MISS : SALSABEEL ALJOUJOU

 Cheddar cheese is a semi-hard cows milk cheese.  It can vary in taste from mild to extra sharp.  The cheese is one of the most well known cheeses in the world, and many countries produce regional versions of cheddar cheese, especially Britain and former colonies.colonies I. Introduction

 Because of the fame of the cheese, it is readily available in most markets, and it varies widely in quality.  Cheese is a highly proteinaceous food made from the milk of some herbivores.

 Cheese is believed to have originated in the warm climates of the Middle East some thousands of years ago, and is said to have evolved when milk placed in goat stomach was found to have curdled.  The scientific study and manipulation of milk for cheese manufacture is however just over a hundred years old.

 About a thousand types of cheese have been described depending on the properties and treatment of the milk, the method of production, conditions such as temperature, and the properties of the coagulum, and the local preferences.

II. Stages in the manufacture of cheese II.1 Pasteurize/Heat Treat Milk Depending on the desired cheese, the milk may be pasteurized or mildly heat-treated to reduce the number of spoilage organisms and improve the environment for the starter cultures to grow. Some varieties of milk are made from raw milk so they are not pasteurized or heat-treated.

 Raw milk cheeses must be aged for at least 60 days to reduce the possibility of exposure to disease causing microorganisms (pathogens) that may be present in the milk. II.1.1 Cool Milk Milk is cooled after pasteurization or heat treatment to 90°F (32°C) to bring it to the temperature needed for the starter bacteria to grow. If raw milk is used the milk must be heated to 90°F (32°C).

II.1.2 Inoculate with Starter & Non-Starter Bacteria and Ripen For cheese prepared at temperatures less than 40°C strains of Lactococcus lactis are used. For those prepared at higher temperatures the more thermophilic Streptococcus thermophilus, Lactobacillus bulgaricus, and Lact. helveticus are used.

Lactic acid has the following effects:  It causes the coagulation of casein at pH 4.6, the isoelectric point of that protein, which is used in the manufacture of some cheeses, e.g. cottage cheese.  It provides a favorably low pH for the action of rennin the enzyme which forms the curd from casein in other types of cheeses.  The low pH eliminates proteolytic and other undesirable bacteria.

 It causes the curd to shrink and thus promotes the drainage of whey.  Metabolic products from the lactic acid bacteria such as ketones, esters and aldehydes contribute to the flavor of the cheese.

II.1.3 Adding of rennet for coagulum formation Chymosin, rennet, and rennin are often used interchangeably to refer to this enzyme. The latter, rennin, should not be confused with renin, which is an enzyme associated with kidneys and does not clot milk. The rennet is the enzyme that acts on the milk proteins to form the curd which is derived from the fourth stomach, abomasum of freshly slaughtered milk-fed calvesmilk proteins

Besides those of calves, the abomasum of kids (young goats), lamb or other young mammals have been used.

II Some commercial microbial rennets and their microbial sources Substitutes from microbial sources have been very successful and continue to be used. Many act like trypsin and have an optimum pH activity between 7 and 8.

Microorganisms, including Bacillus subtilis, B. cereus, B. polymyxa, and Mucor pusillus t (also known as Rhizomucor pusillus) and Rh. miehei have been extracted for their proteasenzymes. The bacilli enzyme preparations were not suited for cheese making because of excessive proteolytic activity while the fungal-derived enzymes gave good results, but not without off flavors such as bitter.

III. Cut Curd and Heat:-  The curd is allowed to ferment until it reaches pH 6.4. The curd is then cut with cheese knives into small pieces and heated to 100°F (38°C).  The heating step helps to separate the whey from the curd

IV. Drain whey The whey is drained from the vat and the curd forms a mat. V. Texture curd  The curd mats are cut into sections and piled on top of each other and flipped periodically. This step is called cheddaring. Cheddaring helps to expel more whey, allows the fermentation to continue until a pH of 5.1 to 5.5 is reached, and allows the mats to "knit" together and form a tighter matted structure.  The curd mats are then milled (cut) into smaller pieces.

VI. Dry Salt or Brine For cheddar cheese, the smaller, milled curd pieces are put back in the vat and salted by sprinkling dry salt (1% and 3% by weight) on the curd and mixing in the salt. VII. Form Cheese into Blocks The salted curd pieces are placed in cheese hoops and pressed into blocks to form the cheese..

VIII. Store and Age The cheese is stored in coolers until the desired age is reached. Depending on the variety, cheese can be aged from several months to several years. IX. Package Cheese may be cut and packaged into blocks