Dairy Husbandry Department
Dairy, Dairy Products, Cream, MilkParson's Test, Mold Mycelia Test
Before any testing is done it is most important to get a representative sample. Frozen cream must be thawed. All cream must be thoroughly stirred. Remember you are licensed by the State Department of Agriculture to sample as well as to test. Butterfat Test. Frequently cream is stirred, sampled and weighed at the time of delivery and testing is clone near the end of the clay. Sour and heavy cream is viscous and may "set" in the sample jar. This means that it must be well stirred or poured from one jar to another several times or may even require some heating to again become fluid enough to get a correct sample. If heated, cool again to about 70 ° F. after weighing into test bottle and before adding acid. Cream test scales must be kept dry and clean and the 9-gran, weight must always be scrupulously clean and dry. Never handle weight with wet hands and never allow acid to corrode it. The scales must be protected from air currents from all angles, leaving only room to work. This is important. Procedure. l. Balance, clean dry test bottles on the scale. 2. Transfer 9 grams of cream into plainly marked test bottles. 3. Remove 9 gram weight and place cream from the next sample in test bottle on opposite pan until a balance is obtained. Beware of over and under weights because errors may be doubled as you proceed in this cross balancing. 4. Acid sulphuric acid (1.82 to 1.83 specific gravity). Use 8 to 12 cc if cream is at room temperature and slightly more if cream and acid are colder. 5. Shake well and add 8 or 10 cc of water at about 160 ° F. as the sample turns from a chocolate to dark brown color. This retards further action and should prevent a charred fat column. 6. Centrifuge 5 minutes; add water at about 160 ° F. to fill bottle to neck; centrifuge 2 minutes and add hot water to bring fat column within graduations in neck of bottle; centrifuge 1 minute. 7. Remove bottles from tester and place in deep water bath at 130 ° to 140 ° F. for 5 minutes. 8. Add a few drops of glymol or red reader in such a manner as to avoid disturbing the fat column. 9. Read and record tests at once.
South Dakota State State College of Agriculture and Mechanic Arts, Agricultural Experiment Station
Totman, C. C., "Testing Dairy Products" (1943). Agricultural Experiment Station Circulars. 43.