Butter is the fat of milk, containing small proportions of caseine,
water, and salt (the latter mostly added), and possessing a somewhat
granular structure. In its preparation the fat-globules of cream are
made to coalesce by the process of churning, and are removed from
the residual buttermilk. Its colour, due to lactochrome, varies from
white to yellow, according to the breed and food of the cow. The
fatty constituents of butter are butyric, caproic, caprylic, capric,
myristic, palmitic, stearic, and oleic acids, which are combined with
glycerine as ethers; the first four are soluble in hot water, the
remainder insoluble. It is very probable that butter fat is composed of
complex glycerides, _i. e._ tri-acid (presumably oleic, palmitic, and
butyric) ethers, of the following character:–
{O.C_{4} H_{7}O
C_{3} H_{5} {O.C_{16}H_{31}O
The table on p. 64 exhibits a summary of the results obtained by
various chemists by the analysis of numerous specimens of genuine
Dr. Elwyn Waller found the following variations in the constituents of
pure butter:–Fat, from 83 to 85; water, from 8 to 10; curd, from 1 to
3; salts, from 3 to 5 per cent.
Butter fat fuses at 28° to 37°, and at 37°·7 its specific gravity
ranges from 0·91200 to 0·91400. The most common adulterations of
butter consist in the addition of water, salt, colouring matters, and
various foreign fats (notably oleomargarine). The first two admixtures
are easily recognised by the proximate analysis; the detection of the
last sophistication involves a somewhat elaborate examination of the
fatty constituents of the butter.
| No. | Water. | Fats.
Analyst. | of |——+——+——-+——-+——-+—–
|Samples.| Max. | Min. | Avg. | Max. | Min. | Avg.
| p.c. | p.c. | p.c. | p.c. | p.c. | p.c. | p.c.
König | 123 |35·12 | 5·50 | 14·49 |85·25 |76·37 |83·27
Bell | 117 |20·75 | 4·15 | 14·2 | .. | .. | ..
| | | | | | |
Hassall { | 48 |15·43 | 4·18 | .. |96·93 |67·72 | ..
{ | |28·6 | 8·48 | .. |96·93 |67·72 | ..
| | | | | | |
Angell and Hehner| 30 |16·0 | 6·4 | .. |90·2 |76·4 | ..
Wanklyn | 50 |24·9 | 8·6 | .. | .. | .. | ..
Caldwell | 26 |30·75 |10·45 | .. | .. | .. | ..
Ellis | 12 |10·5 | 4·9 | .. |89·7 |80·8 | ..
Larue | 12 |16·5 | 8·0 | .. |86·9 |79·14 | ..
| | | | | | |
Fleischman {fresh| .. | .. | .. | 18·0 | .. | .. |80·0
{salt | .. | .. | .. | 12·0 | .. | .. |83·5
| | | | | | |
Blyth | 5 |12·984| 8·58 | .. |87·223 |82·643 |85·45
Schacht | 8 | 9·00 | 1·25 | .. |98·00 |87·00 | ..
| Curd. | Salts.
Analyst. |——-+——-+——+——–+————–
| Max. | Min. | Avg. | Max. | Min. | Avg.
| p.c. | p.c. | p.c. | p.c. | p.c. | p.c.
| | | | | |
König | 4·77 | 0·25 | 1·29 | 5·65 | 0·08 | 0·95
Bell | 4·02 | .. | 1·2 | 15·08 | 0·5 | ..
| | | | | |
Hassall { | .. | .. | .. | 2·91 | 0·3 | ..
{ | .. | .. | .. | 8·24 | 1·53 | ..
| | | | | |
Angell and Hehner| 5·1 | 1·1 | .. | 8·5 | 0·4 | ..
Wanklyn | .. | .. | .. | 10·7 | 0·1 | ..
Caldwell | .. | .. | .. | .. | .. | ..
Ellis | 4·9 | 1·1 | .. | 6·2 | 0·1 | ..
Larue | 5·5 | 1·5 | .. | 3·60 | 0·4 | ..
| | | | | |
Fleischman {fresh| .. | .. | .. | .. | .. | 2·0
{salt | .. | .. | .. | .. | .. | 6·5
| | | | | |
Blyth | 5·137 | 2·054 | 2·5 | 3·151 | 0·424 | ..
