Microwave and atmospheric cold plasma aided debittering of giloy (Tinospora cordifolia Miers.) juice: Effect on bioactive compound content

Abstract

Giloy (Tinospora cordifolia Miers.) is a well-known herbal medicinal plant that is therapeutically rich in secondary metabolites but is bitter in taste, thereby limiting its potential to be used as a functional food. Hence, this study was aimed at reducing the bitterness of giloy juice through cold plasma (CP) (10–30 kV, 10–40 min, CCD with 5 center points) and microwave (MW) (100–180 W, 5–15 min) applications, making it available in a more palatable form, which is quite a noble approach unlike already existing debittering methods like ultrasound and β-cyclodextrin incorporation methods. Bicyclic diterpenoids are the principal bitterness-causing element in giloy; hence, total terpenoid content (TTC) was taken as the gauging factor to scale the bitterness while targeting higher concentrations of various bioactive compounds (BCs) through FRAP, TPC, TFC, and DPPH radical scavenging activity assays. RSM is used to address the change in BCs’ content with respect to the influencing factors. A decrease in TTC in giloy juice was observed by 73% after a CP treatment of 30 kV for 25 min and by 26.5% in a MW treatment of 100 W for 15, which the FTIR results also corroborate. The physical surface morphology of the sample was found to be affected by the CP and MW treatments, as evidenced by the SEM images, which aided in the evaporation and diffusion of BCs and further variations in their functionality owing to the operating conditions. CP though was effective in reducing the TTC but MW was good at extracting terpenoids along with other BCs.