Agro-ecological region based variations in the antioxidant activity of tamarind (Tamarindus indicaL.) fruit pulp

Abstract

Tamarind (Tamarindus indica L.) is a tropical seasonal bearing fruit species grown in relatively dry regions in the tropics. Its sweet and aromatic fruit pulp contains polyphenols, influenced by regional and seasonal factors. Therefore this research investigated the variability of antioxidant activity (AOA) and total phenolic content (TPC) of tamarind fruit grown in six different-ecologically dissimilar growing regions. Ethanolic extracts of tamarind fruit pulp were prepared for analysis. Total phenolic content of the tested tamarind samples ranged within 0.77-5.85 mg GAE g-1 fresh weight (FW). Tamarind fruits collected from agro-ecological zone, DL3 (dry and warm region) had the highest TPC, followed by the fruits from IL1 (moderately dry and warm region) (5.39±1.8 mg GAE g-1 [FW]). Antioxidant activity of fruit pulp from relatively drier (low rainfall) regions, IL1 (70.17±9.9 mmol g-1 [FW]) and DL3 (69.18±7.2 mmol g-1 [FW]) were much higher than the other regions. The lowest AOA was found in the fruit samples from DL4 (30.7±1.1 mmol g-1 [FW]) which is geographically distant to DL3 and IL1. Positive correlations could be established between AOA and TPC contents (r=0.92) of the tamarind fruit pulp. Hence the influence of agro-ecological region based environmental conditions on the AOA and its major contributors, polyphenols in tamarind fruit pulp could be established.