(732, TAKE 1)
Professor Ian Fells, BBC
Prime Minister, thank you for arranging to show us some of your favourite kitchen experiments. What do we have here?
P.M.
Well this morning I am cooking some red cabbage. There it is boiling away. You can see it. Let us just turn it off; it is getting too much smoke.
What I am going to do is pour some of the juice out into this jug so that we can see it more clearly. There! Goodness me, a little splash there. Let me just tidy that up. I do hate an untidy kitchen. There we are!
Now you can see it is really a rather dark purpley colour. That is because, as you and I know, there is something called anthocyanin in it, which is the [end p1] colour that gives … the dye that gives red colour to rose petals, berries, as well as to red cabbage, and to black grapes. I am sorry. We are going to start again. We are stumbling too much! Stumbling too much. (CUT).
(732 TAKE 2)
Professor Ian Fells, BBC
Prime Minister, thank you for arranging to show us some of your favourite kitchen experiments. What have we got here?
P.M.
Well this morning, I have just been boiling some red cabbage. There you can see it bubbling away and steaming away. Just let me pour a little off into a jug. There you are. I think that is enough. Oh dear! It has made rather a mess. Just let me tidy that up. I cannot bear an untidy kitchen. There! Just turn it off.
Now, as you can see, it is a dark, purpley colour. The colour, as you know, comes from a dye called anthocyanin. It is the same dye that makes rose petals red, makes black grapes black, and red berries, rosehips, red.
Now, I am just going to make it a little clearer by pouring this into a glass of water so that you can see the colour more clearly when it is dilute. There [end p2] we are! That is a much better colour!
But now, why I am doing this is to show you that if by any chance I were to put some bicarbonate of soda, which sometimes housewives put into it, it will have a colour change, so here is the same water that has come out of the same saucepan and into there I have put a little bicarbonate of soda which, as you know, is alkaline. Now let us see what happens! It is this. The same thing, same dilution when we get it into there.
There you are!
Professor Ian Fells, BBC
Spectacular!
P.M.
That is quite … I put just rather a lot in, which you can see. Again, that is a lovely green colour because it has gone alkaline.
Now, let us take the same one and pour it into a solution which has a little vinegar in. There is the vinegar. So vinegar is acid, as you know. We often talk about the acid test. Let us try the acid test!
This is the red cabbage water going into water with a little vinegar in it. There we are. Lovely pink colour!
Now you see, that is the same water from the same cabbage boiled up at the same time. That is its natural [end p3] colour. It is very nearly neutral. As you know, red cabbage is just on the acid side but only just. Perhaps that is why there is a little bit more … not quite the same colour as that. We make it alkaline with sodium bicarbonate and then add vinegar and get a complete change of colour, so that is why, if you are boiling up red cabbage, you never put bicarbonate of soda in. If anything, you put just a hint of vinegar.
Of course, as you know, most foods are acid. Indeed, the tummy itself is really quite acid. Things do not get alkaline until they get much further into the system, but most foods are acid and this is just vaguely on the acid side, but there are one or two that are alkaline - one in particular: white of egg, albumen. Let us have a look at that! (CUT)
(732 TAKE 3)
Professor Ian Fells, BBC
Prime Minister, thank you for arranging to show us some of your favourite kitchen science experiments. What have we got here?
P.M.
Well, I have been boiling some red cabbage this morning. There you are! You can see it bubbling away. Just let us turn it off.
What I am going to do is pour some of the liquid [end p4] out so you can see the colour. Let us have a look!
There we are! I think that is enough.
You can see it is really a rather dark, purple colour and I am going just to show you a little bit more clearly. That is plain ordinary water. We will dilute this, so we get a better idea of the colour. There we are! A rather lovely colour. You know, the colour is given it by a dye called anthocyanin. It is the same dye that makes rose petals red, and we know black grapes black and other winter berries red, but it has come out this way now.
