Detection of the Common Food AdulterantsBruce, Edwin M.
Science
Detection of the Common Food Adulterants
Bruce, Edwin M.
Food adulteration and inspection
Aniline red and cochineal carmine are usually employed for this purpose.
The former may be detected, according to Allen, by picking the meat
apart and treating it with methylated spirit, strain or filter the
extract and take up with water. Then a piece of white wool (nun’s
veiling will do) is immersed in the boiling liquid and, if it is dyed
red, rosaniline is present.
Cochineal-carmine may be detected by the method used by Klinger and
Bujard. Cut up fine about 20 grams of the meat and heat in a water-bath
with water and glycerine mixed in equal parts. If the above coloring
matter is present the liquid will become quite red in color, if not
present a slight yellow color results from this treatment. If a
spectroscope is available this dye is easily recognized.
STARCH
IN SAUSAGE, DEVILED MEAT, AND SIMILAR PRODUCTS
Cracker and bread crumbs are often added to these preparations and their
presence is best detected by examining the amount of starch present. Do
this by boiling some of the sample in water, and when cool adding a drop
or two of iodin reagent. The usual blue color is produced if much
starch is present. If there is only a little starch, it may be necessary
to examine it under the microscope to determine whether the starch is
from the pepper and other spices used or from some cereal.
DISEASED MEAT
_The following method is recommended by Ebers._--Hold a small piece of
the suspected meat over a mixture of 1 cc. hydrochloric acid, 3 cc.
alcohol, and 1 cc. of ether. The formation of ammonium chlorid fumes
shows that decomposition has begun. Do not mistake the fumes of the acid
for those of ammonium chlorid.
HORSE FLESH
IN SAUSAGE AND MINCE MEAT
This sophistication is not common in this country. Horse flesh is
detected by testing for glycogen, which is present in it in larger
quantities than in other meats.
_Courley & Coremon’s Test._--Boil 50 grams of the meat for a half hour
with water, strain, and to a portion of the filtrate add a few drops of
potassium iodid-iodin solution (potassium iodid 0.4 gram; iodin 0.1
gram; water 20 cc.). If considerable horse meat is present the glycogen
will color the liquid dark brown, which disappears on heating, but
returns on cooling.
EGGS
It sometimes happens that one wishes to know the age of eggs without
opening them.
_Delarne’s Test._--Place the egg in a 10 per cent solution of common
salt. Perfectly fresh eggs sink to the bottom. Those remaining
immersed, but suspended in the liquid, are at least three days old,
while those rising to the surface and floating are more than five days
old. The older the egg, the higher it floats and the more it will stand
on end. This test is not applicable to eggs that have been preserved.
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