Nuclear magnetic resonance and chemometrics in profiling virgin coconut oil and thermally degraded coconut oil

• Main Author: Flores, Annabelle C.
• Format: text
• Language: English
• Published: Animo Repository 2023
• Subjects: Coconut oil; Nuclear magnetic resonance; Chemometrics; Food Chemistry
• Online Access: https://animorepository.dlsu.edu.ph/etdd_chem/6; https://animorepository.dlsu.edu.ph/context/etdd_chem/article/1007/viewcontent/2024_Flores_Nuclear_Magnetic_Resonance_and_Chemometrics_in_Profiling_Virgin_C.pdf
• Institution: De La Salle University

Virgin coconut oil (VCO) and heat-treated refined, bleached, and deodorized coconut oil (RBDCO) are economic products of the coconut industry that are significant contributors to the Philippine economy. These edible oils offer various health benefits and applications. However, the quality and authenticity of these oils can be affected by different factors, such as the origin, processing method, adulteration, and thermal degradation. There is a need to develop a method to characterize the chemical composition of coconut oil and to discriminate between different types of coconut oil towards a better understanding of its unique consumer value. This work explored on discovering a chemical marker that discriminates different oil samples. VCO samples were collected from different sources. Using 1H NMR spectroscopy and chemometric analysis (PLS-DA and sPLS-DA), changes in the composition of VCO based on geographical origin showed distinct regional variations in VCOs from Luzon, Mindanao, and Thailand, where lauric acid emerged as a chemical marker. In terms of VCO processing methods, chemometric analysis using sPLS-DA revealed the fermentation method is distinctly separated from the expeller and centrifugation methods. The adulteration of VCO was also investigated using NMR techniques and chemometrics (PCA, PLS-DA, and sPLS-DA) to discriminate pure VCO from VCO adulterated with soybean oil (SO). The linoleoyl moieties emerged as a chemical marker in detecting the presence of SO as an adulterant. The degradation of RBDCO based on continuous heat treatments at around the 180 °C frying temperature (150, 175, 200 °C) at different heating times (1-12 hours) was likewise investigated using NMR and chemometrics. Results showed that the presence of n-alkanals is a chemical marker in evaluating the thermal stability of RBDCO. The results demonstrate that NMR combined with chemometrics is an effective and reliable method for assessing and verifying the quality and authenticity of coconut oil, as well as for monitoring its thermal behavior. This study provides useful information for the coconut oil industry, food manufacturers, regulatory agencies, and consumers.