EcoLincNZ

Category: Wine

  • Wine is changing with the times

    For thousands of years, humans have been indulging in the pleasures of alcohol. It is one of the few pastimes that run throughout the history of civilisation. But what did wine taste like without the modern technologies we have today? In the modern day world, wine may be described as somewhat spicy, smelling of roasted walnuts, apples, toasted bread, and curry, with a very dry and sappy mouth feeling.

    Figure 1. A glass of NZ red wine (Photo by Evan Wood)

    Romans would often add herbs, spices, honey, or saltwater before drinking the wine, to experiment with flavour and medicinal properties. As humans became more advanced in the production, storage, and fermentation of grapes, we created more delicate wines with sophisticated flavour profiles, aromas, and textures.

    In the modern world of wine, terroir reigns supreme. This French term encapsulates the unique combination of soil, climate, and topography that imparts distinct characteristics to wine. These terroir factors affect many viticultural practices, such as fruit ripeness, maturation, and harvest dates, which have a direct impact on the quality of wine.

    While much attention is given to the climate and grapes themselves, an equally critical yet often overlooked aspect of winemaking, is the role of microbial communities. Fermentation is at the heart of winemaking, where grape juice transforms into wine through the action of yeasts and lactic acid bacteria. These microorganisms are present within the grape must, the natural, freshly pressed grape juice.

    Figure 2. Landscape of a vineyard located in Marlborough, New Zealand (Photo by Bernard Spragg)

    The yeasts break down sugars to ethanol (alcoholic fermentation), which encourages lactic acid bacteria growth. These bacteria then begin the malolactic fermentation process, where they convert malic acid to lactic acid. Not only do these microorganisms liberate the aromas and flavour profile of the grapes, but they are the tiny soldiers that help give you a little, or large, buzz. So next time you drink a glass of wine or alcoholic beverage, give a toast to these yeasts and bacteria.

    Many winemakers choose to select conventional, commercial strains of microbes for fermentation to ensure gold-standard wine, rather than risk the potential of rotten grape juice. Others opt for spontaneous fermentation, which relies on naturally occurring microorganisms on the skin of grapes or in the environment (air or soil). In such vineyards that use spontaneous fermentation, the diversity, abundance, and role of these microbes are crucial in the development and quality of the wine.

    Figure 3. A barrel of grape must + microbes (Photo by benmacaskill)

    As climate change reshapes our environment, its impact on these microscopic winemakers becomes a fascinating field of study. Dr Aghogho Ohwofasa’s work explores the variation of microbial populations between different vintage years on the same block of a vineyard that consistently uses an organic approach.

    Between vintage years and geographical regions, the climate, such as average temperature, relative humidity, and rainfall that a vineyard receives varies. Climatic variation influences the vintage effect, which is used to describe the variation in yield, quality, and typicality of both grapes and wine from year to year.

    The purpose of Aghogho’s study was to figure out which climatic factors varied between the 2018 vintage and 2021 vintage and how that variation influenced the bacterial and fungal communities present. The first step was to select two areas of the vineyard for each vintage that had the same shared location and would experience the same weather.

    Figure 4. Vineyard near Waipara, North Canterbury (Photo by Vjpaul)

    Next, the microbial communities were compared between each vintage year. Samples were taken from the grape juice at four important fermentation time points. These were the start of fermentation, two times during the process of fermentation, and the end of fermentation. The detection of the yeasts and bacteria in the samples was achieved through metabarcoding, which is able to detect and sequence the DNA of all the organisms present in the sample.

    The results from Aghogho’s study indicated that the diversity and abundance of bacterial and fungal communities varied between the 2018 and 2021 vintage years. The bacterial community and composition of the 2018 vintage had 56 genera (groups of species) that were uniquely present in that particular year and showcased much greater diversity when compared to the 2021 vintage, with only 17 genera.

    In spontaneous wine fermentation, Saccharomyces yeast species typically predominate due to their specific adaptive traits, which give them competitive advantages over other yeast species. The graph below in Figure 6 shows that Saccharomyces yeasts made up 53% and 46% of the yeast species in 2018 and 2021 respectively.

