Rapid determination of saponification value in red fruit oil by infrared spectroscopy and partial least square calibration

Abstract

A simple, rapid and reproducible method for determining the Saponification Value (SV) of Red Fruit Oil (RFO) was developed using Attenuated Total Reflectance-Fourier Transform Infrared (ATR-FTIR) spectroscopy in combination with multivariate calibration of Partial Least Square (PLS). A calibration model was developed using a series of RFO subjected to several thermal treatments, namely at ambient temperature 28, 100, 150, 180, 200 and 300°C, respectively. Based on the optimization processes, the FTIR spectra of RFO samples were measured in the frequency region of 1145-1168 cmG1 for SV determination. The relationship between actual values of SV as determined using AOCS method and FTIR predicted value as determined with FTIR spectroscopy in combination with PLS calibration model showed a close relationship with coefficient of determination (R2) of 0.998 and the value of Standard Error of Calibration (SEC) was 0.79%. This study concluded that ATR-FTIR spectra can be used to determine SV of RFO. The developed method is simple, rapid with a total analysis time per sample of less than 2 min and environment friendly.