When I open a new jar of marmalade the contents are a nice, semi-solid, homogenous mass with a smooth surface, however old the jar is. Yet when I make a spoonful-sized hole in the flat surface to remove some marmalade, the next time I open the jar a couple of days later, the hole has started to fill with a syrupy liquid. What is it about breaking the surface of the marmalade that sets this process in motion? It continues until the jar is empty.
鈥� A proper marmalade contains plenty of pectin, which is fluid while the product is still hot from cooking, but forms a gel as it cools. The gel is a sponge of chain-like pectin molecules in a liquid syrup. The sponge neatly fills the jar as you open it and the syrup neatly fills the sponge, simply because the sponge formed from molecules dispersed evenly through the syrup. If you were to skim your marmalade from the top instead of digging great, vulgar holes in it, the marmalade would remain intact.
But if you tear gaps into the delicate structure, quarrying it, then the fluid syrup from the higher levels of sponge will seep down into the hollows.
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You might feel guilty though when you remember how forgivingly, selflessly, marmalade turns the other cheek, melting obligingly on hot buttered toast. But don鈥檛 trust its treacherous meekness! Lumps bide their time to topple onto your best shirt, smearing elbow, table and floor. And in hotels it will humiliate you in the eyes of guests, hosts, clients or colleagues. Can鈥檛 find that report? What is that sticking to the seat of your trousers?
Jon Richfield, Somerset West, South Africa