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I saw a tweet today that said:

‘If I have three-fruit marmalade on my toast, does that count as three of my five-a-day?’

As a committed marmalade maker (recipe here), this made me think just how thickly would you have to spread marmalade on your toast to get 1 recommended serving of fruit per day.  So I did some rough calculations based on my normal marmalade recipe.

In my experience, 3kg oranges + 4 lemons + 3 kg sugar makes about 20 jars of marmalade

The number of oranges depends on their size but usually there are between 15 an 20 oranges in a batch of marmalade. Lets assume that an orange or a lemon is 1 recommended serving of fruit and there are 20 fruits in 3kg. Conveniently, this means that we need to spread a jar of marmalade on a slice of toast to get 1 serving of fruit.

Now the area of toast on which you spread your marmalade obviously depends on the size of the bread, how close to the edge you spread, etc. But let’s assume a spreadable area of toast of 12 cm by 10cm, giving an area of 120 sq cm.

The jars we use are decagonal (10 sided) and tapered so it’s not trivial to calculate their volume exactly but they are not a million miles away from being a cylinder. The mean diameter is about 7cm and the filled height of the marmalade is about 8cm, giving a volume of marmalade of about 308 cubic cm.

This means that to spread a jar of marmalade on a slice of toast, the marmalade would have to be about 2.6 cm – about an inch-  thick.

So, the answer to the question above is:

‘yes of course, so long as you spread it about 3 inches thick’

I suspect that spreading marmalade so thickly would challenge the structural integrity of the toast but I will leave that as an experiment for readers.

BTW: spreading marmalade 3 inches thick would deliver about 15 times the recommended daily sugar for an adult so is roughly equivalent to drinking 12 cans of Coke.

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