New
Zealand Honeydew
is
one of New Zealand's premium export honeys. It has a history
of export to Europe and specifically Germany since the early
1970s. There are several honeydew producing scale insects in
New Zealand inhabiting a variety of plants. However most of
these are small honeydew sources or intermittent production.
The beech forests of the South Island are a different story
however. Two species of beech tree inhabited by two species
of honeydew insect (the sooty beech scales) produce New Zealand's
largest single exported honey crop. The beech trees are Black
Beech (Nothofagus solandri) and Red Beech (N.
fusca). The two insects are Ultracoelostoma assimile
and U. brittini. U. brittini tends to inhabit
the trunks and larger branches, while U. assimile is recorded
(C.F.Morales) as favouring the upper branches and twigs, thus
U.brittini is the insect most likely to be encountered
by the casual observer wandering in the beech forests.
The black
colour of trees and plants with a honeydew source is due to
the growth of a black sooty mould (Capnodium fungus) on the
surplus nectar exuding over the plant and sometimes even the
ground. Particles of this fungus are typically found in honeydew
and are used as a part of the identification as honeydew.
Colour
Beech honeydew is one of our darker honey types with a Pfund
Scale average of 87.2mm and a Standard Deviation of 10.5mm
(600 records). Colour does depend to some extent on area. There
are some areas that do produce darker honeydew. Whether this
is due to local conditions or blends of lighter (non honeydew)
honeys is uncertain but we can find no correlation between conductivity
and colour. Honeydew is generally a slower honey flow than most
of the other flower honeys (although there are exceptions of
course), and honeybees prefer to store honeys like this closer
to the brood nest, typically in darker combs. This can darken
the colour of the resultant honey.
Conductivity
New Zealand Beech honeydewis typical of most honeydews in having
a high conductivity. This arises from the nature of honedew
production. An insect of the Homiptera order of insects (those
with sap sucking mouthparts e.g. aphids, scale insects etc.)
sucks sap from the host plant and exudes a sweet sticky nectar
which is essentially slightly modified sap. This is then collected
by honeybees as a nectar source and is "ripened" into
honey. This pathway is quite different from that of normal flower
honeys. The direct sucking of the sap, the additional insect
in the production chain, and the presences of sooty moulds,
all add up to an additional mineral content not normally found
in flower honeys. This is indirectly measured by the ability
of honeydew to conduct electricity. The average conductivity
for Beech honeydew is 12.6 mS/cm with a standard deviation of
2.5mS/cm (750 records).
Sugar Profile
Honeydews
are normaly high in Fructose, low in glucose and have higher
levels of higher sugars such as maltose . Their tendency
to crystallise is also low. Beech honeydew is likewise very
slow crystallizing and in fact some beech honeydews never crystallize.
Another feature of New Zealand beech honeydew is the presence
of oligosaccharides (complex sugars) in greater levels than
average flower honeys.
It
has been shown that oligosaccharides are helpful in maintaining
and promoting beneficial bacteria in the gut, particularly after
treatment with antibiotics.
Moisture Content - Presence of Yeasts
Normally honeydew is below 17%
moisture. In the main production area, fermentation is not generally
a concern, but the environment is such that large populations
of yeast can occur in the honeydew forests. This is due to the
presence of large quantities of a food resource (honeydew nectar)
and, particularly after rain, wet conditions. At times the forest
can smell quite sour with a fermentation smell and wasps can
be observed drunk on the tree trunks. Under these conditions,
high levels of yeast may occur in honeydew honey that come from
this environment, rather than from fermentation of the ripened
honey. It is possible that this may be marked against the product
as a perceived quality issue, rather than it being a natural
occurence.
"Oligosaccharides in New Zealand Honeydew
Honey"
K. Astwood, B. Lee, and M. Manley-Harris J. Agric. Food Chem.,
46(12), 4958-4962.
Abstract
"A series of oligosaccharides based upon successive addition
of glucose (1->4) to the glucopyranosyl residue of sucrose
and another series similar to the first but with the final residue
linked (1->6) have been isolated from New Zealand honeydew
honey and fully characterized. Because the trisaccharide in
this series is erlose, it is inferred that the honeydew of the
indigenous scale insect, Ultracoelostoma assimile,
which lives upon the Southern beech, Nothofagus spp,.
is of the erlose type. These oligosaccharides and others have
been quantifed by GC and LC in six New Zealand honedew honeys"
This paper is available online from the publisher at www.acs.org
for US$25.00 in PDF format. The author (to whom correspondence
should be addressed) is manleyha@waikato.ac.nz
neydew
