Xingguo Wang

Kinetic study on the effect of ultrasound on lipase-catalyzed hydrolysis of soy oil: Study of the interfacial area and the initial rates

Comparative studies of lipase-catalyzed hydrolysis of soy oil takes place at the interface between the oil and the aqueous solution in solvent-free system were carried out in shaking bath and in ultrasonic bath. The interfacial area between the oil phase and the aqueous phase influences the rate of hydrolysis. Compared to shaking bath, ultrasonic shaking was found to be a more effective procedure to disperse the oil in water. Larger interfacial area and smaller drop size could be obtained in ultrasonic bath. The initial rate of hydrolysis was increased with the increasing of interfacial area. In ultrasonic bath, the highest initial rate of reaction was obtained with the oil volume fraction of 0.7, which was in accord to the highest interfacial area obtained with the oil volume fraction of 0.7, when the ultrasonic power was 1.64W/cm(2). The higher initial rate of hydrolysis was 161mol/m(3)min. The ultrasonic bath was a useful way to disperse soy oil in water to obtain a larger interfacial area, which caused the higher initial rate of soy oil hydrolysis in the solvent-free system.

Spectrophotometric determination of total serotonin derivatives in the safflower seeds with Ehrlich's reagent and the underlying color reaction mechanism.

A new spectrophotometric method for the determination of total serotonin derivatives in the safflower (Carthamus tinctorius L.) seeds is described. The determination is based upon a color reaction between serotonin derivatives and p-dimethylaminobenzaldehyde (Ehrlichs reagent), which follows the electrophilic substitution reaction mechanism at the indole ring. The main factors affecting correct measurement of total serotonin derivatives concentration were studied. The maximum absorption wavelength of the complex was determined at 625nm. Lambert-Beers law is obeyed in the concentration range of 0.025-0.5mmol/l, with a correlation coefficient (R(2)) of 0.9996, a recovery of 99.7%, and a relative standard derivation (RSD) of 1.5%, respectively. The proposed method presented satisfactory results in the determination of total serotonin derivatives in the extract from a strain of safflower seeds, and thus is recommended as a routine method for total serotonin derivatives quantitation.