Factors affecting the process of deep fat frying.

The common factors influencing the process of deep frying include:

1.  Heat- Frying temperatures ranging from 150 -190°C are necessary to properly prepare the different fried food products. Unfortunately, exposure to high temperatures accelerates all of the breakdown reactions of fats and oils.

2.  Air- Oxygen from the air is necessary to sustain human life, but it also reacts with the double bonds in the frying oils to oxidize the unsaturated fatty acids, which results in offensive odors and flavours and promotes gum formation or polymerization. 

3.  Moisture- All food products contain moisture, which causes hydrolysis of fats and oils, resulting in an increased fat absorption in most foods.

4.  Contamination- Any material associated with the frying process that causes the frying media to deteriorate or accelerate the process is a contaminant. Some examples of frying fat contaminants are: 

• Trace metals - Most metals are pro-oxidants that exert a marked catalytic effect to accelerate fat breakdown, but some metals are much more active than others. These pro-oxidants can be picked up during processing or storage, from frying equipment, the food fried, or some other contact with a metal. Two metals that promote more rapid breakdown of frying than others are brass and copper.
• Soap or detergent- Residue of these materials from cleaning storage tanks, fryers, or utensils which will catalyze fat breakdown.
• Gums or polymerized fats- Addition of polymerized fats or oils to fresh oils act as catalysts to accelerate the formation of more gums, which contribute to foaming and darkening.
• Burnt food particles- Food particles allowed to remain in the frying fat impart a bitter, caramelized and / or burnt taste along with an unappealing appearance to the food fried and accelerate frying oil breakdown.

5.  Time - The extent of the frying oil's exposure to the effects of the above factors determines the degree of product deterioration.   So now you realize, the simple process of deep frying is not actually so simple. Utmost care needs to be taken while using this method to ensure that the quality of the frying oil is maintained.  The next section is devoted to this crucial practical aspect i.e., maintaining the quality of fried oils.