Mānuka plantation research for medical-grade honey

In a world seeking natural remedies and alternatives to our failing antibiotic treatments, mānuka honey and therapeutic products are proving a market winner.

Mānuka honey is often referred to as the ‘king of honeys’. The mānuka flower produces nectar with unique compounds that result in a honey with strong, natural antibacterial properties.

The mānuka honey industry depends predominantly on wild harvesting of honey – this is where hives are set up in areas that naturally have a large number of mānuka trees. This has meant that supply is constrained by issues such as an unpredictable honey yield and varying antibacterial quality across growing regions.

A Primary Growth Partnership (PGP) initiative has brought together key stakeholders to look at how the industry can move from wild harvest to the science-based farming of mānuka plantations.

What’s so special about mānuka honey?

All honeys have antibacterial activity, in part, because they have enzymes that produce low levels of hydrogen peroxide. Mānuka honey is special because it can also contain a high level of non-peroxide antibacterial activity – this is antibacterial activity not connected with hydrogen peroxide. The key compound has been identified as methylglyoxal (MGO).

The ‘quality’ of mānuka honey refers to the grading of mānuka honey using the unique mānuka factor (UMF) grading system. This system, which ranges from UMF 5+ to UMF 25+, measures the honey’s antibacterial activity when compared with an antiseptic. The higher the UMF number, the higher the antibacterial activity of the honey.

The term unique mānuka factor was coined in the early days of the industry – when the antibacterial properties of applied honey (i.e. when honey is applied directly to wounds as opposed to being eaten) were recognised, but the exact compounds were still unknown.

What’s in a name?

Cliff van Eaton tells the delightful story of scientist Peter Molan and marketing guru Bill Floyd sitting in the Wellington sun after a meeting at the Ministry of Health.

It was a sunny day in Wellington, and Bill wasn’t wearing a hat. Being a redhead and also not having all that much hair (beard not withstanding), he began to feel a light tingling. Then it occurred to them. Couldn’t they use some sort of an acronym, like the SPF ratings on sunscreens? They tossed the idea around a bit further.

We now know that methylglyoxal is formed from the conversion of dihydroxyacetone (DHA), which occurs in the nectar of mānuka flowers, during the production of honey in the hive. The higher the levels of DHA in the mānuka nectar, the higher the potential medical grade/UMF factor and the more valuable the honey will be.

Medical-grade honey is in huge demand, and companies like Comvita have utilised the science to create a number of medical applications including wound creams, antibacterial gels and hospital-grade honey-impregnated bandaging.

High-performance Mānuka Plantations programme

The High-performance Mānuka Plantations PGP programme aims to double land planted in mānuka and the mānuka honey harvest by 2028. They’re also aiming to double the harvest of high-grade medical-grade mānuka honey.

The High-performance Mānuka Plantations Programme is a partnership driven by a range of partners including the Ministry for Primary Industries, Comvita and Massey University.

Comvita contributes genetic material for the mānuka trees in order to investigate and identify the cultivars that will provide the highest yield of medical grade honey and that are in turn best adapted to the local climate and soil. Massey University is running an intensive programme of tests to measure the outcomes.

The work is expected to offer a science-based case for the conversion of marginal lands from livestock to mānuka plantations for honey harvesting.

Trialling a mānuka plantation

In seeking solutions to better utilise marginal hill country land and control erosion, Hawke’s Bay Regional Council (HBRC) joined the High-performance Mānuka Plantations programme.

HBRC is trialling a 140 hectare mānuka plantation at Tūtira Regional Park.

People planting mānuka to harvest the honey is not new. However, in these cases, often the trees – whether eco sourced or from local nurseries – do not guarantee a high quality of medical honey. This project and HBRC’s involvement is about being able to give landowners and land managers evidence-based statistics on which they can make decisions.

If we can get better economic and environmental returns for 150,000 ha of erosion-prone, steep farmland, then everyone’s on a winner.

Campbell Leckie, HBRC

HBRC has planted four different cultivars supplied by Comvita and continues to maintain the crop – taking care of weed and pest control. A contracted beekeeper has supplied the hives, and Massey University comes in regularly to assess the plantation and collect tree and honey samples for testing.

What scientific testing is being carried out?

Massey University is monitoring the trial plantations around New Zealand in the High-performance Mānuka Plantations programme. It undertakes regular testing on the trees and the resulting honey to assess:

• floral density
• nectar testing – it has been identified that trees with nectar high in DHA will produce the highest-quality medical grade honey, so during testing, a flower is picked and nectar pipetted from it
• flowering period – the timing of flowering is important, so it works to achieve staggered flowering (where the tree flowers over weeks) in order to assure a good honey yield
• bee ‘attractiveness’
• disease resistance
• hardiness
• honey testing – to assess suitability for medical applications
• weather.

Preliminary results at Tūtira are promising. Mānuka can be hard to establish but has grown well at Tūtira. The planting also had a remarkable 85% survival rate during the 2012 drought.

Early testing shows that the trees are starting to generate a pure, high-grade mānuka honey.

The plantings are also reducing sediment run-off into the lake and adding value to the local biodiversity.

With significant international demand for medical grade mānuka honey, the project could provide an environmental and economic winner for all involved.

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