Qualitative analysis of desi ghee, edible oils, and spreads using Raman spectroscopy

Abstract

Keeping in view the importance of dietary fats in modulating disease risk, a study was planned to compare edible oils, spreads, and desi ghee based on fatty acid composition through Raman spectroscopy. The double bonds in unsaturated oils tend to react more with oxygen causing oxidative stress in living cells; therefore, the excessive use of processed vegetable oils may pose risk for human health. In the spectral analysis, Raman peaks at 1063 and 1127 cm−1 represent out‐of‐phase and in‐phase aliphatic CC stretch for saturated fatty acids. The peak at 1300 cm−1, labeled for alkane, decreases with increase in the double bond contents (unsaturation). Further, the Raman peak at 1655 cm−1 showed a monotonic increase as a function of unsaturation. The double bond contents in the Raman spectra from 1650–1657 cm−1 represent unsaturated fatty acids that changes during the synthesis of spreads and banaspati ghee. Desi ghee, extracted from cow and buffalo milk, showed distinctive Raman peaks at 1650 and 1655 cm−1, which originates because of isomers of conjugated linoleic acid. These Raman shifts differentiated desi ghee from other artificially produced banaspati ghee, spreads, and oils. Conjugated linoleic acid has proved to be anti‐carcinogenic, anti‐inflammatory, and anti‐allergic properties; therefore, the limited use of desi ghee may reduce the risk of cardiac diseases. Principal component analysis has been applied on the Raman spectra that clearly differentiated desi ghee, mono‐unsaturated extra virgin olive oil, and extra virgin olive oil spread from other oils, oil mixtures, spreads, and ghee. In addition, principal component analysis has been blindly applied successfully on 13 unknown samples to classify them with reference to the known ghee sample. Copyright © 2016 John Wiley & Sons, Ltd.

Raman hyperspectral imaging and analysis of fat spreads

“…Raman spectroscopy is widely used to study the distributions of different compounds, such as lipids and proteins in foods . Applications of Raman imaging in food research are more limited.…”

“…Raman spectroscopy is widely used to study the distributions of different compounds, such as lipids and proteins in foods. [13][14][15][16] Applications of Raman imaging [17] in food research are more limited. The technique has been used to study the microstructure of cheese, [18] chocolate, [19,20] cereal grains, [21,22] bread dough, [23] mayonnaise [24,25] and dairy spread [13] , the fat crystallinity of meat [26] , and the distribution of melamine in dry milk.…”

Recent advances in linear and non‐linear Raman spectroscopy. Part XI

“…Ali and co‐workers described the qualitative analysis of the dietary fats such as desi ghee, edible oils, and spreads, using Raman spectroscopy. Principal component analysis has been applied to the Raman spectra that clearly differentiated desi ghee, mono‐unsaturated extra virgin olive oil, and extra virgin olive oil spread from other oils, oil mixtures, spreads, and ghee . Buzzini and Suzuki described forensic applications of Raman spectroscopy for the in situ analyses of pigments and dyes in ink and paint evidence.…”

“…Principal component analysis has been applied to the Raman spectra that clearly differentiated desi ghee, mono-unsaturated extra virgin olive oil, and extra virgin olive oil spread from other oils, oil mixtures, spreads, and ghee. [162] Buzzini and Suzuki described forensic applications of Raman spectroscopy for the in situ analyses of pigments and dyes in ink and paint evidence. In this review, a comprehensive perspective of the forensic applications of Raman spectroscopy for the characterization, differentiation, comparison, and identification of trace evidence and questioned documents, consisting of paint and ink, respectively, is presented.…”

Characterisation of cow and buffalo ghee using fluorescence spectroscopy

“…Due to nutritious benefits of desi ghee, it becomes imperative to investigate its molecular composition for the satisfaction of end users. Few studies have been reported on ghee, which described its basic extraction methods (Ganguli and Jain ), chemical composition (Sserunjogi et al ), storage effects on its molecular composition (Andrewes ) and qualitative analysis of ghee, edible oils and margarines (Ali et al ). Recently, heating effects on its molecular composition has been reported using Fluorescence spectroscopy (Ahmad and Saleem ).…”