Application of NIR Spectroscopy by Determination of Quality Properties of Vegetable Oils and Their Derivatives

Abstract

This study shows that near-infrared spectroscopy is a reliable technique to determine the concentration of the key fatty acid (FA) components (oleic, linoleic, linolenic acid), the acid number, the iodine value and the kinematic viscosity at 40 and 100 °C in sunflower and rapeseed oils. To establish the chemometric model, a calibration set of 36 rapeseed oil samples and 47 sunflower oil samples were used and 51 oil samples were used for external validation. All samples were measured on a BRUKER-MPA spectrometer in transmittance mode. The samples were scanned in a wave number range of 12000–4000 cm-1 with a resolution of 2 cm-1. The sample scan time was 32 scans. To develop and optimize the calibration models partial least squares (PLS) method was used with cross validation. The result of the experiment showed that this technique is sufficiently accurate for estimating the FA composition, the acid number, the iodine value and the kinematic viscosity at 40 and 100 °C in sunflower and rapeseed oil. The calibration results had root mean square error of cross validation (RMSECV) for oleic acid, linoleic acid, linolenic acid, acid number, iodine value, viscosity at 40 °C, viscosity at 100 °C of 0.395, 0.451, 0.0932, 0.208, 0.418, 0.12, 0.0237 respectively and determination coefficient (R2) (%) for the same properties of 99.96, 99.97, 99.95, 99.47, 99.88, 99.7, 99.22 respectively.