HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Judkins, H. F. Search for Related Content PubMed Articles by Judkins, H. F.

Homogenizing Efficiency Test Studies

Sealtest, Inc.

ABSTRACT

1. With very careful control procedures, a plant should be able to meet the U. S. Public Health Service homogenizing efficiency test most of the time. It is felt, however, that a more liberal test would be more practical since there appears to be no reason for such a rigid test.
   
2. The Babcock test as per modification presented is the practical test to use in determining homogenizing efficiency.
   
3. All fat tests should be run in duplicate and if duplicates differ by more than 1/10 of 1 per cent, a retest should be made. Tests showing fat columns that are not perfectly clear should be discarded and retests made.
   
4. Persons well trained in the making of the Babcock fat test will differ but little in the results obtained when making the homogenizing efficiency test.
   
5. The theoretical possible error of 2/10 of 1 per cent in reading top and bottom tests may easily be the determining factor as to whether the homogenizing efficiency test standard is complied with.
   
6. The richer the milk, the less the per cent difference between the top and bottom test is likely to be.
   
7. The pouring method is the preferred method for removing the top milk from the bottle in making the homogenizing efficiency test.
   
8. The top and bottom test difference at the end of 24 hours' storage of the sample is approximately one-half that obtained when the sample is held for 48 hours.
   
9. Samples taken from routes or shipped to laboratories for testing should be inverted ten times and held for 48 hours at 40° to 50° F. before testing.
   
10. If the sample is held at a temperature below 40° F. the difference between the top and bottom test is much less than when the sample is held at temperatures above 50° F. There appears to be no significant difference if the sample is held within a range of 40° F. to 50° F. which it is concluded is a practical range for the average plant.
    
11. The homogenizing efficiency test works equally well on quart, pint and half-pint bottles.
    
12. The difference between the top and bottom test in milk held in a glass bottle is much greater than where the milk is held in a paper bottle for the same length of time.
    
13. Essentially the same results are obtained in bottles having a different top diameter and bottles of so-called "Cream Top" style.
    
14. High and steady homogenizing pressure is essential to good results.
    
15. The difference between the top and bottom test tended to be less when homogenization followed pasteurization.
    
16. The higher the pasteurizing and homogenizing temperature, the less will be the difference between the top and bottom tests.
    
17. It is possible that clarification may make it more difficult to meet the homogenizing efficiency test.
    
18. Failure to use the impact ring in the Manton-Gaulin Homogenizer makes it more difficult to meet the homogenizing efficiency test.
    
19. Other factors making it more difficult to meet the homogenizing efficiency test are:
    
    1. homogenizer valves in poor condition.
       
    2. imperfect gaskets between the homogenizing valve chamber and the homogenizing valve.
       
    3. the use of the processing equipment for both homogenized and unhomogenized milk.
       
    4. the incorporation of an undue amount of air in the milk prior to homogenizing.
       
    
    
20. Homogenizing can be quite inefficient as determined by the U. S. Public Health test before the curd tension of the homogenized milk is appreciably affected.
    
21. The bacterial count in homogenized milk need be no higher than in unhomogenized milk. Our results showed it to be lower, possibly due to the fact that higher temperatures were generally involved in processing the homogenized milk.
    

¹ The writer wishes to give due credit for the work done by R. Whitaker and his staff at the Sealtest Research Laboratory, Baltimore, Maryland. Thanks are also due those in the various plant control laboratories for making various tests as suggested.