Methods Used in the Examination of Milk and Dairy Products (Paperback)

This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1910 edition. Excerpt: ... Carbonate or Bicarbonate of Soda. Carbonate of soda is not used for its antiseptic properties, for it possesses none, but because of its power of neutralising the lactic acid which forms, and which would ultimately curdle the milk. The development of the bacteria is in no way hindered by the use of this "preservative," which must be regarded as harmful, seeing that it permits of a milk being in an advanced stage of decomposition without the appearance indicating the fact. The use of carbonate or bicarbonate of soda was much greater formerly, and is still common to a small extent in some parts. Generally, about 1 g. of anhydrous soda is used to each litre of milk. To prove the addition of carbonate or bicarbonate of soda to a milk, Hilger's method can be used, which consists in diluting 50 c.c. of milk with 250 c.c. of water, heating it, and then precipitating with a small quantity of alcohol. After the solid matter has been filtered off, the filtrate is evaporated to half its former volume and tested for an alkaline carbonate with litmus paper, &c. Soxhlet-Scheibe use another method, which is based upon the quantitative determination of the carbon dioxide in the ash of the milk. The normal amount of carbon dioxide in milk does not exceed 2 per cent. 2. Boracie Acid and, Borax. E. Meissl1 has given the following method for detecting boracie acid or its salts in milk: 100 c.c. of milk are made alkaline with milk of lime evaporated to dryness and then ignited. Lime is preferable to the alkalies because the ignition is much easier. The ash is dissolved in the smallest possible quantity of concentrated hydrochloric acid, the carbon filtered off, and the liquid evaporated to dryness, care being taken to drive off all the acid....