FOOD SCIENCE AND TECHNOLOGY 401LABORATORY INTRODUCTION TO FOOD SYSTEMS

PROCESSED CHEESE

Periods: Three

Period 1: Planning and starter preparation
Period 2: Product processing
Period 3: Product evaluation

Purpose:

To familiarize the students with the manufacturing process and factors affecting the characteristics of the process.

Processed cheese, which started out as a means of salvaging scraps of cheese from packaging operations, has grown into a major industry.  Up to about 50% of the Cheddar cheese in the US ends up as a processed cheese product.  Processed cheese products can be classified into four groups:

·         Process cheese, which contains only cheese and emulsifying salts and the moisture content must be not more the 43% and the fat content willnot be less than 47%

·         Process cheese food, contains other milk ingredients in addition to cheese and most not exceed 44% moistures and not less than 27% fat.  51% of the product must be cheese ingredients

·         Processed cheese spread will spread at room temperature and the moisture content must be more that 44% and less than 60%.  At least 51% of the product must be cheese ingredients. In additoion to dairy ingredients, the product may contain  water conditioning agents (<0.8%), which include a variety of gums.   Sweetening agents and acifiying agents may be used.  The pH must no be less than 4.0.

·          Processed cheese product  contains less than 51% cheese ingredients and a maximum moisture content of 60%. 

Processed cheeses result from the plastisizing of the casein in the cheese into a thermo-plastic material that is fluid when hot and solid when cold.  This is achieved by the use of “emulsifying” salts that are normally phosphates are citrates or combinations of  these.  They are limited to 3% of the final product.  The emulsifying salts do not act as true emulsifiers, but modify the casein in the cheese so that it becomes the primary emulsifier.  Emulsifier salts serve to adjust the pH, chelate calcium and serve as ion exchangers.

Processed cheese food is the model for this project

PROCEDURES:

A.  Selection of ingredients:

The type of cheese, dairy ingredients and emulsifiers need to be deterimed.  Example of some processed cheese food formulations, using various no cheese ingredients are shown in the table below: 

 

 

Recipes for processed cheese food made with various dairy ingredients

Ingredeint

Amount g

% by Weight

% Contribution to                  

 

 

 

Protein

Fat

Moisture

3 month cheese

323.9

35.7

45.8

45.6

32.0

5 month cheese

138.8

15.3

19.8

20.0

13.7

Sodium Caseinate

72.6

8.0

34.4

0.4

0.8

Vegetable Oil

81.7

9.0

0

34

0

Citric Acid

3.63

0.4

0

0

0

Trisodium Citrate

14.5

1.6

0

0

0

Disodium Phosphate

4.5

0.5

0

0

0

Lactose

72.6

8.0

0

0

0

Water

195.1

21.5

0

0

53.5

Total

907.3

100

100

100

100

 

Note:  The age of the cheese and the type of dairy ingredient will influence the selection of the emulsifier.

Young cheese requires more citrate and aged cheese requires more phosphate.

 

B. Processing

 

1.  A Stephan UMC 5 Electronic batch processed cheese maker will be used for the production of the processed cheese product.  This device consisted of a water heater, mixing platform with mixing speed adjustment available between 300 and 3000rpm, timer for six minute increments, a start switch, and a steam jacketed kettle with a temperature probe screwed into its base.  This probe fed readings to an LCD display on the mixing platform.  The kettle also had a lid lined with a rubber seal for vacuum and a hand-stirring blade.  The mixing speed was preset at 600rpm.

 

2.  Weigh  ingredients and place aside while the temperature of the kettle reaches 80  deg C.

3.  Add ingredients after  temperature of  the cooker reaches  80 deg. C.  [Cook temperature can be altered if desired – but should range from 75-85 deg. C.]

4.  Hold at this temperature for four minutes before being emptied into a plastic wrap lined Rubbermaid  rectangular container and place  in a refrigerator at approximately 4  deg. C to cool. .  Product can be evaluated after holding in the refrigerator for 24 hours.

C. Evaluation

 

Evaluate for sensory properties, melting,  texture, color and pH.  

 

Treatment of Results

 

Report the results of your observations and analysis and discuss them concisely and comprehensively. Do not copy the step by step procedure from the outline, but develop a meaningful report, based on key steps, rationale for methods used, and analysis.

Reference:

Zehren V L and Nusbaum DD. 1992  Process Cheese. Schreiber Foods, Green Bay WI.