2009_Book_FoodChemistry

19.2 Honey and Artificial Honey 889
In honey gluconic acid is in equilibrium with its
gluconolactone. The acid level is mostly dependent
on the time elapsed between nectar collection
by bees and achievement of the final honey
density in honeycomb cells. Glucose oxidase
activity drops to a negligible level in thickened
honey. Other acids present in honey only in
small amounts are: acetic, butyric, lactic, citric,
succinic, formic, maleic, malic and oxalic acids.
19.2.1.5.7 Aroma Substances
About 300 volatile compounds are present in
honey and more than 200 have been identified.
There are esters of aliphatic and aromatic
acids, aldehydes, ketones and alcohols. Of
importance are especially β-damascenone and
phenylacetaldehyde, which have a honey-like
odor and taste. Methyl anthranilate is typical
of the honey from citrus varieties and lavender
and 2,4,5,7a-tetrahydro-3, 6-dimethylbenzofuran
(Formula 19.4, linden ether) is typical of linden
honey.
family Ericacea; insane (“mad”) berries; Kalmia
evergreen shrubs; Eurphorbiaceae; and honey
collected from other sweet substances, e. g.,
honeydew exudates of grasshoppers. Rhododendrons
contain the poisonous compounds, andromedotoxin
(an acetylandromedol) and grayanotoxins
I, II and III (a tetra-cyclic diterpene)
used in medicine as a muscle relaxant (I: R 1 =
OH, R 2 =CH 3 ,R 3 =COCH 3 ; II: R 1 ,R 2 =CH 2 ,
R 3 = H; III: R 1 = OH, R 2 =CH 3 ,R 3 =H)(see
Formula 19.5).
(19.5)
The poisonous nature of New Zealand honey is
a result of tutin and hyenanchin (mellitoxin) toxins
from the tutu shrub (tanner shrub plant, Coriaria
arbora). Poisonous flowers of tobacco, oleander,
jasmine, henbane (Datura metel) and of
hemlock (Conium maculatum) provide nonpoisonous
honeys. The production of these honeys
is negligible in Europe.
19.2.1.6 Storage
(19.4)
Honey color generally darkens on storage, the
aroma intensity decreases and the content of hydroxymethyl
furfural increases, depending on pH,
19.2.1.5.8 Pigments
Relatively little is known about honey color pigments.
The amber color appears to originate from
phenolic compounds and from products of the
nonenzymic browning reactions between amino
acids and fructose.
19.2.1.5.9 Toxic Constituents
Poisonous honey (pontius or insane honey) has
been known since the time of the Greek historian
and general, Xenophon, and the Roman writer,
Plinius. It comes mostly from bees collecting
their nectar from: rhododendron species (Asia
Minor, Caucasus Mountains); some plants of the
Fig. 19.16. Hydroxymethyl furfural formation in honey
versus temperature and time (according to White, 1978)