HONEY

Honey consists of the saccharine substance collected by the bee (_Apis
mellifica_) from the nectaries of flowers, and deposited by them in
the cells of the comb. “Virgin honey” is the product of hives that
have not previously swarmed, which is allowed to drain from the comb;
the inferior varieties being obtained by the application of heat and
pressure. As a result of the peculiar conditions of its formation,
honey constitutes a rather complex mixture of several bodies; indeed,
its exact composition is a matter of some doubt. The chief ingredients
are levulose and dextrose, accompanied by a small amount of cane sugar,
and inconsiderable proportions of pollen, wax, and mineral matter.
According to Dubrunfaut and Soubeiran,[60] genuine honey contains an
excess of levulose mixed with dextrose and some cane sugar. In the
course of time the latter is gradually converted into invert sugar, and
a crystalline deposit of dextrose forms, the levulose remaining fluid.

The following analyses made by J. C. Brown[61] and E. Sieben,[62] show
the general composition of pure honey:–

————————+—————-+—————-
| J. C. Brown. | E. Sieben.
————————+—————-+—————-
Dextrose | 31·77 to 42·02 | 22·23 to 44·71
Levulose | 33·56 „ 40·43 | 32·15 „ 46·89
Total glucoses | 68·40 „ 79·72 | 67·92 „ 79·57
Sucrose | .. | none „ 8·22
Wax, pollen and insol | trace to 2·10 | ..
Ash | 0·07 „ 0·26 | ..
Water at 100° | 15·50 „ 19·80 | 16·28 to 24·95
Undetermined | 4·95 „ 11·00 | 1·29 „ 8·82
————————+—————-+—————-

Barth has examined several varieties of genuine honey with the
following results:–

———————————–+———-+———–+———–
| Per cent.| Per cent. | Per cent.
———————————–+———-+———–+———–
Water | 13·60 | 15·60 | 11·06
Dry substance | 86·40 | 84·40 | 88·94
Ash | 0·28 | 0·24 | 0·90
Polarisation of 10 per }Direct | -4·6° | -5° | +11°
cent. solution (in 200 }After | | |
millimetre tube) } inversion| .. | -7·5° | +4°
{Original substance | 69·60 | 72·0 | 60·0
Sugar {After inversion | 69·50 | 77·0 | 74·6
Organic matter, not sugar | 16·52 | 7·16 | 13·44
———————————–+———-+———–+———–

W. Bishop[63] obtained the following figures from the examination of
honey of known purity:–

—————————–+———–+——-+———+———
|Hungarian. |Chili. |Italian. |Normandy.
—————————–+———–+——-+———+———
Reducing sugar | 67·17 | 73·05 | 70·37 | 79·39
Crystallised sugar | 7·58 | 4·55 | 5·77 | 0·
Direct polarisation | -13·70 |-14·15 | -8·55 | -9·25
Polarisation after inversion | -15·40 |-14·85 | -12·0 | ..
—————————–+———–+——-+———+———

The substances said to be employed in the adulteration of honey are
water, starch, cane sugar, and glucose-syrup; the last mentioned is
undoubtedly most commonly used. Hager[64] states that, by treating
corn starch with oxalic acid, a product is obtained which, on standing
two or three weeks, acquires the appearance and taste of genuine
honey; and samples of commercial honey not unfrequently wholly consist
of this or some other form of artificial glucose. The season for
the collection of honey by bees is a limited one, and any existing
deficiency in their natural source of supply is sometimes remedied by
placing vessels filled with glucose near the hives. Occasionally the
bees are also supplied with a ready-made comb, consisting, at least
partially, of paraffine. It has been asserted that in some instances,
this factitious comb is entirely composed of paraffine, but the writer
is informed that, if the sophistication is practised to a proportion
of over 10 per cent., the bees do not readily deposit the honey in the
comb.

Owing to the complex composition of honey and to the rather incomplete
character of the analyses of the genuine article at hand, the detection
of some of the forms of adulteration resorted to is a matter of
considerable difficulty. The presence of starch is best recognised by
the microscopic examination of the honey. This will likewise reveal the
absence of pollen, which may be regarded as a certain indication of
the spurious nature of the sample. There appears to exist a difference
of opinion in regard to the presence of cane sugar in genuine honey,
but it may safely be accepted that the detection of a considerable
proportion of this substance points to its artificial addition. In
all cases of suspected adulteration with cane sugar or glucose, the
determination of the sugar present by means of the polariscope and by
Fehling’s method (both before and after inversion) is indispensable. It
is commonly stated that unsophisticated honey polarises to the left,
and that a sample possessing a dextro-rotary action is necessarily
contaminated with glucose or cane sugar; but, while in the great
majority of cases this is doubtless the fact, it is equally certain
that honey of known purity has been met with which polarised to
the right. Upon the inversion of honey containing cane sugar, the
dextro-rotation is changed to a levo-rotation.

