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NEW ZEALAND BEEKEEPER, MAY 2017
Implications of having giant aphid honey willow The beekeeper and extractor are affected most by this honey. • Melezitose is not digestible for bees. Therefore, any honey they make from GWA honeydew will be of less use for feeding the hive, with energy also being needed to clean out crystals from cells. Perhaps 30% of the honey in heavily crystallised GWA honeydew honey will be unusable by bees. • It is disappointing for a beekeeper to find that the weight of their honey boxes does not translate into the amount of honey they expect in the drum, if there are a lot of melezitose crystals in the comb. • Extractors use a lot of time and energy keeping their filters clean when dealing with frames containing the honey. If the taste and smell of the honey is not what customers are expecting, it could damage the brand of the seller. Of course, people have a wide variety of tastes, and what may be unpleasant for one person could be something another person loves. Just talk to people from the USA or Europe about Vegemite or Marmite! If there are melezitose crystals in drums of honey that are being traded, the buyer will end up with some of the weight of the drum being unusable. A simple way of checking for this is sending a sample of the liquid honey from a drum to a laboratory for melezitose testing. If the results show that there is more than 14% of melezitose in the honey, then there is a high risk of having crystals in the honey, which will affect the overall value of the drum. An alternative test is for salicylic acid, which is a natural component of willow sap. According to Dr John McLean, if you have more than 15 mg/kg of salicylic acid in honey, then you are likely to have melezitose crystals to deal with. High yeast counts in the honey can increase the risk of fermentation, and are considered to be a sign of the honey being unsanitary. You can ask a microbiology lab to carry out a Yeast and Mould Test. The test is relatively inexpensive and will give you useful information. A result of > 200 CFU/gram would result in the honey being considered unfit for human consumption in some countries, and of course a result of close to zero is ideal.
some more investigation, but it will be helpful to get more feedback from people in the industry to confirm or deny or add more detail. 1. In the comb GWA honey is quite crystallised, making it hard to extract using conventional extraction techniques, and crystallises easily. As I understand it, people running extraction plants are getting very good at identifying frames of GWA honey after frustrating days changing filters in recent seasons. 2. GWA honey crystals don’t melt out with gentle warming like other honeys. This is again due to the melezitose, which will form crystals if there is more than 14% of it in the honey. I have heard of one extreme example where a drum of honey had 100 prone to clogging up extraction filters because the melezitose in the honey
kg of crystals in the bottom of it, which the owner could not liquefy using any normal technique like heating or stirring. 3. The honey has a distinct smell and taste, which many Kiwi beekeepers don’t seem to like. However, Dr John McLean has provided samples of GWA honeydew honey to European honey tasting experts who have enjoyed its flavour, so it is very much a case of ‘horses for courses’. 4. Yeast counts in GWA honey may be much higher than would normally be expected, leading to risks of fermentation and perhaps product rejection by customers. The honeydew being collected by the bees is sitting on willow leaves and out in the open—a great environment for natural yeasts and moulds to grow in.
Figure 3. Residual melezitose sugar in ‘extracted’ wet. Photo: Dr John McLean.
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