Schacht | 0·5 | .. | .. | 6·0 | 0·57 | ..
_Proximate Analysis._
About five grammes of the well-averaged sample are weighed out in a
tared platinum capsule, and dried for three hours (or until constant
weight is obtained) over a water-bath (or over a low flame, constantly
stirring with a thermometer), and the decrease in weight (water)
ascertained. As a rule, the proportion of water in genuine butter
varies from 8 to 16 per cent. The residue in the capsule is then
melted at a gentle heat, and the liquid fat cautiously poured off
from the remaining caseine and salt, these latter being afterwards
more completely exhausted by washing with ether. Upon now drying the
residue, the loss in weight will give the amount of fat present.
The caseine is next determined by the loss in weight obtained upon
incinerating the matters left undissolved by the ether, the remaining
inorganic matter being the salt contained.
The proportion of fat present in genuine butter ranges from 82 to 90
per cent.; it should never be below 80 per cent. The average amount of
caseine is 2·5 per cent.; greater proportions, frequently occurring
in unadulterated butter, render it more liable to become rancid. The
ash should consist of sodium chloride, with some calcium phosphate;
the amount of salt is quite variable, but it usually ranges from 2
to 7 per cent. The proportion of ingredients, not fat, in butter
may be conveniently determined by melting 10 grammes of the sample
in a graduated tube, provided with a scale at its lower end, which
is narrowed, adding 30 c.c. of petroleum naphtha, and shaking the
mixture. After standing a few hours, the non-fatty matters collect in
the lower portion of the tube, and their volume is read off. Genuine
butter is said to yield from 12 to 14 per cent. (assuming each c.c. to
equal one gramme), while adulterated specimens may show 20 per cent. of
matters not fat.
_Examination of the Butter-fat._
The most common and important sophistication of butter consists in the
addition of foreign fats, embracing both animal fats (oleomargarine and
lard) and vegetable oils (cotton-seed, olive, rape-seed, cocoa-nut,
almond, palm, etc.). Of these, oleomargarine is doubtless the most
often employed. Oleomargarine is the more fusible portion of beef fat,
and is prepared by straining the melted fat, allowing the oil thus
obtained to stand for some time at a temperature of about 24°, when
most of the stearine and palmitine will separate out, and cooling the
remaining oil until it solidifies. This is next churned with milk, a
little colouring matter (annato) being added, and the product is then
chilled by mixing it with ice; salt is now added, and the mass is
finally worked up into lumps.
It is stated that fifteen establishments in the United States are
engaged in the manufacture of oleomargarine, the annual production
in the State of New York alone being about 20,000,000 pounds. The
rapid increase in the manufacture of oleomargarine is shown by the
following statistics:–In 1880 this country exported 39,236,655
pounds of butter and 20,000,000 pounds of oleomargarine, while in
1885 the exportation of butter declined to 21,638,128 pounds, and
the exportation of oleomargarine reached nearly 38,000,000 pounds.
The present production is said to approximate 50,000,000 pounds per
annum. The most characteristic difference in the composition of genuine
butter and oleomargarine consists in the greater proportion of soluble
fats contained in the former. This is illustrated by the following
comparative analysis of the two products (Mége Mouriès):–
|Genuine Butter.|Oleomargarine.
| per cent. | per cent.
Water | 11·968 | 11·203
Solids | 88·032 | 88·797
| 100·000 | 100·000
_Solids_: | |
Insoluble fats | 75·256 | 81·191
Soluble fats | 7·432 | 1·823
Caseine | 0·182 | 0·621
Salt | 5·162 | 5·162
| 88·032 | 88·797
Lard is likewise occasionally used in the United States as an
admixture to butter, the product, “lardine,” being sold either as
oleomargarine-butter, or as the genuine article. Dr. Munsell mentions
a factory in New York city where the weekly output of larded butter is
5000 pounds. As a result of the efforts of the New York State Dairy
Commission, it has been estimated that the sale of imitation butter in
this State in 1885 suffered a decrease of about 60 per cent., although
the quantity manufactured in the United States showed an increase of 50
per cent.
