258 MANUAL OF MILK PRODUCTS 



volatile acids and olein. It is controlled by the relative pro- 

 portion of the individual fatty acids. 



7. The chemical composition of butter-fat is largely con- 

 trolled by breed, period of lactation, and feed. 



8. The butter-fat from Ayrshires and Holsteins contains 

 less volatile acids and more olein and makes a softer butter 

 than that from the Jerseys. 



9. At the beginning of the period of lactation the volatile 

 acids are highest and the olein lowest. As the period of lactation 

 advances, the volatile acids decrease and the olein increases. 



10. The feed is the most dominant factor controlling the 

 chemical composition of the butter-fat. 



11. Feeds rich in vegetable oils, also blue-grass pasture, pro- 

 duce butter-fat relatively high in olein, low in volatile acids, and 

 make a soft butter. Feeds rich in starches and sugars and poor 

 in vegetable oils, also dry hay, tend to increase the volatile 

 acids, decrease the olein, and produce a relatively firm 

 butter. 



12. The size of the fat globules also affects the mechanical 

 firmness and moisture-content of butter. Other conditions 

 being equal, cream with large average globules makes a softer 

 butter which retains more water than cream with small average 

 globules. 



13. The size of the fat globules is controlled largely by breed, 

 period of lactation, and by changes of feed and other factors 

 affecting the physical condition of the animal. 



14. The Channel Island breeds produce milk with much 

 larger fat globules than the Ayrshires and Holsteins. Milk 

 from fresh cows contains larger fat globules than milk from cows 

 well advanced in their period of lactation. Abrupt changes of 

 feed temporarily increase the average size of the fat globules. 

 Factors not under the control of the butter-maker (Hunziker). 



1 . The richness and acidity of the cream, size of the butter 

 granules, temperature of and churning in wash water, method 



