Determination of trans fatty acid content and fatty acid profile of commonly consumed snack foods in selected parts of the Colombo MOH area using the validated AOAC modified method

Accurate quantification of trans fatty acids (TFAs) in food is critical for regulatory compliance and public health protection. This study aimed to develop and validate a modified gas chromatography–flame ionization detection (GC-FID) method based on AOAC 996.06 and 996.01 for the determination of total fat and fatty acid profiles, including TFAs, in complex street food matrices. The method was validated by assessing linearity, limit of detection (LOD), repeatability, and recovery. The validated method showed acceptable linearity (RSD% = 7.62%), low LOD (1.01%), and high recovery (101.14%), confirming its reliability for TFA analysis in food systems. The method was applied to 35 street food samples collected from selected parts of the Colombo MOH area, Sri Lanka, classified into six categories. Total fat content ranged from 12.9% to 24.8%, with wheat flour-based snacks and pulses, nuts and legume-based items having the highest values. Fatty acid profiling revealed saturated fats as the dominant class across most samples. Notably, TFAs were present in all categories, with pulses, nuts, and legumes showing the highest levels (9.7 ± 7.1%), due to repeated frying and degradation of unsaturated oils. The results emphasize the need for regulatory oversight and healthier oil usage in street food preparation. The validated method provides a robust tool for future monitoring and nutritional risk assessment in informal food sectors.