Cheese making through different protein coagulation methods Flashcards
What are the percentages of different proteins in milk?
20% whey and 80% casein
How is cheese made using the acid-precipitation method?
When milk is acidified to its isoelectric point at pH4.7, an isoelectric precipitate of casein is formed and known as acid casein. The acid neutralizes the negative charge of micelle surface and destabilize it. Simultaneously, the acidity increase the solubility of minerals such that organic calcium and phosphate contained in the micelle gradually become soluble in aqueous phase, Cottage cheese is made using this process
How is cheese made using the rennin?
What are glycomacropeptide?
What are para kappa caseins?
Using the enzymatic precipitation, the rennin or rennet cut the kappa casein molecule between the 105 phenylalanine and 106 methionine into para-kappa casein and glycomacropeptide. The hydrophillic glycomacropeptide is released into whey because it is hydrophilic. Para kappa casein are unable to stop the precipitation of caseins. The ends of the micelle surface are cut and cause micelles to disintegrate, no longer polar and repelled by water, this releases the other 3 forms of casein into the milk. This causes the caseins to float around and precipitate, which results in clumps, that are casein protein matrix that traps fat and water.
What is the site of cleavage using rennin?
between 105 at N terminus and 106 at C terminus
Phe at N terminus and Met at C terminus
Kappa casein via chymosin becomes para kappa casein and glycomacropeptide
Para kappa casein start from N terminus to 105
Glycomacropeptide start from C terminus to 106
How are soy proteins precipitated?
Soy proteins are mainly globulins and precipitated via the addition of magnesium sulphate. Preciptate form by the binding between positively charged magnesium ions and negative charge anionic proteins
What are the 11 steps of cheese making?
What are the specialized steps?l
Choosing of milk, Milk preparation, Coagulation, Cutting, Scalding, Curd maturation or Acidification, Stretching, Shaping, Salting, Sale, Ripening or Maturation
Milk preparation, scalding and curd maturation and shaping
Describe the 11 steps of cheese-making
Step 1 Choosing of milk involves the sourcing of the milk. It can be from buffalo, sheep, goat or a mixture of milk from different species. Hence, there are goat cheese, sheep cheese, buffalo cheese and mixed milk cheese
Step 2 Milk preparation: Not all technologies include this phase, milk is treated as to render suitable for specific transformation (heating, pasteurization, skimming and milk enzyme addition).
Step 3: Coagulation: Milk is transformed into a curd in this phase. Coagulation refers to a liquid turning into a gel-like substance. There are 3 methods. By acid, the pH of milk is lowered to pH4.6 and allow the casein and milk proteins precipitate. By rennet, rennet is the commercial form is rennin, added to milk. By mixed, acid is used with small amounts of rennin added.
Step 4: Cutting: A curd is transformed in proteins of granules of different sizes depending on the kind of cheese.
Step 5: Scalding: Some technology wants the curd to be partially cooked (45 degree Celsius) or fully cooked
(55 degree Celsius) . Hence, there are partially cooked cheese and cooked cheese.
Step 6: Curd maturation: Only used in the production of stretched curd cheeses cheeses characterized by an elastic string curd
Step 7: Stretching:
Step 8: Shaping: Shaping is the word when one makes pasta filata cheese. The mass is shaped into the desired shape. Instead for the other types of cheeses, after the breaking and scalding, curd is put into appropriate molds where it obtains its final shape and size.
Step 9: Salting: Cheese can be salted when already dry. Salt can be sprinkled directly on the cheese or brined (cheese are kept in a salty solution for a period of time, 12 hours per kilogram)
Step 10: Sale: Only fresh cheeses are sold at this stage
Step 11: Ripening or maturation: Fresh curd becomes matured cheese. Ripening needs an environment with a specific temperature and humidity. Throughout this resting period, the proteins and fats in the curd are responsible for the aromatic characteristics of final products, The ripening phase can last several months or years.
Describe the 2 types of cheese in the cutting stage
Large granules of cheese of around a size of a nut contains high % of water makes soft, fresh cheese
Small granules of cheese of around a size of a rice grain contains low % of water makes hard, ripe cheese.
There is a vast range of food used for the cutting process, knife, curd-knife.
fun quiz what is the pasta filata technique?
Pasta Filata cheeses are cheeses for which the curd has been worked or stretched and molded at elevated temperatures before cooling. Mozzarella, Provolone, Caciocavallo, and Queso Oaxaca are made with this technique.
What did we do in practical 2?
We produced acid precipitated casein and rennin coagulated casein.
120ml of milk is heated to 40 degree Celsius and removed from heat, 10ml of vinegar is added in warm milk and allowed to sit for 5-10 minutes. Casein is filtered using filter paper and funnels. Precipitates are weighed and recorded.
120ml of milk is heated to 43 degree Celsius and removed from heat. Half crushed rennet tablet is poured into the heated milk and allowed to sit for 5-10 minutes. The other half tablet is then used, stirred and allowed to sit for 5 minutes.
Is rennet more effective than acid-precipitation?
What is the difference between rennet-made cheese and acid-made cheese?
Rennet is more effective than acid in coagulating milk because it structurally cuts the micelle whereas acid cause structural change of the micelle. Addition of H+ decreases the net charge of the caseins and cause the solubilization of colloidal calcium phosphate from the micelles in the solution, resulting in the collapse of micelle surface hairy layer. The micelles can then cluster around at pH4.6 forming cheese curds. On the other hand, rennet cuts the negatively charged part of the micelle surface hairy layer, allowing the micelles to cluster together without the opposite negative charges repelling each other away, thus forming casein precipitates which trap air and water.
rennet-made cheese is firmer and robust as these is no loss of minerals into the aqueous phase. Acid-made cheese is softer and more delicate.
Why do rennet enzyme work best and creates a better yield in 45 degree Celsius and not at 0 degree Celsius?
45 degree Celsius resembles the temperature of the stomach temperature of calves, hence it is rennet optimum temperature. In low temperatures, the enzyme was unable to collide successfully with substrates due to low kinetic energy of substrates, causing no products to be formed. Higher kinetic energy of substrates and rate of successful collisions in higher temperatures will cause more products to be formed.
