Hydrocolloid-Stabilized Borage Oil-in-Water Emulsions as Reaction Media for Immobilized Amano Lipase A: Effects of Formulation Composition and High-Shear Homogenization

Borage-oil emulsions provide a multiphase reaction medium in which formulation composition can strongly influence immobilized lipase performance. This study evaluated Amano lipase A from Aspergillus niger (AA-ANL) immobilized on IB-ADS-3 in borage-oil emulsion media containing hydrocolloids and conventional formulation additives. Each experimental unit was prepared independently and consisted of an emulsion and an immobilized catalyst (n = 3). Gum arabic, guar gum, gellan gum, and sodium dodecyl sulfate (SDS) exhibited concentration-dependent responses. Among non-homogenized formulations, the composition containing 10.0% gum arabic and 0.1% guar gum showed the highest observed lipolytic activity (32.27 ± 1.96 U/g support). In this formulation, a reaction containing 50 mg of support carrying immobilized AA-ANL exhibited an activity of 1.61 ± 0.10 U, whereas the corresponding reaction with 10 mg of native AA-ANL yielded 0.17 ± 0.00 U. Because the assays combined different amounts and physical forms of enzyme, these values were compared only at the reaction-system level and do not represent an enzyme-specific activity ratio. In a 4 × 2 two-way ANOVA, both the hydrocolloid system and SDS significantly affected lipolytic activity. Moreover, the magnitude of the SDS effect varied across hydrocolloid systems (system × SDS interaction, p = 0.008). The influence of Carbopol® Ultrez 10 likewise depended on the presence of SDS, as indicated by a significant interaction (p = 0.015), while Poloxamer 188 markedly reduced lipase activity at all tested concentrations. Representative microscopy images revealed formulation-dependent differences in emulsion microstructure. However, the qualitative structural features did not consistently correspond to differences in lipolytic activity among formulations. High-shear homogenization of the selected gum arabic–guar gum formulation (performed at 6500 rpm for 3 min) increased observed lipolytic activity to 199.93 ± 5.77 U/g support, representing a 6.2-fold increase (Welch’s t-test, p < 0.001). The magnitude of this effect should be interpreted within the context of the homogenization conditions tested. Overall, these findings demonstrate that the observed lipolytic activity of the AA-ANL-IB-ADS-3 system varied with reaction-medium composition and processing conditions.