I visited the library on Friday and got several books out, including one called Coffee Obsession. It is a Dorling Kindersley book and so well-illustrated, as you might expect from the publisher. Most of it seems taken up with maps of where coffee comes from and descriptions of regional characteristics, which isn’t overly useful to me since I’m not planning on spending lots of money to source specific types of beans. However, there were some intriguing recipes in the back part of the book.
One was entitled Scandinavian Coffee and intrigued me by featuring an egg. In essence, you mix up ground coffee with an egg and little cold water then stir this paste into boiling water. After a few minutes, you take off the heat and dash on some cold water to make the coagulated mix of egg and grounds sink to the bottom and pour off the coffee on top.
The result is meant to be free of the bitter and sour compounds, yielding a smoother drink. I found it was still quite bitter but smooth; it created a naturally sweet after taste. Reading around (the most informative article I found was from Khymos), some methods include the egg shell, which is meant to neutralise some acidity. I might try that in future, and perhaps also brewing at a lower temperature. Egg will coagulate at below 70°C so I am not sure there is a need to boil the coffee and drive off volatile oils.
For me, the jury is still out on this one although it would be a good party trick and I can see it would be immensely handy if you were either stuck without a suitable filtration system or if you were producing a large volume of fresh coffee – apparently this is also known as “church basement” coffee from its use for after service refreshments in Lutheran churches in Minnesota (which have high proportions of people from Scandinavian backgrounds).