The way of preparing garlic thus greatly affects the strength of its smell. Slicing garlic only breaks open
a small quantity of the cell compartments, so only a little allicin can be formed. When garlic is crushed,
however, many more cells are damaged, so there is much more contact between the alliin and the
enzyme, so much more of the intense flavour is produced. Heat however further transforms the allicin
into another group of compounds – the allyl disulfides, which are more mild in flavour and even slighlty
sweet. Roasting or toasting garlic therefore removes the strong pungent taste of raw garlic and
replaces it with a sweeter, milder flavour.
· The crying effect of onions:
Similarly, when an onion is cut, an enzyme called sulfoxide lysase, usually kept separated in a special
compartment, is released and may react with released sulphuric compounds to form new compounds
called thiopropanol sulfoxides. When molecules of sulfoxide lysase evaporate into the air, they irritate
the eyes and makes us cry.
This effect can be prevented either physically (by wearing ski-googles or contact lenses or by cutting
onions under some running tap water), or chemically – by placing a flame next to the work area. The
flame will complete the oxidation of thiopropanol sulfoxide, preventing this irritating effect.
· Preparing aubergines:
Salt is often added to aubergines before cooking to remove their internal water by osmosis. Usually
the loss of water by harvested vegetables is undesired and is known as wilting. Although in this case,
the loss of water will makes them more soggy, it has the major advantage of improving the taste, by
removing with the water the molecule that is responsible for the “bitter” taste of aubergines. This often
is an undesired effect, but sometimes this is done expressely - aubergines contain a water-soluble
molecule that is responsible for its bitter taste. Aubergines are often salted in advance as this removes
water from them by a process known as osmosis and thus the bitter component as well.