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the naked scientists. Hello

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welcome to the Naked Scientists! This

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is the show where we bring

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you the latest breakthroughs in science,

0:45

technology and medicine with me Chris

0:47

Smith and coming up what the

0:49

structure of your retina reveals about

0:51

your risk of developing a range

0:53

of different diseases of we finally

0:55

cracked how the first biological cells

0:57

appeared four billion years ago or

0:59

so and help on skaters survive

1:01

potentially lethal run ins with big

1:04

raindrops from Cambridge University Institute of

1:06

Continuing Education. This is the Naked.

1:08

Scientists. The.

1:18

First this week a new study has

1:20

found that the structure of the retina

1:22

that the back of the I can

1:24

reveal a host of different diseases that

1:26

a person is at risk of developing

1:28

by using machine learning to marry up

1:31

changes seen him. Retinal images with health

1:33

and genetic data taken from tens of

1:35

thousands of people who participated in the

1:37

Uk Biobank study Mass I in a

1:39

hospital Ophthalmologists Mary I'm sick of at

1:41

a Nas Lee's Evidenced think that they

1:43

have come up with a way of

1:46

using the retina to see what a

1:48

person's. future health looks like.

1:50

In recent years the be have come

1:52

to realize that we can find out

1:55

a lot more information from images of

1:57

the I that me Africa was possible.

2:00

And it's opened up this really exciting

2:02

area of research. And

2:04

we were fortunate enough to

2:06

have access to an incredible

2:08

resource, specifically a large, large

2:11

study of about half a million people

2:13

from the UK called the UK

2:15

Biobank. And we

2:17

had images of people's eyes. And

2:20

we were wondering, is there a

2:22

link between images

2:24

of the eyes? And Maryam will talk

2:26

a little bit more about how those

2:28

were obtained and ocular

2:31

and systemic disease. Maryam,

2:34

what are these pictures you've got of people's

2:36

eyes? Are you looking at the outside, or

2:38

are you talking about what's going on inside

2:40

the eye? It's

2:42

inside the eyes. The human

2:45

retina is a multilayer tissue,

2:47

which offers a really unique window

2:50

into systemic health. So here, we're

2:52

looking specifically at that retina, which

2:54

is composed of nine different layers,

2:57

using OCT imaging, optical appearance,

2:59

demography imaging. And that's a

3:01

non-invasive imaging that uses light

3:04

waves to take a cross-section

3:06

picture of your retina. And

3:09

so we have this OCT imaging

3:11

available across 50,000 individuals

3:15

in this biobank. And,

3:17

Nazalee, why should looking

3:19

at the different layers of the retina

3:21

give us an insight into a person's

3:23

overall health or disease risk? Some

3:26

of it is actually really surprising.

3:28

So for example, we didn't know

3:30

before the machine learning models came

3:32

out that we could tell someone's

3:35

age just by looking inside their

3:37

eye, or their sex even.

3:40

But what is the retina

3:42

is a very intricate tissue. It's

3:45

an extension of your brain, essentially.

3:47

And so it's constructed of all these

3:50

different cell layers that are connected to

3:52

our brain and our systemic health, or

3:54

essentially your overall health. So you

3:56

can look at people's eyes. And

3:58

when they say the eye is a window, So into

4:01

your soul, they're not really kidding because

4:03

you're seeing what is

4:06

going on with someone's heart, someone's

4:08

blood pressure potentially, even

4:10

how they're breathing or their

4:13

risk of having certain neurologic problems.

4:16

And Maryam, when you did this study, what

4:19

did you actually measure and what did you marry

4:21

up with what? So

4:23

what we measured was the thickness of

4:25

each of these nine layers of the

4:28

retina and we used this measurement to

4:30

then look at connections to systemic

4:33

health, to disease and also to

4:35

genetics. Nazly, one of

4:38

the key things about any kind of disease,

4:40

we always say prevention is better than cure.

