Extraction of Phenolics, Proteins and Antioxidant Activity from Defatted Tamarind Kernel Powder

The proteins, phenolics and antioxidants were extracted from defatted tamarind kernel powder (10 % extract) using different aqueous solutions of sodium hydroxide, sodium chloride, buffers and water. The extraction of proteins (8.92 gm/100 gm), phenolics (0.45 gm/100 gm) and antioxidants (1.57 gm/100 gm) were better with 0.1 M NaOH when compared to that of buffers, NaCl and water extraction procedures. Further, a 1 % and 5 % extract of defatted tamarind kernel powder was prepared using different concentrations of NaOH (0.1 M to 0.5 M). Maximun amount of proteins (18.2 %), phenolics (0.58 %) and antioxidants (3.66 %) were extracted (1 % extract of the sample) using 0.1 M NaOH. However, increase in the concentration of NaOH did not improve the extraction efficiency. Phenolics and antioxidants are better extracted with organic solvents. Hence, extraction was carried out using aqueous solutions of acetone, ethanol and methanol (80 % solutions). But, the extraction of proteins (0.4gm/100gm), phenolics (0.1gm/100gm) and antioxidants (0.28gm/100gm) was very much less compared to that of 0.1 M NaOH extraction. In contrast, extraction using different concentration of organic solvent (methanol) in presence of alkali (0.1 M NaOH) resulted higher yields. Methanol at lower concentrations (upto 20 %) did not affect the extraction of proteins (20gm/100gm) and phenolics (1.4gm/100gm), but at higher concentrations (> 20%) decreased the extraction of proteins and phenolics. The reduction in the extraction of proteins is due to the insolubility of proteins at higher concentrations of methanol. On the other hand, the extraction of antioxidant (2.6gm/100gm) was almost constant upto 60% of methanol in presence of alkali. Commercial extraction of proteins from tamarind seed kernels can be carried out employing aqueous organic solvents containing alkali.