The invention relates to self-assembling microparticles comprising a solid matrix and probiotic bacteria, wherein the solid matrix comprises soybean protein and a divalent or trivalent metal, and wherein the probiotic bacteria are distributed throughout the solid matrix; said matrix protects said probiotic bacteria during processing, storage, as well as during transit through the gastrointestinal tract, thus prolonging their lifetime and facilitating release into the intestine and improving their probiotic effect. The present invention also relates to the method for obtaining the self-assembling microparticles and to the products and compositions incorporating them.