In-vitro evaluation of targeted release of probiotic Lactobacillus casei (2651 1951 RPK) from synbiotic microcapsules in the gastrointestinal (GI) system: Experiments and modeling

•L. casei follows summative growth on combination of lactose and inulin.•The maximum encapsulation efficiency is 98% for synbiotic microcapsules (24 μm).•L. casei is released after 50 min in simulated large intestinal juice.•A mathematical model is developed and validated for in-vitro GI system.

The microencapsulation processes serve potentially to protect probiotic cells against adversity in the GI tract. The article focuses on the behavior and release characteristics of Lactobacillus casei from synbiotic microcapsules. Monod (μmax = 0.78 h−1, Ks = 2.44 g/L) Haldane (μmax = 0.05 h−1, Ks = 0.2 g/L, KI = 0.52 g/L) and summative models are followed by L. casei during its growth on lactose, inulin and the combination of these carbohydrates respectively. The internal micro-encapsulation efficiency (98%) for synbiotic microcapsules (24 μm) has been optimized with respect to concentrations of sodium alginate (2%), tween-80 and post-cooling temperature (25 °C) using Response Surface Methodology. In agreement with the prediction of proposed “burst release” mechanism, probiotic cells are released after 50 min if 1 g synbiotic microcapsules are initially suspended in 10 mL simulated large intestinal juice. A mathematical model has been developed to predict the concentration profiles of microcapsules and released probiotic cells in the GI system and has been validated through the successful comparison of simulated data with the results of in-vitro experiments. The concentration of released probiotic cells rises to 1.7E10/L in the large intestine. Interestingly, this is the first study on the prediction of release of L. casei from synbiotic microcapsules and is expected to be useful for similar systems.