4:43

So the critical question I can ask you is if

4:45

you do this, does it give

4:47

you a window into the early stages

4:49

of a disease at a time when

4:51

you might be able to intervene meaningfully

4:53

in a person before they actually get

4:55

sick from something? It's

4:58

interesting that you asked that one of the

5:00

key pieces of analysis that we did in

5:02

this manuscript

5:04

was looking at

5:08

future risk of disease. So looking

5:10

at someone's retinal thickness and determining

5:12

if that was linked to future

5:15

disease diagnosis. And

5:18

in fact, the layer thicknesses

5:20

of the retina are predictive

5:22

of future diseases of the

5:25

heart, of the brain, of the kidneys,

5:28

of the lungs, including eye diseases as

5:30

well. So even though

5:32

this needs to be confirmed, our

5:34

study does point to the fact

5:36

that we can use retinal

5:39

thicknesses or retinal phenotypes to be

5:41

able to predict disease before it

5:44

happens and intervene. So

5:46

would the approach be then that rather

5:48

than subjecting a person to a whole

5:51

raft of different tests and blood samples

5:53

and genetic analyses, you could plonk them

5:55

down in front of you, Use

5:58

this technique to look at their retinal thicknesses. And

6:01

then based on what you've learned

6:03

about the associations between the different

6:05

shapes of structures of the retina

6:07

and different disease outcomes, you could

6:10

make predictions about what a person's

6:12

might be a belt to develop.

6:14

Or indeed, he's developing right now.

6:16

And then you can make of as

6:18

he interventions as as necessary. Precisely.

6:21

I think that is exactly how

6:24

the invasion results Like this being

6:26

used. As Maryam previously

6:28

mentioned also A D O C

6:30

T are these light pictures of

6:32

the I are routinely used in

6:34

clinical practice and ophthalmology and so

6:36

you know you can imagine if among

6:39

com than for their eye exam

6:41

then you can use this information to

6:43

tell them you seem to have

6:45

a high risk of Msr, you

6:47

have a high risk of our high

6:49

blood pressure, or you might have

6:52

a high risk of developing diabetes. Sell

6:54

you should go see a primary

6:56

care doctor the other way. You can

6:58

think about. This is exactly as you

7:00

said is what S V Just had

7:02

this as a screening. You

7:05

know tool where people were time in

7:07

get images of their rat know non

7:09

invasive leave without having to do all

7:11

these extra test and they could know

7:13

that they have risk for certain diseases

7:15

that they need to get checked for

7:17

or even treated for. potentially. As

7:20

these of dust and before her marines

7:22

have to that and they just published

7:24

a study in the journal Science Translational

7:26

Medicine. The. Origin of

7:28

Life on Earth and Beyond is a

7:30

mystery and is arguably one of the

7:32

most important questions to answer. We know

7:35

that my started simpli probably with self

7:37

replicating chemical reactions that will most likely

7:39

based around something similar to the Dna

7:42

molecules that we rely on to carry

7:44

out genetic code today. But.

7:46

Pretty. Quickly those reactions found a

7:48

way to wrap themselves up inside

7:51

oily membranes the could protect them

7:53

from the surroundings. A might the

7:55

whole process more efficient, a more

7:57

reliable. a presto the

8:00

was born. But where did those membranes

8:02

made of fatty acids come from in

8:04

the first place? That question

8:06

has bothered biologists for decades. Now

8:09

though, researchers at Newcastle University

8:11

have recreated in the lab

8:13

the conditions found around hydrothermal

8:15

vents, also known as underwater

8:17

black smokers. These conditions,

8:19

John Telling has found, can spontaneously

8:22

generate the very molecules the scientists

8:24

have been searching for. There's a

8:27

few lines of evidence that point

8:29

towards these hydrothermal vents, these hot

8:31

springs, as a likely place for

8:34

where life originated. People

8:36

have tried to find out what the

8:38

earliest cell that everything originates from

8:40

was like. And what they've deduced from looking

8:43

at the genes is that the first cell,

8:45

known as the last universal common ancestor, liked

8:47

it hot. It probably lived

8:49

off of pylogen gas. And it would have

8:51

used carbon dioxide as well to kind of

8:53

build itself. So those lines of evidence all

8:55

point towards these hot springs as a possible

8:57

place for the origin of life. It

9:00

sounds like we actually know quite a bit in

9:02

terms of what we expect that ancestor to have

9:04

been like. But what was the outstanding question you

9:07

were trying to crack with relation

9:09

to it then? Previous

9:11

people have tried running different experiments to

9:13

try and mimic some of the conditions

9:15

that these hydrothermal vents would have had.