The specific gravity and melting point of butter have been suggested as
criteria for its purity; in most cases, however, these determinations
possess a rather limited value; as already stated, butter fat, at the
temperature of 37°·7, has a density ranging from 0·91200 to 0·91400.
The relation between the specific gravity of a fat and the proportion
of insoluble acids contained was first noticed by Bell. This is shown
in the following table which refers to pure butter fat.
Specific Gravity | Per cent.
at 37°·7. | Insoluble Acids
0·91382 | 87·47
0·91346 | 87·89
0·91337 | 87·98
0·91290 | 88·48
0·91286 | 88·52
0·91276 | 88·62
0·91258 | 88·80
0·91246 | 89·00
The following results have been obtained by the analysis of samples of
various animal fats, and oleomargarine butter.
| Specific Gravity | Per cent. Fixed
| at 37°·5. | Fatty Acids.
Mutton suet | 0·90283 | 95·56
Beef suet | 0·90372 | 95·91
Fine lard | 0·90384 | 96·20
Dripping (commercial) | 0·90456 | 94·67
Mutton dripping (genuine) | 0·90397 | 95·48
Oleomargarine butter | 0·90384 | 94·34
„ „ | 0·90234 | 94·83
„ „ | 0·90315 | 95·04
„ „ | 0·90379 | 96·29
„ „ | 0·90136 | 95·60
It will be noticed that the fats mostly used to adulterate butter are
of a lower density. Blyth regards a gravity below 0·911 (at 37°·5) as
clearly pointing to the presence of foreign fatty admixture.
The specific gravity determination is made by means of the areometer,
or by the gravity bottle; numerous indirect methods have also been
proposed. P. Casamajor[26] suggests a process for distinguishing
genuine butter from oleomargarine which is based upon the fact that
the density of a liquid in which a body remains in equilibrium is the
density of the body itself. As the result of his investigations it was
found that pure butter at 15° would be held in equilibrium by alcohol
of 53·7 per cent. (sp. gr. = 0·926), and that oleomargarine would
remain in equilibrium, at the same temperature, in alcohol of 59·2 per
cent. (sp. gr. = 0·905). If equal volumes of alcohol of 53·7 per cent.
and 59·2 per cent. (_i.e._ an alcohol of 56·5 per cent.) are taken,
and a drop of melted butter and of oleomargarine are delivered upon
its surface, the former will sink to the bottom and the latter will
remain at the top, so long as the two globules are warm and liquid.
In case the temperature of the alcohol is about 30°, the butter will
solidify and also rise to the top, whereas the oleomargarine may remain
liquid. On now keeping the alcohol for a short time at a temperature
of 15° the oleomargarine becomes opaque, but remains at the top, while
the solidified butter will sink to the bottom. If alcohol of 59·2 per
cent. is employed, oleomargarine will remain at the surface and genuine
butter fall to the bottom at all temperatures above 15°, and at this
temperature oleomargarine will be in equilibrium. Since not over 33 per
cent. of butter is usually added to oleomargarine, it is proposed to
use alcohol of 55 per cent., and consider as oleomargarine any sample
which does not sink at 15°.
The foregoing method can be applied quantitatively by determining the
strength of the alcohol which will keep in equilibrium a drop of the
fat under examination. Since the difference between 59·2 and 53·7
is 5·5, the difference between the strength of the alcohol used and
53·7, divided by 5·5 (or multiplied by 0·18), will give the proportion
of oleomargarine present. For example, if the globule is held in
equilibrium at 15° in 57 per cent. alcohol, the sample contains about
60 per cent. of oleomargarine, for (57 – 53·7) × 0·18 = 3·3 × 0·18 =
0·594 or, say, 6/10.
