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a b s t r a c tThe aim of this work was to encapsulate casein hydrolysate by complex coacervation with soybean protein isolate (SPI)/pectin. Three treatments were studied with wall material to core ratio of 1:1, 1:2 and 1:3. The samples were evaluated for morphological characteristics, moisture, hygroscopicity, solubility, hydrophobicity, surface tension, encapsulation efficiency and bitter taste with a trained sensory panel using a paired comparison test. The samples were very stable in cold water. The hydrophobicity decreased inversely with the hydrolysate content in the microcapsule. Encapsulated samples had lower hygroscopicity values than free hydrolysate. The encapsulation efficiency varied from 91.62% to 78.8%. Encapsulated samples had similar surface tension, higher values than free hydrolysate. The results of the sensory panel test considering the encapsulated samples less bitter (P < 0.05) than the free hydrolysate, showed that complex coacervation with SPI/pectin as wall material was an efficient method for microencapsulation and attenuation of the bitter taste of the hydrolysate.

Microcapsules were prepared using the probiotic microorganisms Lactobacillus acidophilus (La-05) and Bifidobacterium lactis (Bb-12) and the spray drying technique and cellulose acetate phthalate as the wall material. This study evaluated the resistance of these microorganisms to drying at three temperatures and also the in vitro tolerance of the free and microencapsulated form to pH values and bile concentrations similar to those found in the human stomach and intestine. With an air entry temperature of 130 degrees C and exit temperature of 75 degrees C, the number of viable cells of B. lactis was practically unaltered, whereas the population of L. acidophilus was reduced by two logarithmic cycles. B. lactis was more resistant to the drying process than L. acidophilus under all conditions tested. The morphology of the microcapsules was determined by scanning electron microscopy and the microcapsules presented a rounded external surface containing concavities, a continuous wall with no apparent porosity, average size of 22 microm, moisture content varying from 5.3 to 3.2% and water activity between 0.230 and 0.204. After inoculation into HCl solutions with pH values adjusted to 1 and 2, incubated anaerobically at 37 degrees C, and plated after 0, 1 and 2 h of incubation, microcapsules were effective in protecting the microorganisms, while the populations of both free microorganisms were eliminated after only 1 h at the acidic conditions. Microencapsulated B. lactis and L. acidophilus, both free and microencapsulated, were also resistant after 12h to bile solutions.

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