Bacteriological techniques for dairy purposes.

  • Ministry of Agriculture, Fisheries and Food
Date:
1968
Catalogue details

Licence: Public Domain Mark

Credit: Bacteriological techniques for dairy purposes. Source: Wellcome Collection.

    32/192 (page 24)
    AC acid clot; litmus is pink and milk clots; at a later stage whey may appear as the curd shrinks and hardens; WE alkaline; litmus is slightly blue or blue; SC ase sweet clot; often the clot is quite soft and remains so and may readily be broken by tilting the tube; the reaction is not acid but may be alkaline; D aot digestion; the milk, whether liquid or clotted, as the protein is peptonized, becomes clear; the reaction may be alkaline; G = gas production; small bubbles may be seen escaping from medium; if milk is clotted, gas bubbles may be trapped in curd and disrupt it. More than one reaction often occurs, particularly with longer incubation times. For example, (i) reduction accompanies acid clot, but the medium is seldom entirely reduced and acidity is shown by a pink band at the surface of the medium (RAC); (ii) digestion may follow alkaline reaction or sweet clot (ALK, D or SC, D). Indefinite or slight reactions, e.g., slight acid, partial digestion (a few mm at the surface of the tube) should be indicated by bracketing the symbol thus: (A) or (D). 14. YEAST DEXTROSE LEMCO BROTH This medium has been found suitable for the culture of most bacteria isolated from milk. Peptone y ‘ . 10g Lab. lemco . ; : : : 10g Yeastrel 4 : ; ; : 3¢g Sodium chloride. 52 Distilled water . : L 1,000 ml Dextrose : ; : : : 5zZ Dissolve all ingedients except dextrose by steaming for 4 hr. Cool to room temperature and adjust pH to 7-0. Add dextrose, shake to dissolve and then filter. Tube in 5 ml quantities. Autoclave at 115° for 15 min. Incubate sterilized media at 30° for 3 days and check sterility. ,