The melting-point of butter is below that of most of its fatty
adulterants; as previously stated, it varies from 28° to 37°. The
determination is made either in the ordinary manner by means of a
fine tube, or a little of the chilled sample is attached to a looped
platinum wire, placed near the thermometer-bulb, in water which is
gradually heated until fusion takes place. Blyth gives the following
table of the melting-points of various fats:–
Butterine 31·3
Cocoa butter 34·9
Butter (average) 35·8
Beef dripping 43·8
Veal dripping 47·7
Mixed 42·6
Lard, from 42 to 45
Ox fat, from about 48 „ 53
Mutton fat, from about 50 „ 51
Tallow 53·3
Numerous qualitative tests have been proposed by various authorities
for the detection of foreign fats in butter, of which the following are
perhaps sometimes of use. It should be added that the value of these
tests, when applied to mixtures, is limited and very uncertain.
1. A little of the sample is heated in a test-tube: pure butter froths
and acquires a brownish colour; with foreign fats there is but little
foaming, and, although the caseine present darkens, the liquid itself
remains comparatively clear.
2. If a sample containing oleomargarine is melted and the oil burned
in an ordinary lamp-wick, a decided odour of burning tallow will be
produced upon extinguishing the flame. Specimens of real butter,
however, have been found to also emit a tallow-like odour.
3. The melted sample is filtered and treated with boiling ether;
pure butter fat dissolves much more readily than do lard and tallow.
Upon adding methylic alcohol to the solution the latter fats are
precipitated, whereas pure butter will remain in solution.
4. If the filtered fat is distilled with a mixture of alcohol and
sulphuric acid, the distillate will possess the odour of butyric ether
_in a very marked degree_, in case it consists of butter.[27]
5. The strained fat is treated with a solution of carbolic acid (1 part
acid and 10 parts water): genuine butter dissolves to a clear solution;
beef, mutton, and swine fat form two layers, the upper one becoming
turbid upon cooling.
6. If the sample consists of butter or oleomargarine, and is mixed
with about ten parts of glycerine and the emulsion digested with a
mixture of equal parts of ether and alcohol, two layers of solution
will be produced, without any deposit of solid matter between them;
if, however, lard, suet, or starch is present it will become deposited
between the layers.
It has already been mentioned that butter differs from some of its
fatty adulterants in containing a considerable proportion of fatty
acids which are soluble in hot water, the acids present in most
foreign fats being, on the other hand, almost entirely insoluble. The
estimation of the relative amounts of soluble and insoluble acids
contained in a fat possesses therefore much importance; indeed, more
significance attaches to this determination than to any other. The
processes most frequently employed in the quantitative examination of
butter fat are those of Koettstorfer, Hehner, and Reichert.
Koettstorfer’s method[28] is based upon the fact that, as butter fat
contains the fatty acids, having a smaller molecular weight than those
present in other fats, it must contain more molecules of acid, and will
therefore require a greater amount of an alkali to effect saponication.
The process is executed as follows:–One or two grammes of the filtered
fat are weighed out in a narrow beaker and heated over a water-bath
with about 25 c.c. of one-half normal alcoholic solution of potassium
hydroxide. The saponification of the fat is assisted by repeated
stirring; when it is completed the beaker is removed from the bath,
a few drops of alcoholic phenol-phthaleine added for an indicator,
and the excess of potash used titrated back with one-half normal
hydrochloric acid. It has been found that pure butter fat requires from
221·4 to 232·4 milligrammes of potassium hydroxide for saponification.
The following are the number of milligrammes of alkali necessary for
the saponification of one gramme of various other fats:–
Olive oil 191·8
Rape-seed oil 178·7
Oleomargarine 195·5
Beef tallow 196·5
Lard 195·5
Mutton suet 197·0
Dripping 197·0
Taking 227 milligrammes as the average amount of potassium hydroxide
required to saponify one gramme of pure butter fat, the following
formula has been suggested for the estimation of the proportion of
admixture in a suspected sample:–
(227 – _n_) × 3·17 = _x_,
in which _n_ represents the number of milligrammes of potassium
hydroxide used, and _x_ the percentage of foreign fat added. In the
Paris Municipal Laboratory, 221 milligrammes of K(OH) are regarded as a
standard for the saponification of one gramme of genuine butter.
