David Burslem
speaker
45 appearances
1 recordings
1 series
first heard Jul 2026
last heard 22 Jul
David Burslem’s voice in public audio — every appearance, attributed to the second.
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My background is in plant science research and I work primarily on woody plants, so shrubs and trees, and I'm very interested in the way that those plants interact with soils and microorganisms.
I responded to a request that came from a group of Scottish tea growers who were interested in developing a method for authenticating the geographical origin of their tea.
At the time, I didn't know why they were interested in that, but I took it as an opportunity to develop some work on tea, which I had been hoping to do for some time.
We did consider looking at DNA, but the issue with DNA, of course, is that it's dependent on the origin of the material.
We needed a method that was sensitive to the growing environment, the conditions where the tea plants were actually growing, and that is independent of their genetic origin.
Yes, especially the underlying geology, which gives rise to variation in the chemical composition of soils.
And it's the chemical composition of soils which gives the geographical stamp of origin.
We ignore elements like nitrogen and phosphorus, which are typically added by growers in fertilisers.
We're interested in micronutrients and elements sometimes called trace elements, which are present in most soils and which are taken up passively by the plants.
So it's things like molybdenum, lead, arsenic, selenium, cadmium, nickel, things that are present in very tiny concentrations in plants and which we can pick up using precision instruments.
The first thing I did was collect samples of tea from each of the estates within the network of growers that had approached me.
And we found very quickly that there were variation between those growers themselves.
So we could identify individual estates within Scotland based on the chemical signatures within their tea.
The next step was to determine whether, as a group, the Scottish-grown teas were different from overseas teas in general.
So this required me to work with an importer who gave me about 100 samples of imported tea of known location.
And the Scottish-grown teas clustered separately in a statistical ordination sense to the overseas samples.
So they gave me samples which they had themselves bought, which was labelled as if it was Scottish grown, but they, at the time, and they were clear about this with me, they were concerned it wasn't grown in Scotland.
They actually did things like go in and book the Scottish tea experience at the Balmoral and then they surreptitiously collected that.
Yeah, it's probably true that some of these samples are a bit smaller than they were when they first arrived.
And there's plenty left if you would like to have a cup of tea.
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