Synthesis of activated carbon from hydrothermally carbonized tamarind seeds for lipase immobilization: characterization and application in aroma ester synthesis

BACKGROUND This study aimed to evaluate the effect of hydrothermal carbonization on the activated carbons properties of tamarind seeds, which were used as a support in porcine pancreatic lipase (PPL) immobilization, and to evaluate the biocatalyst in the butyl butyrate synthesis. RESULTS The activated carbon from hydrochar (ACHT) had oxygen functional groups content about 32.5% higher and a lower point of zero charge (4.42) when compared to those obtained from crude bran (ACT). Differences in textural properties were also observed, with an average pore diameter of 3.20 and 6.46 nm for ACHT and ACT, respectively. The optimal immobilization pH was 5.0, resulting in enzyme loading of 71.8 ± 1.42 mg.g1 and 53.03 ± 0.31 mg·g−1, and in a hydrolytic activity of 222.47 ± 2.80 U·g−1 and 257.18 ± 7.31 U·g−1 for ACT and ACHT, respectively. The addition of Triton X‐100 0.025 w·v−1 to the immobilization buffer led to an increase in ~7% of the hydrolytic activity. The PPL immobilized in pH 5.0 was used in the butyl butyrate synthesis, using a mixture of butanol (240 mmol L−1) and butyric acid (120 mmol L−1), with an esterification yield of ±83% after 4 h of reaction at 40 °C. CONCLUSION The PPL immobilized on ACHT showed a small decrease in activity over time, with a residual esterification yield of 84% after 4 cycles of reuse. The present results suggest that the supported biocatalyst has the potential to be used in aqueous and organic media, such as hydrolytic lipid reactions and aroma synthesis mostly used in the food industry. © 2021 Society of Chemical Industry (SCI).