EFFECT OF MICROENCAPSULATION LAYER BY LAYER FOR THE SURVIVAL OF LACTOBACILLUS ACIDOPHILUS AGAINST THE SIMULATION OF GASTROINTESTINAL CONDITIONS, RESISTANCE TO THERMAL TREATMENTS AND ITS STABILITY DURING THE STORAGE

The objective of this study was to produce and evaluate pectin microparticles containing Lactobacillus acidophilus by ionic gelation followed by the adsorption of polyelectrolytes overlayer based on whey protein concentrate. The particles were characterized in terms of morphology (optical and scanning electron microscopy), mean size (laser diffraction), encapsulation efficiency was determined [amount of microencapsulated microorganism (log UFC/g-1) / free culture (log UFC/g-1) × 100%] and the viability of free and microencapsulated lactobacilli after in vitro exposure to gastrointestinal conditions. Furthermore, the microparticles resistance was evaluated after the heat treatments heat treatments and its stability was evaluated at -18ºC, 5ºC and 25ºC during 120 days of storage. The simulation test of the gastrointestinal tract was performed through changs of pH and the enzymes that simulate esophagus/stomach, duodenum and ileum. For first portion simulation, pepsin was used for 90 minutes and pH was gradually being reduced to 2.0; On second portion simulation, pancreatin and bile salts were used and the pH was adjusted to 5.0 for 20 minutes; for the simulation of ileum, pH was adjusted to 6.5 with NaHCO3 and microparticles were exposed for 90 minutes. At the end of each simulated step, the viable cell count was performed. The results revealed that LA/P0 microparticle presented the higher encapsulation efficiency (87.91%) and the larger average size when compared to the other treatments. The microparticles were spherical and oval, with probiotics distributed through encapsulating matrix. Exposure to different pHs that simulate the gastrointestinal tract showed that LA/P0, LA/P1 and LA/P3 microparticles were able to protect L. acidophilus because the free cell decreased its counts while probiotic counts were increased. On heat treatments, the LA/P1 microparticle - submitted to 63ºC/30 min - demonstrated great probiotic resistance once its viability was maintained: 9,57 log CFU/g-1. When submitted to 72ºC for 15s, the reductions of L. acidophilus were 2,14 log CFU/g-1 for LA/P1 and 5,4 log CFU/g-1 for free culture. This demonstrates that microencapsulated L. acidophilus resisted more than the free ones. Also, the other microparticles proved to be resistant. The best viability was obtained at -18°C storage with counts of 7,86 log CFU/g-1 for the LA/P1 microparticle at 120 days, and 6,55 log CFU/g-1 for LA/P3 on 105 days, since they presented counts > 6 log CFU/g-1. This study indicated that ionic gelation is effective and can be used for the production of pectin microparticles with whey protein concentrate overlay to promote greater viability to Lactobacillus acidophilus, since they resisted exposure to different pHs that simulated the passage through the gastrointestinal tract, resisted the applied heat treatments and the different storage temperatures when comparing the free cultures, demonstrating the relevance of the encapsulation for the probiotics viability.