9:18

People had either tried to recreate,

9:20

say, the high temperatures or the high pressure

9:22

or the kind of continuous flow

9:25

where you're mixing sea water with this

9:27

hotter fluid. But nobody had really

9:30

gone on trying to combine all of

9:32

those at once. So that's what

9:34

we wanted to do. So we built some new apparatus

9:36

and allowed to try and get that,

9:38

get the high pressure, get the high temperature,

9:40

and get the continuous flow all

9:42

in one experiment and try and react this

9:45

hydrogen gas and this carbon dioxide over these

9:47

metals to see if we could generate organic

9:49

molecules. What sorts of molecules were

9:51

you looking for? Ones we

9:53

were particularly interested in were these molecules

9:56

known as fatty acids. They have a

9:58

fatty end and a sort of water

10:00

loving end. And the interesting thing about

10:02

them is if they get enough of

10:04

them in that water then they can

10:06

form these what's known as called a

10:08

membrane structures, these vesicles or liposomes sometimes

10:10

they're known as but they basically form

10:12

these little round balls surrounded

10:14

by a membrane which separates what's in

10:16

them from what's outside. So

10:19

it's acting in a way as a

10:21

sort of first cell membrane potentially which

10:23

could separate the external environment from the

10:25

internal and let different chemistry happen. I

10:28

understand where you're going with that because obviously that

10:30

was the big question wasn't it? If life gets

10:33

started as a series of chemical reactions where did

10:35

cells come from? So if you've got a reaction

10:37

that can produce the oily bags that surround all

10:39

our cells that is 90% of the equation. Well

10:43

it's certainly a good step forward yeah

10:45

I mean it's the first step to

10:47

creating a self yes something different from

10:49

what's outside so the ability to do

10:51

that and then concentrate other chemicals differently

10:54

to outside generate different reactions would be

10:56

a I think an essential step for

10:58

how life started. So what are

11:00

the raw materials that you're feeding into

11:02

your pretend hydrothermal vent and what

11:04

chemicals did you see coming out at

11:06

the end in these conditions that leads

11:09

you to think that is possibly how

11:11

some primitive cell light structures could have

11:13

formed? So what we fed in

11:16

the basis of it was hydrogen gas which

11:18

we added under pressure and then we combine

11:20

that with dissolved carbon dioxide.

11:22

We're reacting them over a mineral in

11:24

this case an iron rich mineral known

11:27

as magnetite to form hydrocarbons organic molecules

11:29

and in particular we were looking for

11:31

these fatty acid molecules which are a

11:33

type of hydrocarbons. And do you

11:36

get many and how quickly? The

11:38

experiments we run so far we only ran

11:40

for 16 hours and in that

11:42

time yeah we generated enough to find

11:44

them so we don't know if

11:46

we run it for longer we might find that

11:48

we we generate even more of them but there

11:50

are certainly enough of these organic molecules for us

11:53

to to analyze. Do They

11:55

start to self-assemble because the point you're

11:57

making is that the fatty bits love

11:59

other. He beat so they tend to

12:01

get together suitable at all to see that

12:03

happening. As yet,

12:06

No, because. When. They

12:08

fall match reform on the mineral surface. The

12:10

next stage of experience we want to do

12:12

is to try and do this to actually

12:15

change the kinda current conditions within the maybe

12:17

for might be drawn more alkaline. We can

12:19

get some of these molecules particular these fatty

12:21

acids to lift off and hopefully we couldn't

12:24

see them self assemble. So

12:26

if we bring what you found to

12:28

the party that that already people had.

