An exhibition on the science of cheese curated and designed by Jake Walker at the St. Louis Science Museum.
Jake Walker 1918 Seven Pines Dr. Saint Louis, Missouri 63146 Š2012 by Jake Walker All Rights Reserved Published by Sloppy Joes Publishing Co. Saint Louis, Missouri This book cannot be used or reproduced in any manner without consent from publisher.
This book is dedicated to anyone who has ever pushed me to try harder.
Table of Contents Foreword
13
The Importance of Milk
14
Bacteria Culture
16
The Addition of Rennet
19
Separating the Curds and Whey
21
Shaping the Cheese: Molding
22
Old Age, the Final Step
24
Acknowledgement
27
12
Foreword There are very few people on this planet that don’t like cheese. It seems to be a staple in most homes. It can be eaten by itself as a snack or incorporated into a dish to make a meal that much more tasty. Surprisingly, with how popular cheese is, not a whole lot of people know how it’s made, or once they do learn they’re grossed out. Truth is, it’s not that disgusting. It’s also not that hard. In fact, you could make your own cheese at home if you wanted to, and a lot of people do. The purpose of this booklet is to break down cheese making into simple steps to help you understand just what goes on when it’s made. Who knows, maybe you’ll go out and make your own once you’re done!
The Importance of Milk Cheese starts with milk. This milk can come from cows, goats, sheep, or buffalo. Most cheese that we eat in the United States comes from cows. The temperature this milk is kept at will effect the cheese that is made. The milk will come from either the cow, goat, sheep or buffalo, and head to either a cheesemaking facility, or a small artisan cheese maker. If it’s going to a big facility, it’ll travel in a big truck. It’s also possible to make your own cheese at home, with milk from the store and the right ingredients. The quality of the milk is of utmost importance. If using raw milk in cheesemaking it has to be perfect, or it will create flaws in the cheese. Before it can be used to make the cheese though, it has to be pasteurized to make sure it’s safe to consume in the long run. It is unsafe to use sour milk before the cheesemaking process begins because it can harbor harmful bacteria. Once pasteurized, the milk is off to the facility to have other ingredients added and eventually become delicious cheese for you to consume.
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Fig. 1 The four animals from which milk for cheese can come from. Cow's milk is the most popular.
Bacteria Culture A lot of people know in the back of their head that cheese has bacteria in it, but they don’t like to think about it. The thing is, the bacteria affects exactly what type of cheese will come out of this process, and it plays a huge role. The bacteria will sour the milk, and thus begin the cheese making process. As mentioned before, the type of bacteria used will affect the type of cheese that is made in the end. For instance, the bacteria Penecillium Roqueforti is used in the ripening of blue cheese. This is the bacteria that causes the blue veins and ‘off’ smell in these types of cheeses. These fungi is found commonly in nature and is believed to have been discovered by cheesemakers ageing their cheese in cool, damp caves.
16
Fig. 2 A close up of the bacteria Penecillium Roqueforti, the bacteria that causes the blue, veiny appearance in blue cheese.
Milk and Bacteria
Fig. 3 Rennet is added to the milk and bacteria mixture to cause it to coagulate and separate into curds and whey.
18
Rennet
Curds Separating from Whey
The Addition of Rennet Before the milk and bacteria concoction can become cheese, it needs to coagulate and separate into curds and whey. In order for this to happen, rennet is added. Rennet is an enzymefound in the stomach of calves. This enzyme causes the milk to curdle. Rennet contains an enzyme called chymosin that is traditionally obtained from the “abomasum� (fourth stomach) of a newborn calf or lamb. Adult mammals don’t have this enzyme--newborn calves and lambs need it to help digest and absorb milk. Almost all European cheeses still use animal rennet. Vegetarian rennet has been obtained from fig leaves, melon, safflower and wild thistle, but most commercially available non-animal rennet is now produced in laboratories from fungal or bacterial sources (not sure if they use baby fungi and bacteria or not), and works like the animal-based product.
Fig. 4 The curds being cut to separate them from the whey. In this case a rake-like object will move through the mixture to separate the two.
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Separating the Curds and Whey With the curds and whey formed and loosely separated from each other, the curds need to be cut up into smaller pieces to be sufficiently separated and able to move on in the cheese making process. If being made in a cheese making factory, the curds will be cut either by hand or machine with a giant rake. How much they are cut will again depend on the type of cheese being made. Softer cheeses will have more whey still in them with bigger curds, where as harder cheeses like cheddar have really small curds and almost no whey in the end. The whey will go on to become a byproduct. Whey protein, which is derived from the whey, is commonly found as whey protein powder, and is used by many body builders. Food scientists are working on a way to convert whey into lactic acid. Lactic acid is an organic acid used as an acidulant in the food industry. More recently it has been used to produce polylactic acid, a biodegradable polymer and as a new method to treat meat carcasses to combat E. coli bacteria. Conversion of whey permeate to lactic acid is environmentally sound because it produces a valued product from an otherwise waste stream.
Shaping the Cheese: Molding Once the curds and whey are successfully separated from each other as much as they need to be, the curds are ready to be pressed and molded. Molding is important in cheese making because without it the cheese would have no shape and the curds would not bond to each other. Basically the cheese just wouldn’t exist in its right form. When being put into a mold the cheese will be pressed. The pressure will depend on the type of cheese. The harder the cheese, the harder it will be pressed. This causes more whey to be squeezed out, thus resulting in a hard, dry cheese. If the cheese is to be a softer, moist cheese, it won’t be pressed nearly as hard or in some cases not at all. The key to this is keeping more of the moisture of the whey in with the curds and letting it bond that way
22
Cheese Coming Out of the Tank
Cheese Press
Pressed Cheese
Fig. 5 Curds falling into a mold, and then being pressed to form a wheel of cheese.
Old Age, The Final Step Some soft cheeses like cottage cheese and cream cheese can be sold as soon as they’re processed completely. However, most cheeses (or at least the good ones, in my opinion) need to age before they’re sold and on your plate. Once again, how long the cheese ages depends on the type of cheese being made. Hard cheeses such as Cheddar and Parmesan can be aged for several years, where as mentioned before, softer cheeses are almost always ready to go right out of the vat. The rooms cheese ages in are temperature controlled. The aging cheese has to be checked on frequently to make sure it isn’t over aged or moldy. Below is a brief aging chart to give you an idea of the scope of time needed to age some cheeses.
Aging Times Monterey Jack Parmesan Bleu Cheese 24
Brie
1 month 12+ months 3 – 6 months 6 weeks
Fig. 6 Cheese aging on shelves. Cheeses such as Parmesan and Cheddar would age just like this.