Passage 1

When you have a biscuit with your cup of tea, do you dunk it? And if so, what's the perfect way to do it? That's the subject of today's Science in Action report. It may be hard to believe but scientists at the University of Bristol have been analyzing this question. And after a two-month study they devised a mathematical formula for dunking biscuits. So no more melting chocolate, or biscuit crumbs in the bottom of your cup, which is the fate of one in four biscuits that are dunked in tea, according to research by a biscuit manufacturer. Doughnut dunkers don't face the same problems because doughnuts are held together with an elastic net of protein, gluten. 

This substance allows the doughnut to absorb liquid without breaking down its structure. The structure of a biscuit, however, is held together by sugar which melts when placed in hot tea or coffee.

So what is the answer? The researchers, led by Dr Len Fisher, discovered that holding the biscuit in a horizontal position – or "flat-on" – has a significant effect on the amount of time that a biscuit can stay in hot liquid before falling apart. In fact this horizontal dunking results in a dunking time up to four times longer than traditional vertical dunking.

What's the reason for this? It seems that the answer is related to diffusion, in other words, the length of time it takes for the liquid to penetrate the structure of the biscuit. Basically, it takes longer for the liquid to travel through the channels of a biscuit when it is laid flat on the surface of the liquid. Also the fact that when a biscuit is dunked horizontally, with the biscuit submerged in the liquid, and the chocolate coating staying out of the liquid, the chocolate helps hold the biscuit together. Another factor influencing the equation is the temperature of the tea – the hotter the tea, the faster the sugar melts.

The researchers also found that by dunking a biscuit into tea or coffee, up to ten times more flavour is released than if the biscuit is eaten dry. So it's worth experimenting yourself. If you are wondering how you can perfect the horizontal dunk, the researchers have come up with an idea for a biscuit-holding device to make dunking biscuits easier. They are even now working on producing a table giving guidelines on dunking times for different types of biscuits. On that note, I think it's time to go off to the canteen for a tea break!

Answers

3 Correction：

  1 Scientists at the University of Bristol carried out a two-month study to find the best way to dunk a biscuit.

  2 One in four biscuits break up when dunked.

  3 Unlike biscuits, doughnuts are held together by gluten, which doesn't breakdown in hot liquids.

  4 Horizontally dunking a biscuit into tea allows a lpnger dunking time, as the liquid takes longer to soak into it.

  5 The hotter the tea, the faster the biscuit breaks up.

  6 Dunking a biscuit in a hot drink releases up to ten times more flavor than eating the biscuit dry.

4 Listen to Passage 1 again and complete the sentences.

Answers

  1 dunking biscuits

  2 held together

  3 absorb liquid

  4 travel through

  5 hold the biscuit

  6 producing a table