ing the sample in the presence of magnesium oxid. In several of the
samples examined high ammonia results were obtained which might
indicate some degree of putrefaction. It is questionable, however,
whether the ammonia results obtained by the magnesium oxid
method are not too high.
Many investigators have stated that ammonia salts are present in
meat extracts. Probably the ammonia combines with acids of the
fatty series to form these salts, which are soluble in alcohol and vola-
tile with alcohol vapor. The ammonia is estimated by dissolving 10
grams of the meat extract in water, adding barium carbonate and
distilling. It has been suggested that ammonium salts, especially
ammonium sulphate, are added to meat preparations to increase the
nitrogen content, and in some of the extracts examined a relatively
high sulphur content was noted.
Weidel b first called attention to the presence of succinic acid in meat
extracts. Salkowski, c Kutscher and Steudel/ and others claimed
« IT. S. Dept. Agr., Bureau of Chemistry, Bui. 107, p. 9.
bLiebig'sAnnalen, 1871, 158:353.
cZts. klin. Med., 1890, Supplement to vol. 17, p. 77.
d Zts. physiol. Chem. , 1903, 38 : 101.
42 MEAT EXTRACTS.
that succinic acid was a putrefaction product and its presence in
meat extract showed that fresh meat had not been used in manufac-
turing the extract. Siegfried held that the source of the succinic
acid is a definite substance of acid character and he called this sub-
stance " Phosphorfleisch Saure" or "Muskelnucleon." Later work,
however, indicates that succinic acid is a cleavage product of fresh
meat formed by the action, at high temperature, of dextrose or other
reducing substance on amido acids, especially aspartic acid. Conse-
quently, the presence of succinic acid in a meat extract does not
mean that spoiled meat was used in its manufacture. In 1904 two
or three brands of American meat extract were tested for the pres-
ence of succinic acid by means of ether extraction and the pine sliver
test and this body was shown to be present. .
The question of the presence of succinic acid in meat extracts is
thoroughly discussed in a recent publication of the German Board of
Health. 6 "
The ether extract should not be above 0.6 per cent in a sample of
meat extract, as the fat is liable to become rancid and injure the
flavor of the product. Moreover, a high fat content shows lack of
care in preparing the extract.
The provisional method employed for determining the ether ex-
tract c is conducted as follows:
Dry the sample over night in the presence of dry sand in a lead dish
at the temperature of boiling water. Then thoroughly grind and
extract the dried sample with anhydrous ether, in a continuous ex-
traction apparatus for sixteen hours. Satisfactory duplicate results
are obtainable by this method, but it is the opinion of the authors
that the sample should be digested with pepsin and acid before ex-
tracting with ether, in order to break up the proteid matter and thus
expose the fat to the action of the ether more completely.
That glycerol has Deen added to fluid meat extracts and other
similar preparations is well known, and it was found in several of the
samples reported in this bulletin. The purpose in adding it seems
to be to give the product additional smoothness and bod}". More-
over, glycerol is of considerable value as a preservative. Glycerol
is burned in the body and thus becomes a source of energy, but it
does not act as a proteid sparer.
Various methods were tried for the determination of glycerol in
meat extracts and related products, including the method of the
a Zts. physiol. Chem., 1903, 39 : 126.
&Arb. kaiserl. Gesundheitsamte, 1906. vol. 24.
cU. S. Dept.- Agr., Bureau of Chemistry, Bui. 107, p. 114.
METHODS OF ANALYSIS. 43
Association of Official Agricultural Chemists a for the determina-
tion of glycerol in wines, and Lane's method, 6 as well as numerous
extraction methods. Among the solvents used were benzol, amyl-
acetate, gasoline, carbon tetrachlorid, carbon bisulphid, and acetone.
All of these solvents extract varying amounts of meat bases, or
extractives, and give different results on the glycerol present. The
following reagents were used to precipitate the dissolved meat bases:
Lead acetate, silver nitrate, and phosphotungstic acid. The best
results were obtained by extracting with acetone, the meat bases
being precipitated first with silver nitrate, lollowed by phospho-
tungstic acid. The glycerol in the filtrate was estimated by the
Hehner c method.
Shukoff and Shestakoff d describe an acetone extraction method,
but weigh the glycerol, and it is impossible to estimate this bod}" in
the case of meat extracts by weighing on account of the salts and
extractives dissolved by the acetone and weighed as glycerol.
A method using anhydrous copper sulphate and extracting with
acetone is now under investigation.
