Metabolic Profiling of Averrhoa carambola Fruit Extract using UHPLC-ESI-QTOF-MS and Determination of the Concentration of Essential Elements using MP-AES

A rapid and sensitive ultra-high-performance liquid chromatography-electrospray ionization quadrupole time of flight mass spectrometry (UHPLC-ESI-QTOF-MS) based method was developed to separate and identify 44 phenolics and non-phenolics present in Averrhoa carambola fruit in three different stages of its growth. 5 anthocyanins, 9 phenolic acids, 3 flavones, 5 flavanols, 3 flavanones, amino acids, vitamins and other phenolic and non-phenolic compounds were identified. The identification and quantification of 27 bioactive compounds from methanolic star fruit extract are being reported for the first time. All the metabolites were quantified by normalizing the area under the peaks with that of the internal standard hydrocortisone. The extraction of metabolites by using a homogeniser (bead beater) was found to be the best method for the extraction of metabolites. Four essential microelements (Zn, Fe, Mn, Cr) and three macroelements (K, Mg, Na) were quantified from star fruit using MP-AES. The zinc concentration (6.988 mg/100 g) in star fruit was found to be higher than in many cereals, vegetables and fruits. The methanolic star fruit extract showed excellent DPPH scavenging activity of 93% after 30 min of incubation in dark for the dry weight sample concentration of 50 mg/ml. In conclusion, the UHPLC-ESI-QTOF-MS based method developed and MP-AES results presented here can be used in the quality control of food supplements and medicines.