Thermal Processing Effects on in vitro Antioxidant Potential of Fresh and Packaged Turmeric (Curcuma longa), Coriander (Coriandrum Sativum) and Cumin (Cuminum Cyminum)

Turmeric (Curcuma longa), Coriander (Coriandrum sativum) and Cumin (Cuminum cyminum) are three very important spices and essential flavoring agents in many cuisines, particularly in South-East Asia. The spices are available both as fresh and in commercial packages. The present study deals with the analyses of their in vitro antioxidant profile before and after thermal processing in water. The thermal processing resembled methods commonly practiced in India for cooking, viz. pressure cooking and microwave treatment. The assays performed included DPPH radical decolorization assay, reducing power assay and assay for total phenolic contents. It was observed that the antioxidant activity and total phenolic content was different in the two types of spices, and the packaged spices were better than the fresh samples. Antioxidant activity improved in case of all the three spices after thermal processing, probably due to better solublization of the antioxidants in hot water by thermal treatment. Improvement in the total phenolic contents also substantiated the radical scavenging abilities of the spices after aqueous extraction. Among the different extraction procedures, microwave extraction was found to be most effective with respect to radical scavenging abilities.