    Figure 5. Relative abundance of bacterial communities between 2018 and 2021 vintage (Data from Aghogho Ohwofasa)

    Other dominant yeast species included Auerobasidium, Hanseniaspora, Stramerella, and Metschnikowia. Despite the dominance of Saccharomyces within the 2018 and 2020 vintage, there was variation between other yeast species, namely Stramerella (2018 vintage) and Metschnikowia (2021 vintage).

    Inevitably each year, a batch of grapes will have a unique profile of microorganisms that influence the development of the wine. But since different yeasts unlock different aromas, what risks may vineyards be facing due to these changing populations?

    The dominant lactic acid bacteria involved in winemaking include the Lactobacillus, Pediococcus, Leuconostoc, and Oenococcus genera. The activity of these bacteria can modify the wines appearance, flavour, aroma, and texture, as well as reduce its acidity.

    Figure 6. Relative abundance of yeast communities between 2018 and 2021 vintage (Data from Aghogho Ohwofasa)

    Most of the bacteria present in Aghogho’s study are common and expected throughout the wine regions of the world. They have also been extensively studied, and their contribution to the winemaking process well-known.

    The Tatumella genera, which was overly abundant (61%) within the 2021 vintage but had less than 2% abundance in the 2018 vintage, is much less studied. So how might this organism be affecting the quality of wine between these two seasons? This is a question that we simply don’t know the answer to.

    Dr Aghogho Ohwofasa and colleagues’ work highlights that climatic variables, such as temperature, rainfall, and relative humidity, influence the bacterial differences that occurred between the 2018 and 2021 vintage. Rainfall and humidity were key variables driving the populations of bacterial and fungal communities within the 2018 vintage, whilst maximum temperature had a large influence in the 2021 vintage.

    Different species and strains of yeasts and bacteria can contribute to the sensory characteristics of wine, which may be beneficial or detrimental to the quality of wine. So, what does this mean for wine making worldwide?

    We don’t fully understand the extent to which these ‘wild’ microbes play a role in affecting the flavour profiles and aromas within our wines. Will climate change disturb the composition and abundance of these microscopic winemakers that will ultimately impact the taste of our wines? If so, how do we protect our wine from changing with the times?

    This article was prepared by Bachelor of Agricultural Science with Honours student Charlotte Tinsley as part of the ECOL608 Research Methods in Ecology course.

    Reference:

    Ohwofasa A, Dhami M, Zhang J, Tian B, Winefield C, et al. (2024) Influence of climatic variation on microbial communities during organic Pinot noir wine production. PLOS ONE 19(2): e0296859. https://doi.org/10.1371/journal.pone.0296859

  • Induced resistance, Sting, and the blades of Westernesse

    It’s a big, bad world out there and it is nice to find something that adds to our protection.This can range from vaccines against viruses, to seatbelts in cars, to laws against causing physical harm. As a naked ape we are not especially intimidating on our own and we often seek out tools to make us safer.

    “With both hands he held the elven-blade point upwards …; and so Shelob, with the driving force of her own cruel will, with strength greater than any warrior’s hand, thrust herself upon a bitter spike. Deep, deep it pricked, as Sam was crushed slowly to the ground.
    No such anguish had Shelob ever known, or dreamed of knowing, in all her long world of wickedness. Not the doughtiest soldier of old Gondor, nor the most savage Orc entrapped, had ever thus endured her, or set blade to her beloved flesh.” Lord of the Rings, JRR Tolkien (Image by Tony Galuidi; main image by Alan Lee)

    One of the key points of “The Lord of the Rings” (and all of Tolkien’s writing) is that small, seemingly ineffectual, individuals can make a real difference in the world. It’s not by chance that hobbits are smaller than humans, weaker than dwarves, less knowledgeable than elves. Tolkien emphasised their ‘normality’.