Now, if we were to pour a little of the same liquor from the same saucepan into a solution of sodium bicarbonate - in every housewife's cupboard, often used - let us see what happens to the colour. Here we go! Water from red cabbage into a dilute solution of sodium bicarbonate! There! Look! Lovely green colour. Have I got quite enough in? There is still a little bit more! Quite a spectacular colour change. So clearly, you do not put that in when you are boiling red cabbage or it comes out a rather nasty colour.
Professor Ian Fells, BBC
So that is just alkaline. [end p5]
P.M.
So that has made it alkaline. Sodium bicarbonate is alkaline, as you know; this is just on the acid side.
Well now, let us do what we often call the “acid test” and it is a phrase we use in life. Let us pour this same liquor into vinegar. I have chosen clear vinegar so that the colour of the ordinary kind of vinegar does not get in the way. Same water from the same cabbage. There we are! Lovely red colour! And that is what the vinegar has done to this water. So there it is in its natural state. That is into a solution of sodium bicarbonate when it has gone green; and that is in vinegar when it has made it much clearer and much red. That is the alkaline and that is the acid.
Professor Ian Fells, BBC
Which is really very pretty. It is very like the colour change we get with litmus which perhaps people are more familiar with.
P.M.
Yes. Well, we always used litmus paper. All Schoolchildren are familiar with it and most people from their own school.
Professor Ian Fells, BBC
Well that is right and that is extracted from [end p6] lycin. It is another plan dye in fact.
P.M.
Is it?
Professor Ian Fells, BBC
Yes.
P.M.
I have been so used to those little bits of litmus paper. This is a much better test. I think the colours come up much better.
Professor Ian Fells, BBC
Yes.
P.M.
But as you know … well we both know … that most foods are on the acid side, just a little bit, and this is no exception. Some are much more acid than this, and indeed, the tummy is acid. It does not really get … food does not get alkaline until much further down in the system.
Professor Ian Fells, BBC
Yes. Of course, coffee is surprisingly acid and we all know that wine is acid … (CUT) [end p7]
(733, TAKE 1)
Professor Ian Fells, BBC
Of course, these changes are very similar to the changes that we get with litmus, litmus paper, which most people are familiar with at school and that is another plant extract actually from lycin.
P.M.
Litmus?
Professor Ian Fells, BBC
Yes.
P.M.
I did not know that. We are all used to using litmus paper. You know, you plunge it in and it tells you whether the solution is acid or alkaline.
Professor Ian Fells, BBC
I think this colour change actually is really rather better. Of course …
P.M.
It is very pretty … very clear and very pretty.
Professor Ian Fells, BBC
Most foods are acid, nearly all of them, but [end p8] there is one very interesting one which is just alkaline, and that is egg-white.
P.M.
Well let us have a look at that! Right!
(733, TAKE 2)
Professor Ian Fells, BBC
Of course, we get the same sort of change with litmus paper, which we are really much more familiar with at school now. Did you know that litmus is another plant extract from lycins?
P.M.
No, I had no idea and I have used it for years and so have so many schoolchildren and most adults too.
Professor Ian Fells, BBC
Now, of course, most foods are acid. Nearly all foods. Coffee, for example, and wine, but there is one very interesting food which is alkali and that is egg white.
P.M.
Yes indeed. It is rare to have an alkali food, I agree. Let us have a look at see the properties of albumen. (CUT) [end p9]
(734, TAKE 1)
Professor Ian Fells, BBC
Prime Minister, thank you for arranging to show us some of your favourite kitchen experiments. What have we got here?
P.M.
I have just been boiling a little bit of red cabbage. There it is, simmering away. Let us turn it off. What I am going to do is pour it out so that you can see the colour of it - into this jug. There we are! A rather lovely dark purple colour.
Of course, you and I know that what gives it the colour is something called anthocyanin. It is the same dye that gives blackberries their black colour, red berries their red colour and rose petals their red colour. Just so that you can see the colour better, I am going to pour it straight into a glass of water - nothing but water in that glass. We will dilute it and we will get a better idea of the colour. There we are. A rather lovely purple colour.
Now, I am going then to pour it into this glass which has in it bicarbonate of soda, something in every housewife's cupboard. She often uses it. As you know, it makes the water alkaline. Let us look what happens to the colour. Water from the same cabbage. There [end p10] we are.
