Ξ February 9th, 2009 | → 1 Comments | ∇ Interviews, Technology, Wine History, Wine News |
A small article appeared on Decanter.com January 23rd reporting on the discovery by wine scientists of a way to prove the origin of a wine chemically, what is called ‘wine fingerprinting’, through the measurement of ‘over 60 trace elements’ not only in the wine but also in associated vineyard soils. What caught my attention, apart from the subject itself, was that the two scientists whose original work was cited, Alex Martin and John Watling, both of the University of Western Australia, were not wine scientists per se but forensic scientists, an interesting distinction unexplored by Decanter. Now, forensics is ‘the application of a broad spectrum of sciences to answer questions of interest to the legal system. This may be in relation to a crime or to a civil action.’ It was clear the work of Mr. Martin and Mr. Watling must be of a different intellectual character, perhaps using different tools, than found in a strictly viticultural research program.
I wrote Mr. Martin for a few additional details, and also asked after an interview. He responded quickly, providing me with all the information I had requested, including this paper Mr. Martin wrote which appeared in the Dec. 2008 Western Australia Wine Industry Newsletter, the basis, I believe, of the Decanter gloss. He added that he was a PhD candidate working under the very capable Prof. Watling, a man of 30 years experience as a scientist. I should instead contact him. I did. What follows is, quite frankly, the most intriguing and rich conversation I have enjoyed in quite some time. Not only was Prof. Watling forthcoming, tolerant of my questions, but by his rapid fire responses, the full command of his subject, it was very clear to me I was speaking with a first-rate mind. Shuttling between the role of student and interviewer, the conversation took me back to my own university days, to the thrill of discovery.
As you will read in greater detail below, and in a subsequent post of the balance of this extensive interview coming by Friday, February the 13th, Prof. Watling is the head of a group of scientists whose larger mission is the determination of the provenance of a great many objects and products through the use of forensic science. Though we as readers may be principally interested in wine, for Prof. Watling this is just one subject with which he works. And his success in other forensic research areas leads him and his group to believe that one may be able, in the not too distant future, through the careful analysis of the concentrations of trace elements in a given wine, to determine that wine’s origin to the very vineyard from which it came.
Though the full list elements searched for is, in fact, longer, a matter explained below, I had asked Mr. Martin for his list of 60 elements measured for the purposes of determining a wine’s fingerprint. They are:
Li7 Be9 B11 Na23 Al27 P31 S32 K39 Ca40 Sc45 Ti49 V51 Cr53 Mn55 Fe57 Co59 Ni60 Cu65 Zn66 Ga69 Ge72 As75 Se82 Rb85 Sr87 Sr88 Y89 Zr90 Nb93 Mo95 Pd105 Ag107 Cd111 In115 Sn120 Sb121 Te125 Cs133 Ba138 La139 Ce140 Pr141 Nd146 Sm147 Eu153 Gd157 Tb159 Dy163 Ho165 Er166 Lu175 Hf178 Ta181 W182 Hg202 Tl205 Pb208 Bi209 Th232 U238
(A final note. The interview occurred the day before the terrible fires began raging in South-Eastern Australia. Our hearts go out to the families of the souls lost.)
Admin We’re enjoying some delightful rain here in California just now. I’m sure you’d welcome such a change to the awful heat you’re currently going through.
John Watling Yes, it’s quite hot at the moment. This weekend [2/7,8] it’s going to be 28, 29 [centigrade] but we’re looking forward to 48 this week. It’s just too hot. It’s just incredibly too hot!
And I imagine the grapes are suffering.
JW They are indeed. It’s a big problem, though on this side they are probably two or three weeks behind in maturation. In the Eastern States they’re coming on board now. But we are two or three weeks at least behind. We had very, very bad wind in one of the areas of Margaret River which is south of us, which is a wine growing area. The wind ripped trees up that were over a 100 years old and did damage to the grapes and vines as well.
Well, the first question is about your general research background in forensic science, and how forensics assist in the determination of a wine’s geographical origins.
JW My recent background, I am the head of a group of scientists in forensic science. We exist to establish the provenance of where various things come from, in your case I guess it’s called terroir or something like that. But what we do in our group is we have developed technologies to source the provenance of crime scene debris, things like bullets, like plastics, like paper, cannabis, drugs, plants, diamonds, all of this encompassing about 47 different matrices, including foods. We’ve a major part of a Eurasian/Australasian program that is centered around determining the provenance of foodstuffs, and in that respect we provenance things like tea, coffee, cocoa, and meat, milk, vegetables, determining exactly where the come from. In terms of why the country of origin is so that the sales can be confirmed. You can’t sell, let us say, Brazilian orange juice if in fact it comes from somewhere else, and we can’t sell Australian orange juice if it’s Brazilian. We trace these things back.
So is your research program associated with the Australian government in coordination with law enforcement?