12:31

Envisaged as to how life could ago

12:33

started, help you bring and unite your

12:35

discovery of of how these fatty acids

12:37

begin to form with what people thought

12:40

might also be going on around the

12:42

same time about four billion years ago

12:44

that that was the start of life.

12:47

People. Have found these reactions

12:49

going on. At higher temperatures

12:51

for example before what we've done his

12:53

duties, experiments and more realistic conditions as

12:55

to what the conditions may have been

12:57

like on the early earth and it

13:00

just gives that greater likelihood. I think

13:02

that be really important organic molecules may

13:04

well have been formed within these sub

13:06

ocean hydrothermal vents and it might also

13:08

increase or understanding as well. I think

13:10

on about how life may have originated

13:13

in in other places in our solar

13:15

system with other similar chemistry might might

13:17

be going on as gonna wash about

13:19

that because. Acoustical missions that are

13:21

gonna be lucky Europa which is

13:24

one of Jupiter's moons people have

13:26

also considered and syllabus. One

13:28

of Saturn's moons which appear to

13:31

have warm liquid oceans beneath her

13:33

suffice. So it's possible the conditions

13:35

there might be similar to the

13:37

conditions your mimicking in New the

13:39

board tree. Exactly. So yes,

13:41

I mean I think the best characterized I

13:44

since I saw is actually Saturn's moon on

13:46

settled isps that see a spacecraft which is.

13:49

Traveled. Around minus Cassini it's actually sample

13:51

these plumes which people think or emanating

13:53

from beneath the kind of I see

13:56

lack of on settled us into this

13:58

ocean sealed part is ocean ice beam

14:00

blast it out into space and and

14:02

an unfit analyzed and when I've analyzed

14:05

sort of papers and particles are in

14:07

this claim they sounds hydrogen gas by

14:09

sounds carbonate soap. Signs. Of

14:11

carbon dioxide there as well, and I've

14:14

also analyzed different organic molecules. It seems

14:16

that all the ingredients potentially for an

14:18

origin of life might be there, but

14:20

it's gonna take a sassy more experiments

14:22

are trying to that down said absolutely.

14:25

Society Findings: Newcastle University John Telling this

14:27

and that papers just come out in

14:29

the journal Nature Communications, Earth and in

14:31

Farm and. The

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Productions You listening to The Naked Scientists?

14:59

With me? Chris Smith? Still to come?

15:02

Hell or Palm Skaters Able to survive

15:04

potentially lethal run ins with raindrops. The.

15:07

First back to medicine and health. Now

15:09

because Sarah Ferguson, the Duchess of York has

15:11

revealed that she's been diagnosed with malignant melanoma.

15:13

The sixty four year old author and

15:15

form a high profile member of the Royal

15:18

family said she was grateful for the

15:20

love and support the she'd received, and she

15:22

urged people to look out for signs of

15:24

potentially cancerous moles. To tell us more

15:26

about the science and medicine of malignant melanoma.

15:29

His. Restraints. Malignant.

15:32

Melanoma affects more than three hundred thousand

15:34

people around the world each year, and

15:36

it's ability to metastasize or spread to

15:38

other parts of the body can make

15:41

it basically pernicious. The. Disease accounts

15:43

for any four percent of all

15:45

skin cancers is responsible for seventy

15:47

five percent of deaths caused by

15:49

these malignancies. Melanoma. you

15:51

case is your chance of surviving as long

15:54

as it depends on how early it's court

15:56

and if he didn't spread your lymph nodes

15:58

or another party be body and it's highly

16:00

likely that simply removing it will cure you.

16:03

So what should we know about how it develops in

16:05

the first place? Melanoma

16:07

is caused by ultraviolet light and in

16:10

particular UVB rays from the sun and

16:12

also sun tanning beds. The

16:14

light damages the DNA melanin producing cells

16:16

in the deepest layers of our skin.

16:19

This stops the cells repairing their DNA

16:21

from further damage and locks

16:24

them into an uncontrolled growth cycle. Although

16:27

melanoma cases have roughly doubled since the

16:30

1990s, some of us are at greater risk

16:32

than others. People with

16:34

fair skin, fair hair and freckles are

16:36

particularly susceptible, as are those with

16:38

a history of the disease and their immediate family.