Professor Ian Fells, BBC
Spectacular change!
P.M.
A lovely spectacular change of colour, a really rather lovely emerald green colour and that is what happens to the cabbage water when it is alkaline, so you do not really put bicarbonate of soda when you are boiling red cabbage. It would make it a horrid colour.
Now this is not water. This is clear vinegar. That is the acid. As you know, we call it the acid test, so let us do the acid test. Water into the vinegar, and see what happens to the colour. There! Lovely pink colour. There we are! That is the water diluted; similar dilution; a solution of sodium bicarbonate; similar dilution in vinegar. Acid, alkaline, and in its natural state. (CUT)
(735 TAKE 1)
P.M.
So there we are! That is what the cabbage water looks like without anything added to it. That is what it looks like when it is alkaline. That is what it looks like when it is acid. [end p11]
Professor Ian Fells, BBC
It really is a very attractive test and it is like the litmus test that we all did at school. People are much more familiar with litmus and that is actually plant extract from lycin.
P.M.
I had no idea it came from plants. Of course, I have done a litmus test many many times and so have most people, but this is prettier and it is much much clearer. Three lovely colours. But it shows you, you do not want to put sodium bicarbonate into red cabbage unless you want a disaster at the dinner table!
Professor Ian Fells, BBC
Quite right! Now, of course, most foods are acid. Nearly all the ones we use. Coffee is acid, wine is acid, but there is one very interesting food which is alkaline and that is egg white.
P.M.
Ah yes, let us have a look at egg white. (CUT)
(736, TAKE 1)
P.M.
Well now, here is the egg white. It has been separated very carefully … (CUT) [end p12]
P.M.
Well now, here is the egg white. It has been separated very carefully from the egg yoke, so there is not a trace of yoke in the white. I am just going to beat it up. There we are. I use an old-fashioned egg whisk. I do not like too many gadgets. It will take a little bit of time.
Professor Ian Fells, BBC
Whilst you are whisking up the egg white, Prime Minister, I would be intrigued to know what sparked off your interest in chemistry.
P.M.
Well really it was I wanted to know the reason why things happened. When you are ill, why do you have to take a certain medicine? What does it do? What happens and what is the composition of something like this bench? What are plastics all about? What happens if you put a little drop of acid on metal? Why does it dissolve? All the reasons why and that is the way I was taught chemistry and it is absolutely fascinating. Do you know, this egg white is taking quite a time to do! Maybe an electric whisk would have done it quicker!
Professor Ian Fells, BBC
It seems to be coming along rather nicely now! [end p13]
Professor Ian Fells, BBC
It is interesting the way that sometimes it does come up nicely.
P.M.
Sometimes it beats beautifully, and as every housewife knows, sometimes it is a nuisance. Let us just see where we have got to. Oh, it is not too bad! It is not too bad. There we are. Now that has come out into quite good peaks. Beatrice RobertsMy mother always used to turn it upside down to see if it would stick. Let us just try! Ah, not bad! There we are!
Now look! I said I wanted to know the reason why. As I understand it, what happens is this: when the egg white is just liquid like that, the molecules - they are protein molecules all curled up in little balls - as you beat them, they uncurl and come out like that and then are free to get into a kind of lattice structure. They are protein and they go into this quite firm but only temporary structure and the air gets trapped in the middle. They have got quite a firm lattice structure, but it would not have happened if we had had any trace of fat in. That is why you have to be very careful.
Professor Ian Fells, BBC
Now, of course, we can actually cook it, turn it into a meringue, can't we? [end p14]
P.M.
Yes, the next thing I would do, if I were going to do that, would be to fold in some sugar very gently and pure meringue I find very difficult to cook, but if you put a little sugar in and put this on top of some stewed fruit it is delicious. And then, of course, you get a much more stable, much more permanent structure.
Professor Ian Fells, BBC
Yes. I suppose the heat coagulates the protein even more and that firms the whole …
P.M.
That I understand is what happens.
Professor Ian Fells, BBC
… firms the whole thing up.
P.M.
Yes.