JW No. We follow in a dual role. We’re a university group that has a spin off commercial company that does this kind of work. The university recognizes the fact that senior members of staff and research scientists are hamstrung in their communications when working within industry and government. There is too much bureaucracy in the university to be able to work effectively and efficiently with industry and with commerce and with government. So they have allowed us, as a trial group, to go essentially independent, with a number of strings and a number of caveats. Essentially we are independent of the university but still retain our university obligations in terms of teaching and PhD students and that sort of stuff. We are a commercial group allowed to interact privately with the community to support our infrastructure and to grow in that environment. We are an independent company.
What we also do is we are the primary provider to the Australian Federal Police Force, which is the police force that governs the whole of the country, and we are also a provider of forensic services to the state police of Western Australia. In that aspect we cover Australia, but we also provide internationally. I’ve worked with your FBI, I’ve worked with your companies and excise people, and I work internationally around the globe. So we have a reputation with Europeans. We work with your universities as well, and we work with European and Asian police forces, law enforcement agencies in forensic services in order to establish provenance of various things that they’re interested in.
We have a very large footprint! (laughs) It’s a smallish group but it has a very large foorprint.
I see. That is much more elaborate than I had imagined. So your lab’s determinations carry significant weight.
JW Yes, they do. We work with about twenty international police forensic services and law enforcement agencies, including, as I said, your FBI, your CIA, people like that, in England with Scotland Yard, in France with Deuxieme Bureau, those types of internationally recognized police forces. Our services, obviously we don’t do everything, of course we don’t, but we supply some specialist services to those groups and to commercial companies in the US. I have major contracts with US companies to do the provenance of their products and… let’s leave it at products, shall we. We work internationally with governments, companies, and law enforcement agencies. We are internationally recognized as expert witnesses in these particular areas.
So, the recent Chinese milk scandal, for example, is something your research group might have looked into.
JW It certainly might.
I see. Now, specifically with respect to the geographical origins of wine, you’ve chosen about 60 elements, all stable isotopes. I imagine that you’ve chosen 60 elements to, first of all, provide the widest possible, most useful data base. Is that fair to say?
JW Pretty much. We also look at light stable isotopes as well, the Carbon, Hydrogen, Oxygen, and Nitrogen isotopes, Deuterium, C12, C13… We look at those isotopes as well, not just the metals. We use where we can the simplest techniques which may be the metal examination. We use the methodologies we have developed for provenancing tea, for example, where we use a combination of light stable isotopes (C, H, N) and trace element association patterns to link specific tea samples back to the “Garden of Growth”. We are capable of identifying the actual plantation from which a tea sample was taken, this is stopping mislabeling (e.g. Darjeeling tea which is not from that area or specifically from a tea garden), an “industry” worth many millions a year. And we’re doing the same with wine.
We have in fact worked for about six years trying to get the right mechanisms, the right sampling, the right techniques for analysis, the right analytes sorted out for wines. We think we’ve done that now. That’s why we’ve put Alex Martin on to a PhD degree to actually reel all this together and sort of tie it up in a nice bow for the sake of his PhD.
Indeed. He sent me a list of the elements you search for. And Carbon 12 and Carbon 13, both stable, were left off the list. Is there any reason one stable isotope is chosen and not another?
JW Well, we use both of those. Essentially, Alex has left Carbon, Hydrogen, Oxygen and Nitrogen off the list because somebody else is doing that work. He’s concentrating on the metals per se. Somebody else is looking at the light stable isotopes. But the light stable isotopes at the moment are being used mainly for our work in provenancing oil and producing a fingerprint of all reservoirs of oil so that we can use it for exploration. So we’re not really developing the technology beyond oil at the moment, although we’re applying it to this work.
In your research have you detected differences a grape variety might make in the taking up of trace elements, in their concentrations? For example, with respect to flavor characteristics, the phenolics, are they at all dependent on the soil micro-nutrients or elements, a pinot as opposed to a cabernet?
JW What we’re looking at, and let me stick with what we’re doing with provenance establishment for wines at the moment with Alex, is that we are looking at a wide variety of of grape varieties in a range of soils, in a range of areas.
Let’s go back just one small step. A lot of soil scientists say, well, if you look at the particular vineyard the soil varies incredibly all over the vineyard. And that is absolutely true. You have some areas that are better drained than others, some areas that are more gravely than others, you have some areas with a different soil chemistry, but what we do find is, though, that the plant roots themselves, the vine roots themselves, have the capability of selectively removing metals from the soil and taking it up through the plants. The uptake of those metals into the leaves and into the grape, and into the wine itself does vary with species. They are subtle variations but there are some variations with species, so that if you grew right next door to each other two different varietals you would get slightly different fingerprints for those. So we do need to know what the varietal is before we can confirm the fingerprint. But generically we can get a good fingerprint on the wine from a particular area.
We know that in certain areas certain trace metals are present, so we can use that as a mechanism to, if you like, generically say these wines came from particular areas. And then we start going into detail with variety and metal content and metal distribution factors.
