If deep-frying oils are used for too long, rarely changed, never filtered or even stored for too long, the fried food consumed from them can be dangerous to health.
Spoiled frying oils are hazardous to health and have a reduced value. This means that restaurants, for example, that use this type of frying oil can deceive their customers and therefore face fines from the food control authorities.
For this reason, the following rules must be observed when deep-frying:
- Use heat-resistant cooking oils or cooking fats.
- Heat the frying oil in stages to a maximum of 170 °C to avoid localized overheating. This significantly reduces oil spoilage.
- Wet, seasoned fried food accelerates oil spoilage. If possible, place dry and untreated food in the deep fryer and only season, salt or add sugar after frying.
- Avoid keeping the frying oil hot for several hours unnecessarily, as this significantly impairs the quality of the oil.
- Cover the oil after use.
The following control measures should be applied to ensure good frying oil quality:
- The quality of the frying oil must be monitored regularly.
- Checks can be carried out using various devices (frying oil tester, indicator sticks, etc.). If the total polar percentages (TPM) in the frying oil are measured, the maximum value of 27% in accordance with the Foreign Substances and Ingredients Ordinance (FIV) must be observed.
- The visual assessment of used oil is imprecise. However, dark brown, cloudy, foaming, thick or viscous oils that smoke at temperatures below 180 °C are spoiled.
Recommended cleaning:
- If used regularly, the frying oil must be filtered daily and the oil pan cleaned.
- Cleaning work and oil changes must be recorded in writing as part of the self-monitoring concept.
Correct disposal:
- Used oil must not be emptied into the sewage system, but must be disposed of at the used oil collection points.
- Deep fryers that are not in use must be emptied and cleaned.
Acrylamide
Acrylamide occurs naturally during the heating of carbohydrate-rich foods, during the usual browning process that is important for tasty foods. Animal studies have shown it to be carcinogenic. Particularly high levels are found in potato products such as French fries, rösti, and fried potatoes. To minimize the formation of acrylamide, foods should not be heated for too long or at too high a temperature.
Careful frying:
The oil should be kept at approx. 170 °C. Fry portions of approx. 50-100 g of potatoes per liter of oil. Carefully monitor the frying process and finish in good time, i.e., “gild the food instead of charring it.”
Source: DEPARTMENT OF HEALTH AND SOCIAL AFFAIRS Office for Consumer Protection Obere Vorstadt 14, 5000 Aarau, www.ag.ch/dgs Status: 04.09.2014 – INFORMATION SHEET 8, “Frying oil” accessed on 15.09.2016
