SCIENCE OF COOKING
MAKING A PASTE
Breaking down the ingredients in a pestle and mortar raptures the cell walls and allows the volatile flavour molecules to be released. A small amount of salt is added to act as an abrasive and speed up this process. The finer the ingredients are ground down, the more surface area is exposed, resulting in more flavour able to be extracted and released. The smaller the particles of food are, the faster the aroma molecules will infuse into anything it comes into contact with. Something to keep in mind is that, the longer the paste is kept, the more aroma molecules will escape into the air instead of into the dish itself. This is one of the reasons why freshly made curry paste is preferable to a ready made one which has had prolonged exposure to the air.
DRY TOASTING SPICES
It is always best to buy whole spices, toast them and grind them just before use, this maximizes their aroma and freshness. The technique is simple, toast whole dried spices in a dry pan over a low heat, constantly stirring or tossing the pan to ensure even heat distribution, alternatively this can be done in a low oven. This process adds depth and complexity, intensifying their aroma molecules contained in their aromatic oils. Make sure that only one type of spice is toasted at a time, as each spice has a different volume and density and react to heat differently.
BREATH OF THE WOK
A process used in chinese style stir fried dishes and also referred to as ‘wok hei’, it imparts a smokey aroma. A well seasoned wok is essential, make sure items are tossed in the wok quickly and in small quantities so that the temperature of the wok does not fluctuate. A rapid process of caramelization takes place over intense heat, 200 degrees Celsius and above, coupled with tilting the wok slightly so that oil particles comes in contact with the gas burner and the wok catch fire, known in Thai as ‘ Pad fai daeng’ Executed correctly, this process should take no longer than a couple of minutes and will impart a wonderfully unique aroma.
Boiling often occurs when the heat source at the bottom of the pot filled with liquid creates vaporization, soon a steady current is created as the hot water rises to the top, this occurs at 100 degrees Celsius. By placing a food item into to boiling liquid, cell damage starts to occur, which breaks down the cell walls, softening the food item, making them palatable. Timing is key in this process, as items are heated in the liquid, cell walls starts to collapse and the food item will lose its structure, as well as leeching its flavour molecules into the boiling liquid.
Meat with high connective tissue should be slowly simmered at 60 degrees Celsius, unravelling the collagen in the meat and gelatinizes the connective tissue so that it melts in the mouth. If the meat is rapidly simmers above 60 degrees Celsius, chemical reactions in the meat speeds up, proteins molecules bunch together and precious moisture in the meat is squeezed out, the key to an excellent braise is to cook it low and slow.
Excess moisture on the surface of the meat should be removed by blotting, as a drier environment speeds up the process, Heat is the key factor, the maillard reaction occurs at above 140 degrees Celsius, proteins and carbohydrates react with each other, forming new chemical compositions, creating a wonderfully rich aroma and brown colour. When the temperature reaches 180 degrees Celsius pyrolysis occurs, more commonly known as burning, which blackens the surface of the meat and creates carcinogens resulting in bitterness.
This process involves the transfer of flavour molecules from one substance to another. This can take place from a solid to liquid, When making a tom yum soup, fragrant herbs are sliced on an angle, to maximize surface area, rapturing the cell walls. These herbs are suspended in the liquid and flavour molecules escapes into the liquid broth. This process can also occur when thai sweets are arranged in a jar and a fragrant candle is blown out creating smoke. The lid is placed onto the jar and the sweets becomes infused with the wonderful fragrance.