A qualitative test for nitrates was made in 28 samples of meat
extracts, meat peptones, fluid meat juices, and fluid extracts. The
samples were collected in July, 1907, and in general represent the
same brands as were used in the other studies.
The diphenylamin e test was used. The reagent was made by
dissolving 1 part of diphenylamin in 100 parts of concentrated sul-
phuric acid. The test was applied as follows:
Transfer 1.5 grams of the semisolid, or 1 cc of the liquid extracts,
to a 250 cc beaker and boil with animal charcoal for two or three
minutes. Filter the solution hot and test one drop of the filtrate
on a porcelain plate with three drops of the diphenylamin reagent.
A blue color indicates nitrates, and the depth of color shows in a
general way the amount of nitrates present.
Negative tests for nitrates were obtained in the case of 14 of the
28 samples examined. The results on the 14 samples giving posi-
o U. S. Dept. Agr., Bureau of Chemistry, Bui. 107, p. 83.
b Unpublished. The method reads as follows:
Precipitate a known weight or volume with basic lead acetate, make, up to a known
volume with alcohol, filter, take an aliquot part, add a little anhydrous lime, distil
nearly to dryness in a steam bath (keep the flask immersed), add an excess of anhy-
drous CaO, mix, moisten with alcohol to facilitate mixing if necessary, distil again
on steam bath to combine water with CaO, and extract with two-thirds alcohol and
one-third chloroform, as usual.
cj. Soc. Chem. Ind., 1889. 8:4.
*Zte. angew. Chem., 1905, 18:294.
eArch. Hyg., 1884, 2:373.
44 MEAT EXTRACTS.
tive reactions showed in 6 cases a slight trace and in 8 cases a very
strong reaction, indicating that the "liquor" from the parboiling of
corned beef was used in their preparation. (See p. 13.)
Under this head are included nonnitrogenous organic matter as
well as glycerol and carbohydrates. Glycerol has been considered
under a separate caption. The amount of undetermined matter
present depends on the mode of preparation of the extract; not
more than 10 per cent should be present in a meat extract. Inosite
and various amido acids, from which the nitrogen has been split off,
also constitute a portion of the undetermined matter.
Several of the samples which gave a high per cent of undetermined
matter were tested for starch, reducing sugar, and glycerol. The
following qualitative results were obtained:
Qualitative tests for starch, reducing sugar, and glycerol.
The albumose and peptone products which are high in undeter-
mined matter, according to the tables, contain carbohydrates (starch
and sugars). In the case of several of the fluid meat extracts, or
juices, and in one or two solid extracts, glycerol is present.
HISTORICAL NOTE ON NUTRITIVE VALUES.
It has long been known that gelatin is present in various amounts
in meat extracts. The collagen of the muscle on hydration yields
gelatin, and if the hydration be carried far enough soluble gelatin,
gelatoses, and gelatin peptones are found. Gelatin, while rich in
nitrogen, is not capable of keeping the body in nitrogenous equilib-
rium, since the nitrogen is not present in a form available to the body
as in all true proteids. This has lately been explained by Kaufl-
mann a on the ground that the gelatin molecule is lacking in the
tyrosin, cystin, and tryptophane groups and that by feeding these
amido bodies with gelatin animals are kept in nitrogenous equilibrium.
KaufTmann states that one-fifth of the proteid of a ration can be
replaced by gelatin, but when used in large proportions the body is
aPfluger's Arch., 1905, 109 :440.
NUTRITIVE VALUES. 45
not kept in equilibrium. This was demonstrated by an experiment
conducted by the author on himself, and also on dogs. Mancini*
has fed large amounts of gelatin and little proteid and claims that
gelatin has a proteid sparing action. Murlin^ has replaced two-
thirds of the proteid nitrogen by gelatin in the case of both dogs and
men reduced to a starvation level and finds the equilibrium is not
changed by this substitution. Gelatin and its cleavage products have
been studied by Chittenden and Solley e and Levene * among others.
A valuable contribution to the literature on the subject of the nutri-
tive value of gelatin by Murlin 6 has recently appeared. The review
of the literature here given is in part taken from this article. The
experiments performed by this author were made on dogs and the
fasting requirement of nitrogen was used as a working basis. Murlin
states that the power of the organism to utilize gelatin as a proteid
substitute depends to some extent on the proteid condition of the
body at the beginning of the experiment, as well as upon the loss of
proteid during its progress.
