Tea Trivia - Biscuit Dunking
Posted by Melody Wren on A Nice Cuppa.
British physicist, Len Fisher, has been employed by a well-known biscuit (cookie) manufacturer to define the optimum dunking time for its confectionery. His findings are way off the mark. For the uninitiated, bickie dunking is a procedure by which you plonk yourself down in your favorite chair, take the weight off your feet and slurp, never chew, your way through a series of half-soggy biscuits that you have dipped into a cup of hot tea. No trivial matter when you consider that this tea ceremony is celebrated by Brits of every class right up to the Queen’s sister, Her Royal Highness, Princess Margaret herself. The basic premise underlying the professor’s work is the idea that bickie dunking can be mathematically regulated, whereas every Brit from Land’s End to Windemere will tell you that it has, and will always be, an art form.The challenge lies in immersing the biscuit of your choice in a cup of your preferred size and diameter and dunking for a period of time known only to you. The type of cup, temperature of the tea, presence or absence of milk and sugar are similarly important factors to be taken into account. Weather, time of day, the emotional status of the dunker will also influence the apres-dunk trajectory of the biscuit from cup to mouth. Impersonal and sterile laboratory conditions do not, and should not apply.
With a skill honed by years of practice, I rarely experience the humiliation of seeing sloppy bits of disintegrated biscuit goo sinking to the bottom of the cup, or, worse still, sliding down chin, clothes and upholstery. This is in distinct contrast to the doctor’s published results: “One in four dunks is estimated to end in mishap.”
Dr. Fisher’s experiments involved, among other things: the use of an X-ray machine, weight-testing materials, a belt sander, and an unspecified number of biscuits. He even coated one biscuit in 24-carat gold and examined it under an electron microscope to examine its minute structures. His investigations also included the use of the 1920 Washington equation that governs the permeation of a liquid into a porous material, thus calculating the amount of time necessary for hot tea to penetrate halfway through a biscuit. (Optimum biscuit-dunking time equals four times the viscosity times [the height of liquid displaced upward by the biscuit] squared divided by the surface tension of tea times the average biscuit pore diameter.)
In this way, the professor was able to announce that the period varies with the viscosity of the liquid involved, and increases significantly with the amount of sugar in the drink. These experiments also revealed that hot tea not only dissolves the sugar that normally keeps the biscuits glued together, but also swells the starch grains sufficiently to give them enough temporary strength to ensure a safe post-dunk journey from cup to mouth. We are also told that the crucial point at which this marvelous state of unglued strength can be reached lies along a continuum from two to eight seconds. Ginger Nuts, he declared, give highly satisfactory results at 3.5 seconds, whereas digestive biscuits, chocolate or plain, take eight seconds.
The response of the British public in the media, has, so far, been robust and positive, advocating the time-honored, individual, intuitive approach flavored with regional differences and historical nuances. If science supersedes inherited wisdom, the bitter debates about the Euro will have to take second place while tea-making routines are completely reorganized.
