Extraction evaluation and chemical characterization of ginger oleoresins; a functional food ingredient

Ginger oleoresins being rich in coloring, flavoring and other phytochemical compounds have strong potential for industrial applications. In this study, 5 different oleoresins' extraction methods are compared in terms of yield and phytochemical characterization of oleoresins. Petroleum ether exhibited the highest yield (5.51 +/- 0.08%) among all selected methods. In terms of chemical characterization of extracted oleoresins, oleoresins yielded by supercritical fluid extraction (SCFE) exhibited the highest total phenolic content (TPC), Total f1avonoid content (TFC), total volatiles and antioxidant activity. SCF extracted oleoresins with best phytochemical profiling were further subjected to structural studies through fourier transform infrared (FTIR) spectroscopy and fatty acid profiling through gas chromatography attached with flame ionization detector (GC-FID). Several functional groups were detected through FTIR including alkane with the highest peak at 2934.0968 cm- 1 wave number indicating C-H bonding followed by ester with C = O stretching bond type at 1751.5953 cm- 1 wave number. Similarly, total 11 fatty acids were analyzed ranging from 3.00 to 25.30% concentration through GC-FID. Methyl palmitoleate was found in the highest concentration (25.30%) with 21.36 min. retention time while methyl butyrate was detected in the lowest amount (3.00%) with 2.18 min. retention time. Data was interpreted statistically and it was concluded that oleoresins extracted through SCFE exhibited a bit lower yield (3.98 +/- 0.05%) but were found best in terms of purity and phytochemical characterization. Oleoresins' yield and quality can further be enhanced by optimizing the extraction conditions resulting in their better and more acceptable utilization by food and other pharmaceutical industries.