In the experiments with dogs as high as 58 per cent of gelatin nitro-
gen was substituted for proteid nitrogen, the amount varying with the
diet. In the case of man, if two-thirds of the potential energy were
in the form of carbohydrates it was found to be possible to supply 63
per cent of the total nitrogen in the form of gelatin nitrogen for a
period of two days and maintain a daily retention of nitrogen of 0.71
Exact knowledge of the nutritive value of gelatin had its beginning
in the researches of Carl Voit/ published in 1872. As early as 1860
Voit and Bischoffs' had established experimentally the truth first
perceived by Donders, A that gelatin reduces the proteid requirements
of the body; but they were of the opinion at this time that it could
perform all the work of proteids and replace them entirely in the diet.
After Voit 1 had shown that a part only of the nitrogenous excreta
is derived from the proteids of the body tissue, a portion coming from
the "circulating" proteids, he again investigated the extent to which
gelatin could be substituted for proteid, and reached the following
Gelatin exercises its sparing power on the proteids both with large and with small
quantities of proteid (meat) fed at the same time, and with small quantities in much
"Arch. d. Farmacol. sperim., 1906, 5: 309, 337.
&Proc. Soc. Exper. Biol, and Med., 1904, 2 :38.
cj. Physiol., 1891, 12 .2%.
dZts. physiol. Chem., 1904, 41:8.
«Amer. J. Physiol., 1907, ^9:287.
/Zts. Biol., 1872,5:297.
y Die Gesetze der Ernahrung des Fleischfressers, Leipzig, 1860.
h Die Nahrungsstoffe, Crefeld, 1853.
*Zts. Biol., 1869, 5:329.
46 MEAT EXTEACTS.
higher degree than either fat or carbohydrates. It can be shown that large quantities
of gelatin spare more proteid from combustion than do small quantities; that, however,
proteid is lost from the body even' if with large quantities of gelatin the greatest possible
amount of fat be given. A direct laying-on of gelatin, either in the glutin-yielding
tissues or in the proteid-forming tissues, is not possible, and it must therefore be
assumed that when gelatin is formed in the body it is at the expense of proteid. Gela-
tin, for this reason, is capable of replacing proteids of the food only in part. "
Voit made no special attempt to set the limits within which proteid
may be so replaced, but gives for a large dog these figures: 168 grams
of dry gelatin spared 84 grams of dry flesh. 6
The next investigation bearing on the comparative value of gelatin
and proteid was that of Oerum, c who placed a dog on a daily diet of
meat, starch, butter, and meat extracts; he then replaced all of the
meat with enough gelatin to maintain the same nitrogen supply. He
records a considerable increase in the nitrogen of the urine in the
Pollitzer, d in the course of some experiments undertaken to prove
that the products of proteid digestion are to be classed with the pro-
teids themselves, and not with the proteid-sparing foods merely,
compared the effects of gelatin on the nitrogen output with those of
horseflesh and its products of gastric digestion. He concludes that
peptone and hemialbumose (prepared by Kuhne's methods) have a
nutritive value which is in "sharp contrast with the considerable loss
of nitrogen which takes place after feeding an equivalent amount of
Ganz e fed PaaFs glutin-peptone and was able to cover more than
half of the total nitrogen requirements therewith. Gerlach f also pre-
pared a "glutin-peptone," and found that it is a good "sparing agent,"
but is not of itself able to replace proteid.
Munk a in a brief series of experiments attempted to find the "upper
limit for the substitution of food proteid with gelatin," and reached
the conclusion that at least half as much proteid must be fed as is
destroyed by the animal in fasting, if nitrogen equilibrium is to be
Kirchmann, A in a very painstaking research with proteid-free
gelatin, determined that the proteid destruction may be reduced
under the influence of gelatin alone as much as 35 per cent, and that
this maximum effect is obtained when 62 per cent of the body's
energy requirement is supplied by the gelatin.
"Zts. Biol., 1872, 5:297.
cXordiskt medicinskt Arkiv, 1879, vol. 11, reviewed by Hammarsten in Maly'fl
Jahresbericht fur Thierchemie, 1879, 9: 308.
d Archiv gesam. Physiol., 1885, 37 : 301.
« Quoted by Kirchmann, Zts. Biol., 1900, 40:54.
/ Die Peptone. Hamburg and Leipzig, 1891.
9 Archiv gesam. Physiol., 1894, 58 : 309.
h Loc. cit.
NUTRITIVE VALUES. 47
Krummacher, a carrying the work begun by Kirchmann still
further, found that when the entire energy requirement of the dog
was covered by gelatin the total sparing was only 37.5 per cent of
the fasting nitrogen. Applied to a man whose energy requirement
is 2,500 calories daily Krummacher calculates that if 5 per cent of
his requirements were supplied in gelatin (i. e. about 33 grains of dried
and purified gelatin), the proteid' destruction in his body would be
reduced from 70 grams to about 56 grams, or, in other words, the 33
grams of gelatin would replace 14 grams of proteid.
