Effect of Traditional Sun Drying on Indigenous Star Fruit (Averrhoa Carambola) from India

Objective: The objective of the study was to analyse the effect of traditional sun drying on the antioxidant activity of Averrhoa carambola L using standard antioxidant assays and analytical techniques. Materials and Methods: Star fruit was shade dried and its aqueous acetone extract (SD) prepared. The antioxidant activity of aqueous acetone extract of fresh star fruit (SF) was compared with SD using assays like total phenolic content, DPPH free radical scavenging activity, ABTS·+ free radical scavenging activity, ferric reducing assay, phosphomolybdenum assay and metal chelating activity. HPLC-ESI-MS and FT-IR was used to identify the phytochemicals in SD and SF. Results: TPC of SD and SF was 1.0 and 2.7gGAE/100g extract respectively. IC50 of SD and SF in DPPH RSA was 100 and 150μg/ml while TEAC of SD and SF were 1.07 and 0.3 respectively. Antioxidant capacity of SD and SF was 392.5 and 113.75mmolesAAE/g extract. IC50 of SD was 147 ppm and that of SF, 123 ppm in TRP. The MCA of SD increased with increasing dose while SF showed no significant increase in activity. HPLCESI- MS and FT-IR enabled identification of three possible phytochemicals namely protocatechuic acid trimer (1) and sinpaic acid teramer (2) which contributed significantly to the distinct behaviour of both the extracts towards the different assays. Conclusion: The antioxidant activities of SF and SD behaved variedly with different assays which was contributed by the bioactive compounds present in both extracts. Clearly, the shade drying process effected the antioxidant potential of star fruit.