We are going to begin by defining some items used in the cheese making process that we will need to be familiar with to understand this class.
As its name implies, the starter culture is the first ingredient added to pasteurized milk to make cheese. Milk is pumped into a cook vat where starter culture containing specific bacteria are added. That bacteria forms acids in the milk, lowering the PH to a critical acidity level. It causes the lactose in the milk to turn to lactic acid. It is the culture which gives different cheeses their special characteristics. If the specific temperature is not maintained, the bacteria in the starter culture fail to multiply and the cheese process could not continue. Starter culture certainly needs to be kosher, and some agencies require that, as a coagulant, it needs to be put into the cook vat by a mashgiach for reasons we will discuss. Kosher symbol
Rennet Rennet will be the single most discussed ingredient we will deal with. First let us define what it is, and then we will discuss what it does, after which, we will discuss why it is such a halachically sensitive ingredient. There are two types of rennet, animal rennet and microbial rennet. Animal rennet is a complex of enzymes produced in the abomasum of a calf. The abomasum, pictured below, is the fourth stomach of a calf. These enzymes are only produced in the abomasum of a calf, and are used as the main ingredient to coagulate milk into curds which eventually form cheese. In earlier generations, cheese making involved putting a piece of an abomasum or the scummy contents of an abomasum into milk to cause it to coagulate. Nowadays, rennet can be extracted from the glands of the abomasum.
Rennet The second type of rennet, microbial rennet, is widely used today in cheese productions. This rennet is produced by growing the protein on microorganisms. These rennets are readily available with reliable kosher certification, and can cause the same coagulating effect as animal rennet when added to milk. In my experience, many more cheese factories use microbial rennet than animal based rennet today, although animal rennet is used in more expensive artisan cheeses. It should be noted that the bulk of today’s cheese manufactured in mainland Europe does contain animal rennet. Furthermore, lipase—an enzyme added to some cheeses to hasten the breakdown of fat and endow a more powerful flavor—is almost always animal-derived (lipase is extracted from the tongues of domesticated animals), although artificial lipase substitutes are becoming more widespread. Romano cheese is usually treated with goat, lamb or kid lipase, and blue cheese often contains calf lipase.
Rennet Before we get into our sources for this evening, it is important to know that all ingredients going into cheese would need to be kosher; therefore, producing cheese with rennet from a calf that was not properly slaughtered in accordance with halacha would render the cheese non kosher. Animal rennet and lipase can be kosher, however. If the kosher source animal is slaughtered, de-veined, salted and processed according to kosher law, its rennet and lipase are fine for kosher use. (There is no halachic problem with using animal-derived enzymes in cheese [mixing meat and milk] since the amounts used are miniscule. Moreover, the enzymes are not cooked with the milk, and they are flavorless. Still, even cheese made with glatt kosher animal rennet and lipase is forbidden when manufactured by non-Jews, which will be the main discussion of our class.
Curds The rennet that allows the milk to coagulate and set. The coagulated milk is formed into a smooth, custard-like solid called the curd. Finally, the curd is ready to be cut which means that the cheesemaker breaks up the curd, separating a rich, cloudy liquid from the solid pebble-like curds. The liquid cloudy water is known as whey, and the pebble-like curds is the basis of the cheese.
Whey Whey is the basic by-product of cheese manufacturing. It is the portion of the milk that did not precipitate out of the milk and form cheese curds. The milk’s casein protein and much of its fat exit the milk and become curds. The remaining milk material, no longer white and thinner, is whey. Liquid whey is rich in protein, lactose and minerals. Whey's functionality has only been realized in the past 25 years. But general use of nisyovay d'chalvah, whey, has been known for thousands of years and is mentioned in the Talmud.
Whey There are many products made from whey. Often, liquid whey is used in making Ricotta cheese. The process includes cooking liquid whey at very high temperatures with live steam. An acid, usually acetic acid or vinegar, is added, resulting in a curded ricotta cheese. Some companies substitute milk instead of whey to make the ricotta. Whey is also used to create whey cream butter. Like whole milk, whole liquid whey can be separated into sweet whey and whey cream. The whey cream can be added to regular milk cream and be churned into butter or the whey alone can be churned into whey cream butter. Just like kosher whey, kosher whey cream butter would be acceptable. One of the most prevalent whey products is powdered whey. Through a water filtration process known as osmosis, whole liquid whey can be separated into its basic components, i.e., whey protein and lactose. Today, whey protein and lactose are used for a host of food applications. However, it is impractical to use them in their liquid form. When used as food ingredients, they are dried into a powder. A popular technology used to dry these ingredients is known as spray drying.