Cocoa-nut oil, unfortunately, requires a figure (250 mgr.) considerably
above that of butter, and it is quite possible to prepare a mixture
of this oil and oleomargarine, that by the foregoing test would show
a result almost identical with that afforded by pure butter. Hehner’s
process,[29] which is often employed for the determination of the
insoluble fatty acids, is as follows:–About 4 grammes of the melted
and strained sample are dissolved in 50 c.c. of alcohol, containing two
grammes of potassium hydroxide in solution, and the mixture is heated
until complete saponification takes place. The alcohol is removed by
evaporation, the residue dissolved in 200 c.c. of water, and the fatty
acids precipitated by adding dilute sulphuric acid to distinct acid
reaction. The fatty acids are next melted by heating the liquid and are
then allowed to cool, after which the insoluble acids are poured upon
a tared filter and repeatedly washed with hot water until the washings
cease to show acidity. The filter and contents are finally cautiously
dried and weighed. In genuine butter the proportion of insoluble fatty
acids ranges between 86·5 and 87·5 per cent.; it should not be above
88 per cent.[30] Oleomargarine, lard, mutton, beef, and poppy, palm,
olive, and almond oils contain about 95·5 per cent. of insoluble
The preceding process is also imperfect in not effecting the detection
of cocoa-nut oil, which affords only about 86 per cent. of insoluble
fatty acids, and although the presence of any considerable proportion
of this oil in butter would probably be indicated by the decreased
melting point of the admixture, an estimation of the soluble fatty
acids is by far the most reliable means for its detection. For this
determination Reichert’s method[32] is eminently adapted. In this
process advantage is taken of the facts that the amount of soluble
acids in a mixture of fat bears a direct relation to the proportion
of genuine butter present, and that, if the aqueous solution of a
saponified fat is decomposed by an acid and heated to boiling, the
greater portion of the soluble acids escape with the watery vapours and
can be collected and determined in the distillate. The details of this
method are essentially as follows:–2½ grammes of the filtered sample
are introduced into an Erlenmayer flask together with 1 gramme of
potassium hydroxide and 20 c.c. of dilute (80 per cent.) alcohol, and
the mixture is heated over the water-bath until complete saponification
is effected, and the alcohol _entirely_ removed. The soap thus formed
is dissolved in 50 c.c. of water, and decomposed by adding 20 c.c.
of dilute sulphuric acid (1:10). The flask is next connected with a
Liebig’s condenser and the contents carefully distilled until 50 c.c.
have passed over. The distillate is now freed from any insoluble acids
possibly present by filtration; it is then titrated with decinormal
soda solution, a few drops of litmus solution being employed as an
indicator. As the result of numerous tests, it has been found that
genuine butter, when examined by the above method, requires from 13 to
15 c.c. of the decinormal solution. The following are the number of
c.c. required by various other fats:–
Lard 0·2
Rape oil 0·25
Kidney fat 0·25
Olive oil 0·3
Sesamé oil 0·35
Oleomargarine 0·7 to 1·3
Cocoa-nut oil 3·70
Dr. Elwyn Waller[33] modifies the foregoing method of procedure by
adding 50 c.c. of water to the contents of the flask remaining after
the first distillation, and again distilling off 50 c.c., the process
being repeated until the final distillate neutralises only 0·1 c.c. of
the decinormal alkali. With butter fat, it was found that the first
distillate contained about 79 per cent. of the total volatile acids
present. By means of this modification, a distinction between the
rate of distillation of the volatile fatty acids of different fats is
possible. The non-volatile acids left in the flask are washed several
times with water, in order to remove the glycerine and potassium
sulphate present, and are then dried and weighed.
For estimating the percentage of pure butter fat in a sample of mixed
fat, Reichert employed the formula: B = 7·3 (_m_ – 0·3), in which _m_
is the number of c.c. of soda solution used in the titration.
Baron Hübl[34] has recently suggested a method for butter testing,
which is founded upon the fact that the three series of fats (acetic,
acrylic, and tetrolic), unite in different proportions with the
halogens (iodine, bromine, and chlorine), to form addition products.
Iodine has been found especially well adapted to the examination of
fats. The standard solution employed is prepared by dissolving 25
grammes of iodine in 500 c.c. of 95 per cent. alcohol, and adding to
the solution a solution of 30 grammes of mercuric chloride in 500 c.c.
of alcohol. The reagent is then standardised by means of a solution
of 24 grammes of sodium hyposulphite in 1 litre of water. The test
is applied as follows:–1 gramme of the sample under examination is
introduced into a flask and dissolved in 10 c.c. of pure chloroform.