    Hobbits do have their strengths though, especially in resilience. They are able to withstand the corruption of the ring far longer than other races. Boromir, a doughty man, only has to see the ring once before plotting to ‘borrow it’ for helping with his people. Both Bilbo and Sam, ordinary hobbits, are both able to wear the ring and give it up freely, which no others have done.

    Still, even Tolkien realised that the hobbits needed a little bit of an assist, something that would help to bring out their resilient traits. Tolkien chose to give each hobbit a long dagger with an ancient pedigree. Sting was found by Bilbo. It was a blade that shone with a faint light when evil was near. Sting was made long ago in the first age by elves of Gondolin. Tom Bombadil rescues the hobbits from a barrow wight and gives them each a dagger of Westernesse. These were made a couple of thousand years before in the early Third Age by men of the Dunedain Northern kingdom.

    Each of these blades become crucial to the hobbits achieving beyond their expectations. Pippin stabs a troll chief, who are largely immune to most weapons, and makes a difference at the Battle of the Moranon. Merry cuts the Witch King’s sinews allowing Eowyn to destroy the head Nazgûl in the Battle of the Pelennor Fields, when no one else can touch him. Sam uses Sting to wound Shelob and scare her off, when nothing else would work.

    Importantly, the blades were built with different foes in mind. The blades of Westernesse were built to fight the Witch King and his minions but are useless against giant spiders. Sting was built at a time when Ungoliant’s spider brood were numerous and roaming the world, and so it is effective against Shelob and her webs.

    Merry stabs the Witch King and breaks the spell allowing Eowyn to destroy him.
    “No other blade, not though mightier hands had wielded it, would have dealt that foe a wound so bitter, cleaving the undead flesh, breaking the spell that knit his unseen sinews to his will.” – Lord of the Rings, JRR Tolkien

    So, the hobbits left the Shire with their natural hardiness and common sense, but were primed with blades to make themselves more resilient to the difficult situations that they were to face.

    There is a similar concept when it comes to immune systems. Most plants and animals have evolved sophisticated immune systems that respond to pathogens in the surrounding environment. Having a complex immune response is especially important in dense populations where disease and parasites can quickly spread. One such situation is with crop species.

    Crops, where individuals from one species are packed tightly together, are targets for various pest species that can infect an individual and easily move to the next. For the last 100 years or so we have had the luxury of applying chemicals to help keep the plants healthy by reducing pathogens. This is no longer an an attractive option as it once was as pathogens have become resistant and people have become less tolerant of nasty chemicals in their landscapes and food sources.

    One solution is to create induced resistance through biological and chemical inducers. These inducers can artificially trigger immune defences and enhance their responses. For example, grape crops can suffer from downy mildew. Chitosan, a sugar obtained from the shell of crabs, can be sprayed on vines, triggering immune responses that can reduce downy mildew by 90%, compared to what would happen if grapes responded ‘normally’!

    “His little sword was something new in the way of stings for them. How it darted to and fro! It shone with delight as he stabbed at them.” The Hobbit, JRR Tolkien (Image by J. Catlin)

    Just like the blades of Westernesse helped the hobbits, these inducers allow the individuals to respond faster, more intensely, and achieve more than they would otherwise be able to do. Some inducers are useful for a variety of pathogens in many crops, such as Acibenzolar-S-methyl (ASM), and some are very specific, such as Saccharomyces yeast extract.

    Helen Rees, Lincoln University, and colleagues from Plant and Food, University of Auckland, and Scotland’s Rural College have put together a review in the journal Phytopathology about where the field of induced resistance in crop species stands. They look at what has worked on particular crops and the future roles and opportunities for inducers. They conclude that it is an exciting time for this field and that future crop protection may revolve around the next generation of inducers, playing a pivotal role in moving to a reduced pesticide future.

    While inducers may not have the glamour of a Bilbo using Sting to free dwarves from giant spider webs in Mirkwood, they have world-wide contributions to make to feeding a hungry planet by countering the ravening hordes of crop pathogens. Cutting edge indeed!

