The major compound formed, allyl isothiocyanate, is also called mustard oil and is a chemical that can be both useful and dangerous. In the plant itself, its most important function is to protect against insect attacks. If an insect or a larvae starts eating the Brussel sprouts, the chemical is immediately generated from sinigrin.
Recent trials at the Institute of Food Research in Norwich, England, have demonstrated that if rats with pre-cancerous cell growth in the guts are given allyl isothiocyanate, the growth stops and the cells die. It remains to be seen if the effect is the same on human pre-cancerous gut cells. Large doses might have severe side effects. Skin contact with the pure compound can give rise to blisters in almost the same way as from the chemical warfare agent mustard gas. Inhalation of allyl isothiocyanate can cause lung oedema; by eating it severe kidney damage can arise. Earlier, the compound was sometimes used in abortion attempts. At the same time it is this compound that gives the Brussel sprouts their characteristic mildly bitter taste. How the taste is perceived is hereditary. A quarter of all people are supertasters and find the taste very bitter, whereas another quarter are non-tasters and will only notice a faint bitterness. Maybe here is an explanation to many children's dislike of Brussel sprouts.
Brussel sprouts also contain another interesting chemical, 3-indole-carbinol. There is a form of recurrent respiratory papillomatosis which appears in the aerodigestive mucosa, also in children. Normally these "warts" are benign but they can rapidly develop into a malign growth. One alternative to the surgical removal of these "warts" is to treat them with 3-indole-carbinol, which frequently will make them disappear. Red cabbage gets its beautiful red colour from anthocyanines, compounds made up out of sugar and phenolic pigments called anthocyanidines. In the same way as litmus paper, the colour depends on the degree of acidity or pH. Usually, when you cook red cabbage you add vinegar, lemon or acid apples to ensure that the presence of some acid will preserve the red colour. If you instead add something alkaline, e.g. sodium bicarbonate, the red cabbage will turn into blue cabbage!
"Long cabbage" and "brown cabbage" are not cabbage varieties but instead Swedish ways of preparing cabbage. "Long cabbage" comes from the province of Halland and is prepared from kale, which is first fried in lard from the Christmas ham and then mixed with a rich cream. "Brown cabbage" has its origin in the province of Scania in the southernmost part of Sweden. It is prepared from coarsely cut cabbage which is first fried in lard together with molasses, then moistened with some of the liquid remaining from the boiling of the Christmas ham and left in the oven for an hour. When molasses is fried, the small sugar molecules are changed into brownish polymers of high molecular weight, at the same time as some new nicely tasting compounds are formed. This process of caramelisation is also the basis for the production of some of the Christmas sweets.