Topics In This Section
1. Introduction
2. General Rules of Frying
3. Temperature Control
4. Preparation of Food
5. Fat Absorption and Topping Up
6. Choice of Frying Medium
7. The Spoilage of Fats and Oils
8. Cleaning
9. Frying Specific Foods
10. Recommended Frying Temperatures
11. The Basic Chemistry of Fats and Oils
12. The Chemistry of Fat Spoilage
13. The Visible Effects of Chemical Spoilage
14. The Role of the Oil Refiner
15. The Role of the Fryer
16. Fire Hazards
Reproduced with permission from Pura Food Products Limited
3. Temperature Control
Accurate control of temperature is essential and is best achieved by the use of a thermostat or by the regular use of a thermometer. It is also
important to check the accuracy of the thermostat and thermometers themselves from time to time and to ensure that any instrument used is kept clean and
is actually measuring the temperature of the oil. In purchasing a thermometer, remember that the temperature to be measured will be high and probably at
least 205C (400F) at times. Ensure that the instrument purchased is rated for use at these high temperatures.
An automatic cut out which comes into operation at a temperature above normal frying temperature and well below the flash point of the frying medium
(see Section 16), as is useful as a safety precaution.
Heating a fat or oil to the normal frying temperature of 191C (375F) greatly increases its tendency to spoil and is one of the most important factors governing
the life of an oil. The higher the temperature, the quicker the oil will deteriorate. On frying equipment where gas flames are used, the flame must be adjusted so that
it does not flare up round the sides of the frying vessel and never to a height above the surface of the oil, because of the danger of fire. Hotspots
are also dangerous and should be corrected.
As well as speeding up the breakdown of the frying medium, frying at too high a temperature will result in food which is darkly coloured - or charred on the outside
before the inside is properly cooked.
If the frying temperature is too low, the resulting product will be greasy because the surface of the food is not sealed rapidly enough on entering the frying
medium. Low temperature frying will also result in excessive absorption of fat by the food.
An important factor when considering the frying temperature is the relative amount of frying medium to the food being fried. When too small a quantity of oil
is used, the sudden introduction of an excessive amount of food - at room temperature or below - will result in a large drop in temperature and the appearance of
faults associated with low temperature frying. This is even more important in the case of frozen foods; for example, falls of temperatures of 18-28 C (30-35F) can
occur when frozen fish pieces are immersed in hot oil. On the other hand, when too large a quantity of oil is used, only a small proportion of it will be lost by
absorption. Only a low rate of 'topping up' is then required and because regular topping up with fresh oil tends to damp down the rate of spoilage, the bulk of
the oil in the fryer can deteriorate more rapidly.
As a general rule, one part of food should be fried in six parts of oil or fat.