Kosher Dairy Primer – What is a Kosher Dairy Product

We are often confronted with many ingredients and products grouped loosely under the kosher Dairy category. The purpose of this discussion is to clarify what those products are and their Halachic status.

I. Hard Cheese

Fluid milk is composed of protein (primarily casein and whey, as well as some trace enzymes), lactose, butterfat, minerals, and water. “Hard” cheese is made by souring (fermenting) the milk to impart the desired flavor and then curdling the casein fraction of the milk. This curd forms a matrix, which entraps whey and fat to form cheese. Historically, milk was curdled by using an enzyme called rennin, which is a protease (an enzyme which affects protein) derived from the stomach of a suckling calf. In the times of חז“ל this enzyme came either from the flesh of the stomach itself (עור הקיבה) or from the milk found in the calf’s stomach (קיבה). Today, an extract is made from the stomach and is called rennet. More recently microbial rennets have been developed, where a microorganism produces “rennet” in a process called fermentation. While not true rennet, they are proteases that have functionality very similar to that of true rennet. An even more recent advance has been the development of genetically engineered rennet, where the microorganism has been modified with the genetic coding of a calf so that it produces virtual calf rennet.

All of these types of rennet cleave the casein protein molecule in a way that makes it precipitate forming cheese curds. Cheeses which use rennet as the primary coagulant (e.g. Cheddar, Muenster, Mozzarella) are called rennet set cheeses and are subject to the laws of גבינת עכו“ם. This גזירה applies equally both to cheeses made with microbial rennet as well as to those using animal rennet. In addition to conventional Kosher ingredient concerns, the גזירה of גבינת עכו“ם requires that a Mashgiach be present during the production and, according to many שיטות, he must add the rennet to each vat. The only exception to this requirement is where a Jew owns the milk, in which case only the ingredients are of consequence. Acid set cheese (such as cream or cottage cheese) is made by a different process and will be discussed separately. [See Section II below]

The manufacture of Kosher cheese involves the following additional Halachic concerns. Cheese is generally salted, and in the manufacture of many types of cheese this is done by soaking the cheese in a liquid solution of salt called brine. Brine used for non-Kosher cheese cannot be used to salt Kosher product due to the בליעות of גבינת עכו“ם in the brine. Changing brine is often not a simple matter since the spent brine cannot simply be dumped to the sewer (it fouls sewage treatment systems). Even if the brine were changed, the same brine tanks could not be used for Kosher cheese without Kashering.

There are a number of ingredient issues that are of concern in the manufacture of Kosher cheese. The rennet must be Kosher, either microbial or from special productions of animal rennet using Kosher calf stomachs. The cultures that are used to sour the milk must also be Kosher. In addition, some cheeses use additional enzymes to aid in the development of specific flavors, particularly lipase. Lipase is an enzyme which lipolyzes fat and is added to Romano, Parmesan and Provolone cheese to enhance their flavor. Such enzymes are generally made from animal tissue and are not Kosher. While they are not the מעמיד of the cheese, they are נותן טעם in it. Kosher microbial versions are available, as well as one derived from Kosher animal tissue.

Aged cheese has a much stronger and more complex flavor than fresh cheese, and these aged products are of great importance to the cheese connoisseur. Since aged cheese has a more potent flavor, it is this type of product that is used for cheese flavorings. In order to avoid the high cost of actually aging the cheese a product called enzyme modified cheese (E.M.C.) is produced. Fresh cheese is treated with various enzymes (protease and lipase) to hasten the degradation of the cheese and yield a product with an exceptionally powerful flavor. Such products have two Kashrus requirements. The first is that the original cheese must be גבינת ישראל and the second is that the enzymes used must be Kosher. Again, the typical enzyme blend used for these products is of non-Kosher animal material, so Kosher E.M.C. requires special formulation.

It should be noted that American Cheese is not a natural cheese and is more properly known as American Process Cheese Food. It is made by melting various cheeses (primarily Cheddar) along with additional ingredients into a homogeneous blend and extruding the molten cheese into blocks or slices. In addition to ensuring that the base cheese is Kosher, a thorough Kashering of the cooking and extruding systems must be done for each production.

