
for about 0.5% of the solids. The acids account for
the low average pH (3.99) value, which is in part
responsible for the excellent stability of honey.
Several acids have been found in honey, gluconic
acid being present in considerable excess over the
others. It arises from glucose through the action of
the enzyme glucose oxidase, added by the honeybee.
The combined effect of its acidity and the hydrogen
peroxide concurrently produced assist in preserving
nectar and honey from spoilage. Less prominent acids
reported to be in honey are formic, acetic, butyric,
lactic, oxalic, succinic, tartaric, maleic, pyruvic, pyr-
oglutamic, a-ketoglutaric, glycollic, citric, malic, 2-
or 3-phosphoglyceric acids, and glucose 6-phosphate.
(See Acids: Properties and Determination.)
Proteins and Amino Acids
0021 Protein and amino acid levels in honey are reflected in
nitrogen content, which is low, 0.04% on the average,
but variable, ranging up to 0.1%. About 40–80% of
the total nitrogen in honey is in protein, and most
of the remainder resides in the free amino acids.
About 20 different nonenzymatic proteins have been
identified in honey, many of which are common to all
honeys. Some appear to originate in the honeybee,
and others in the plant source of nectar. Except for
the honey enzymes, little is known about many of the
proteins in honey. Their presence results in honeys
having a lower surface tension than they would have
otherwise, and this encourages the formation of fine
air bubbles and a marked tendency to foam. (See
Protein: Food Sources.)
0022 The quantity of free amino acids in honey is small and
of no nutritional significance. Honeys have been found
tocontainbetween11and21freeaminoacids.Proline
accounts for about half of the total, most of which
originates from the honeybee, rather than from nectar
or pollen. Aside from proline, the amino acids glutamic
acid, alanine, phenylalanine, tyrosine, leucine, and iso-
leucine are present in the highest levels. Amino acids
react with some of the honey sugars to produce yellow
or brown materials, and age-related darkening of honey
is probably a result of these reactions.
Flavor, Aroma, and Color
0023 The dominant flavor of honey is sweetness, arising
from the blend of the major sugars fructose and glu-
cose, and the wide array of other sugars. Sweetness is
common to all honeys, regardless of the floral source
of the nectar. Other components common to all
honeys, such as gluconic acid and proline, also make
contributions to the general flavor of honey. The
uniqueness of a given honey is due to contributions
of compounds from the wide variety of floral nectar
sources. Honey assumes many of the subtle flavor and
aroma characteristics of these sources, and there are
perhaps as many variations in flavor and aroma as
there are nectar sources. Flavors are sufficiently dis-
tinctive that experienced honey tasters can identify
dozens of different floral sources. Typical flavors
range from the most delicate and desirable to those
that are harsh and objectionable. (See Flavor (Fla-
vour) Compounds: Structures and Characteristics.)
0024As many as 129 components have been separated
from extracts of honey, and many of these are
volatile organic compounds. Each of these is
present in very low levels. About two-thirds have
been identified, and many of these probably contrib-
ute to honey flavor and aroma, and perhaps color.
Low-molecular-weight aldehydes, ketones, alcohols,
and esters, make up the bulk of the compounds. One
compound present in all honeys is hydroxymethylfur-
fural. This is produced from decomposition of sugars,
especially fructose, in the presence of acid. The high
fructose level and low pH of honey combine to favor
its formation, which is accelerated when honey is
heated. Synthetic honey flavors contain a large pro-
portion of phenylacetic esters, as most of these com-
pounds have a honey taste and aroma. A closely
related compound, phenylethyl alcohol, is present in
several natural honeys. The flavor and delicate bou-
quet of honey are vulnerable to heat and improper
storage, which can level the subtle distinctions among
unique floral sources. Honey is heated during com-
mercial processing in order to delay granulation and
avoid fermentation, but careful attention must be
given to the time and amount of heat, or valuable
flavor and aroma compounds can be lost.
0025Generally, lighter colors are associated with the
milder, more pleasantly flavored honeys. Honey
cannot be judged solely on the basis of color, as
some of the most distinctively and strongly flavored
honeys, such as basswood, are very light, whereas
very mild and pleasant honeys such as tulip poplar
can be quite dark. Color limits are often specified in
trading of honey, however, because flavor is so sub-
jective. Several systems are used for the objective
measurement of honey color, and some are designated
as official in various countries. Seven classifications
are used for international trade; water white, extra
white, white, extra light amber, light amber, amber,
and dark amber.
Quality Assurance
0026Much of what has been learned about the compos-
ition and properties of honey has resulted from re-
search aimed at verifying its authenticity. Being of
HONEY 3129