16:42

Intense and intermittent sun exposure, including

16:44

frequent sunburn, is associated with the

16:46

greatest risk. The average age

16:48

for diagnosis is 66, but it is not

16:51

uncommon for people in their 30s to develop

16:53

it. Thankfully greater awareness

16:55

has led to a reduction in the

16:57

number of children dying from melanoma in

17:00

recent years. This has been in

17:02

no small part due to successful health campaigns

17:04

run around the world, including in

17:06

Australia and New Zealand, which have the

17:08

highest global rates of melanoma. The

17:11

famous Slip, Slop, Slap campaign in the

17:14

1980s, which featured Sid the Seagull encouraging

17:16

people to slip on a shirt, slop

17:19

on the sunscreen and slap on

17:21

a hat, remains great advice to

17:23

reduce and avoid sun exposure. So

17:25

what should we be looking out for if we think

17:28

something isn't quite right? Sarah Ferguson

17:30

said her melanoma was discovered following the

17:32

removal of what turned out to be

17:34

a cancerous mole during treatment for breast

17:36

cancer. The NHS advice

17:38

here in the UK says that in

17:40

order to catch the disease as early

17:42

as possible, we should all be looking

17:44

out for new moles, a change in

17:46

an existing mole, large moles and even

17:48

moles that are either uneven in shape

17:50

or a mixture of colours, and

17:53

especially those that are particularly dark,

17:55

itchy or tend to bleed. that

18:00

will not cause further problems. The first

18:02

step in treatment is usually surgery to

18:05

remove the affected area and check that

18:07

it has been completely excised. This

18:09

is curative in the majority of cases, but

18:12

some people will present with disease that

18:14

has already spread from the primary site

18:16

or return with a relapse later, in

18:19

which case patients are treated with chemo

18:21

or immunotherapy. Professor Sarah Allenson

18:23

has written a great piece in

18:25

the conversation about the huge improvements

18:27

in treatment over the past decade,

18:29

including the development of drugs such

18:31

as dabraphenib or tremetinib. These

18:34

new agents prevent cancerous cells from growing

18:36

and also allow the immune system to

18:38

recognise them as hostile and destroy them.

18:41

Some patients have now been cured

18:43

with these therapies, despite presenting with

18:45

extensive disease, proving that they can

18:47

work in some cases. Now

18:49

the race is on to work out how to

18:51

make the process as effective for everyone. Nevertheless,

18:54

when it comes to cancer, prevention

18:56

is, of course, always better than

18:58

cure. So be sure to

19:00

remember the advice of Sid the Seagull, and

19:02

slip on a shirt, slop on sunscreen and

19:04

slap on a hat. And if you notice

19:06

that you have new mould, a change in

19:09

an existing mould or large moulds, then speak

19:11

to your doctor and get yourself checked out

19:13

as soon as possible. Back to you Chris.

19:15

Thank you Riz. Nature now,

19:17

and researchers in the United States have

19:19

made a big splash in the science

19:22

field this week by using ultra-fast photography

19:24

to watch what happens when pond skaters,

19:26

which are called water striders in America,

19:28

are hit by falling raindrops, which massively

19:31

outweigh these tiny insects. For

19:33

them, it's like one of us standing under

19:35

Niagara Falls, so says the

19:37

study's author of Florida Polytechnic University,

19:39

Darren Watson. We did this by

19:42

first capturing the insects from our

19:44

local ponds, and we

19:46

had to create a rainfall simulator. So

19:48

we had a reservoir of

19:51

water that we pump through

19:53

a nozzle that mimicked raindrops.