The כלים used for the production of most other cheeses (e.g. Cheddar) generally do not require Kashering since the entire cheese making process takes place at temperatures of less than יד סולדת. Even though the cheese vat is heated, the cheese itself does not reach יד סולדת. This is not the case in the production of Swiss cheese, where the cheese is heated to about 126oF. Mozzarella and Provolone cheeses have an additional כלים concern in that the curd is cooked and stretched in a hot water bath and is extruded into molds while hot. The cooker as well as the molds must therefore be Kashered.

II. Soft Cheese

Acid set, or “soft” cheeses, include cottage, cream, and farmers’ cheese. These products involve curdling milk through an entirely different process. Casein protein can only remain in solution when the pH of milk is above 4.6. Acid set cheese is made by acidifying milk below that level, causing the casein molecule to become insoluble and precipitating out of solution. Classic cottage cheese was produced by allowing unpasteurized, bacteria laden milk to ferment, creating lactic acid which acidified the milk into a mixture of curd and whey. Since fluid milk is about 4% butterfat, this became the standard for regular cottage cheese. Modern production of cottage cheese, however, differs from the classic process. Milk is first skimmed to remove the butterfat (since cream will not readily curdle) and is then inoculated with a culture and allowed to ferment. [Some companies bypass this fermentation step and reduce the pH by simply adding phosphoric acid to the milk.] The curd is then separated from the whey, and a dressing made from milk and cream at about 20% butterfat is then added to the dry curd to make full fat cottage cheese. Lower fat cottage cheeses uses dressings that contain less cream and more gums and stabilizers. In addition to making two different types of cheese, acid and rennet set cheese each yield whey with different characteristics – acid whey and sweet whey [see below Section IV concerning whey].

The major Kashrus issue concerning acid set cheese is whether or not it is subject to the גזירה of גבינת עכו“ם. The גמרא discusses a number of reasons for this גזירה, including מפני שמעמידים בקיבת נבילה, מפני שטחין פניה בשומן חזיר, ומפני שמערבין בו חלב טמא עיי“ש. There is also significant discussion among the ראשונים as to whether the גזירה applies in situations where the reasons for the גזירה does not apply, such as in countries where cheese is not made with animal rennet or where there is no חשש ניקור. The מחבר follows שיטת הרי“ף והרמב“ם, and quotes the הלכה that all cheese is subject to the rules of גבינת עכו“ם even in cases where העמידו בעשבים. Accordingly, a concern of גבינת עכו“ם should exist with acid set cheese even though it does not use rennet as its primary coagulant. Rav Moshe Feinstein זצ“ל discusses this issue in response to a שאלה from Rav Schwab זצ“ל if there is a need למחות ביד אלו שאוכלים גבינה כזו Rav Moshe argues that since this type of cheese can be produced without any כלל העמדה (i.e. merely allowing the milk to ferment naturally will produce cottage cheese) and is markedly different from rennet set cheese (שהרי הוא ענין גבינה אחרת שלא דמי לא בטעם ולא במראה ולא נאסרו מעולם כלל אף לרמב“ם) it may not be subject to the rules of גבינת עכו“ם. He further writes that even if small amounts of rennet were used to make such cheeses it would still not be considered a “rennet set” cheese, since the primary coagulant is the culture and the rennet only serves to hasten the process. While Rav Moshe’s ruling referred only to the issue of not requiring a מחאה, other פוסקים consider such cheese equivalent to butter and permit it לכתחילה.

[The difference in the level of rennet used for the two types of cheese is quite clear. Acid set cheese uses no more than 2.0 ml of rennet per 1000 lbs. of dairy milk, while rennet set cheese generally requires between 50 and 90 ml of rennet for the same amount of milk. Since cheesemakers are very creative in choosing names for their products, the distinction between acid and rennet cheese must be based on an analysis of rennet usage (if any) as opposed to product name.]

III. Casein and Caseinates

In addition to being used to make cheese, casein protein is recovered from fluid milk and sold as a powdered milk protein. It is used in many products such as creamers, infant formula, and imitation cheese. Interestingly, due to an idiosyncrasy in American law designed to protect domestic milk producers, such products must be labeled as Non Dairy, although they are clearly Milchig.