Gregor 6 used gelatin in feeding infants in certain cases where
excess of proteid was contraindicated, and concluded that with a diet
containing 4.8 grams of nitrogen per day (of which "nearly all" was
gelatin N), not more than half as much nitrogen was lost from the body
as in starvation.
Brat c prepared a gelatose, which he identifies by 'Chittenden's d
method as a deuterogelatose, and fed it to convalescent patients as a
substitute for a portion of the proteid in their diets.
Mancini 6 studied the nitrogen balance of five convalescents from
typhoid fever, while giving " large quantities" of gelatin. He
observes a considerable retention of nitrogen, but doubts whether
proteid nitrogen can be replaced by gelatin nitrogen.
Kauffmann / studied the replacing power of gelatin in a diet con-
taining "only as much proteid (mainly casein) as is necessary with a
sufficient supply of energy for maintenance of the body's condition."
He concludes from his experiments on dogs that not more than one-
fifth of the proteid in such a diet can be replaced by (pure) gelatin
if nitrogen equilibrium is to be maintained. With one-fourth of the
proteid nitrogen so replaced a small minus balance occurs. Kauff-
mann's paper is concerned chiefly with the attempt to bring gelatin
up to the full nutritive value of proteid by adding to it the amido-
acids which it lacks, but which casein contains.
Rona and Muller,^ in attempting to confirm Kauffmann's results
with gelatin, tyrosin, and tryptophan, found first "the smallest
quantity of proteid nitrogen with which the animal could well get
along," and then replaced one-fifth of this proteid (casein) with
gelatin nitrogen. Their observation as regards the amount which
would be replaced was quite in accord with Kauffmann's, for when
gelatin was substituted for two-fifths of the casein there was a dis-
tinct minus balance.
oZts. Biol., 1901, 42:242.
& Centralblatt fur innere Medicin, 1901, 22 : 65.
c Deutsche medicinische Wochenschrift, 1902, p. 21.
rfj. Physiol., 1891, 12:23.
eReale Accademie dei Fisiocritici di Sieni, 1905, 17:667.
/Archiv gesam. Physiol., 1905, 109:440.
9Zts. physiol. Chem., 1907, 50:263.
48 MEAT EXTRACTS.
The conclusions reached by the various investigators may be sum-
marized briefly as follows: Gelatin can replace proteid only in part
(Voit, Oerum, Pollitzer); it has, however, a high proteid-sparing
effect, whether fed alone (Kirchmann, Krummacher), or with other
foods (Voit, Oerum, I. Munk, Kauffmann, Rona and Muller) in infant
feeding (Gregor), or in convalescence (Brat, Mancini) ; this proteid-
sparing effect is exerted also by gelatin-peptones (Ganz, Gerlach)
and gelatoses (Brat).
MEAT EXTRACTS AND JUICES.
The various protein bodies and amido acids are so closely asso-
ciated that it is impossible to produce amido acids without produc-
ing albuminoses and peptones. Consequently, every commercial
meat extract must consist partly of albuminoses, peptones, etc. The
best extracts on the market to-day contain about 50 per cent of the
total nitrogen in the form of meat base nitrogen. When a meat
preparation contains only a small amount of its nitrogen in the form
of meat base nitrogen, the term " extract" seems to be no longer
applicable. And it is evident that the product represents much less
meat than an extract with 50 per cent of its nitrogen in the form of
meat base nitrogen, provided the total nitrogen in both cases is
approximately equal. Moreover, it is necessary to distinguish
between a meat extract containing large amounts of stimulating amido
acids and relatively small percentages of albumoses, peptones, and
insoluble proteid matter, and an extract (or, more properly, a meat
product) which consists largely of albumoses, peptones, and insoluble
matter and relatively small amounts of amido acids. The food value
of this last group of products is undoubtedly greater than that of the
former group, but they should not be classed as extracts because
of their different nature. The value of the amido bodies as food is
uncertain, but at least they furnish energy to the body. It appears,
therefore, that the value of meat extracts lies principally in their stim-
ulating qualities, the active principles of tea and coffee being on a
The question of the nutritive value and relative worth of the vari-
ous nitrogenous constituents of meat preparations is a much-dis-
cussed but unsettled problem. Beef juice prepared from fresh beef
by pressure and heating and used unchanged is an ideal product,
containing the extractives as well as a large amount of nutritive
material. As a commercial product, however, it is impracticable.