19:55

Those raindrops struck the insects,

19:57

and we observed the interaction

20:01

using our high-speed video cameras in the

20:03

lab. So you go in the shower,

20:05

basically? Yeah. How

20:07

fast is fast? When you say high-speed imaging,

20:09

how many pictures a second are you taking

20:12

of this? We can capture

20:14

up to 4,000 frames per second, so

20:17

it's very fast. We see the

20:19

droplets moving on the order of

20:22

milliseconds. Talk us through

20:24

them. When you look at this footage, what

20:26

does it show? Before

20:28

we talk about what occurs with

20:31

the insect, when our raindrop is

20:34

a pool of water, what you're going to

20:36

get is a splash. And we are all

20:38

familiar with splash. We see this during rainfall.

20:41

But that splash constitutes a

20:44

couple different phases. So we see

20:46

an underwater crater. We see

20:48

a jet that goes back up

20:50

above the water surface. And it

20:53

was important for us to look

20:55

at how the insect interacts with

20:57

these different components of the

20:59

splash. So when

21:02

the insect is dropped by a

21:04

raindrop, we see that the raindrop

21:06

pushes the insect into the water

21:08

body. And the insect, you'll find

21:11

that along the

21:13

inner surface of

21:15

that particular raindrop as it creates

21:18

a crater inside the body of

21:20

the water. So we find that

21:23

the insect is, you can

21:25

say, attached to the water

21:27

at that point in time. So then

21:30

when the jet is formed,

21:32

it is transported out of

21:34

the water with the jet. So

21:38

the water gets pushed downwards

21:41

and outwards and compressed

21:43

by the incoming droplet. And what is

21:45

it, a rebound of the water coming

21:47

back in underneath the insect that creates

21:49

a jet, almost like a

21:51

geyser underneath it that pushes it up in the air? Yes.