The iodine reagent is then gradually added from a burette, the mixture
being well shaken, until the coloration produced indicates that an
excess is present, even after standing for about two hours; 15 c.c.
of a 10 per cent. potassium iodide solution and 150 c.c. of water are
then added and the excess of iodine present determined by means of the
sodium hyposulphite solution, and deducted from the total quantity
used. The amount of iodine (in grammes) absorbed is calculated to 100
grammes of the fat; this is termed the iodine number. The examination
of numerous samples of genuine butter and oleomargarine, and other
fats, made at the laboratory of the New York State Dairy Commissioner,
furnished the following results:[35]–
Iodine Number.
Genuine butter from 30·5 to 43·0
Oleomargarine „ 50·9 „ 54·9
Cocoa-nut oil 6·8
Lard 55·0
Mutton fat 57·3
Oleine 82·3
Olive oil 83·0
Pea-nut oil 96·0
Sweet-almond oil 102·0
Cotton-seed oil 108·0
Poppy oil 134·0
It has been proposed to differentiate between butter and oleomargarine
by a determination of the proportion of glycerine contained.
Liebschütz[36] employs the following process for this estimation: 10
grammes of the sample are saponified by heating with 20 grammes of
barium hydroxide, until the water of crystallisation has been almost
entirely expelled. Alcohol is then added with constant stirring;
saponification quickly takes place, and is completed by evaporating
the mass nearly to dryness. The glycerine is extracted with boiling
water, the solution filtered, and the barium contained removed by
means of sulphuric acid. The filtrate from the barium sulphate is then
concentrated by evaporation, and the excess of sulphuric acid present
neutralised by adding a little barium carbonate. The filtered liquid
is now again evaporated to a small volume, and most of the salts
present precipitated by addition of absolute alcohol. After filtration
the alcoholic solution is evaporated over the water-bath, then dried
at 100° until constant weight is obtained. It is finally ignited and
the proportion of glycerine contained estimated by the loss in weight
sustained. This process is certainly far from being exact, owing
principally to the volatilisation of glycerine that occurs in the
evaporation of its aqueous and even alcoholic solutions. The following
results were obtained upon treating genuine butter and oleomargarine
according to the above method:–
Per cent. Glycerine.
Butter 3·75
Oleomargarine 7·00
Gelatine is said to have lately been used as an adulterant of butter,
more especially of artificial butter. Its detection is a matter of some
difficulty. The following method has been suggested. A considerable
quantity of the suspected butter is boiled with water, the solution
strained, a drop of acetic acid and a little potassium ferrocyanide
added, and the liquid boiled until the precipitate formed becomes
bluish in colour. The solution is then filtered hot and the filtrate
examined for gelatine by adding tannic acid to, or conducting chlorine
gas through it.
A sample lately imported under the name of “butter preservative” was
found by the author to consist of a dilute solution of phosphoric acid.
The use of this agent does not, however, appear to be prevalent to any
great extent.[37]
_Artificial Colouring._–The list of colouring matters said to be
added to butter includes the vegetable dyes, annato, carotin, fustic,
turmeric, marigold, and saffron; the coal-tar colour, Victoria
yellow (potassium dinitrocresylate), and Martius yellow (potassium
dinitronaphthalate), and the mineral pigment chrome yellow (plumbic
chromate). Of the foregoing, annato and carrot colour appear to be most
commonly employed. Mr. Edward W. Martin[38] has proposed a method for
the isolation of the former which consists in dissolving the butter in
carbon disulphide, and shaking the solution with a _dilute_ solution
of potassium hydroxide, in which the colouring matter dissolves; it
is subsequently identified by further tests. According to Mr. R. W.
Moore,[39] the presence of carotin in butter may be detected by first
agitating the carbon disulphide solution of the fat with alcohol, which
fails to extract this colour. Upon now adding to the mixture a drop
of dilute ferric chloride solution, again shaking the liquid and then
putting it aside for a short time, the alcoholic solution dissolves the
carrot colour, and if no other colouring matter is contained in the
butter, leaves the carbon disulphide colourless.
