. Bacteriological methods in food and drug laboratories, with an introduction to micro-analytical methods. Bacteriology; Food; Drug adulteration. TEST FOR WATERED MILK I31 The following quick and simple test is recommended to dis- tinguish between raw and boiled milk! Reagent Methylene blue (alcoholic) 5 cc. Formaldehyde (40 per cent.) 5 cc. Water (distilled) 190 cc. Add I cc. of this reagent to 20 cc. of the milk and heat for 10 min. at 40^-45° C. Raw milk is decolorized while boiled milk retains the blue coloration. This test should in all cases be checked by the microscopical examination. B
. Bacteriological methods in food and drug laboratories, with an introduction to micro-analytical methods. Bacteriology; Food; Drug adulteration. TEST FOR WATERED MILK I31 The following quick and simple test is recommended to dis- tinguish between raw and boiled milk! Reagent Methylene blue (alcoholic) 5 cc. Formaldehyde (40 per cent.) 5 cc. Water (distilled) 190 cc. Add I cc. of this reagent to 20 cc. of the milk and heat for 10 min. at 40^-45° C. Raw milk is decolorized while boiled milk retains the blue coloration. This test should in all cases be checked by the microscopical examination. Boiling the milk causes the fat globules to unite and adhere more or less, a characteristic which is also noticeable in pasteurized milk. The flavor and odor of boiled milk is in itself quite characteristic. Knapp recommends the following test for determining the addition of water to milk. 10 cc. of the suspected milk are run into a test-tube and curdled by adding one drop of rennet and placing the tube in the water bath for about 2 min. at a temperature of 35^-40° C. The whole is then poured upon a very fine wire sieve and the liquid allowed to drain off into a tube graduate, pressing the curd with a glass rod so as to remove the liquid as completely as possible. The amount of liquid remaining in the curd is fairly constant in the tests and therefore ,. ,, ,..,,. ^. Fig. 41.—Gelatin practically neghgible for comparative purposes, culture of Siaphylo- If the amount of liquid drained off exceeds 8 coccus aureus 1 vfe&\L CC, water has been added. This test should be checked by the chemical butter fat tests and also by the microscop- ical method for determining the fat content, as already explained. Among the micro-organisms which cause the coagulation of milk and which are often found in sour milk, particularly in old sour 10. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearan
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Keywords: ., bo, bookcentury1900, bookdecade1910, booksubjectfood, bookyear1915
