How many times have you put a pan on the hob to cook vegetables let’s say, without thinking of what’s happening to, or what’s best for the food you are cooking? I’m guessing not often. Boiling, poaching, simmering – but what’s the difference? Not a lot you may think. But understanding but the application of wet heat is one of the most misunderstood methods of cookery.
Taking a closer look.
Water boils at 100°c and boiling is unmistakable. The water bubbles vigorously and steam rises from the pan. Now try turning up the heat, the water will bubble faster, and more steam is produced causing the water to evaporate and the level of the water in the pan to drop. However, the water does not get any hotter all you are doing is bashing and stressing anything you are trying to cook in the pan.
Simple – well not that simple, the temperature of the water can be raised by increasing the pressure of the atmosphere around the water. This is exactly how a pressure cooker manages to cook more efficiently and reduce cooking time. Likewise, the boiling temperature will be reduced if the pressure is lower. If you have every wondered why the tea is never good in a plane, now you know.
Think about what you are cooking and how the heat in the liquid will affect the food. So much food especially fish is ruined by poaching at too high a temperature. I always use a Probe Thermometer to simplify the process and confirm you have the correct temperature for your purpose.
Boiling, 100˚c – Rapid movement with large bubbles, and lots of steam.
Main uses.
Sterilising utensils and storage jars – see The Golden Rules of Home Preserving
Green vegetables need to go into rapidly boiling water. By adding salt to the water, we increase the temperature slightly helping to retain colour and nutrients. This can be followed by plunging the vegetables into iced water to stop the cooking and set the colour (known as blanching). The vegetable can then be gently heated when required simplifying serving the meal. Place a lid on the pan after adding the vegetables but remove it as soon as the water returns to the boil. Green vegetables give off an acidy gas when heated. Which if recycled back into the water can spoil the colour of the vegetables.
Cooking pasta. The rapid movement of the water helps separate the pasta and helps prevent it sticking to each other. The high heat also forms a skin on the paste to prevent it disintegrating in the pan.
Simmering. 80-95˚c – smaller bubbles forming some movement in the pan, steam rising.
Main uses.
Often following boiling, to continue the cooking without breaking up the product. When cooking main crop potatoes as soon as they boil reduce the heat and simmer gently. If your spuds always break up in the pan, you’re a slave to the boil. Also used to allow a larger item of food to cook through without drying out.
Poaching. 60-80˚c – Some circulation in the pan and a little light steam present.
Main uses.
Possibly the most misunderstood and badly executed methods of cooking. Critical for the successful cooking of fish and producing the best poached egg. Plenty of energy to cook the foods without drying out and toughening the protein.
Recognisable by small bubbles forming in the liquid then rising and falling. A small amount of steam may also be visible.
Steaming – water 100˚c – steam 80-95˚c. Constant steam seen to be escaping from the steamer basket.
Main uses.
Here the food is suspended above boiling liquid to apply a more gentle heat. The heat of the steam itself depends on how well the cooking container is sealed. Under pressure the steam can reach well over 100˚c often used to cook more delicate foods like fish or broccoli.
The cooking medium.
In the case of boiling the cooking liquid is most commonly water. In the case of Simmering, Poaching, and steaming a flavoured liquid can be used. When cooking fish, it may be poached in a white wine stock. A medium known as a Court Bouillon (aromatic vegetables, herbs, water salt and a dash of vinegar). Is used to cook oily fish like salmon.
Adding a few herbs and spices to the water used to steam food will enhance the flavour of the food been cooked.
So next time you are cooking something in a liquid, give some thought to the food you are cooking, and how you want it to cook. Your, food will all the better for it!