Quality assessment and degradative changes of deep-fried oils in street fried food chain of Kashmir, India

Repetitive use of same oil for deep-frying over a prolonged time period is a common practice followed by street vendors across various developing countries. This practice usually results in generation of harmful compounds imposing serious health threats to consumers. Frying oil samples (fresh, in-use and discarded) and commonly consumed fried street foods of Kashmir were randomly collected from 16 street food vendors of srinagar town and its adjacent areas for the assessment of their quality changes during repetitive deep frying. Significant increase in total SFA (saturated fatty acids), total MUFA (monounsaturated fatty acids) and total TFA (transfatty acids) content and decrease in total PUFA (polyunsaturated fatty acids) was observed in in-use, discarded oil and street foods as compared to fresh oil, reflecting the higher degree of oxidative degradation on repetitive use of same oil. The extent of oxidative degradation was highly influenced by the type of food fried, with lipid-based products showing higher degradation. High free fatty acid value (FFA˃1%), peroxide value (PV˃10meq/kg), P-anisidine value (P-Av˃6), color (higher ΔE), and TOTOX (Totox value˃19.5 mEq/kg) value revealed that only 20% of the in-use frying oil and 10% food products were safe for consumption. However, TPC test, a widely used measure of oxidative degradation suggested that majority of the in-use frying oil were of acceptable quality, thus greatly underestimating oil degradation. •Frying practices of 16 commercial street vendors were assessed.•Fresh, in-use, discarded and commonly consumed street foods were analysed.•Fatty acid profile and other physico-chemical characteristics of samples were evaluated.•Fat rich products reportedly shows higher oxidative degradation.•Majority of the in-use frying oil and street foods were highly degraded.