Infrared Spectroscopy-based Principal Component Analysis For Differentiation Of Soaps Produced From Vegetable Oils And Animal Fats

The soap-making process involves heating, encompassing various mechanisms such as oxidation and thermal reactions. These reactions can potentially modify the chemical structure of both animal and vegetable oils, making it challenging to trace their original sources in processed products. In this study, seven distinct bar soaps were produced using the saponification method, employing locally available commercial oils, including Canola Oil (LA), Coconut Oil (CN),Corn Oil (CO), Olive Oil (OV), Palm Oil (PO), Sunflower Oil (SF), and animal fat from Lard (LD). The chemical profiles of the raw lard and vegetable oils, as well as their respective soaps and the fats/oils extracted from the soap, were obtained using Attenuated Total Reflectance Fourier Transform Infrared (ATR-FTIR) spectroscopy, followed by analysis through a chemometric approach. Principal Components Analysis (PCA) was employed after pretreatment of the FTIR dataset to discern their distribution in a score plot for determining clustering. For clustering lard from vegetable oils, the wavenumbers ranging from 1500 to 1000 cm-1 were selected in the PCA analysis. The extraction of fats/oils from the final product, coupled with the chemometric method, successfully demonstrated the differentiation of soaps produced
from vegetable oils and animal fats commonly sold in the market.