Liquid smoke is a manufactured substance that mimics the flavour and taste of food smoking processes. This substance is used, primarily in food production, to make food look, taste and smell like it has been through a specific smoking/smoked process even when it hasn’t.
Liquid smoke is manufactured via a specific process that mimics a traditional smoking process. This involves lighting wood chips but keeping them very damp so that they smoke a lot. This smoke is then captured and put through a distilling process so that it turns into a liquid. This liquid retains the taste and smell of the smoke and is then bottled up for sale or use. Some liquid smokes are also aged to change their flavours.
Liquid smoke is most often used in food preparation. Some consumers will buy this (although it is often hard to find) and will use it themselves. It can, for example, be used on barbeques to give more of an instant smoky taste and smell which can be useful if you need to cook food quickly or are simply finishing off food on a barbeque having cooked it previously in an oven.
You need to use liquid smoke sparingly in most cases as it can have an extremely strong taste and smell. Many people like to use it on their barbeques to get a specific taste and smell. In this instance the smoke wouldn’t be applied to the food but to the barbeque coals themselves. This is usually best done before you light the barbeque -- once it is lit then the particular smell of the smoke you choose will pervade through the food that you cook.
You will also find liquid smoke used quite a lot in food manufacturing. It is often, for example, used in marinades and sauces where a smoky taste and smell is required. The type of woodchip or other material used in the manufacturing process will play a big part in how the smokes smells and tastes and different methods are used to create different kinds of liquid smoke.
Some experts believe that liquid smoke can be useful in food preparation as it has a slightly antibiotic effect -- it has been shown to kill off bacteria on meats in some cases. The toxins often found in standard smoking processes may also be removed during the production of liquid smoke which technically makes food prepared with this substance safer than that prepared and smoked traditionally.