ΤΟ ΦΥΤΟ ΜΑΝΟΥΚΑ KAI ΚΑΝΟΥΚΑ -MANUKA AND KANUKA

Manuka Honey

Manuka honey is produced in New Zealand from two plants, both of which are from time to time called manuka. Το μέλι Μανούκα παράγεται στην Ν.Ζηλανδία από δύο φυτά που ονομάζονται μανούκα. The most common honey source of these is Leptospermum scoparium, and of the two, is the most commonly called manuka. Η πιο κοινή πηγή μελιου είναι από το είδος L.s. The other is Kunzea ericoides (but formerly known as Leptospermum ericoides) and is called manuka and kanuka, with kanuka being the more common usage. Το άλλο είναι το Κ.e. ή αλλιώς Leptospermum ericoides και ονομάζεται κανούκα. The Leptospermums are a genus comprising around 50 species that is widely spread throughout the South West corner of the Pacific. Το γένος Leptospermums περιλαμβάνει 50 είδη και είναι ευρεία διαδεδομένο στα νοτιοδυτικά του Ειρηνικού. Both the manuka and kanuka plants have historically been used by Maori and early European settlers for medicinal purposes. These includes use of the bark as a poultice, for colds, for flu, and stomach aches. Both plants are called "tea tree" from the practice of making a tea from the leaves. The honey is dark coloured, (around 84mm average colour ± 11.8mm SD - Pfund scale), strongly flavoured, with a herby, woody characteristic, and is often highly "thixotropic" (jellied) like European Heather honey (Calluna vullgaris). Another Leptospermum in Australia also derives its name (Jellybush) from the thixotropic nature of its honey. Manuka is classified as an over represented pollen type and has a higher than normal conductivity (about 4 times that of normal flower honeys.) Conductivity Conductivity is an indirect measurement of the mineral content of a honey. Most flower honeys have low mineral content and a low conductivity. Manuka however has a conductivity that is approaching that of some honeydews. It has an average of 5.8 ± 1.54 SD. This may be due to manuka being a honeydew source, or it may be a feature of manuka honey. Manuka as a Honeydew Source Both manuka and kanuka are inhabited by a variety of scale insects, but particularly Eriococcus orariensis and Coelostomidia sp. These scale insects are producers of honeydew and the consequence of this is often seen as black sooty mould on the plants, and the plants exuding a sweet honeydew smell. Often this smell can be detected more than 200 metres away from the source. The sooty mould is seen as a blackness all over the plants but particularly on the branches and stems of the plants. It is common for honeydew elements (fungal particles from the sooty mould) to be found in manuka honey. It is likely that some of the high conductivity for manuka honey is caused by it being a honeydew source. Pollen Analysis Pollen analysis of manuka honey is a reliable determinant of its floral origin in most cases. There are instances however where some other honey plants can provide a significant proportion of the nectar without contributing to the pollen spectrum. Two in particular are worth noting. These are Rewarewa and Beech honeydew. Both these honeys have a colour similar to manuka and both have stronger flavours that are not completely dissimilar to manuka. In the case of Rewarewa, it has a low total pollen count. Any honey purporting to be manuka with a low total pollen count (less than 100,000 pollen grains per 10 grams) and with the presence of Rewarewa pollen, should be carefully examined, even if it has more than 70% manuka. The same applies to blends of manuka and Beech honeydew. This particular blend can be very difficult to assess due to the high conductivity and presence of honeydew elements of manuka. Local knowledge of the production location is helpful here. The pollen of both manuka and kanuka are indistinguishable from each other under a compound microscope. Any attempt to differentiate between the two honeys is thwarted by this and also the close proximity of both plants to each other, their close (often overlapping) time of flowering, and the fact that both plants are referred to by the common name "Manuka". Antibacterial Activity in Manuka Honey - "Active" Manuka Honey One area that is of particular interest regarding manuka honey is its antibacterial activity. Often this is just shortened to "Active" or "Active Manuka". Most honeys are in some way antibacterial (some quite highly so), but normally this antibacterial activity is almost exclusively derived from Hydrogen Peroxide (H2O2) and is referred to as Peroxide Activity or PA. This is created from the activity of the enzyme Glucose Oxidase in honey. Like many enzymes, Glucose Oxidase is inactivated by light and heat. The stronger the light and/or heat, the faster it is inactivated. Room temperature and low light, given enough time, will also reduce the Glucose Oxidase activity. Non Peroxide Activity Manuka honey also has this varying degree of antibacterial activity due to H2O2, but has been found to have a further amount of antibacterial activity that is present after the Glucose Oxidase and H2O2 have been neutralized with Catalase. This activity is referred to as the Non Peroxide Activity (NPA). Recently the letters UMF ("Unique Manuka Factor") have been privately trademarked in New Zealand (UMF®) to represent a standard of NPA antibacterial activity. This standard represents a manuka honey with an NPA that is equal to, or greater than, the antibacterial activity of a 10% solution (%w/v) of phenol/water. The UMF® letters may be appended with a number. This number refers to the %phenol/water. e.g. UMF12 equals an NPA activity equal to or greater than a 12% solution (%w/v) of phenol/water. Unlike Glucose Oxidase (the source of PA), the NPA in Manuka is stable to moderate heat, light and even Gamma radiation. To date, a small part of this additional antibacterial activity has been accounted for with the discovery of a number of naturally occurring compounds in manuka honey. However the agent or mechanism creating the majority of this activity remains unidentified. Not all manuka honey has PA and not all manuka has NPA. Some manuka honeys have both types of activity, and some have little or none. There is also a great deal of seasonal variation, with both types of activity being individually either present or absent in any particular honey season. To date, manuka has been tested in the laboratory against several strains of wound infecting bacteria and found to be effective in inhibiting the growth of most of them. Additional References Manuka Honey and Stomach Ulcers (Helicobacter pylori) "Active" Manuka honey has also been shown in vitro (in the test tube) to inhibit the growth of Helicobacter pylori - the bacteria considered the main cause of stomach ulcers. However clinical trials in New Zealand with manuka (and repeated by clinical trials in the UK) failed to show manuka to be effective against Helicobacter pylori in the stomach. Further research on this, particularly the ideal delivery system,including dosage rates, is needed before claims of a cure for stomach ulcers can be made. IMPORTANT! Anyone contemplating using manuka honey as a treatment for stomach ulcers should only do so under the guidance of a health professional.