Quantitative Analysis of Peroxide Value in Virgin Coconut Oil by ATRFTIR Spectroscopy

Abstract

Oxidation of fats and oils is an important indicator for performance and shelf life of oils. As other vegetable oils, virgin coconut oil (VCO) is not susceptible to lipid oxidation. Thus, a rapid method for quantitative analysis of peroxide value in VCO was developed in this study using Fourier transform infrared (FTIR) spectroscopy coupled with attenuated total reflectance (ATR). Thirty training samples of VCO were subjected to oxidative condition in convection oven at temperature of 70⁰C up to 20 days to accelerate the lipid oxidation process. The peroxide values were determined periodically using the standard method of American Oil Chemists' Society (AOCS) and then analyzed with FTIR spectroscopy. Calibration model using partial least square (PLS) was developed by studying the spectral features for regions that correlated with peroxide value content (absorption of oxidation compounds band near 988 to 900 cm -1 ) and validated by removing one sample at a time. A linear calibration curve was obtained for the actual value against FTIR predicted value which yields an equation of y = 1.0398x + 0.0468 and satisfactory results of root mean square error of prediction (RMSEP) of 0.4978 and correlation coefficient (R 2 ) of 0.9826. Thus, FTIR spectroscopy with PLS regression can serve as important tools for determining the peroxide value in VCO. Application of FTIR is rapid, accurate and environmental friendly compared to the conventional chemical analyses.

Fatty Acids Composition and Physico-Chemical Constants of Punica Granatum L. Seed Oil

“…Oxidative stability is an important indicator to determine oil quality and shelf life [21]. The level of unsaturation of the oils may be expressed by the iodine numbers.…”

Infrared spectroscopy for quantitative analysis and oil parameters of olive oil and virgin coconut oil: A review

“…[48] The actual value of PV A c c e p t e d M a n u s c r i p t 14 FTIR spectroscopy has been used for stability of VCO during thermal oxidation.…”

Evaluation of Oxidation and Quality Parameters of Babassu Oil by Medium Infrared Spectroscopy with Fourier Transform (FTIR) and Multivariate Calibration

“…O número de peróxidos presentes em óleos vegetais reflete seu nível de oxidação e consequentemente sua tendência em tornar-se rançoso. 15 Os métodos oficiais para determinação desses parâmetros fundamentam-se nos padrões da American Oil Chemist's Society (AOCS). No entanto, os métodos químicos consomem muito tempo e são laboriosos, apesar de relativamente simples.…”

“…21,22 Porém, ela tem ganho popularidade na análise quantitativa devido ao fato de que, a energia emitida por infravermelho é diretamente proporcional a concentração de compostos que estão presentes na amostra. 23 A FTIR tem sido avaliada na quantificação de vários parâmetros de controle de qualidade de óleos, 24 inclusive índice de peróxido 15,25 e de acidez. 14,26 Por ser uma técnica não-destrutiva, consumir pouco tempo de análise e gerar pouco resíduo químico, essa técnica tem sido muito aplicada na análise de óleos.…”