Classification of Groundnut Oil Using Advanced ATR-MIR Spectroscopy and Chemometrics

In this work, attenuated total reflectance (ATR) mid infrared (MIR) spectroscopy has been used for analysis of edible cold pressed (CP) and other different brands of refined/hot pressed (HP) groundnut oils (Brand 1-3) for the first time. Frequencies at the MIR region, mainly at wavelengths of 5-11 mu m, are examined for classification of groundnut oils. The effect of temperature of cold pressed and hot pressed commercial oil brands are investigated by heating oil samples at different temperatures of 50, 75, 100, 125, 150, 175, and 200 degrees C. Partial least square regression (PLSR) and K-means derivative spectra revealed the best calibration models to differentiate cold pressed oils and different brands of hot pressed groundnut oil samples, with coefficient of determination (R2) of 0.999 and root mean standard error of cross validation (RMSECV) of 0.285 and 0.373, respectively. It is noted that pure cold pressed and commercial brand groundnut oils showed a different trend of oxidation at different temperatures. Heated cold-pressed groundnut oil revealed notable spectral variations, than heating other commercial brands of oil.

Automated summary

In this study, ATR-MIR spectroscopy was used to analyze the characteristics of cold pressed and hot pressed groundnut oils for the first time. The effect of temperature on the oils was also investigated. The results showed that PLSR and K-means derivative spectra provided the best calibration models for differentiating cold pressed oils and different brands of hot pressed oils.