Just as there are two means of making casein into cheese (acid set and rennet set) there are two analogous types of casein – acid casein and rennet casein. Acid casein is produced by adding hydrochloric acid to milk and drying the coagulum. [Another type of acid casein, called lactic casein, is produced by adding a culture to milk, allowing the fermentation to produce sufficient lactic acid to coagulate the milk. From a chemical perspective, both of these types of casein are essentially the same and are often lumped together as acid casein.] Rennet casein, on the other hand, is produced by adding rennet (either natural or microbial) to milk to form the coagulum.

While casein protein is a desired raw material, it is difficult to use because of its insolubility. This problem can be overcome with acid casein (both acid and lactic), however, by neutralization with alkali solutions (such as sodium or calcium hydroxide) with converts the casein protein into soluble casein salts (called caseinates). Acid casein is therefore the most common type of casein used, while rennet casein is usually reserved for the production of imitation cheese.

Based upon the position discussed above [Section II] concerning the distinction between acid set and rennet set cheese for the issue of גבינת עכו“ם, rennet casein is considered subject to the גזירה and requires a משגיח to be present for the production. Acid casein, on the other hand, is essentially acid set cheese and may not be so encumbered.

IV. Whey

After the milk has coagulated, it is cut into small pieces and heated to allow most of the non-coagulated fluid to separate from the milk. The fluid that is not curdled or entrapped in the curd is drained from the cheese as liquid whey, to which חז“ל refer as נסיובי דחלבא. This fluid is actually a mixture of whey protein, lactose, minerals and water. One means of separating whey protein from liquid whey is by heating the fluid until the protein precipitates out of solution, which is the process described in the ראשונים. Whey protein derived in this manner is called lactalbumin. When the protein is concentrated through ultra-filtration it is known as whey protein concentrate [WPC], and the liquid removed is called permeate. Being rich in lactose and minerals, this permeate is used as an animal feed, or the lactose is crystallized and recovered leaving almost pure water. Indeed, cheese companies have begun recovering this water and using it for cleaning purpose (with possible Kashrus ramifications).

חז“ל tell us that there is a component of milk called מי חלב which is not considered milk מדאורייתא. However, there is a ראשונים מחלוקת as to which component of milk does the גמרא refers to as מי חלב. Some שיטות maintain that נסיובי דחלבא (liquid whey) is מי חלב, while others hold that only the clear liquid derived from whey [called מימי חלב or permeate] is what חז“ל call מי חלב. According to these ראשונים, whey protein is חלב מדאורייתא.

According to many פוסקים, whey–while a direct result of the cheese making process–is not subject to the rules of גבינת עכו“ם. Rav Moshe Feinstein זצ“ל held that all whey could be מותר even if the cheese from which it was derived was made with animal rennet and even if the whey were cooked together with the curd (which is considered גבינת עכו“ם) at temperatures above יד סולדת. ויב“ל, Rav Wosner שליט“א holds that when non-Kosher rennet is used the whey is מותר, but prohibits any whey from עכו“ם גבינת which is heated together with the curd above יד סולדת. The policy of most Kashrus organizations is to permit whey recovered from גבינת עכו“ם productions but to be מחמיר and require that all ingredients used are Kosher and that the whey is not heated together with the curd to temperatures in excess of 120° F.

Mozzarella cheese plants pose another Kashrus issue that affects whey. Mozzarella curd must be cooked and stretched in a hot water bath. The water in which the גבינת עכו“ם is cooked must be constantly changed, and the spent water contains significant amount of butterfat and milk solids. The common practice in the industry is to skim the fat off this water and use it to make butter (see below Section VI concerning butter) and to mix the cook water together with the rest of the whey. Since this cook water is not considered Kosher, a השגחה for whey in such a plant poses serious problems and may affect the Kosher status of such whey according to all שיטות.

V. Lactose

Lactose, or milk sugar, is crystallized from whey or from whey permeate. Lactose is clearly מימי חלב (and is Pareve מדאורייתא but dairy מדרבנן) and there is a basis to consider all lactose as Kosher even if the whey from which it is derived would not otherwise be acceptable. [NOTE—the no longer relies on this leniency (which is described more fully in A-157) (DC-Jun 2003)]. Also, since lactose is invariably produced from whey, it would be subject to the previously discussed התרים of whey regarding חלב עכו“ם.

