Effect of Drying and Extraction Methods on Phytochemicals and Free Radical Scavenging Activity of Camellia assamica

Abstract

 The  results achieved from  this research  demonstrated  that  scavenging  activity  of  Camellia assamica, tea increased  significantly during freeze drying operation when  comparing with vacuum dryer  and oven dryer.  Freeze drying  is  found as finest method and the product shows outstanding results regarding phenolic content and scavenging potency. Moreover among the three extraction methods we found that ethanol extraction was best regarding the determination of the phenolic content, flavonoid content and free antioxidant activity.  Interestingly, the best rehydration capability  of  green tea was also found on freeze drying. Our study also demonstrated the presence of wide variation in caffeine content between different tea samples studied. In this research, we found that  the  caffeine content  was  approximately  between  2.89%  -  4.1%. The variation of caffeine content depending on some major factors like diversity of tea, location, time of cultivation, age and other climatological conditions for tea plantation, it is therefore reasonable that the previous factors might be responsible for the variation of caffeine present in tea samples. We also observed that maximum amount of caffeine   was  found  in  sample  1 i.e. Mithinga  Tea  Garden.  Tea  leaves  lose  their  tannin  contents  with  increase  in  age analyzed that tannin occurs at almost 4.5%. This difference may be by cause of different variety selected for analysis and also for different manufacturing process. Overall, our study reflects that ethanol extraction and freeze drying method was found to be the finest in terms of determining  the constituients of tea.