    Adrian Paterson is a lecturer in Pest-Management and Conservation at Lincoln University. He likes Sting (both in the Lord of the Rings and in The Police).

  • Tricks of the underground trade: networking below the vines

    Life in the soil can be a tricky business for plants and microbes. Nutrients are a limited commodity for some, and competitors may swindle and cheat to gain the upper hand. Strategic partnerships are highly sought after enabling exchange of one commodity for another within elaborate networks.

    In a tough economy, well-connected networks promote resilience, sharing of ideas and opportunity to those participating in mutual exchange. However, an efficient network should be an intentional one. Making simple connections is one thing, but choosing the right friends and trade partners is another.

    Although it may not appear that obvious on the surface, most land plants are proficient networkers. Below ground, plants form selective partnerships with microorganisms in the soil to access nutrients, water, and protection from pathogens. Those with strong networks are favoured in times of scarcity and change.

    Fungal mycelium consisting of thread-like hyphae. Photo by Lex vB at Dutch Wikipedia, (CC0 1.0)

    Within soil communities, fungi known as mycorrhizae play a major role in the growth and survival of plants. It is estimated that more than 80% of vascular plants form partnerships with mycorrhizae, an ancient evolutionary network approximately 450 million years old.

    Mycorrhizae are of particular importance in the viticultural industry as grapevines are highly reliant on these partnerships for growth and nutrient uptake influencing grape composition, vine health and occurrence of disease. In fact, grapevines form associations with entire communities of mycorrhizae known as arbuscular mycorrhizal fungi (AMF).

    AMF form close associations within the root tissue of plant hosts through specialized tree-like structures called arbuscules. These allow exchange of mineral nutrients from the soil for carbon fixed by the plant host which is transferred through the extensive hyphal network in the soil. These hyphae form interconnected “superhighways” within the soil, linking neighbouring vines and nearby crops transferring nutrients, such as nitrogen, from one host to another.

    Arbuscule of Rhizophagus irregularis colonising a plant root. Photo by Hector Montero, Flickr (CC BY-SA 2.0)

    AMF are highly diverse and have different effects on nutrient uptake and growth on grapevines. Depending on the situation, AMF can have positive, neutral, or negative effects on plant growth and stress resistance. However, under field conditions, plants are selective in the networks they build. These communities perform a diverse range of functions which collectively contribute to plant health and characteristics. Therefore, investing in the right trade partners is crucial.

    Until recently, the effects of whole AMF communities on grapevines had been largely unexplored. A research project at Lincoln University lead by Dr. Romy Moukarzel sought to understand how AMF different communities influence nutrient uptake and growth of different grapevine rootstocks. 

    In other words, who are the trade partners behind the vines and what is the return from these communities?

    To answer these questions, AMF communities were recovered from the roots of three different grapevine rootstocks across three different vineyards. Each rootstock was inoculated with its own (“home”) community or communities from other rootstocks (“away”) within three different vineyards. Vine growth, nutrient uptake, and chlorophyll levels were measured to find out if different communities had positive or negative effects on the different rootstocks.

    Consistent with previous work, different vineyards and rootstocks had their own unique communities. Growth and nutrient uptake differed depending on the composition of the community and rootstocks responded differently to the same communities. While some species in these communities improved nutrient uptake, others improved growth. In particular, a diverse community with a large representation of AMF of the Glomeraceae family resulted in the greatest increase in grapevine growth.

    In one vineyard, home advantage was also evident with “home” communities having greater increase in vine growth compared to “away” communities. Interestingly, when the amount of each AMF inoculum was equalised, home advantage was no longer observed.

    By changing the community composition, the positive effects on plant growth were reduced.

    New Zealand vineyard. Photo by Jorge Royan (CC BY-SA 3.0)

    Moukarzel and colleagues suggested that altering the composition may have resulted in competition between AMF leading to reduced positive effects on the host. AMF are known to compete for host resources, soil nutrients and colonisation sites. As a result, cooperation, and rivalry between AMF within different communities may have major implications for vine productivity.