Casein and Caseinates Casein is the main protein found in milk and subsequently found in the cheese curds. Casein is used in a plethora of food applications, and defines cheeses that are used as an ingredient in industrial applications. It can be used as an emulsifier in coffee whiteners, a stabilizer in ice cream or a thickener in soups, gravies, or whipped toppings. It can also be used to provide texture to pasta, nutritional food bars or bakery products. Casein, like cheese can be created by adding either rennet or acid to milk to cause it to coagulate. Acid based casein can undergo further processing to create other casein products known as caseinates. Caseinates are used in other food ingredient applications. When the wet casein is mixed with sodium hydroxide, the resulting product is known as sodium caseinate. This is a popular ingredient which, among other things, may be used as an emulsifier in coffee whiteners, a nutritional ingredient in bakery products, nutritional food bars and beverages, as well as a thickener in soups and gravies. Casein can also be combined with calcium (lime) to create calcium caseinate, an ingredient in cereals such as Special K.
Rennet Based Cheese Vs Acid Based Cheese There are two main methods for curdling cheese. The first is adding animal or microbial rennet to coagulate the milk. Rennet based cheeses form more solid curds that can be easily separated from whey. The second method of creating cheese involves adding acidic bacterial cultures to cheese to cause it to coagulate. The resultant cheese curds are softer and are harder to separate from the whey. Often, a small amount of rennet is also used in creating acid based cheese. Rennet based cheese is often referred to as hard cheese while acid based cheeses are referred to as soft cheeses. Rennet based cheeses include cheddar, mozzarella, provolone, and hundreds of others. Acid based cheeses include cream cheese, cottage cheese, and farmers cheese.
Review Starter Culture- first ingredient added to pasteurized milk to make cheese. Made of specific bacteria that form acids in the milk, lowering the PH to a critical acidity level. Rennet- the main ingredient to coagulate milk into curds which eventually form cheese. Can be animal based or microbial. Curds-coagulated milk is formed into a smooth, custard-like solid called the curd. Whey- the basic by-product of cheese manufacturing. It is the portion of the milk that did not precipitate out of the milk and form cheese curds. Casein- the main protein found in milk and subsequently found in the cheese curds. Defines cheeses that are used as an ingredient in industrial applications. Rennet based cheese- Cheese whose main coagulant is rennet. It is often referred to as hard cheese, as it forms more solid curds than acid set cheese. Acid Based Cheese- Cheese whose main coagulants are acids added to the milk. It is often referred to as soft cheese, as it forms softer curds than rennet set cheese.
Sources I. Original Source: Mishnah Avodah Zarah 29b אמר רבי יהודה, שאל רבי ישמעאל את רבי יהושוע כשהיו מהלכין בדרך, " מפני מה אסרו את גבינת הגויים ?" אמר לו, מפני שמעמידין אותה בקיבת נבילה... R. YEHUDAH SAID: R. YISHMAEL PUT THIS QUESTION TO R. YEHOSHUA AS THEY WERE ON A JOURNEY, 'WHY,' ASKED HE, 'HAVE THEY(THE SAGES) FORBIDDEN THE CHEESE OF NON JEWS?' HE REPLIED, BECAUSE THEY CURDLE IT WITH THE RENNET OF A NEBELAH (AN ANIMAL THAT WASN’T SLAUGHTERED PROPERLY)...(TAKEN FROM THE SONCINO TRANSLATION, AVODAH ZARAH 29B) II. Shulchan Aruch ( YD 87:11): “IF ONE COAGULATED MILK WITH THE SKIN OF A KOSHER CALF ABOMASUM, IF THE RESULTANT MIXTURE HAS A TASTE OF MEAT- IT IS FORBIDDEN, IF IT DOES NOT- IT IS PERMITTED.” III. Shach ( YD 87:11 SS 34): “IF IT HAS A TASTE OF MEAT- MEANING, IF THE MILK DOES NOT CONTAIN ENOUGH LIQUID TO NULLIFY THE PIECE OF ABOMASUM BY A RATIO OF 1/60.”
Sources IV. Shulchan Aruch ( YD 115:2): “CHEESE PRODUCED BY NON-JEWS IS FORBIDDEN BECAUSE THE COAGULATE IT WITH THE ABOMASUM OF AN IMPROPERLY SLAUGHTERED CALF, EVEN IF IT IS PRODUCED USING VEGETABLE SOURCES.” V. Rama ( YD 115:2): “IF A JEW SEES THE CHEESE BEING PRODUCED AND THE MILKING, IT (THE CHEESE) IS PERMITTED. AND SO IS THE CUSTOM IN ALL OF THESE COUNTRIES…” VI. Shach ( YD 115:2 ss 20): “WITH REGARD TO CHEESE MADE BY A NON-JEW UNDER JEWISH SUPERVISION, THE JEW NEEDS TO BE ACTIVE IN THE CHEESE MAKING PROCESS, MEANING- TO INSERT THE PIECE OF ABOMASUM INTO THE MILK. IF THE NON-JEW DOES IT, EVEN SUPERVISED AND WITH KOSHER INGREDIENTS, THE CHEESE IS FORBIDDEN.”