Our Changing World
Thursday 28 May 2015, with Alison Ballance, Ruth Beran & Veronika Meduna
On This Programme
- The Art and Science of Beer
- A Transportable MRI
- Flower of the Underworld - A Parasitic Treasure
- The Road to Paris - New Zealand's Climate Change Target
The Art and Science of Beer
By Veronika Meduna
What we’re trying is to breed hops that are going to give some uniqueness to craft brewers and also to the bigger brewers in New Zealand.
Ron Beatson, Hop Lab
Ron Beatson essentially inhales beer, in the name of science and business.
His quest is to breed hops that combine just the right mix of bittering agents and flavours to provide interesting new cultivars in support of New Zealand’s burgeoning craft beer industry.
He simply loves the aroma of hops, and it is a scent that follows him and his team around throughout the year, as they breed, grow, process and analyse thousands of hop plants in search of new and unique flavours.
Last September, Plant & Food Research added a micro research brewery, known as the Hop Lab, to its Motueka site, where the team also keeps a hop garden and a chemistry lab. It allows the team to complete the full cycle of beer production, from breeding the hops to analysing the chemical composition of the cones and, finally, producing experimental brews under strict scientific scrutiny.
What we’re trying to do here in this brew house is to brew beer which is standardised for all the things apart from the hops. Each brew we put in has got a different hops selection going into it, but we have standard malts that go in and we brew it to a certain alcohol content. We brew them as pale ales so we use pale ale yeasts – so at the end of the day, the only thing we try to vary is the hops.
Hops belong to the cannabinaceae family, which has only two genera: hops and cannabis. The centres of origin for hops are central Asia, North America and central Europe, but the plants have been spread across the world.
They arrived in New Zealand during the 1800s with gold miners and early settlers, keeping hop gardens for community home brewing. But Ron Beatson says as commercial beer production became more important and more geared up, the Nelson region proved the best place to grow hops on a larger scale.
Hops are perennial, growing as a climbing vine during summer and dying back to a root stock in winter. Female and male plants are separate, and the plant of commerce is the female.
Once the plants have flowered, the first quality test is a “rub and sniff” of the cones, or strobiles, which contain small, orange glands. The hop aroma comes from these Lupulin glands, where aromatic and bittering compounds are stored.
The bouquet that you smell when you pick up a nice fresh glass of beer is often the hoppy essence coming through.
The team's tasks are to produce natural crosses of hops and to raise thousands of seedlings from these crosses – and then to pick out the most promising ones for chemical analysis and brewing trials.
“You start off with a cast of thousands and, if you’re lucky, you end up with a cast of one. You’ve got a lot of unknowns. It’s quite challenging and quite exciting to go out there and think that you’re looking at plants that could be a cultivar in the years ahead, but you have no idea of their value until you observe them and start doing selection work.”
First, the team checks for agronomic traits – how well the plants grow and perform and how easily they can be harvested. Then comes the rub-and-sniff test to get an idea of the aroma. Post harvest, the chemical analysis captures different essential oils and the acids that act as bittering agents in the brewing process.
“We identify about 40 different essential oils. New crosses have the same types of compounds but in varying ratios. What you smell in a hop cone, or in a beer, is a complex of a lot of compounds. It’s the different combinations, the different ratios and proportions of each of those essential oil compounds that give those fine aromatic differences.”
The Hop Lab has a capacity to produce 50-litre batches of beer using hops from a single seedling. The pilot brew house has produced 41 brews since it opened in September, and Ron Beatson says there is one hop selection that stands out.
We’ve done repeat brews with it because it’s come up trumps in sensory trials by industry people and our own team here. That’s a pretty good strike rate. We weren’t expecting it, but we have struck gold.
The next step will be to grow more of this particular cross to have a big enough harvest for larger-scale brewing trials with a commercial brewer next year. In the meantime, Ron Beatson says there is a small supply left for more experimental brews to see if the team may indeed have a new promising hop cultivar – joining cultivars known as Motueka, Riwaka and Nelson Sauvin that are all “cult heroes of craft brewing”, selling out every year to brewers around the world.
