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An ice cream laboratory guide

Chapter 28: EXERCISE NUMBER XIX
By W. W. Fisk
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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 XIX

STANDARDIZE MIX TO A GIVEN
PERCENTAGE OF FAT

The following materials will be furnished: cream, milk, sugar, chocolate, fruit, vanilla and gelatin. From them make up a receipt and freeze a batch of ice cream to contain a given per cent. of fat as assigned.

Test the frozen ice cream for fat and report the result to the instructor at time of testing.

Include your receipt and all calculations and tests on opposite page.

Mark plainly each can of ice cream with the receipt number, your name, and the date.

  • No. 1. Vanilla ice cream to test 14% fat.
  • No. 2. Vanilla ice cream to test 12% fat.
  • No. 3. Vanilla ice cream to test 9½% fat.
  • No. 4. Fruit ice cream to test 11% fat.
  • No. 5. Chocolate ice cream to test 12% fat.

EXERCISE XIX REPORT

Date_________________________ Receipt Number_______________
 
CREAM: ICE CREAM:
Age _______ Gallons _______
Acidity _______ Weight per gallon _______
Temperature _______  
  SWELL:
STANDARDIZATION: Gallons________ Per cent. _______
Per cent fat in cream _______  
Per cent fat in milk _______ FREEZING:
Standardize_______ pounds Freezer used _______
of cream testing _______ Pounds ice used _______
per cent fat.   Pounds salt used _______
TIME:
Of starting freezer _______
That mix reaches 30° F _______
Required to reach 30° F _______
That freezing is completed _______
Total time required to freeze _______
 
Give proportion.
x = the pounds _______  
Pounds of cream used _______ TEMPERATURE:
Pounds of milk used _______ Of mix entering freezer _______
  Of brine when mix reaches 30° F _______
MIX: Of ice cream when removed _______
Pounds _______ Of brine at this time _______
Gallons _______  
Weight per gallon _______  
Per cent fat it should test _______  
Was gelatin used? _______ By method 1, 2 or 3? _______
In milk or water? _______  
Remarks:
 
 
Comments on ice cream after it is hardened:
 
 

SCORE CARD FOR ICE CREAM

The comparison of ice creams is accomplished best by reducing their quality to a numerical basis. This is done by use of a score card. Two score cards are suggested as follows:

  Modification of the
Cornell Score Card   Wisconsin Score Card  
Flavor 45 Flavor 40
Body and texture 35 Body and texture 25
Richness 10 Bacterial count 15
Appearance 5 Richness 10
Package 5 Appearance 5
    Package 5
  100   100

It may be more advantageous to use the Cornell score card in the Laboratory because immediate results can be obtained, while with the modified Wisconsin score card bacterial counts must be made of the ice cream, so that it would be two to three days before the final score of the ice cream could be obtained.

Discussion of Qualities of Ice Cream

Flavor. The ice cream should have a pronounced flavor which will blend with the flavor of the cream to give a clean, desirable typical flavor.

Body and Texture. The body should be firm and mellow. It should not be tough or rubbery neither soft or mushy. The texture should be smooth and velvety and entirely free from graininess and lumpiness.

Richness. If the ice cream meets the legal requirements, it should be given a perfect score. If it falls below the legal requirement, it should be scored zero.

Appearance. The ice cream should have an attractive appearance and be of the characteristic uniform color.

Package. The package should be neat and clean and, if for long shipment, some provision should be made to protect the ice on top of the packing tub.

Bacterial count. An ice cream which has a count of 20,000 should be considered perfect. For each increase of 20,000 above this one point should be deducted from the score.

Application of score card. When judging samples of ice cream, it is best to try some of them to obtain some idea of the qualities of the samples to be scored. This is necessary so that the score will not run above 100 and to set a standard. Then with a definite standard in mind, the samples may be carefully scored. The cuts in score should be made in proportion to the quality of the ice cream and the definite standard in mind.