A new microencapsulation technique of probiotic cultures using pectin and whey protein

GEREZ C.L., FONT DE VALDEZ G., GIGANTE M.L., GROSSO C.

San Miguel de Tucumán, Tucumán, Argentina

Simposio; III Simposio Internacional de Bacterias Lácticas y 2do. Encuentro de la Red Argentina de Bacterias Lácticas (Red-BAL); 2009

Centro de Referencia para Lactobacilos (CERELA-CONICET)

Most probiotic lactic acid bacteria lack the ability to survive in the harsh acidity and bile concentrations commonly encountered in the human´s gastrointestinal tract. Microencapsulation has been widely applied to enhance the viability of probiotics both in commercial products and in the intestinal tract by using various encapsulating materials and methods. However, results reported on the effectiveness of encapsulation for protecting probiotic cultures are not always favorable. The aim of this work was to encapsulate a probiotic strain of Lactobacillus casei, using pectin and whey protein combined with two techniques, the ionic gelation and the complex coacervation. Lactobacillus casei was encapsulated using low methoxyl amidated pectin plus butter and whey protein (C1) or low methoxyl amidated pectin and butter (C2) by ionotropic gelation with Ca2+ and covered with a layer of whey protein by complex coacervation. Microparticles were characterized with respect to average size, swelling after drying and morphology. The C2 capsule (200 µm) showed a higher average diameter compared to average size of C1 (170 µm). Both capsules surface morphology and inner morphology was obtained by scanning electron microscopy, observing microparticles of flattened shape, not perfectly smooth, but without visible cracks or pores on the surface of the microparticles. The whey protein layer was clearly identified using scanning electronic microscopy and also laser scanning confocal microscopy. The survival of probiotic bacteria (free and encapsulated) was evaluated under simulated gastrointestinal conditions at pH 1.2 or 2.0 (2 h) with pepsin, and then changing to pH 7 with pancreatin (5 h). At pH 2.0, both C1 and C2 microparticles were able to protect bacteria cells. However, at pH 1.2, only C2 formulation was successful at protecting the encapsulated bacteria. Both capsules were able to survive against 1% bile salt solution (5 h). Microparticles (C1 and C2) showed enteric properties by maintaining integrity at pH 1.2 and being solubilized at pH 7.0 containing pancreatin. The technique of microencapsulation developed had some advantages, i.e., it was carried out at low temperature, the procedures are very simple, the wall materials are non toxic and easily available, and the whey protein has high nutritional value. Application of this study might be particularly important for the immobilization of probiotic bacteria and efficiently protect cells in acid environments. These facts make this approach potentially useful for delivery of viable bacteria to the lower gastrointestinal tract of humans.