A Transportable MRI
By Ruth Beran
A pop-up MRI or magnetic resonance imaging machine that could be transported in a shipping container has been designed by the Robinson Research Institute.
Currently in the concept-stage, a smaller experimental version of the MRI has been developed that can scan human extremities like arms and legs.
MRIs use a magnetic field and radio waves to create detailed images of the organs and tissues inside the body. The machines use superconducting magnets, and at the moment, the large MRI machines in hospitals require liquid helium, a cryogen, to keep the magnets cold.
The new MRI, located at Gracefield near Wellington, does not need liquid cryogen because it uses a high temperature superconductor.
A superconductor is a type of electromagnet, but unlike the more common electromagnets made from coils of copper wire, superconductors have no resistance.
You can leave it on as long as you like, it won’t consume any power,” says physicist and engineer Rob Slade from the Robinson Research Institute.
There is a catch though. Superconductors only work when they are very, very cold.
For example, the superconductors in hospital MRIs need liquid helium to work. “It’s the only liquid which gets cold enough and doesn’t freeze at -269˚C to get the conventional magnet sitting in a liquid,” says Rob.
Liquid helium is expensive in New Zealand. Hospital MRI machines also require a large quench duct to take the helium, which could be an asphyxiation hazard if it boils and turns into a gas, out into the atmosphere.
High temperature superconductors still need low temperatures, but not nearly as cold. For example, the new MRI at Gracefield operates at -253˚C.
This means it can use an electrical refrigeration unit, or cryocooler, instead of a crystat of liquid helium to cool the magnet. This is obviously a disadvantage if there is a power failure but it does mean the machine can be switched on and off, unlike a hospital MRI which is always on. It can also be easily moved.
The experimental MRI has a bore size of 28cm, which is the diameter hole in the middle of the magnet where an arm or leg would be placed. The machine looks a little like a front-loading washing machine and is a similar size.
The magnets are manufactured by the company HTS-110, and are precision wound from 5mm wide tape stiffened with stainless steel to make what Rob calls “pancake coils”. The high temperature superconductor is a ceramic which sits inside the tape. “It looks like an old fashioned tape deck,” says Rob. “And the wire is built up, one turn on top of another to create an annular coil.” The coils are then stacked on top of each other to make the magnets.
Creating a human size MRI would require investment to make larger coils but eventually the idea would be to build a machine that is transportable. It was inspired by military requirements for a field hospital.
We think we can fit the whole thing into the back of a shipping container, [and] because you don’t have any of that liquid helium it makes that a more achievable prospect,” says Rob.
If funding is found, the next stage would be to build a prototype.
In 2010, Bob Buckley and Jeff Tallon were awarded the Prime Minister's Science Prize in 2010 for their work on high temperature superconductors. Listen to a previous Our Changing World story with Jeff Tallon here.
High Temperature Superconductors ( 19 min 52 sec )
Listen to a previous Our Changing World story with Bob Buckley here.
High Temperature Superconductors ( 12 min 30 sec )
And a story about a cryocooler being developed for use with high temperature superconductors.
Developing a Cryocooler ( 14 min 48 sec )
Flower of the Underworld - A Parasitic Treasure
By Alison Ballance
“There’s something interesting and mysterious about the plants. There’s also something addictive about them.”
David Mudge, Nga Manu Trust
“Dactylanthus is a fully parasitic plant, a flowering plant – and without the flowers we wouldn’t actually be able to find it. It looks like a warty tuber, attached to the roots of native trees, and it’s the only one of its kind. It only lives in New Zealand, and is very unique on many levels.”
