room for this purpose every 45 minutes or so to be ready for the next cheese production.
In the event that the mashgiach cannot monitor vat activity from this area, as well as in cases in which the milk or rennet is Jewish-owned, many kashrut agencies require the mashgiach to also maintain a presence at the vat location, so as to be sure to provide the physical supervision as stipulated by Rema.
What kind of cheese must be gevinat Yisrael? Common practice, adopted by many kashrut agencies, is to follow the opinion that that the prohibition of gevinat akum was only declared on hard cheese, as only hard cheese uses rennet to form into curd and was therefore subject to such a prohibition.
Soft cheese, such as cream cheese, cottage cheese, and so-called “acid-set cheese,” does not need rennet to coagulate. Since it can acidify and form on its own, such cheese is not subject to the rule of gevinat akum. Nonetheless, some other authorities maintain that even soft cheese is subject to the enactment of gevinat akum.