It is not intended by the above remarks to cast any discredit upon the value of beef extract, as its value has been attested in numerous cases. It is only designed to call attention to the fact that as food these extracts have comparatively little value. They may be useful as stimulants or as condimental substances or as a means of speedily introducing a soluble nutrient in the case of disease where it is extremely important that even small amounts of nutritious material should enter the body.
Beef Juice.—A distinction is made between a beef extract and a beef juice. The latter term applies solely to the liquid naturally remaining in the fresh meat after its proper preparation for consumption, that is, after the withdrawal of the blood and the proper cooling and storing of the flesh. The fresh meat is then subjected to strong pressure and the juices which are extracted are concentrated in vacuo to the proper consistence. The meat of old bulls is often used. A true beef juice must be extracted from the cold meat and not with the aid of heat, hot water or other solvents. It is difficult to preserve an extract of this kind without sterilization, and the heat required for sterilization is likely to coagulate some of the albuminous material which is expressed. It is a great temptation, therefore, in some cases to preserve the beef juice by a chemical preservative other than common salt. Boric acid and sulfite of soda may be used for this purpose, but these substances are objectionable on the score of possible injury to health. Glycerine is also used. Inasmuch as these juices are usually given to invalids or those whose digestive functions are impaired it is most important that injurious substances should be omitted. In case of pressure it is advisable, in some cases, to chop the meat very fine, and in this comminuted condition extract the juice with cold water. This does not produce any change in the character of the juice and the water is subsequently removed by evaporation at a low temperature in vacuo. Beef juices are usually prepared from heated meats.
Composition of Beef Juice.—The composition of beef juice from different parts of meat which was previously heated externally is shown in the following table.
COMPOSITION OF BEEF JUICE AND MEAT EXTRACT.
Beef Juice. Meat Extract.
Water, 90.65 21.66
Ash, 1.36 20.46
NaCl (salt), .15 5.47
P_{2}O_{5} (phosphoric acid), .36 4.55
Fat, .19 .50
Acid (as lactic), .15 8.42
Nitrogen (total), 1.15 7.66
" insoluble and coaguable, .68 .48
" as proteoses, .04 2.02
" as peptones, .14 1.90
" meat bases, .30 3.05
" creatin, .75
" xanthin bases, .04
" ammonia, .21
