Cheddar Cheese

In general terms, cheese is a concentrated food made from fluid cow's milk. In the process of cheesemaking, the casein protein component of the milk is induced to coagulate. The network structure formed entraps the milk fat globules, but allows much of the water and soluble components (whey) to drain out. Typically, casein coagulation is induced by a combination of acid production by starter culture organisms and also the action of the enzyme rennet. After coagulation, cheese undergoes a number of steps to separate the whey from the curd, followed by an aging step of variable length. The aging step allows characteristic flavour development due to microbial and enzyme activity.

The vast majority of cheddar cheese produced is made from pasteurized milk (held at a temperature of 61.6 oC for not less than 30 minutes or a time temperature combination of equivalent lethality). Pasteurization of cheesemilk destroys pathogenic bacteria, and also reduces the population of other micro-organisms present, thereby promoting starter culture growth. Cheddar cheese can also be made from raw milk or milk that has been mildly heat treated just to reduce the population of organisms in competition with the starter culture. Some believe that cheese made with these types of milk that have been exposed to a lower heat load has better flavour than cheese made from pasteurized milk because more of the enzymes and microbes that contribute to flavour are allowed to survive. Safety is an issue with cheeses made from milk that is not pasteurized and so these cheeses require long aging times (minimum 60 days from the beginning of the manufacturing process) to allow the development of conditions that are unfavourable for pathogenic organisms. Cheese that is not made from pasteurized milk can be used as a food ingredient only provided the food is manufactured or processed so as to pasteurize the cheese to meet legal specifications.

Once the cheesemilk is prepared, starter culture is added to generate lactic acid from lactose and this acid production, along with activity of added rennet, serves to produce the casein coagulum. The coagulum is cut and then stirred and warmed to release the whey from the curd and the whey is drained off. The next step, in the process is distinct to cheddar cheese processing and is known as cheddaring. In this step the curds are allowed to mat together to form large blocks of cheese mass. These are worked and turned to further expel whey and also produce the characteristic fibrous texture of cheddar cheese. During the cheddaring process, the curds also become further acidified by the continuing action of the starter culture on residual lactose in the curd. After cheddaring the curd is milled into smaller pieces and salted for flavour and preservative effects. Finally, the curds are pressed into blocks and then allowed to age (although cheese intended for further processing can be aged in curd form without pressing). Mild cheddar is aged three months, medium cheddar is aged four to nine months and strong or sharp (old, extra old) cheddars are aged from nine months to several years. During aging, flavour develops largely due to the breakdown of some lipid and protein components.

Cheddar cheese can also be made by what is known as a stirred curd process. The steps for forming, cutting and cooking (heating gently to release whey) the curds and draining the whey are exactly the same as in the regular cheddar process. The difference is that for the stirred curd cheddar, the curds are not cheddared, instead the drained curds are constantly stirred until the desired acidity is reached. The curds are then salted and pressed and the cheese allowed to age (although cheese intended for further processing can be aged in curd form without pressing). With the constant stirring of the curd rather than cheddaring, the curd particles are not allowed to mat into a cohesive mass. The resulting cheese may have a more granular appearance. In terms of composition, stirred curd cheddar is quite similar to regular cheddar. The advantages of the stirred curd process are that it is faster and easier than the traditional process. A notable amount of the cheddar cheese used in further processing is produced by the stirred curd method with processed cheddar production a major application.

Cheddar cheese is used as an ingredient to add zesty flavour, nutritional value and colour to foods. It may be used in its native form or further processed by spray drying or heating for improved functionality and shelf life. Cheddar cheese is very high in protein and each serving provides an excellent source of Vitamin D, a good source of calcium and a source of phosphorous, riboflavin, niacin, and Vitamins B12, A and E.