Avi Holzapfel, Department of Conservation
In early autumn, the regenerating forest that borders parts of Pureroa Forest, on the western shores of Lake Taupo, is redolent with a musky, fruity fragrance. Photographer David Mudge, from the Nga Manu Trust, says the smell reminds him of a honey shed, while botanist Avi Holzapfel from the Department of Conservation says that to him it’s a cross between over-ripe fig and rock melon. It’s a very distinctive aroma, one that is as distinctive as the plant itself.
Maori know it as pua o te reinga, ‘flower of the underworld’ and waewae atua, ‘toes or fingers of gods’. Botanists call it Dactylanthus taylorii. It’s also known as the Flower of Hades, and as the wood rose (although read on to discover why this name doesn’t actually refer to the plant itself). Dactylanthus is New Zealand’s only fully parasitic native flowering plant – it is a root parasite that relies on its host for all its water and nutrients, unlike other native plants such as the mistletoe, which is a hemiparasite with green leaves that are capable of photosynthesising. It does not harm its host in any way. “When the host dies,” says Avi, “or the root gets damaged, then the Dactylanthus will die as well.”
Dactylanthus has a unique relationship with an unusual pollinator. When it flowers for just two to three weeks in early autumn its musky scent attracts short-tailed bats, which come down to the ground to drink the copious nectar and spread its pollen, which it produces in generous quantities. Chris Ecroyd was the first to discover this relationship between parasite and bat, more than 25 years ago, but over the last five years David Mudge’s remarkable photographs have been casting more light on the unlikely duo, and he says that a bat feeding on the nectar at the base of the flowers ends up with a “face covered in white, as if a child’s been in a bowl of icing sugar.”
David sets up elaborate camera traps over patches of flowering Dactylanthus – each trap might have two to four cameras involved, as well as sensors and flash lights, and they are powered by large camera batteries that need to be replaced every week or two. Some of his camera traps are movement triggered, while others operate in time lapse mode, taking photos every few minutes and allowing David to follow the flowers as they bloom and then fade. The time lapse video (above) was taken by David over a few days, and shows a group of flowers blooming and then dying off - of particular note are the large numbers of different insects visiting the plant.
David says the reason he goes to such efforts to document the plant and its life is that he is a curious person, and also that he knew that “there was much more going on with the plant than I was aware of.” He has photographed bats, rats, possums, hedehogs, birds, wasps, many weta, land snails and a whole variety of insects visiting Dactylanthus flowers.
David has even been able to document the plant’s rich nectar production – watch the video below to see the nectar oozing from the base of the inflorescence.
“A single tuber, with about 40 inflorescences, will produce half to a full cup of nectar over its 10-day flowering period,” says Avi. “That means many litres of nectar are produced in quite small areas of forest.” The nectar contains a mammalian pheromone, squalene, which explains why it is so attractive not only to the bat but to species such as the brush-tailed possum. Waikato University chemistry student Connor Haisley is currently analysing nectar collected from male and female flowers during this year’s flowering season to find out what else it contains.
What most of us would call the ‘flowers’ of Dactylanthus are actually inflorescences: the protea-like ‘flower head’ is actually made up of about 3500 flowers, each just a millimetre-or-so across, arranged on finger-like spadices, which a non-botanist might think were the petals. A sunflower is another example of an inflorescence.
The actual Dactylanthus plant is a warty underground tuber that can grow to the size of a large basketball. The plant begins life as tiny seed, one of thousands produced by a single inflorescence. That seed germinates and waits for the root of a preferred host tree to grow past it. If that happens the seed’s radicle establishes an intimate relationship with the root, but doesn’t actually penetrate it. In response, the root develops a flared surface that the tuber fits around, like a bottle-top fitting around a bottle. It is the distinctive shape of the roots that are the ‘wood roses’, which for many years were collected as curios, and passed down as family heirlooms.