The artificially coloured butter may be dissolved in alcohol and tested
with the following reagents:–
(_a_) Nitric acid: greenish coloration, _saffron_.
(_b_) Sugar solution and hydrochloric acid: red coloration, _saffron_.
(_c_) Ammonia: brownish coloration, _turmeric_.
(_d_) Silver nitrate: blackish coloration, _marigold_.
(_e_) Evaporate the alcoholic solution to dryness and add concentrated
sulphuric acid: greenish-blue coloration, annato; blue coloration,
(_f_) Hydrochloric acid: decolorisation, with formation of yellow
crystalline precipitate, _Victoria or Martius yellow_.
(_g_) Separation of a heavy and insoluble yellow powder, _chrome
yellow_ (see p. 130).
_Microscopic Examination._–The microscopic examination of butter has
lately received considerable attention as a means for the detection
of the presence of foreign fats. Genuine butter generally exhibits
under the microscope a crowded mass of globules of fat, fatty crystals
being commonly absent. In oleomargarine a more crystalline structure
is observed, with pear-shaped masses of fat and but few globules.
While the presence of crystals in a sample may justly be regarded as
suspicious, it is by no means a positive evidence of adulteration,
since, under certain circumstances, pure butter may present the same
indications. In applying the microscopic test, a small portion of the
fat is made into a thin layer on the slide, and then protected with a
glass cover, applied with rather gentle pressure.
Plate VI.[40] represents the microscopic appearance of genuine
butter and oleomargarine. It will be observed that in butter (Fig.
1) numerous globules but no crystals of fat are presented, the
crystals present being those of salt. In oleomargarine (Fig. 2) the
distinctive pear-shaped masses of fat, accompanied by only a small
number of fatty globules, are to be seen. Dr. Thomas Taylor (of the
U.S. Department of Agriculture), has made an elaborate investigation
of the microscopic appearance of various fats when viewed by polarised
light. He regards the presence of peculiar globular crystals and the
black cross commonly termed St. Andrew’s cross as characteristic of
genuine butter.[41] Lard, beef, and other fats are said to exhibit
different and, to some extent, distinctive crystalline forms. Prof.
Weber,[42] however, affirms that mixtures of lard and tallow fat,
under certain conditions, cannot be distinguished from butter by means
of this method of examination. More recently, Dr. Taylor states that
the distinguishing difference between butter and other fats under the
microscope is that the former, when observed by polarised light through
a selenite, exhibits a uniform tint, whereas the latter shows prismatic
colours. Although the results of these investigations cannot as yet be
considered as perfectly satisfactory or conclusive, they certainly are
entitled to rank as a highly valuable and important step in advance of
the optical processes hitherto employed.
[Illustration: Fig. 1, Butter × 400.]
[Illustration: Fig. 2, Oleomargarine × 400.]
[Illustration: Butter × 40.]
[Illustration: Butter × 40.]
[Illustration: Beef × 40.]
[Illustration: Lard × 160.]
[Illustration: Butterine × 40.]
[Illustration: Oleomargarine × 40.]
Plate VII. exhibits the appearance of butter, oleomargarine, beef, and
some other fats, when viewed by the microscope and polarised light. It
will be noticed that, while a discrimination between lard and butter is
readily made, oleomargarine presents the St. Andrew’s cross, stated to
be characteristic of genuine butter. These photomicrographs represent
the results of investigations made in the Chemical Division of the U.S.
Department of Agriculture.
The question of the sanitary effects of oleomargarine and other
substitutes for butter, has been studied by many scientists, and with
very discordant results. Doubtless the great divergence of opinion
which at present exists, is largely due to the fact that the artificial
products examined have been made according to different processes,
and with varying regard to the quality of the fats used in their
manufacture, and to the degree of care and cleanliness observed. The
attention of the American public has very lately been directed to the
oleomargarine question, by the recent enactment of a national law
imposing a tax upon the manufacture of the article.
