Microencapsulation of probiotic bacteria using two different methods and comparison of the effects of cell stability in ayran during storage period

In this thesis, Lactobacillus plantarum (VISBYVAC® Serie 1000-Product Nr 40022951, Germany) microencapsulation was performed by extrusion and electrospray methods and stability of the cells in ayran samples was evaluated. Firstly, capsules were produced by extrusion and electrospray methods and the microencapsulation yield was calculated. Diameter of the capsules was measured using light and inverted microscopes. Then, the resistance of the capsules to simulated gastric fluid (SGF) and simulated intestinal fluid (SIF) was determined. The capsules were added to ayran samples pasteurizated at 60oC for 15 min and stored at +4oC for 21 days. Every seventh day of the storage period, the viable cell count was determined in capsules which were filtered from ayran samples and filtrates. In conclusion, microencapsulation yield by electrospray method was 86.35% and microencapsulation yield by extrusion method was 84.56 %. The average diameter size of extrusion capsules was 258.7 µm by light microscope and 275.7 µm by inverted microscope and the average diameter size of electrospray capsules was 85 µm by light microscope and 97.6 µm by inverted microscope. After exposure to SGF-SIF, a loss of 3.3 log units in viable cell counts was determined in control group while they were 0.52 and 1.11 log units by extrusion and electrospray methods, respectively. At the end of the storage period in ayran samples, there was a 4.34-log loss in viability in control group while there were 0.5 and 1.38 log viability losses of the capsules by extrusion and electrospray methods, respectively. During 21 days of storage period, cells were released from the extrusion capsules on 14th day and reached log 1.61 cfu/ml at the end of the storage period. Cells were released from the electrospray capsules on 7th day and reached log 2.52 cfu/ml at the end of the storage period.