78 MODERN BUTTER MAKING. 



acid necessary in cream is influenced by the varia- 

 tion of the per cent of fat and the per cent of serum 

 in the cream. The per cent of lactic acid to which 

 cream of varying richness should be ripened will be 

 found in table No. IV on page 80. 



104. A first class sweet cream testing 30 per cent 

 fat may be ripened to .60 per cent acidity without 

 injuring the flavor, aroma or keeping quality of the 

 butter. But whenever cream is a day or two old 

 and has developed some acidity before arriving at 

 the factory the ripening must not be so high as with 

 good sweet cream. It has been found from practical 

 experience that it is much better to vary the acidity 

 in cream in relation to its fat content than to ripen 

 all cream alike. Due to the difference in the test of 

 various creams and to a slight change in the market 

 in demanding milder acid flavored butter, it was 

 found that a table which would serve as a guide 

 would be useful to the creamery operator. The rela- 

 tive acidity table on page 80 is a mathematical cal- 

 culation based upon practical experience and gives 

 the acidity of cream in relation to its fat r-ontcnt. 

 The working basis on which this table is based and 

 which is considered by practical creamorynien as the 

 proper per cent of acidity in cream, is, that cream 

 testing 25 per cent butter fat be ripened to .60 per 

 cent aciditJ^ This is taken as a standard and is based 

 upon sweet cream ripened to .60 per cent and is not 

 based upon mixed cream of various ages and degrees 

 of acidity. The latter kind of cream should be 

 handled differently and we find in the column of 

 mixed cream the per cent of acidity to which such 



