330 MILK AND CREAM TESTING 



form a sticky resinous deposit on the bottles which is hard 

 to remove. 



ERRORS TO AVOID IN TESTING 



The following are the chief causes of inaccuracy : 



1. Gross sample not a true one, because 



(a) Cream sour and clotted. 



(b) Cream dried on surface. 



(c) Cream partly churned. 



(d) Cream good, but not well mixed before sampling. 



2. Test bottle sample not correct because 



(a) Cream measured instead of weighed. (18 grams required.) 



(b) Cream weighed with inaccurate scales. (Keep all bearings free 

 from rust and gum.) 



(c) Of slovenly work in weighing. 



3. Aoid mistakes — 



(a) Too much or too strong acid (burns fat). 



(b) Too little or too weak acid (leaves white curd under the fat). 



(c) Acid too warm (burns fat: 60 to (55 degrees F. works best). 



(d) Acid poured through cream (burns in clots). 



(e) Acid not well mixed when shaking is commenced (burns in clots) . 

 (Four or five c.c. lukewarm water will check acid action). 



4. Mistakes in whirling. 



(a) Speed too slow. (Fails to secure all the fat or to dry the fat.) 



(b) Not turned long enough (5 or 6 minutes necessary). 



(c) Bottles too cool while turning (fat cannot rise; should be 180 to 

 200 degrees F.). 



5. Mistakes in adding water — 



(a) Water too cool (190 to 200 degrees F. right). 



(b) Water dirty (causes gray cloud below fat). 



(c) Water hard (the lime in hard water often causes unreliable 

 results ; use rain water or condensed steam ) . 



6. Mistakes in reading fat — 



(a) Reading too hot (fat expanded; 130 to 140 degrees F. right). 



(b) Reading too cold (fat contracted, not volume enough). 



(c) Upper surface of fat not leveled (a few drops of amylic alcohol 

 on top of fat makes a flat surface of the concave one. This is 

 used on cream only). 



7. Inaccurate graduation of test bottles — 



(a) Every bottle should have been tested. 



When so small a quantity of cream has to represent so large a 

 quantity, it is exceedingly important that every step in the 

 process be performed with the utmost care. 



