Prof. Dr. Ir. Sri Kumalaningsih, M.App.Sc Process of yogurt and Cheese Prof. Dr. Ir. Sri Kumalaningsih, M.App.Sc

What is Yogurt? Bacterial fermentation of milk Lactobacillus acidophilus bacteria consume the sugar in milk (lactose) and produce lactic acid Lactic acid gives yogurt a tangy flavor, coagulates the milk proteins, and preserves the yogurt

Is Yogurt Nutritious? High in: Protein Calcium Riboflavin Vitamin B6 & B12 Many people who are lactose-intolerant can eat yogurt May aid in digestive tract health

Production line for set yogurt

To get the milk from the cow Standardisation: allows to make consistent the composition of milk coming from various farms Then the milk is going to a tank (a skimer) for adjusting the level of fat

Degassing: The aim of degassing is to take off the bad smell of the milk After that there is a homogenization and pre pasteurization, that the goal is to kill bacteria. Pre pasteurization is done in few secondes at 75°C. And after is cooled at 5°C

Adjust milk composition and blend ingredients homogenize

Pasteurize milk The aim is to kill pathogenic bacteria in heating at 72°C, and cooling again Bacterial fermentation During the fermentation, the production of lactic acid by the bacteria modify the structure of proteins in the milk

The lactobacillus bulgaricus bring acidity to the milk The streptococcus thermophilus develop aroma

Packaging The yogurt is pumped from the fermentatio vat and packaged as desired

Incubation The yogurt is putting in a steam room, at 42-45°C during 3 hours until having an acidity around 70°D Storage in an cold room The quick cooling keeps the acidity

KEJU Free Powerpoint Templates

Berdasarkan keras tidaknya Keju Keju lunak Contoh : keju krim (cream cheese), quark, cottage, camembert, dan roquefort Keju keras Contoh : cheddar, gouda/edam, emmenthal, parmesan dan mozarella. Keju semi lunak Contoh : muenster dan stilton.

Pembuatan Keju Bahan yang dibutuhkan: susu sapi, garam dapur, stabilizer, susu skim, dan starter mikroba: Lactobacillus bulgaricus, Streptococcus lactis Diagram alir 

Starter Culture 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. (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. 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. 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. Acid based casein can undergo further processing to create other casein products known as caseinates.  Caseinates are used in other food ingredient applications. 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.