    So, what can grapevines teach us about networking?

    Basically, choose your trade partners wisely. Identify friends and adversaries within the network and invest in those relationships with the greatest return.

    As proposed by marketing expert, Porter Gale: the so-called ‘new model’ of networking should focus less on ‘handing out as many business cards as possible’ and more on making connections based on how you want to grow. In other words, efficient networking should focus on investing in specific needs and interests. A well connected network with diverse partners offers wide opportunity and stability if components are co-operative.

    Overall, the findings generated from the study will be an invaluable insight towards leveraging AMF communities to target specific growth and nutrient requirements of grapevines. This is of particular importance to the viticultural industry as the composition of these communities play an important role in determining vine health, yield, nutrition, grape composition, and wine characteristics.

    Featured image: vineyard inter-row by rawpixel.com (CC0 1.0)

    While this study has provided a step towards understanding the communities below the vines, soil is a complex system with a wide range of players and there is much to learn about the orchestration of these networks. There are likely many more tricks of the underground trade to uncover.

    Moukarzel, R., Ridgway, H. J., Waller, L., Guerin-Laguette, A., Cripps-Guazzone, N., & Jones, E. E. (2022). Soil Arbuscular Mycorrhizal Fungal Communities Differentially Affect Growth and Nutrient Uptake by Grapevine Rootstocks. Microbial Ecology. https://doi.org/10.1007/s00248-022-02160-z

    This article was prepared by a Master of Science postgraduate student Malina Hargreaves as part of the ECOL608 Research Methods in Ecology course.

  • When grapes lead to war

    Would you steal a loaf of bread to feed your hungry family? Fair enough. What about a couple of grapes to save yourself the misery of wasting nine dollars on sour fruit?

    Grapes, waiting to be sampled.
    © Colin Jensen

    “Try ‘em before I buy ‘em,” is my dad’s usual response to that question, as he pops grapes from three different bags one-by-one into his mouth. A red one here, a green one there, maybe even a dark purple if the season is right. In spite of earnest pleadings from embarrassed children and grocery store placards, there would be no purchase of grapes unless a thorough investigation of both quality and taste had been completed. 

    As weird as it may sound, it turns out my dad is not alone in his grocery store grape grabbing. A quick google search yields numerous articles, blogs, polls and debates on the topic. A more recent article used an extensively rigorous survey of 40 people on Facebook to tackle the question, with results showing that half of respondents advocated for, and actively participated in, grape sampling while shopping. As for the other half? Some seemed to side with this NZ Herald article which refers to grape samplers as both thieves and stealers, while others suggested that this type of behaviour is a “hanging offense”. As a conservation biologist, I am not typically one for philosophical debates, so I’ll leave the ethics of grape sampling and capital punishment up for you to decide. 

    Unfortunately, a jump back into the conservation sphere does not make me immune to grape stealing dramatics. As it turns out, nature, just like the produce aisle of my parent’s local grocery store, is home to its own collection of fruity felons. Among those felons is the European starling. You may know starlings for their incredible vocal range, beautiful coloration, or the massive flocks (or mumurations) they sometimes form (check them out if you haven’t). But to winemakers in New Zealand, starlings may be more well-known for being “vicious” and “wasters of fruit.” Unfortunately the problem that starlings cause in vineyards is nothing new, and in fact, it was this very problem that was the inspiration for research at Lincoln University over 20 years ago. 

    European Starling CC courtesy of Eric Ellingson on Flickr

    Flashback to 1999 – Napster is in its heyday, Brittney Spears’ “Baby One More Time” is on the radio, and, besides a little bit of Y2K hysteria, life is good. Amidst the excitement of a new millennia, researchers Yuki Fukuda, Graham Hickling, and Chris Frampton from Lincoln University were hard at work trying to solve the problem of the grape stealing starlings. To do so, they tested out two devices designed specifically for scaring birds away from agriculture areas – the Peaceful Pyramid and eye-spot balloons. The Peaceful Pyramid, as the name suggests, was meant to be a “peaceful” alternative to other more aggressive bird deterrents like “noisy gas guns”. It featured a rotating pyramid with mirrored sides, which would reflect rays of sunlight towards incoming birds. The goal was to overload the birds vision to the point that they would no longer have the desire to land and feed. The eyespot balloon was a large balloon with yellow and black patterning designed to mimic the eyes of a large predator. 

