Sonochemically prepared bovine serum albumin microcapsules: factors affecting the size distribution and the microencapsulation yield

Abstract Bovine serum albumin (BSA) microcapsules containing organic solvents have been synthesized from the mixture of bovine serum albumin solution and organic solvents using an ultrasound irradiation technique. The microencapsulation yield of the organic solvents and the size distribution of the microcapsules have been determined as a function of various experimental parameters, such as frequency of the ultrasound, the time period of ultrasound irradiation, albumin concentration, the kind of organic solvents and their volume fractions. As the concentration of bovine serum albumin increases from 0.005 to 0.02% (w/v), the microencapsulation yield increases. Also, the microencapsulation yield decreases when the volume fraction of toluene, a microencapsulated organic liquid, increases over 0.5. The highest microencapsulation yield was obtained by the irradiation of the ultrasound at 28 kHz. The microencapsulation yield was lower at 45 kHz and no microcapsules were obtained at 100 kHz. Ultrasound irradiation between 5 and 10 min is required to obtain microcapsules. Microcapsules with a narrower size distribution were obtained by the ultrasound irradiation at 45 kHz than at 28 kHz. Also, the size distribution of the microcapsules is dependent on the kind of liquids, which are microencapsulated. Microcapsules containing toluene have a narrower size distribution than those containing chloroform. The average diameter of the microcapsules containing toluene is smaller than those containing chloroform. When vegetable oils, such as soybean oil and peanut oil are microencapsulated, the size of the microcapsules is smaller than that of microcapsules containing toluene or chloroform.