21:55

The rebound occurs as the dented

21:57

surface of the water tries to

21:59

go back. so it's original state. So

22:03

raindrop pushes the insect beneath

22:05

the water and then there's

22:07

a rebound and you have the jet

22:10

come in upwards. Does

22:12

the action stop there or

22:15

do you then get secondary effects because obviously

22:17

what goes up must come down if you've

22:19

made a jet. Do you then get secondary

22:22

rain effectively off the back of having hit

22:24

the insect the first time? Yes

22:28

and that is where the danger

22:30

lies for the insect because that

22:33

jet then disintegrates to create what

22:35

you would have termed secondary rain

22:38

and it then pushes

22:40

the insect inside the body of the

22:43

water again and we find

22:45

that the rebound is going to

22:47

be so precipitous that the insect

22:49

is going to be left beneath

22:51

the water line. Does

22:54

it have to swim up and then how

22:56

does it break through, assuming it does, the

22:58

surface of the water because there's surface tension

23:00

there between the air and the

23:02

water isn't there? So how does the

23:05

insect get back through there and end up on the

23:07

air side rather than on the

23:09

water side? This is rather innate

23:12

to the insect because the insects are

23:15

generally born beneath the

23:17

water line and their youngs,

23:20

what they do, they swim to

23:22

the top to where that water

23:24

line is and they break the

23:27

surface to get onto the air side. So

23:29

the adults are also able to

23:31

do that and they do that through a series of

23:34

what we call power strokes applied

23:37

at an acute angle and that

23:39

allows the insect to be able

23:41

to break that water line to

23:43

get back onto the air side

23:45

of things. They obviously do it

23:47

quite well because there's loads of them and if I

23:49

look at the pond near where I live there's many

23:51

many to count so they're obviously pretty good at this

23:53

especially with the terrible weather we have but

23:56

what are the applications of this because it's

23:58

interesting and a fascinating to understand how these

24:01

insects have evolved to have this behaviour. But

24:04

understanding this now as you do, can

24:06

you apply it to any other aspects

24:08

of what we see in the marine

24:10

or aquatic realm? Yes,

24:12

we can. Our results here, they

24:14

will allow us to better understand

24:17

the transport of floating particles

24:20

like microplastics on the

24:22

Earth's water bodies. Now, microplastics

24:24

are similar in size

24:27

to our water striders

24:29

or, in your case,

24:31

pond skaters. And they

24:33

would likely share a similar experience

24:35

during rainfall. As

24:38

a matter of fact, in some of

24:40

our experiments, we replaced water striders with

24:43

floating particles and observed these similar

24:45

interactions. So that's the main real

24:47

world application of the study at

24:49

the moment. And we're going to

24:51

be seeking to explore transport

24:53

of microplastics on our water bodies

24:57

going forward. Darren Watson, and he

24:59

just published that study in the journal

25:01

PNAF. Question of the

25:03

week time now, and James Titko has

25:05

been enjoying getting his teeth into this

25:07

tasty scientific morsel. Hello, it's

25:09

Celia here. My question is, why

25:12

does stollen go floppy in the

25:14

toaster instead of crispy? We tried

25:16

to toast our slats of stollen

25:19

thinking it would be the Christmas

25:21

equivalent of toasted hot cross buns.

25:24

But instead of the crispy

25:26

toasted texture we were expecting,

25:28

our slices became floppy and

25:31

had to be removed from the toaster with tongs.

25:34

Thank you Celia. Now for the

25:36

uninitiated, this delicious German fruit

25:38

bread contains marzipan and spices

25:40

and is inextricably linked to

25:42

the festive period. I

25:45

asked culinary queen Nicola Lamb to

25:47

help find out why Celia's leftover

25:49

Christmas stollen might have gone sloppy

25:51

in her toaster. She's the

25:53

author of Sift, The Elements of Great Baking,

25:56

which comes out this May. relatively

26:00

high amount of mix-ins in the form of

26:02

dried fruit and marzipan. So

26:04

there's problem one, there's relatively less

26:07

bread to toast. When you

26:09

toast bread it undergoes the Maillard reaction,

26:11

which is a chemical reaction between a

26:13

reducing sugar and a protein present in

26:15

the bread dough. The result

26:17

is that lovely browning, crisping effect.

26:20

Spollen has almost double the amount of mix-ins

26:22

to a dough compared to something like a hot

26:24

crisp bun. Some recipes are about

26:27

40% fruit and marzipan by

26:29

weight. The lower proportion of

26:31

bread, combined with the high proportion of fat

26:33

in the marzipan and butter in the dough

26:35

itself, will mean the stollen could soften rather

26:38

than crisp up. Another issue

26:40

is moisture. The Maillard reaction cannot

26:42

take place in the presence of

26:44

water. Just think about the colour

26:46

of boiled food versus roasted food. In

26:49

the enclosed space of a toaster, the moisture

26:51

from all those add-ins, I think in particular

26:53

the buttery steamy marzipan, might result

26:56

in the stollen steaming rather than toasting.

26:59

There's just nowhere for the moisture to

27:01

evaporate, further contributing to your soggy

27:03

stollen. I expect the

27:05

traditional powdery sugared crust in most

27:07

stollen recipes could also be playing

27:09

a role. I feel like everything

27:11

matters in baking. It

27:14

probably attracts quite a lot of

27:16

moisture to the crust since sugar

27:18

is so strongly hygroscopic, meaning

27:20

it likes to absorb moisture from the air. In

27:23

general, I think you'd be better off grilling

27:25

your stollen, flipping it halfway, that

27:27

way it has space for the moisture to evaporate

27:30

and to allow the toasting to happen. Many

27:32

thanks to Nicola Lamb and be sure

27:34

to look out for Sift, the elements

27:36

of great baking. Join us

27:39

next time when we'll be answering

27:41

this question from listener Satya. She

27:43

says, why do languages evolve completely

27:45

differently between countries, even when they

27:47

directly border each other? Why

27:50

do they have such different dialects? That's

28:01

all we have time for this week, but do tune

28:03

in on Tuesday when we're going to be looking at

28:05

the shipping industry and how it's hoping to tackle the

28:07

climate crisis head on as we take

28:09

a voyage on the ship of the future. The

28:12

Naked Scientist comes to you from the University

28:14

of Cambridge's Institute of Continuing Education. It's supported

28:16

by Rolls-Royce. I'm Chris Smith. Thank you for

28:19

listening and from all of us here at

28:21

The Naked Scientist, until next time, goodbye. Tired

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