The effect of pressure was studied in an enzymatic reaction with an immobilized biocatalyst. Naringinase immobilized by entrapment in calcium alginate beads was the biocatalyst used to catalyze, at high-pressure, the hydrolysis of naringin to naringenin. These molecules have great potential in the pharmaceutical industry due to their recognized anti-oxidant, anti-inflammatory, anti-carcinogenic, anti-hypertensive and hypocholesterolemic effects. At high-pressure, the influence of relevant parameters on naringinase catalytic activity such as temperature, substrate concentration, and biocatalyst reuse was studied. At 160 MPa, naringinase entrapped in Ca-alginate beads displayed higher activity, namely in the range of 35-40 degrees C, whereas the optimum, at atmospheric pressure, was 35 degrees C. The immobilized naringinase presented a Michaelis-Menten kinetic, with a 65% higher maximum initial rate (V-max(ap) = 0.069 mM min(-1)), and a 70% lower K-M(ap) (0.097 mM) at 160 MPa, as compared to kinetic parameters, at atmospheric pressure (V-max(ap) = 0.042 mM min-1 and K-M(ap) = 0.303 mM). A positive effect of pressure on naringin hydrolysis by immobilized naringinase, in MCa-alginate beads was confirmed with a negative activation volume (Delta V-not equal) of -9 mL mol(-1). The stability of immobilized naringinase was also evaluated at high-pressure. (c) 2006 Elsevier Inc. All rights reserved.