Starch

Got this from Sunday's Taste section today. Something I've been wondering for a long time and presto, here's the answer!

Q: I find that when you use corn flour to thicken a dish it becomes watery after a while. Some suggest the use of sweet potato flour, especially if you need to thicken lor mee. May I know what type of flour I shoudl use as a common thickener?

A (Chris Tan): The pure starches commonly used for thickening in Asia have different properties, and each does different things well.

Corn starch is popular as it thickens quickly and efficiently. However, corn starch-thickened sauces are cloudy and, if over-stirred or over-cooked, become watery, as you've noticed. Hence, corn starch is most ideal for dishes that are quickly cooked and promptly served.

Flavour-wise, it's also the most compatible thickener for dairy-based sauces and soupls.

Potato starch and sweet potato starch make clear, beautifully glossy sauces that start out very thick, but thin out as simmering continues. They are good for lor mee, mee rebus and other gravies that need to be creamy-smooth but are not boiled at length.

Arrowroot starch is similar to corn starch, but is less cloudy and more stable. It's also less concentrated, so you need slightly more of it. Arrowroot-thickened sauces do not become gluey or jelly-like as they cook. Unlike other starches, arrowroot isn't affected by acidic ingredients, so it's great for dishes like hot and sour soup, or fruit pie fillingss. It doesn't mix well with diary products though.

Tapioca (cassava) starch has the most neutral flavour of all, suitable for both sweet and savoury dishes. It's wonderful for fruit pie fillings or bright, shiny fruit tart glazes. Cold soups and sauces are a no-no though, as tapioca yeilds stringy, gel-like consistencies when cool.

Water chestnut starch is expensive and has a slight but distinctive flavour. however, it gives sauces a lovely shine and less heavy texture than corn strach. It's often gritty so pulse it in a food processor to break it up. You have to stir it energetically to dissolve it in water.