Raman-Chemometric Framework for Rapid Authentication of Edible Oils in Processed Foods Using a Validated One Step Sampling Technique

Authentication of cooking oils in processed foods is essential for food safety, quality control, and regulatory compliance, yet routine analysis remains constrained by solvent-intensive extraction procedures and limited applicability to complex food matrices. This study presents a proof-of-concept Raman–chemometric framework for direct oil authentication in processed foods using minimal, solvent-free sample handling. Potato chips were selected as a representative fried food matrix, and five commonly used edible oils (sunflower, soybean, groundnut, palm, and vanaspati) were analyzed in both pure form and corresponding chip matrices to enable systematic cross-matrix evaluation. A one-step tissue paper blotting method was employed for rapid oil recovery, followed by Raman spectroscopic analysis. Fatty-acid-associated Raman bands were identified and systematically combined into chemically interpretable inter-peak intensity ratios reflecting variations in saturation and ester content. A statistically grounded two-stage marker selection workflow integrating Random Forest importance ranking with non-parametric Kruskal–Wallis testing was applied, followed by using one-way analysis of variance and coefficient of variation analysis. Five robust ratiometric markers (I₁₆₅₂/₁₇₄₂, I₁₆₅₂/₁₄₃₄, I₁₇₄₂/₁₂₅₉, I₁₆₅₂/₁₂₅₉, and I₁₂₉₆/₁₄₃₄) showed strong association with saturated versus unsaturated fatty acid profiles. Multivariate analysis based on these markers revealed pronounced separation among oil types (91% explained variance; F-values up to 22,629; p < 0.001) and statistically significant discrimination within chip matrices (77% explained variance), despite attenuation effects from the food matrix. Multivariate analysis of variance confirmed robust separation (Wilks’ Λ = 0.0307; p < 0.0001). Overall, this framework establishes an interpretable, extraction-free, and scalable foundation for high-throughput oil authenticity screening in processed foods.