The higher forms of nitrogen, insoluble proteids, alkali and acid albu-
mins, and coagulable proteids, as well as the unchanged proteids, are
the most desirable forms for the healthy individual. The invalid
may require partly digested proteids, such as proteoses and peptones.
A large amount of nitrogen in this form should be avoided, as many
NUTRITIVE VALUES. 49
investigations have shown that diarrhoea and other disorders follow
the feeding of peptones. The stimulating properties of the amido
acids are most valuable in that they create an appetite and prepare
the system for food.
The scope of this report will not permit of the exhaustive treat-
ment of this' subject, but brief mention is made of the following con-
tributions as indicative of the tendency of the results obtained :
Biirgi a states that meat extracts are not foods, and that all mate-
rial taken in this form is quickly eliminated. Only 4.57 per cent of
the nitrogen, 14.85 per cent of the carbon, and 17.55 per cent of the
energy content is retained. According to Rubner 6 meat extracts,
after they have served their purpose of stimulating digestion, are
eliminated from the body as rapidly as possible. W. H. Thompson
has fed arginin to dogs and found from 37.6 to 77 per cent in the
urine; on injecting arginin 82 per cent appeared in the urine. A
part of the arginin nitrogen appeared in the urine as ammonia. Voit d
claims that the value of meat extracts lies in their flavor, which pro-
motes the flow of the digestive juices. As the constituents of meat
extracts are largely in a form ready for elimination, Rubner e holds
that they have little food value.
Pfeiffer, Einecke, and Schneider / have fed asparagin to cows and
report a favorable effect on the milk and its constituents, and W.
Yoltz^ claims asparagin can replace proteid without lowering the
quality of the milk and that it acts as a proteid sparer in herbivora.
In omnivora its proteid sparing power is small and it seems to have
no such power in carnivora but rather increases proteid cleavage.
In feeding experiments with mice on a zein ration Willcock and Hop-
kins * found that on adding tryptophane to the ration the lives of the
mice were lengthened. Henriques and Hansen* have maintained
nitrogenous equilibrium on feeding hetero-albumose.
Rubner i discusses the alcohol-soluble and alcohol-insoluble por-
tions of fluid beef. The nutritive value of fluid beef is considered at
length and the author concludes that if enough of such product for an
entire ration were taken the cost would be enormous. The claim that
two teaspoonfuls of fluid meat have a nutritive value equivalent to
one and one-fourth pounds of cooked meat is deemed correct. Two
a Arch. Hygiene, 1904, 51:1.
»Ibid, p. 19.
cj. Physiol., 1905, &*: 106.
d Stoffwechsel, 1882, p. 449.
«Zts. Biol., 1883, ^9:343.
/Mitt, landw. Inst, konigl. Univ. Breslau, 1905, 5:179.
^Fuhlings landw. Ztg., 1905, 54 (2) :41; (3) : 96.
fcj. Physiol.. 1906, 35: 88.
<Zts. physiol. Chem., 1906, 48: 383.
iZts. Biol., 1879, 15:485.
43689— Bull. 114—08 4
50 MEAT EXTRACTS.
teaspoonfuls of fluid meat weigh about 52 grams and are equivalent
to 65 grams of pure meat free from fat and bones. Barker a recently
published a thorough review of the question and has taken up several
new points. In normal man the amido bodies do not appear in the
urine to any extent; therefore, they must be of value, and the author
believes they are synthesized into protein by the cells of the small
intestine. W. Yoltz b claims that amido bodies of different chemical
constitution produce varying effects on the nitrogen and caloric bal-
ances of the body. The tightly bound NH 2 groups, holding an inter-
mediate position in the molecule, such as are found in glycocoll, tend
to increase the nitrogen retention less than the carboxyl NH 2 groups,
which are more easily separated from the molecule. The amids in an
ordinary diet give more favorable results than when fed alone. On
feeding various amids to dogs the author obtained favorable results.
An unsigned article in the Pharmaceutische Zeitung c discusses the
manufacture of meat extracts, and says that when meat (fat and bone
free) is extracted with water by heating, the extract does not taste
like the commercial meat extract, and is whitish, but after continued
heating over an open fire and the addition of 30 per cent of salt, the
commercial product, a brown aromatic extract with a characteristic
taste, is obtained. In preparing meat juice, 1 pound of meat cut up
and pressed yields 60 to 100 grams of a red-colored juice. Evaporate
this at 60° C. in a vacuum to one- third its bulk and a slightly red
solution with a taste of meat, but no salty taste, is obtained — a