VI. Butter and Butter Oil

Another common dairy food is butter. Butter is classically made by churning fresh dairy cream so that the butterfat flocculates clumps together) and forms butter, leaving buttermilk behind (see below concerning buttermilk). Butter contains about 80-85% butterfat, the balance being water and other milk components. [A new process for the production of butter involves the separation of butterfat from cream using high speed centrifuges after which the butterfat is cooled in a Votator, similar to the production of margarine.] Butter in הלכה enjoys special consideration in that many שיטות do not consider butter to be subject to the restrictions of חלב עכו“ם. However, butter available today may indeed not have the same הלכה as discussed in the פוסקים.

While fresh dairy cream poses no Kashrus issues (see Section VII below concerning cream) other than concerns of חלב ישראל, other sources of cream are available. Whey, the byproduct of cheese making, contains a significant amount of butterfat which is collected and sold as “whey cream”. As previously discussed, Mozzarella cheese is cooked in a hot water bath, and the fat that leeches from the cheese into this water is also recovered and sold as whey cream (although this terminology is not wholly accurate). Cream from both of these sources can be used to make butter, and each has its own Halachic issues.

Whey cream is subject to the same Kashrus requirements as whey itself (see Section IV). Cream that is recovered from the cook water of non-Kosher Mozzarella cheese—where the cheese is cooked to temperatures well in excess of יד סולדת בו—is not acceptable. Since both of these types of cream are used to make butter, appropriate safeguards must be put into place to ensure that butter which is approved for Kosher use is not subject to these concerns. The USDA has established a grading system for butter. Grade AA is considered the highest quality, followed by Grade A, Grade B, and lower qualities. The basis for this grading is “organoleptic”—one of taste—the milder the taste the higher the grade regardless of the type of cream used. [Ironically, the butter with the more “buttery” flavor is graded lower than its blander cousin.] While it is true that fresh dairy cream has the freshest taste and is best suited for the manufacture of Grade AA butter, it is also the most expensive. Whey cream suffers some degradation during the cheese process and typically has a stronger flavor—but it is also less expensive. Butter makers are adept in blending various grades of whey to be able to obtain a Grade A – or even a Grade AA – butter from less than pure fresh dairy cream.

“Butter oil” and “anhydrous milk fat” are made from butter which is heated to remove the milk curd and moisture, leaving pure milk fat. Kosher concerns for this type of product are complicated by the fact that the typical butter used for this purpose is lower grade material, the type most often made from whey cream.

Another common butterfat ingredient is lipolyzed butter oil (L.B.O.). This material is made by treating cream or butter oil with a lipase enzyme to give it an extremely pungent buttery flavor. Again, lipase routinely used for this purpose is derived from non-Kosher animal tissue, so a reliable Hashgacha for this type of product is imperative.

Other issues relating to “pure” butter involve the use of various ingredients added to the product. Lactic acid, cultures, diacetyl, and starter distillate (in addition to salt) are often added to butter to improve its flavor. These ingredients, while generally Kosher, may pose issues regarding חלב ישראל.

VII. Buttermilk and Cream

There are other Dairy ingredients which may be confusing. “Cream” may not be pure cream and “buttermilk” may have nothing to do with butter. “Whipping” cream often contains emulsifiers, gelatin, and other ingredients—clearly not the fresh cream skimmed from the top of milk bottles.

There are also “two דינים” in buttermilk. True buttermilk is the fluid left over after churning cream into butter. This is generally the “powdered buttermilk” used in industrial applications such as ice cream and baked goods. As we have noted, butter may be made from whey cream and such buttermilk is therefore subject to the same Kashrus considerations as butter made from non-Kosher whey cream as discussed above. The “buttermilk” sold in the refrigerated section of the supermarket, however, usually is completely unrelated to butter manufacture. It is actually called “cultured buttermilk”, and is made by adding a culture to skim milk, along with emulsifiers and stabilizers which may include non-Kosher glycerides and gelatin.

OU Kosher Staff