In this study water solubility curves were constructed and calorimetric measurements obtained for reverse micellar systems consisting of an alcohol (isopropanol or butanol), surfactant (AOT) and organic solvent (isooctane or hexane). Also evaluated were the effects of alcohol and solvent type and surfactant concentration on the extraction of the α‐lactalbumin (α–la). From the obtained solubility diagrams for ternary systems, it was concluded that isooctane presented the highest water solubility capacity in the center of the micelle systems with hexane, since isooctane has greater molecular volume and greater effect of the surfactant aggregation number. With respect to the alcohols, it was observed that isopropanol and butanol act in the system as a co‐surfactant, since they prefer to adsorb at the water/solvent interface. It was also verified that butanol improved water solubility inside the reverse micellar due to its contribution to increase the critical packing parameter. The amount of α‐la extracted increased proportionally with the AOT concentration for systems with isooctane and hexane. However, for systems with the latter solvent, the concentration of extracted protein first increases and then decreases. The extraction power of reverse micellar systems with isooctane was influenced by the type of alcohol with butanol showing better results. For systems containing hexane there was no effect of the alcohol added to the system on extraction power of α‐lactalbumin.
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.g 1 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.
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