WeRead Powered by ReaderPub
An ice cream laboratory guide cover

An ice cream laboratory guide

Chapter 5: STANDARDIZATION
By W. W. Fisk
Open in WeRead

Explore more books like this:

Cooking & DrinkingEngineering & TechnologyHow To ...Science - Chemistry/Biochemistry

About This Book

A laboratory manual guides students through the scientific manufacture of frozen desserts, combining equipment descriptions, sanitation practices, and stepwise laboratory exercises. It explains methods for standardizing mixes and testing fat and solids, the use of stabilizers, and principles of freezing, hardening, and measuring swell (overrun). Practical recipes and procedures cover plain, fruit, nut, custard, parfait, and molded products, ices and sherbets, and related preparations; supplemental exercises address microbial counts, gelatin testing, varying ingredients and processing treatments, judging criteria, and visits to commercial plants for applied observation.

EXERCISE NUMBER I

INSPECTION AND STUDY OF
ICE CREAM MACHINERY

Artificial refrigerating systems.

I. State briefly the principles involved in an artificial refrigerating plant.

II. Make drawings showing the working principles of the refrigerating system.

III. Tell how to start and stop the compressor.

Ice cream freezers.

I. Tell the principles on which the various types of freezers work.

II. How can the temperature in the different types of freezers be regulated?

Cleaning utensils.

I. How should utensils be washed? Why?

II. Are all utensils so constructed that they may be easily and thoroughly cleaned? What provisions have been made to make cleaning easy?

EXERCISE I REPORT

  •  
  •  
  •  
  •  
  •  
  •  
  •  

STANDARDIZATION

One of the main requirements for a successful ice cream business is uniformity of quality. In order to obtain this, it is necessary to have cream each time containing the same percentage of fat. As it is impossible to always get cream of a uniform fat content, the cream must be standardized. That is, the percentage of fat must be either increased or decreased to the desired amount. It is the usual practice to have richer cream than is to be used and reduce it by the addition of less rich cream, whole milk, or skim milk. If the cream was lower in percentage of fat than was desired, it could be standardized only by the addition of richer cream.

Prof. R. A. Pearson has devised a very simple method, known as the rectangular method of standardization. This method is as follows: draw a rectangle and place in the center the percentage of fat desired. At the left hand corners place the percentages of fat in the materials to be mixed. It is customary to place the larger figure at the top, thus:

Then subtract diagonally, placing the remainders at the right hand corners, as shown above. These show the proportions by weight in which the materials must be mixed to give the desired percentage of fat.

A problem may serve to illustrate the method.

How many pounds each of 30% cream and 4% milk are necessary to make 260 lbs. of 20% cream?

This shows 16 lbs. 30% cream and 10 lbs. 4% milk make 26 lbs. of 20% cream, but 260 lbs. is required. This is best solved by simple proportion:

10 lbs. milk ∶ 26 lbs. 20% cream ∷ x lbs. milk ∶ 260 lbs. 20% cream.

Solving x = 100 lbs. 4% milk required and 260-100 lbs. milk = 160 lbs. 30% cream required which may also be determined by proportion.

To be sure no mistakes are made in figuring, it is best to prove all standardizations. The proof is simple.

260 lbs. 20% cream contains  52 lbs. fat (required).
160 lbs. 30% ” ” 48 lbs. ”
100 lbs.  4% milk ” 4 lbs. ”
Making a total of 52 lbs. fat, the amount required.

In the above problem a definite amount of the mixture was required. There is another class of standardization problems in which the amount of one of the materials is given, to find the quantity of the other required to standardize it:

How much 4% milk must be mixed with 420 lbs. of 40% cream to make a mixture testing 25% fat?

This shows that 15 lbs. of 4% milk will standardize 21 lbs. of 40% cream to a cream tasting 25% fat. But there are 420 lbs. of 40% cream to standardize. By simple proportion,

15 lbs. 4% milk∶ 21 lbs. 40% cream∷ x lbs. 4% milk∶ 420 lbs. 40% cream.

Solving x = 300 lbs. 4% milk

420 lbs. cream + 300 lbs. milk = 720 lbs. 25% cream.

Proof:
 
720 lbs. of 25% cream contains  180 lbs. fat.
300 lbs. of  4% milk   ” 12 lbs. ”
420 lbs. of 40% cream ” 168 lbs. ”
Making a total of 180 lbs. fat.