Edible oil adulteration
is a common and serious issue faced by
human societies across the world. Iodine value (IV), the total unsaturation
measure, is an authentication tool used by food safety officers and
industries for edible oils. Current wet titrimetric methods (e.g.,
Wijs method) employed for IV estimation use dangerous chemicals and
elaborate procedures for analysis. Alternate approaches for oil analysis
require sophisticated and costly equipment such as gas chromatography
(GC), liquid chromatography, high-performance liquid chromatography,
mass spectrometry (MS), UV-Visible, and nuclear magnetic resonance
spectroscopies. Mass screening of the samples from the market and
industrial environment requires a greener, fast, and more robust technique
and is an unmet need. Herein, we present a handheld Raman spectrometer-based
methodology for fast IV estimation. We conducted a detailed Raman
spectroscopic investigation of coconut oil, sunflower oil, and intentionally
adulterated mixtures with a handheld device having a 785 nm excitation
source. The obtained data were analyzed in conjunction with the GC–MS
results and the conventional wet Wijs titrimetric estimated IVs. Based
on these studies, a specific equation for IV estimation is derived
from the intensity of identified Raman spectral bands. Further, an
algorithm is designed to automate the signal processing and IV estimation,
and a stand-alone graphical user interface is created in user-friendly
LabVIEW software. The data acquisition and analysis require < 2
minutes, and the estimated statistical parameters such as the
R
2
value (0.9), root-mean-square error of calibration
(1.3), and root-mean-square error of prediction (0.9) indicate that
the demonstrated method has a high precision level. Also, the limit
of detection and the limit of quantification for IV estimation through
the current approach is ∼1 and ∼3 gI
2
/100
g oil, respectively. The IVs of different oils, including hydrogenated
vegetable oils, were evaluated, and the results show an excellent
correlation between the estimated and reported ones.