Answer to Question 1
Heat denatures and coagulates proteins, which results in change of form and texture. Often, proteins toughen when exposed to heat. Heat causes browning of carbohydrates through the Maillard reaction. Some browning is desirable, but too much browning may occur with an excess of sugars, amino acids, or lactose in the cheese. Heat causes high-fat cheeses to melt. Higher-fat and higher-moisture cheeses have greater meltability. Ripened cheeses tend to melt and blend more easily when exposed to heat. One drawback of high-fat cheese when exposed to heat is the tendency to oil off by allowing free fat to be released and glisten on the surface of the product.
Answer to Question 2
Cheese food must be at least 51 natural cheese by weight, which is the same as cheese spread but less than processed cheese; cheese food also has higher moisture and lower fat content. An example is Velveeta cheese. Cheese spread has even more liquid, an emulsifier, and less milk fat. It is also softer and more spreadable than cheese food or processed cheese. Processed cheese is made from combining a variety of natural cheeses and includes an emulsifier; the moisture content must not exceed 40. The fat content is similar to that of the natural cheese from which it was derived.
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