The Employment of FTIR Spectroscopy and Multivariate Data Analysis for Authentication Study of Sacha Inchi Seed Oil

Abstract

Sacha inchi (Plukenetia volubilis) is recognized as one of the world’s most versatile plants, with nearly all parts suitable for use as food ingredients. Sacha inchi seed oil (SIO) commands a premium price in the online market, approximately tenfold higher than conventional vegetable oils such as palm oil (PO), making it a prime target for economically motivated adulteration. This study aimed to establish a robust analytical approach for the discrimination and quantification of PO and soybean oil (SBO) adulterants in authentic SIO using Fourier Transform Infrared (FTIR) spectroscopy coupled with chemometrics. FTIR spectral data were acquired for pure SIO, PO, SBO, and their mixtures across the mid-infrared range (4000–650 cm⁻¹). Principal component analysis (PCA) of full-spectrum absorbance values revealed spectral proximity between SIO and SBO, indicating potential challenges in visual differentiation. Principal component regression (PCR) applied to selected spectral regions (3010–2830 and 1800–700 cm⁻¹) yielded the highest calibration and prediction performance, with coefficients of determination (R²) values of 0.9991 and minimal root mean square error of calibration (RMSEC=0.620) and validation (RMSEP=0.658). The developed models demonstrated high accuracy and precision, validating the reliability of FTIR-chemometric integration for authenticating SIO and detecting adulteration with lowercost oils. This approach offers a rapid, non-destructive, and cost-effective solution for quality control in functional oil authentication.