Any liquid can be reduced just by heating it - but why would you want to do that?
The answer comes back to two of our old friends, flavor and consistency (texture).
By reducing any flavored liquid you intensify its flavor and at the same time thicken it. You can continue this process until what you have left is a syrup if it contains sugar, or a sauce if it does not.
This is one of the most important tools in the kitchen, believe it or not, because a great sauce can rescue an indifferent meal.
And literally ANY liquid can be reduced.
A few uses
Wine is frequently used in cooking, both as a marinade and as an addition to sauces for meat.
There are some problems with it though, one of which is that you need a really good wine and quite a lot of it to produce a reasonable sauce for, say, six people.
On the other hand, if you use pure grape juice and reduce it to a syrup, that syrup, added to any sauce (or gravy if you prefer) will lift it into the realms of 'gourmet'.
What's more, you don't have to make your reduction on the night you prepare your meal. You can reduce a liter of grape juice at any time to the consistency and flavor you want; then just store it in the fridge.
You can do the same thing with any fruit juice - prune is sensational - and store it until needed. Just about all of them will do things for ice cream, pies or tarts that will have your guests demanding the recipe!
Pork with apple sauce? Use a carton of fresh apple juice from the supermarket and reduce it. And if you want a real sensation add in a glass of apple brandy during the reduction process.
Are you getting an idea of how simple this is?
Take any carton of fresh stock straight of the shelf and reduce it. You will transform it into something even the manufacturer won't recognize. But beware!
You need to start out with good quality in the first place, because when you reduce a liquid you intensify ALL the flavors, and not just the good ones.
If it's salty to start with, for example, it will be salty beyond belief by the time you've reduced it even by half. So if you are going to use a supermarket stock, make sure it's an extremely good one.
And believe me when I tell you that stock cubes should not be used for reduction sauces.
Because you will be tasting as you go (won't you?), you may find that you get the flavor you want before the desired consistency is reached.
So here's a couple of hints right now for your sauces.
Sweet ones can be thickened successfully without loss of color by adding in liquid glucose early on in the reduction process. Surprisingly, this will add little in the way of sweetness and produces a beautiful velvety sauce when whisked.
For meat sauces, one of the most effective ways to thicken is to mix corn starch with water and whisk this into your sauce a little at a time until the required thickness is reached. You do this at the end of the reduction time.
If you get it wrong and add too much, no problem. Stir in a little extra water to thin it.
Reductions need to happen rapidly in order to preserve flavors. And the greater the surface area of the liquid the faster the water will evaporate.
For fast reductions, therefore, I often use a skillet, or frying pan, only transferring the sauce to a deeper pan when I want to whisk it. (whisking 'finishes' off a sauce, making it shine)
However you may want to whisk something into the sauce while its cooking - such as butter or olive oil for example - and for that I find a small wok is best; one with a handle.
A wok is less likely to reduce so fast that the sauce is burnt while your back is turned. But try both methods and see which you prefer. You may even end up using something totally different.
There's no magic to this. Whatever works for you, that's what you should use, in this and everything else to do with cooking.
Just bear in mind that what you're after is speed and ease of use. As well as a great tasting result, of course. :>)
For the most part, reduced liquids can be frozen in cubes and used as needed. However if the sugar content is high this may not work too well and they would be better stored, covered, in the fridge.
If they should dry out, simply add a little water and heat through.
Sauces containing meat juices of any kind must be frozen if you're going to keep them, and should be brought to boiling point before being used again. There is no need to thaw them out to do this, in fact it's better not to. Simply drop the frozen cubes into a saucepan, melt them over a gentle heat, and then bring swiftly to the boil.
Why do you do this? To avoid food poisoning, that's why. You are making sure that any bugs introduced into the sauce during the preparation process are killed off.
Don't worry, this will not be because of anything you have done wrong (I hope!), but because bacteria are part of our everyday lives and they exist in every kitchen, however clean.
In fact your food, and especially your meat, is crawling with wildlife that you will never see. Don't worry about them. Careful handling and simple precautions will ensure that these miniature monsters can never multiply enough to harm either you or your guests.
For more information on the subject, see my booklet "Hygiene In The Kitchen", which is available free through the Cool Cook's Club.
Michael Sheridan is an acknowledged authority and published writer on cooking matters. His website at http://thecoolcook.com contains a wealth of information, hints, tips and recipes for busy home cooks.