The effect of microencapsulation technique on the stability of probiotic cultures Lactobacillus acidophilus KPb4b and Lactobacillus rhamnosus KPb7

In this study, L. acidophilus KPb4b and L. rhamnosus KPb7 were selected potential strains after determining their 16S rRNA sequence analysis and molecular diagnosis and this strains were microencapsulated with 1.5% alginate, 1.5% manucol and 1.5% alginate + 0.5% starch by Nisco moduler microencapsulation unit Var A. Morphological structures of produced microcapsules such as microencapsulation yield, mechanical stability, secretion, oxygen toxicity, low pH resistance, and resistance in artificial gastric and intestinal environment, and at the +24ºC, +5ºC, -18ºC storage stability were determined. Also, stability of microcapsules in model food environment were investigated.According to the results of molecular diagnosis, the strain with the best probiotic characteristics, L. acidophilus KPb4b and L. rhamnosus KPb7, were selected and microencapsulated with 1.5% alginate, 1.5% manucol and (1.5% alginate + 0.5% starch). Coating process were made using emulsion electrostatic vibration technique with a nozzle of 150 ?m. The capsule size of obtained capsules were between 370 µm - 404 µm; the highest microencapsulation yield and mechanical stability were obtained from the coating with 1.5% alginate. In secretion testing, L. acidophilus KPb4b strains is more stable than L. rhamnosus KPb7 strains, but in terms of oxygen toxicity L. rhamnosus KPb7 culture is more resistant than of L. acidophilus KPb4b; the oxygen toxicity test in food environment, microorganisms are protected best in alginate+starch microcapsules, in terms of temperature resistance after 30 minutes, both microorganisms were also determined to decrease vitality. In terms of storage stability, storing at -18ºC causes damage to the structure of microbeads. It has been determined that storage at +5ºC with alginate+starch capsules was the most suitable temperature and coating material for the best protection of the vitality of the bacteria. Coating process in the artificial gastric environment is not effective for preserving microbial viability. However, in small intestine environment alginate+starch capsules provide the best protection for both bacterial cultures. The highest scores in food samples that were prepared using coated probiotic cultures for both bacteria were obtained in alginate+starch application.