    Peaceful Pyramid
    © Great Expectations

    Both devices were tested at a vineyard in Dunsandel, and at the University vineyard here in Lincoln. Although both were found to scare starlings away from the grapes initially, within a few days almost all the birds had become habituated to both scarers, and they quickly became ineffective. Ultimately, it was determined that both the eyespot balloon and the Peaceful Pyramid were not practical methods for protecting vineyards. Although these researchers did not find a solution to counteract the stealing starlings, they at least helped re-affirm the idea that anti-bird measures need to be thoroughly tested before they are trusted for protection. 

    In the 24 years since the research at Lincoln was done, there has been no shortage of innovation and testing of bird scaring devices. There has also been some work (here and here) on what birds are doing in the vine-yards. Among the myriad of devices tested, we have seen air cannons, chemical repellents, introduced falcons, large-scale netting, and a few of my favourites, the sci-fi sounding laser scarecrow (unfortunately, this doesn’t look as cool as it sounds), and the RobotFalcon (fortunately, this does look as cool as it sounds). 

    All of these projects have had the same goal: deter birds from pillaging in agricultural settings. Unfortunately, despite each of these ideas producing some level of protection, they all come with limitations. One is too expensive, another is too time and labour intensive, and some only work in good weather. For many, it seems as if finding a fix-all solution to the crop stealing problem is a fruitless endeavour. If it’s not the Peaceful Pyramid, and it’s not the laser scarecrow, then really what more can we do? 

    Well, researchers from the University of Sydney think that they have finally found the answer. (If you have been surprised by any of the bird scaring techniques already described, you may want to sit down for what comes next). Like something out of a Stanley Kubrick film, these researchers have employed techniques that they can only describe as “psychological warfare.” 

    The weapons of war used in this study consist of a stuffed bird attached to a drone (UAV), which is flown through the vineyard whilst playing recorded distress calls of pest birds from a loudspeaker (see image below). The idea is that visual and auditory stimuli on their own are not effective long-term. By tapping into the birds psychology through visual (dead bird) and audio (distress call) cues, they might be able to trigger the birds anti-predator behaviour, and keep them away for good.

    Early results show that crop damage in areas patrolled by this flying fearmongerer are up to four times less than areas which used visual scarers alone. It also appears that this system is just as effective as large-scale netting (currently the most effective way to protect grapes), but is much more cost effective. While these results are preliminary, and further testing is still needed, it seems that hope may be flying (and screaming) in on the horizon. 

    © Zihao Wong – UAV bird scarer as used in: Psychological warfare in vineyard: Using drones and bird psychology to control bird damage to wine grapes

    So there you have it. Starting with a couple of grapes at the grocery store, we end with a weapon of war designed to create fear and confusion. While we may not be any closer to answering the debate about grocery store grape sampling, we at least seem closer to solving the grape stealing starling situation. Will psychological warfare finally be the fix-all solution? Perhaps, but only time (and research) will tell. 

    As for me, I still don’t quite understand what it is about grapes that causes both the starlings and my dad to lose all sense of self-control. Maybe with 24 more years of research, innovation and whatever military tactic comes after psychological warfare, we will finally find that out. I am sure it will be a wild ride. 

    This article was prepared by Master of International Nature Conservation student Colin Jensen as part of the ECOL608 Research Methods in Ecology course.

    Citation: Y. Fukuda , C. M. Frampton & G. J. Hickling (2008) Evaluation of two visual birdscarers, the Peaceful Pyramid® and an eye‐spot balloon, in two vineyards, New Zealand Journal of Zoology, 35:3, 217-224, DOI: 10.1080/03014220809510117