As far as the taste is concerned, taste is essentially on organic compounds, it’s not on metals. The range of variety of organic compounds is something, at the moment, that we are not looking at in detail. Our brief is only to virtually find out if we take a bottle of wine coming from this particular vineyard, can we trace it back unambiguously. And that’s where we’re going rather than the taste and the flavor, all those sorts of things.
Are the soil samples taken from the root zone?
JW Soil samples are taken, from every vine that we sample, from the surface, in ten centimeter intervals, down to seventy centimeters. So we have seven soil samples from the surface to below the root level. A few [vine roots] go down to that depth but not many. We go down from above the root level, right at the surface, right down to below the root level. We are looking at extraction of metals, various solubilization mechanisms, from each of those zones, for each of those vines, to each plant we actually look at. What we are doing is undertaking a variety of chemical extraction techniques at each level to establish which metals are mobile and under what conditions. And in an area we will take, I guess if you imagine that the study areas we’re looking at vary, of course, but we will take no fewer than eight plants in a single area be it small, let us say half a hectare, something like that. We would take about eight samples, eight individual plants in that area.
Of the participating wineries in your study, are they producers of more expensive bottlings?
JW Not necessarily at all! It doesn’t matter how expensive the wine is. You’re dealing with uptake mechanisms that are the same with an expensive wine as a cheap wine, it’s just the varietal and how you actually produce it, and what you do with it. The uptake chemistry of the vine is the same. I mean, a fast race horse is pretty much the same as a slow race horse. A very expensive grape is produced in the same type of soil, in different areas, of course, but the flavors are there because of the plant and what the plant puts into the grape and the grape into the wine. The uptake of metals is not associated with that.
I see. Can you tell me the names of any of the participating wineries?
JW I’m just thinking about that one. At the moment we haven’t released the [names] of the specific wineries that we have dealt with. But I can tell you that because we are in Perth in Western Australia, and Western Australia is obviously a wine growing area, we are very involved with vineyards in the Margaret River area, the Pemberton area, and in Swan Valley in Perth. Those are the three major wine growing areas. In addition to that we have material from the Hunter Valley and the Barossa Valley which is probably more familiar to you guys in America, so we have samples from other areas, from the Eastern states of Australia.
Is it possible for viticultural practices to skew the elemental signature?
JW Well, we look at the leachability of various leach fractions and various leach techniques on the soil. We constantly monitor the water that’s coming into the area. We look at the agricultural water that’s used for irrigation plus the rainwater, and we look at the fertilizing regime as well, what’s put on the material [vine] in terms of anti-fungicides and fertilizers onto the soil the vines are grown on. All of these are taken into consideration.
And what of an organic vineyard grown alongside a conventionally farmed vineyard?
JW In the metals, I don’t believe so. We are looking at that. There are not a huge number of organically grown wines; we have one organic vineyard in our work program. But we have looked at organic versus commercial, if you like to call it that, onions, potatoes, carrots, apples, plums, we’ve looked at a number of these vegetables to see if we can tell, trace chemically as far as the metals are concerned, the difference between plants that are grown near each other, one in an organic environment, one in a more commercial environment. You can’t. The only thing we’ve gone a little bit towards is the difference between onions that are grown organically and more commercially. But that’s about it. Oh, and tomatoes, that was the other thing we looked at.
Actually, the trace metals that come in, come in predominantly from the soil and these ones are the same whether you’re growing in a soil that is maintained in an organic regime or more commercial regime. The only differences that occur are if you start using hydroponics and then you can pick up significant differences. We’ve seen this with hydroponic cannabis as opposed to soil cannabis.
Alex Martin, your PhD student, has written “there was a significant degradation in concentration of elements present in bottled wines with respect to delay in analysis after opening the bottle. Consequently, to achieve optimum sensitivity, the wine should be analysed within the first 24 hours after opening the bottle.”
Why might this be the case?
JW I think you’re getting tannin precipitation in some cases. If you don’t store it [the sample] correctly you are getting oxygen present in the sample, there would be some degree of oxidation, an oxidative breakdown of some of the sugars, and the chemical composition of the wine changes slightly. If you actually leave wine around and let it evaporate, let it get oxidized, let air get into it, you’re changing the chemical composition of the organics to a large extent, and this is also reflecting precipitation of organics and the sequestration of the metals onto the walls of the bottle and into tannins which precipitate out.
So, can we say to a vineyard in the Eastern states, can you put some of your wine into this tube and send it to us and two or three days later it arrives, that it is the same now as when it started? That is one of the studies we’ve been working on for the past six years. We now have protocols in place that can keep the metals in solution in analyzable form for period of five to six weeks. So we reckon any where in the world can send samples to us, backwards and forwards, and still preserve it. The initial studies were certainly indicative that the trace metal chemistry changed in the identified wine but we’ve now ways to preserve the wines in trials for six weeks with no change in their chemical composition.
END OF PART 1