Slow march of the penguins
It’s one of the most extraordinary events in nature, depicted in the film March Of the Penguins. Every autumn, Emperor penguins of breeding age leave the ocean to walk inland to their breeding grounds.
It is a gruelling journey which, if they could fly, would take only a couple of hours.
they are thought to have evolved from a flying auklike ancestor. As such, legs were never an option. In line with evolution, they have adapted their wings and feathers to achieve optimal efficiency within their habitat, which is water.
Biomechanics suggests the birds’ wings became more and more efficient for swimming and diving and eventually lost their ability to get off the ground.
their short, stiff wings are well adapted to their environment: they allow them to glide effortlessly through water propelled by their webbed, flipperlike feet. their legs are set farther back in the body and together with the tail form an underwater rudder to their streamlined bodies. their bones are far denser than those of flying birds to facilitate diving. An adult Emperor penguin can hold its breath for more than 20 minutes and dive to 1,500 ft. More efficient diving increased the opportunities to forage for food at depth. Furthermore, penguins are more at risk of predation in the water than they are on land, so there has been strong selection to make their swimming and diving as efficient as possible. Another adaptation is the penguin’s plumage. their feathers are not arranged in tracts, as in other birds, but are evenly packed. their slick, waterproof exterior facilitates diving while the downy inner layer is not much use for flying, but provides excellent thermal insulation in extreme conditions. Dr Ken Bristow, Glasgow.
QUESTION How does French butter differ from English butter? Is one superior to the other for making pastry?
sOcAllEd English butter is also known as sweet cream butter. It is produced by churning pasteurised cream until the buttermilk separates from the butterfat. As the butterfat is churned, the fat cells clump together until the butter is formed. sweet cream butter is mild and creamy in flavour and has a fat content of about 80 per cent.
French or Europeanstyle butter is cultured. A live culture, such as buttermilk or yoghurt, has been added. the bacteria will then turn lactose (milk sugar) in the cream to lactic acid, giving the butter a slightly sour taste.
this is the traditional method for butter making and the result is a more flavoursome product with a higher fat content, typically 82 to 85 per cent.
cultured butter is excellent for cakes and pastries. More butterfat means that your pie crust will be flakier, colourful and more flavourful.
Excellent for croissants and patisserie, it’s also particularly tasty slathered on a piece of warm, fresh bread.
the smooth texture and lower fat content of sweet cream butter make it better for delicate sauces and scones. the lower fat content is preferable in biscuits and shortbread.
When baking, always use unsalted butter so you can control the flavour.
Florence Lewis, Alconbury, Cambs.
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