According to federal standards of identity, cheddar cheese is the product made by coagulating milk to form a curd and subjecting the curd to the cheddaring process or any other process that produces a cheese having the same physical, chemical and organoleptic qualities as cheese produced by the cheddaring process. The moisture content cannot exceed 39% and the milk fat content may not be less than 31%. Permitted additives include:

• salt
• flavourings (other than cheese flavouring)
• colouring agents
  • annatto, b-carotene, chlorophyll, paprika, riboflavin or tumeric in amounts consistent with good manufacturing practice
  • beta-apo-8'-carotenal and ethyl beta-apo-8'-carotenoate in amounts not to exceed 35 parts per million (ppm) alone or in combination)
• calcium chloride (as a firming agent in amounts not to exceed 0.02% of the milk)
• wood smoke as a preservative in accordance with good manufacturing practice preservatives
  • propionic acid, calcium propionate or sodium propionate in amounts not exceeding 2000 ppm calculated as propionic acid
  • sorbic acid, calcium sorbate, potassium sorbate or sodium sorbate in amounts not exceeding 3000 ppm calculated as sorbic acid
  • any combination of the above preservatives in an amount not exceeding 3000 ppm calculated as propionic and sorbic acid
  • natamycin on the surface of the cheese in an amount not exceeding 20 ppm or 10 ppm for grated or shredded cheese
• for grated or shredded cheese, calcium silicate, microcrystalline cellulose or cellulose (anti-caking agents) in total not to exceed 2%.

Cheese is of high nutritional value due to its high concentration of proteins. Casein contains various levels of all the essential amino acids although it is relatively low in sulfur containing amino acids. As a result, the protein quality of cheese is slightly less than that of milk, which retains the sulfur rich whey proteins.

In terms of microbiological standards, all cheeses made from pasteurized milk must contain fewer than 100 Escherichia coli per gram and fewer than 100 Staphylococcus aureus per gram. If the cheese is made from unpasteurized milk, the allowable levels are 500 E. coli per gram and 1000 S. aureus per gram.

Cheddar cheese is a multifunctional ingredient suitable for use in virtually all types of products including entrées, side dishes, bakery products, soups, sauces, snack foods, meat products, vegetable products, etc.

• Bakery products: cheddar cheese provides flavour and visual appeal to baked products. It may be melted on the surface of baked products or shredded and added to dough prior to baking.
• Soups and chowders: aged cheddar cheeses add flavour to soups. Young cheddar can be treated with enzymes to rapidly develop flavour for use in these products.
• Fondue's and sauces: spray dried cheddar cheese powder adds flavour and consistency to hot fondue's and sauces.
• Frozen foods: shredded cheddar cheese provides added value to frozen appetizers, garlic bread, quiche and as part of a cheese blend on pizza. The cheddar supplements the flavour, texture and appearance of these products.
• Snack foods: Spray dried cheddar cheese is suitable for use in coatings for snack foods and produces a characteristic "cheesy" flavour. Young cheddar that has undergone accelerated aging by the addition of enzymes is often used for this application.

• Cheddar cheese is primarily added to products for its flavour. The distinct flavour of cheddar cheese adds character to many different types of foods. Aged cheddars, with their strong flavours, are particularly good additions to low fat foods as not much cheese is required to get the desired flavour effect.
• Cheddar cheese can be used to add colour to products, particularly if an orange cheddar is used.
• Melted cheddar or cheddar cheese powder can be used to add viscosity to sauces when sauce preparation involves heating and high shear.
• Melted cheddar cheese on the surface of products such as baked goods improves the sensory appeal of these products.
• Young cheddar cheese is a firm cheese and when solid, adds a characteristic texture to products. The longer the cheddar is aged, the harder and more brittle it becomes. However, when melted, the texture of cheddar cheese becomes smooth and creamy.
• Baked cheddar undergoes some browning when baked, which enhances the appearance of some foods.
• Cheddar cheese can be frozen, which preserves its flavour, but the textural quality of the cheese may be diminished when thawed.
• Cheddar cheese is an excellent addition to cooked products but care should be taken to ensure that the cheese is not overheated. Over cooking of cheese can cause fat separation and protein denaturation, which unfavourably alters the properties of the cheese, particularly related to texture and appearance.

For more information on cheese, please visit the University of Guelph's Dairy Science and Technology Web site.