Purification of anthocyanins from jamun (Syzygium cumini L.) employing adsorption

• Adsorption was successfully employed for purification of jamun anthocyanins.
• Adsorption process was correlated best using Langmuir isotherm.
• Evaluation of purified anthocyanins ensured the stability of anthocyanins.
• HPLC–MS/MS was carried out to know the different anthocyanins of jamun.

The present study deals with the downstream processing of anthocyanins from jamun (Syzygium cumini L.) in order to obtain anthocyanins in a purified form. Adsorption was carried out employing six different adsorbents and among these, Amberlite XAD7HP showed the highest adsorption capacity (1.07 mg/mL of adsorbent) and desorption ratio (87.62%). Aqueous acidified ethanol (above 40%, v/v) could effectively elute the anthocyanins. Adsorption results were found to correlate best using the Langmuir equation at all the temperatures studied. Second order kinetics model was found to be more appropriate to describe the adsorption of anthocyanins. The dynamic adsorption process parameters for the purification of anthocyanins using Amberlite XAD7HP arrived at were as follows; for adsorption: processing volume, flow rate and temperature were 6.5 BV, 1 mL/min and 25 ± 1 °C, respectively and for desorption: eluent volume and flow rate were 4 BV of acidified aqueous ethanol (40%, v/v) and 1 mL/min, respectively. Anthocyanins extract after purification was found to be free of sugars, which are the major cause for degradation of anthocyanins. After the purification by adsorption, the degradation constant and non-enzymatic browning index of anthocyanins were found to decrease from 0.93 to 0.19 and 0.45 to 0.29, respectively. The qualitative determination of anthocyanins after adsorption was evaluated by the physio-chemical characteristics and the structural stability was confirmed by HPLC–MS/MS.