According to Lenz,[65] the specific gravity (at 17°) of a solution
of 30 grammes of pure honey in exactly twice the quantity of
distilled water is never less than 1·1110, a lower density indicating
adulteration with water. Hehner[66] states that the ash of genuine
honey is always alkaline, whereas that of artificial glucose is
invariably neutral. The proportion of phosphoric acid present in honey
varies from 0•·013 to 0•·035 per cent., which is considerably less
than the proportion contained in starch sugars. Honey contaminated with
starch sugar will generally show about 0·•10 per cent. of phosphoric
acid, and artificial honey, made from cane sugar, will usually be free
from the acid.

The addition of commercial glucose may often be detected by the
turbidity produced upon adding ammonium oxalate to a filtered aqueous
solution of the sample; this is due to the presence of calcium
sulphate, a common impurity in the commercial varieties of glucose.
If the glucose employed for admixture contains much dextrine, as is
very often the case, this fact can be utilised in its detection as
follows:–2 c.c. of a 25 per cent. solution of the honey are introduced
into a narrow glass cylinder, and 0·•5 c.c. of absolute alcohol is
cautiously added; with pure honey, the point of contact of the liquids
will remain clear or become so upon allowing the mixture to stand at
rest, whereas in presence of artificial glucose a milky turbidity will
appear between the two strata. Genuine honey may, it is true, contain
a small proportion of dextrine and exhibit a slight cloudiness when
treated with alcohol, but the difference in the degree of turbidity
caused is very considerable, and sufficient to render the test of
service.

The test may also be applied by dissolving 20 grammes of the suspected
honey in 60 c.c. of distilled water and then adding an excess of
alcohol. Under these circumstances pure honey merely becomes milky,
while, if commercial glucose is present, a white precipitate of
dextrine is formed, which can be collected and weighed. If the sugar in
the sample is determined by Fehling’s solution, both before and after
inversion with a little sulphuric acid, and an estimation of the amount
of dextrine present is made by precipitation with alcohol, it often
occurs that the quantity of the latter substance is proportional to the
difference between the amount of sugar found.

According to the late investigations of Sieben,[67] fairly
satisfactory methods for the detection and determination of glucose
syrup in honey are based upon the following facts:–

1st. When genuine honey undergoes fermentation, the substances which
remain undecomposed, are optically inactive. Glucose, or starch syrup,
on the other hand, leaves a considerable amount of dextrine, which
is strongly dextrogyrate. The test is made by dissolving 25 grammes
of honey in about 160 c.c. of water, and adding 12 grammes of yeast
(free from starch). The mixture is allowed to ferment at a moderate
temperature for two or three days, after which aluminium hydroxide is
added, and the liquid made up to 250 c.c. and then filtered. 200 c.c.
of the filtrate are evaporated to a volume of 50 c.c., and a 200 mm.
tube is then filled with the concentrated solution and examined by the
polariscope.

2nd. The substances remaining unaffected by the fermentation of pure
honey are not converted into a reducing sugar by boiling with dilute
hydrochloric acid, as is the case with those obtained from starch syrup
under the same circumstances. 25 c.c. of the solution employed for the
polarisation test, as just described, are diluted with an equal volume
of water, 5 c.c. of strong hydrochloric acid added, and the mixture
is placed in a flask and heated for an hour over the water-bath. The
contents of the flask are neutralised with potassium hydroxide, then
diluted to a volume of 100 c.c., and the proportion of reducing sugar
estimated in 25 c.c. of the solution. Honey containing different
proportions of starch sugar gave the following percentages of reducing
sugar:–

Starch-Sugar Present. | Reducing Sugar Obtained.
per cent. | per cent.
5 | 1·472
10 | 3·240
20 | 6·392
40 | 8·854

3rd. If the cane sugar originally present in genuine honey has been
changed into invert sugar, and the honey solution is boiled with a
slight excess of Fehling’s reagent, no substances capable of yielding
sugar when treated with acids will remain undecomposed. Starch syrup,
when subjected to this treatment, yields grape sugar in about the
proportion of 40 parts to every 100 parts of the syrup used. The test
is applied as follows:–14 grammes of honey are dissolved in 450 c.c.
of water, and the solution is heated over the steam-bath with 20 c.c.
of semi-normal acid, in order to invert the cane sugar present. After
heating for half an hour, the solution is neutralised, and its volume
made up to 500 c.c. 100 c.c. of Fehling’s solution are then titrated
with this solution, which may contain about 2 per cent. of invert
sugar (in case the sample examined is pure, from 23 to 26 c.c. will
be required); 100 c.c. of Fehling’s reagent are next boiled with 0·5
c.c. less of the honey solution than was found to be necessary to
completely reduce the copper. The reduced liquid is then passed through
an asbestos filter, the residue washed with hot water, the filtrate
treated with a slight excess of concentrated hydrochloric acid, and the
solution heated for one hour on the steam-bath. Sodium hydroxide is
now added, until only a very little free acid remains unneutralised,
and the solution is made up to 200 c.c. Upon well shaking the cooled
liquid, a deposit of tartar sometimes separates. 150 c.c. of the
filtered solution are finally boiled with a mixture of 120 c.c. of
Fehling’s reagent and 20 c.c. of water, and the proportion of grape
sugar estimated from the amount of metallic copper obtained. (See p.
111.) When pure honey is submitted to the preceding process, the copper
found will not exceed 2 milligrammes. The quantities of copper obtained
when honey adulterated with various proportions of starch sugar was
tested were about as follows:–

