304 



BUTTER. 



Table LXX\'I. shows the eSect of keeping oa the percentage 

 of water contained in the butter ; fresh and salt butters, which 

 were all prepared at the Aylesbury Dairy Company, are kept 

 separate. 



TABLE LXXVI.— Variations of Water in Butters 

 ON Keeping. 



Taking butters from twenty-four to forty-eight hours old to 

 represent commercial butter, it is seen that salt butter contains 

 rather less water than fresh butter. The contrary is usually 

 stated ; but this is not according to the author's experience. 



Fresh butter loses its water chiefly by evaporation, and it is 

 seen that this loss is small : salt butter also loses water by brine 

 running out. It will usually be noticed that salt butter looks 

 wet on being cut, while fresh butter rarely has this appearance. 



Action of Salt. — The action of salt, which is added both to 

 give a flavour and as a preservative, seems to be as follows : — It 

 first dissolves in the buttermilk left in the butter, and forms a 

 strong solution, which curdles the buttermilk, giving an insoluble 

 precipitate of protein matter and a clear whey. The salt solution 

 has a smaller viscosity than the buttermilk ; hence a smaller 

 layer is condensed round the particles by surface energy, and 

 there is liquid which is very loosely held in the butter ; this 

 gradually runs out, and gives rise to the wet appearance of salt 

 butter. It is noticed that the liquid which runs out, or is squeezed 



