RAPID INVESTIGATION OF THE METABOLITE CONTENT IN HIBISCUS SABDARIFFA var. UKMR-2 CULTIVATED UNDER THE INFLUENCE OF ELEVATED CO2 USING TRI-STEP FT-IR SPECTROSCOPY

Abstract

Rapid methods based on untargeted analysis technique such as Fourier Transform Infrared (FT-IR) spectroscopy can provide much faster and easier solution for food authentication. However, studies on the metabolite content in UKMR-2 calyces using FT-IR spectroscopy has not been reported yet in any previous studies. Thus, the present study was performed to analyze the differences in metabolite content in UKMR-2 calyces under the influences of different [CO2] treatment by applying tri-step infrared based fingerprinting. The UKMR-2 plant cultivation was exposed to ambient [CO2] (400 µmol/mol) and elevated [CO2] (800 µmol/mol) treatment. The UKMR-2 calyx extracts were analysed by conventional infrared (1D-IR), second derivative infrared (SD-IR) and two-dimensional correlation infrared (2D-IR) spectroscopy. The 1D-IR spectrum results revealed a similar absorption spectrum in the range of 1900 - 650 cm-1, which suggest similar major metabolites content present in both extracts. For SD-IR spectrum, both treatments clearly showed have more peaks with different shape, position and intensity in the range of 1650 - 1450 cm-1 and 1200 - 950 cm-1, which is likely to have different flavonoid and carbohydrate content in UKMR-2 calyces. The 2D-IR synchronous correlation spectrum in the range of 1000 – 650 cm-1 clearly distinguished the metabolite content in the UKMR-2 calyx extract from different [CO2] treatment. Therefore, this tri-step infrared based fingerprinting has the potential as one of the effective methods to discriminate extract samples with similar infrared fingerprint features and indicate that the metabolite content in UKMR-2 calyces were influenced by different [CO2] treatments.