Avi thinks individual Dactylanthus plants may live for 20 to 50 years, and that a population might live in an area of regenerating forest for about a hundred years while it is populated with tree species such as mahoe and five finger. But as the forest reaches a climax stage and the larger podocarps begin to take over, then the Dactylanthus population in that area will die out. “As long as the host trees are there, Dactylanthus will be there as well”, says Avi. Waikato University student Cass Parker has been identifying which species of trees in particular are the host trees at Pureora, and her preliminary work suggests that Pseudopanax is the main host.
Dactylanthus is vulnerable to damage by a range of introduced species. Possums are attracted over great distances by the smell of the nectar, which is why the Department of Conservation traps year-round at Pureora, explains DoC ranger Thomas Emmitt. David Mudge says possums eat out the centre of male flowers “like a kid eating the ice cream out of a cone.” Wasps, on the other hand, sometimes drill through the base of the flower to get to the nectar, or else completely dismember the flower.
Avi has undertaken sowing trials, and has managed to successfully establish Dactylanthus at new sites. Avi, David and Thomas all agree that it would be relatively easy to incorporate Dactylanthus into revegetation schemes, provided the appropriate host species are planted. David points out that Dactylanthus spreads downhill along small waterways and seepages, and this could be taken into account in any planting schemes. Avi’s experience shows that newly seeded plants produce many female flowers, which produce a large seed set and can quickly establish a new population – ‘sort of like an upside-down Ponzi scheme’ says Avi laughingly, with one plant quickly giving rise to many more.
“We’re not just seeding a generation now, but we’re planning for the future,” says David.
Dactylanthus was once widespread across the North and South Islands. The oldest Dactylanthus pollen dates back 28 million years, and it has been found in kakapo coprolites, or fossilised droppings. Today, Pureora and Little Barrier Island are the plant’s strongholds, with other significant populations in Northland and East Cape. There are also quite a few small remnant populations, of ‘grandmother and grandfather plants”, that produce a few male plants but are heavily browed by possums and are not likely to last much longer.
Dactylanthus is the most southerly occurring member of the largely tropical family Balanophoraceae. One of the Top 10 New Species for 2015 is the related Balanophora coralliformes, described from the Philippines by University of Canterbury’s Pieter Pelser and Julie Barcelona.
The Road to Paris - New Zealand's Climate Change Target
by Veronika Meduna
Hundreds of people turned out for a meeting in Wellington this week, calling for stronger and faster action on climate change.
The meeting was the last in a series of government consultations, held by the Ministry for the Environment throughout the country to hear people's views on how New Zealand should manage its greenhouse gas emissions.
Many expressed frustration about the process itself as well as the government’s cost-benefit approach to emissions reductions, saying that the cost of doing nothing about climate change had not been taken into account.
People also raised specific issues about the consultation documents the ministry provided and the economic modelling used to estimate the costs of emissions reductions, including the fact that the document omits to mention New Zealand's current target, gazetted but not legally binding, to reduce emissions by 50 per cent relative to 1990 levels by 2050.
Most speakers called for New Zealand to show leadership on climate change mitigation and to commit to an ambitious target of least 40 per cent reductions on 1990 levels by 2030.
The consultation process is part of the government's preparation for international negotiations under the United Nations Framework Convention on Climate Change (UNFCC), which will be held in Paris in December this year to work out a new agreement that will determine the course of global climate change policy after 2020.
Ahead of the Paris meeting, countries are expected to signal how they plan to manage emissions and mitigate their impact on the climate. The European Union, the United States, China, Russia, Mexico, Norway and Gabon have already submitted their emissions reduction targets, known as Intended Nationally Determined Contributions (INDCs). Recently, the EU, which has committed to reducing greenhouse gas emissions by at least 40 per cent on 1990 levels by 2030, with the longer-term goal of 80-95 per cent reductions by 2050, has called on New Zealand to join the endeavour.
Although the consultation process is now completed, there is still time to make a submission until June 3. The consultation documents and submission forms are available on the Ministry for the Environment website or through Generation Zero’s Fix Our Future campaign.
In the audio feature below, you can listen to what people had to say about how New Zealand should manage its emissions and the impacts of climate change.