Key Update

A McDonald’s outlet on Brigade Road in Bengaluru has come under scrutiny after a Karnataka Food Safety and Drug Administration inspection found the outlet using magnesium sulfite (MgSO₃) to treat used frying oil.

Officials made the finding during a three-day inspection drive that concluded on August 9. During a compliance check, they found the outlet using the chemical to “purify” used cooking oil. The authorities issued a notice to the food business operator and will examine the practice under applicable food safety regulations. They will decide on further action based on their findings. The inspection drive also found that several hotels and restaurants were using cooking oil that was unfit for consumption.

Magnesium sulfite is a white crystalline compound used in industrial processing, food preservation and water treatment. Its use in frying oil has also surfaced in an earlier controversy involving another major food chain, which faced suspension in 2024 over a similar practice.

What Repeated Frying Does to Cooking Oil

Repeated deep-frying can degrade cooking oil significantly. High temperatures, moisture and repeated frying break down the oil and increase the formation of free fatty acids (FFAs). As FFAs accumulate, the oil may begin to smoke at lower temperatures, develop a rancid odour, darken and foam excessively. Once the oil exceeds prescribed safety limits, food businesses should stop using it and discard it rather than continue frying with it.

Why TPC Levels Matter

Repeated heating also increases total polar compounds (TPC), which serve as an indicator of cooking-oil deterioration. High TPC levels have been linked to adverse health effects and conditions including hypertension, atherosclerosis, Alzheimer’s disease and liver disease. Food businesses should therefore monitor frying-oil quality regularly and replace the oil when it crosses the permitted limit.

When Should Frying Oil Be Discarded?

The Food Safety and Standards Authority of India (FSSAI) sets the permissible TPC limit for frying oil at 25%. Once TPC exceeds this level, businesses must not use the oil for frying and should discard it. For food businesses, replacing degraded oil rather than attempting to restore it remains an important food-safety responsibility.

Source: Deccan Herald