Professor Ian Fells, BBC
Now, I notice that you have a very attractive copper bowl there that you were beating up the egg whites. Now why is that?
P.M.
Well you know, they do not always beat, but in [end p15] the old cookery books you always find it said beat, if you can, in a copper bowl. Now they did not know why, but they knew it worked. Years later, we discovered that the copper combines with the protein molecule and it stabilises the whole structure, so you do not get it going all runny on the bottom; you get a very good structure like that, and that only happens in a copper bowl.
If you have not got a copper bowl, because they are quite expensive, it helps, this being alkaline, if you just put a pinch of cream of tartar in, because the acid again helps to stabilise the structure. But there it is, we started with liquid and look it is still … it is holding … oops … no, no, no … I picked up too much. Let us see if we can still turn it down … no, you see underneath it is still &dubellip; if I do not beat, it is tending to go back to its liquid state, even though it is in a copper bowl, but that is very different from the albumen we started with and it is this protein structure, kind of lattice structure, all because of the protein. (CUT)
(738, TAKE 1)
Professor Ian Fells, BBC
Prime Minister, what are you doing here?
P.M.
Well this is a lump of flour kneaded with water, [end p16] kneaded into a ball with water, and what I am trying to do now is to wash out the starch from the flour, because most of us do not what to have too much starch in things because it puts on a little bit too much weight.
Now, if I go on doing that, kneading it like that and washing out the starch &dubellip; you can see, some of it is in this bowl already &dubellip; it would take quite a time, but gradually all the starch will come out and it will finish up, as this one did, which took a little longer, like this, all the starch out. Look at it!
Professor Ian Fells, BBC
Looks like chewing gum, doesn't it?
P.M.
Just like chewing gum. In fact, as you know, it is protein. It is the protein that is left, and a particular protein called glutin … it will stretch like that. Now if I put that into a small baking tin and bake it, it will come out like this and that is because in that you have got the same sort of protein structure and there is water inside it and when it goes into the oven the water goes into the steam and the steam puffs it right up until it is like this. You see what I mean? There. Look at those big bubbles and that is the glutin, and that is the structure of almost every bread, but of course, in ordinary bread as you know, these bubbles are got not by steam but by carbon dioxide from [word missing] [end p17] but it is the glutin, this protein, this structure which you can pull, which is the mainstay of every loaf of bread.
Professor Ian Fells, BBC
Prime Minister, I can see you are fascinated by the chemistry and I know you studied chemistry, you worked as a chemist. Why did you give it up?
P.M.
Well I did work and I loved doing some of the research work, but you know, it can take you a long time to get out some of the results, and I just did not like staying in the laboratory that long. I wanted to have more direct work to do with people. I know that what we were doing is in the end to the benefit of people and scientists produce more to the benefit of people than perhaps almost any other group of people, when you are talking about the research they do into medicine, for example, but for me, I wanted more direct contact with people, and so I left it. But you know, I have never regretted taking science. It is marvellous training for everything. People used to say Latin and Greek. These days science. It teaches you to think straight. It teaches you to know what is going on in some of the very important things in the world, in which for example nuclear things may be involved. You have got the training in there and you can recall it and you can [end p18] mug it all up and you can work on it again and understand it. Marvellous. (CUT)
(NOISES OFF)P.M.
There we are!
Professor Ian Fells, BBC
Yes, beautiful. Open structure.
P.M.
Yes, you can see. You can see where the steam went and there is all the structure and that, of course, shows you that glutin is the real structure of every loaf of bread.
(739 THE END)
(740)
Professor Ian Fells, BBC
Prime Minister, you are obviously fascinated by chemistry and I know you studied chemistry and you worked as a research chemist. Why did you give it all up? [end p19]
P.M.
Well yes, I enjoyed the research and I still keep in touch with it but somehow, working day after day in a laboratory was not quite satisfying enough for me. It is for other people, thank goodness, but I wanted to have more contact day by day with people, not only scientists but with ordinary people, and so I gave up science as a profession, but my goodness, thank goodness I learnt it. It has been so useful to me as a politician! (CUT)