Without entering to any great extent into the subject of the
wholesomeness of artificial butter as it is generally met with in
commerce, it will be of interest to refer to the conclusions reached by
two or three sanitarians who have devoted particular attention to this
aspect of the question. Prof. W. O. Atwater[43] summarises the results
of his investigation of oleomargarine as follows:–
“1. The common kinds of imitation butter, oleomargarine, butterine,
etc., when properly made, agree very closely in chemical composition,
digestibility, and nutritive value with butter from cow’s milk.
“2. In fulfilling one of the most important functions of food, namely,
that of supplying the body with heat and muscular energy, they, with
butter, excel in efficiency all, or nearly all, our other common food
“3. Considering the low cost at which they can be produced, as well
as their palatability and nutritive value, they form a food product
of very great economical importance, and one which is calculated to
greatly benefit a large class of our population whose limited incomes
make good dairy butter a luxury.
“4. Imitation butter, like many other manufactured food materials,
is liable (but in actual commerce has been found not to be so) to be
rendered unwholesome by improper materials and methods of manufacture.
It is also open to the especial objection that it is largely sold as
genuine butter. The interests of the public, therefore, demand that
it should be subjected to competent official inspection, and that it
should be sold for what it is, and not as genuine butter.”
Dr. S. B. Sharples[44] states: “When well made, it (oleomargarine) is
a very fair imitation of genuine butter; being inferior to the best
butter, but much superior to the low grades of butter too commonly
found in the market. So far as its influence on health is concerned,
I can see no objection to its use. Its sale as genuine butter is a
commercial fraud, and as such, very properly condemned by the law. As
to its prohibition by law, the same law which prohibited it should also
prohibit the sale of lard and tallow, and more especially all low-grade
butters, which are far more injurious to health than a good sweet
article of oleomargarine. A good deal has been said in regard to the
poor grade of fats from which the oleomargarine is made. Any one making
such assertions in regard to the fats is simply ignorant of the whole
subject. When a fat has become in the least tainted, it can no longer
be used for this purpose, as it is impossible to remove the odour from
the fat after it has once acquired it.”
_Per contra_, Dr. R. B. Clark, in an exhaustive report on butter,[45]
affirms with great decision, that artificial butter is not a wholesome
article of food, for the following reasons:–
“1. On account of its indigestibility.
“2. On account of its insolubility when made from animal fats.
“3. On account of its liability to carry germs of disease into the
human system.
“4. On account of the probability of its containing, when made under
certain patents, unhealthy ingredients.”
The two last grounds for condemning oleomargarine are evidently
affected by, and, in fact, dependent upon the character of the fat and
the exercise of care employed in its manufacture. In regard to the
relative digestibility of butter and its imitations, actual experiments
have been made by several chemists. A. Mayer,[46] from the results of
feeding human beings for three days on butter and on oleomargarine,
found that 1·6 per cent. less of the latter was absorbed by the system
than of the former, and inclines to the opinion, that with healthy
persons this proportion is so inconsiderable, that it is of little or
no importance. Dr. Clark considers these experiments of too limited
duration to be regarded as conclusive, although, so far as they went,
the results reached coincided with those obtained by him by a more
exhaustive investigation. Dr. Clark has made an examination of the
artificial digestion of butter as compared with oleomargarine and
other fats, including beef and mutton suet, and lard, cotton-seed,
sesamé, and cod-liver oils. The method of examination pursued was as
follows:–About 2 grammes of the melted fat was added to a digestive
fluid consisting of 0·33 gramme of “extractum pancreatis,” and 0·33
gramme of sodium bicarbonate, dissolved in 10 c.c. of distilled
water. This mixture was introduced into a test-tube, well shaken, and
then exposed to a temperature of 40°. The contents of the test-tube
were microscopically examined at the lapse of intervals of one,
four, and twelve hours. It was found from these tests that cod-liver
oil exhibited the most perfect state of emulsion, after which came
genuine butter, next lard oil, and then commercial “oleo.” Plate VIII.
represents the results obtained from the experiments made with butter
and commercial oleomargarine, as presented at the end of one, four,
and twelve hours. The globules of butter-fat, it will be observed, are
smaller in size and more uniform in appearance. Dr. Clark likewise
instituted experiments which tended to demonstrate the relative
insolubility of the fats used in the preparation of artificial butter.