Ill 



Dairying in Australia. 



THE HON. F. R. MOOR'S IMPRESSIONS. 



{Con 



THE following is a further instalment 

 of the pamphlet : — 



Testing Acidity op Cream. 



During the last two seasons many 

 systems have been adopted at our factories 

 for recording the acidity of cream before 

 churning. It is unfortunate that one 

 standard system was not carried out. At 

 many places alkaline tablets are used. 

 Some use acidimetric tablets. Others use 

 phenolphthalein as an indicator, and an 

 alkali — either lime water, caustic soda, or 

 potash solution— to determine the per- 

 centage of lactic acid. Again, a differ •ence 

 IS found in the method of applying the 

 various tests. One adds the solution of 

 pure cream, another to a 50 per cent, 

 cream solution, and the next to a 33^ per 

 cent, solution. 



The data recorded is of the greatest 

 value to the buttermakers themselves, 

 but difficulties are met with when an 

 attempt is made to compare experiences. 

 Working from so many standpoints is 

 prejudicial to mutual improvements— the 

 policy of the Australasian Butter and 

 Cheese Factories Managers' Association. 

 It would assist the progress of the industry 

 if that body were to discuss this matter 

 and agree to the adoption of a uniform 

 system as a standard. Doubtless a com- 

 parison could be made by finding the 

 percentage of lactic acid per the respective 

 systems. Hitherto this was impracticable, 

 as the rules available failed to give corre- 

 sponding results, either the tablets or the 

 tables being incorrect. About O.C per 

 cent, of lactic acid is the quantity required 

 to be developed in cream before churning. 

 The percentage should range from 0-55 to 

 0-65 per cent, of acid. 



The system that gives best satisfaction 

 is known as the Titration method. This 

 test is based on the fact that if an alkaline 

 solution is added to an acid solution a 

 point is reached where the mixture is 

 neither acid nor alkaline. Then, if an 

 alkali of known strength is used, all that 

 remains necessary is an indicator hy which 

 to tell when the point of neutrality is 

 reached. 



tinued.) 



The apparatus required for the test is a 

 20 c.c. burette for measuring the cream, 

 a 50 c.c. glass-stoppered burette for lime 

 water, a cup, a glass stirring rod, and a 

 medicine dropper, a bottle of full-strength 

 lime water, and a bottle of phenol- 

 phthalein. The method of operating is 

 to measure with the burette 20 c.c. of the 

 cream to be tested into the cup, then 

 rinse the burette with an equal quantity 

 of rain water into the cup. Into this 

 mixture put four drops of phenolphthalein 

 indicator with the medicine dropper. Fill 

 the 50 c.c. burette up to the top of the 

 giaduations with lime water. Let the 

 lime water go into the cup slowly iintil 

 the pink colour no longer disappears o:i 

 stirring. The quantity of lime water 

 taken to produce this permanent pink 

 colour determines the amount of lactic 

 acid present. 



Temperature for Chcjrning. 

 Generally GO deg. may be quoted as the 

 churning temperature. 



If the temperature be too high an un- 

 due loss takes place in the buttermilk ; 

 the butter will be soft, and cannot be 

 readily handled, and the quality may be 

 injured. If the temperature be too low, 

 time is wasted in churning. It is always 

 better to be a little low than high in 

 temperatui e for churning. When fresh 

 or sweet cream is churned the temperature 

 needs to be lower in order to recover as 

 much of the butter as possible. Equally 

 good results are obtained at one place at 

 60 deg. as in another at 54 deg. at the 

 same time of year. The proper tempera- 

 ture also varies slightly in the same places 

 at different seasons — the range being 

 about from 54 to t)2 deg. Owing to the 

 rise that takes place in temperature when 

 churning, the cream needs to be lower in 

 the summer as compared with the winter 

 time. This variation is accounted for by 

 the relationship or proportion that the 

 liquid and solid fats in ihe butter bear to 

 one another. The melting point of butter 

 varies according to the pasture, the period 

 of lactation of the cows, ami the season 

 of the year. 