Starch Sugar | Milligrammes of
contained. | Copper found.
per cent. |
10 | 40
20 | 90
30 | 140
40 | 195
50 | 250
60 | 330
70 | 410
80 | 500

——————————–+———————————–
|Dextrose.
| +—————————-
| |Levulose.
| | +———————
| | |Invert Sugar,
Character of Samples. | | | by Fehling’s Method.
| | | +————-
| | | |Cane Sugar.
| | | | +——
| | | | |Total
| | | | |Sugar.
——————————–+——+——+——-+——+——
| per | per | per | per | per
|cent. |cent. | cent. | cent.| cent.
Adulterated with cane sugar | .. | .. | 56·39 | 19·45| 76·84
„ „ „ „ and | | | | |
water |25·63 |25·42 | 51·06 | 10·62| 61·67
„ „ 15 per cent. | | | | |
glucose syrup|37·20 |31·80 | 69·18 | .. | 69·00
„ „ 65 per cent. | | | | |
glucose syrup|21·75 |19·60 | 41·30 | .. | 41·35
„ „ 40 per cent. | | | | |
glucose syrup|34·61 |23·89 | 58·83 | .. | 58·50
„ „ 40 per cent. | | | | |
glucose syrup| | | | |
and with cane| | | | |
sugar. |25·47 |23·51 | 49·04 | 7·06| 56·04
„ „ 80 per cent. | | | | |
glucose syrup|21·92 |12·83 | 35·00 | .. | 34·75
——————————–+——+——+——-+————-

——————————–+————————-
|Water.
| +——————
Character of Samples. | |Dry Substance.
| | +———–
| | | Not Sugar.
——————————–+——+——+———–
| per | per | per
|cent. |cent. |cent.
Adulterated with cane sugar |20·85 |79·15 | 2·31
„ „ „ „ and | | |
water |36·48 |63·52 | 1·85
„ „ 15 per cent. | | |
glucose syrup|18·54 |81·46 |12·46
„ „ 65 per cent. | | |
glucose syrup|18·65 |81·35 |40·00
„ „ 40 per cent. | | |
glucose syrup|17·81 |82·19 |23·69
„ „ 40 per cent. | | |
glucose syrup| | |
and with cane| | |
sugar. |19·94 |80·06 |24·02
„ „ 80 per cent. | | |
glucose syrup|18·12 |81·88 |57·13
——————————–+——+——+———–

——————————–+——–+—————————-
|Polarisation after Fermentation.
| +—————————-
| I |Residue of Fermentation when
| |treated with acid gave Grape
Character of Samples. | | Sugar.
| | +——————
| | |Milligrammes of
| | |Copper found by
| | |Method 3.
——————————–+——–+———+——————
|degrees.|per cent.| mgr.
Adulterated with cane sugar | 0·0 | 0·0 | 0
„ „ „ „ and | | |
water | 0·0 | 0·0 | 0
„ „ 15 per cent. | | |
glucose syrup| × 4·4 | 4·2 | 66
„ „ 65 per cent. | | |
glucose syrup| × 25 | 12·4 | 366
„ „ 40 per cent. | | |
glucose syrup| × 13 | 7·6 | 196
„ „ 40 per cent. | | |
glucose syrup| | |
and with cane| | |
sugar. | | |
„ „ 80 per cent. | | |
glucose syrup| × 34 | 15·2 | 492
—————————————–+———+——————

The tabulation on p. 127 exhibits the results obtained by the
application of the foregoing tests to adulterated honey.[68]

The detection of paraffine in honeycomb is easily accomplished. Genuine
bees’-wax fuses at 64°, paraffine usually at a lower temperature.
The latter is not affected by treatment with concentrated sulphuric
acid, whereas bees’-wax is dissolved by the strong acid, and undergoes
carbonisation upon the application of heat. The amount of potassium
hydroxide required for the saponification of one gramme of bees’-wax,
as applied in Koettstorfer’s method for butter analysis (p. 71), widely
differs from the quantities consumed by Japanese wax and paraffine. Mr.
Edward W. Martin has obtained the following figures:–

Milligrammes K (O H) required
to saponify one gramme.
Bees’-wax 7·0
Japanese wax 212·95
Paraffine none

18 out of 37 samples of strained and comb honey, examined in 1885 by
the Mass. State Board of Health, were adulterated with glucose and
ordinary syrup.