5466
Mona Mahmoud Ahmed Mahmoud
Evaluation of Modified Microencapsulation Methods of Lactic Acid Bacteria Used in Dairy Products
Microencapsulation, Lactobacillus plantarum, Streptococcus thermophilus, Sodium alginate, Extrusion
Nowadays, selecting the most suitable encapsulating agent for microencapsulation of lactic acid bacteria is a great concern. In the present study, the survivability of Lactobacillus plantarum and Streptococcus thermophilus microencapsulated with alginate (Alg) combined with skim milk (Sm), dextrin (Dex), denatured whey protein (DWP) or coated with chitosan (Ch) was evaluated under simulated food processing and gastrointestinal conditions. Moreover, the encapsulated cells were evaluated for production of different bioactive compounds such as exopolysaccharides and antimicrobial substances. The results showed that only Alg-Sm gave thermal stability to the cells at the pasteurization temperature (65 oC for 30 min), however, all the encapsulating agents were efficient in protecting S. thermophilus under the same conditions. Under freezing storage condition, Alg-DWP and Alg-Sm enhanced the survival of L. plantarum for 3 months, while Alg-DWP seemed to be the most efficient in protecting S. thermophilus under the same condition. Interestingly, storage under refrigeration conditions (≈8 ᵒC) increased the viability of L. plantarum entrapped within all the tested encapsulating agents for 4 weeks. However, all the encapsulated S. thermophilus showed little bit growth reduction during the refrigerated storage up to one month. All the microencapsulated L. plantarum and S. thermophilus tolerated NaCl concentrations up to 5%. Tolerance of the microencapsulated cells toward organic acids was varied depending on the type of the organic acid. Only Alg-Ch and Alg-Sm provide better survival for L. plantarum under simulated gastric juice, however, Alg-Ch and Alg-DWP were the most efficient in protecting S. thermophilus under the same conditions. Alg-Sm and Alg-DWP offer a good survival for L. plantarum and S. thermophilus, respectively under simulated intestinal condition. The results also revealed that microencapsulation does not affect the metabolic activity of the entrapped cells. Generally, Alg-Sm and Alg-DWP proved to be the most promising encapsulating agents that maintain the survivability of L. plantarum and S. thermophilus, respectively under almost all the stress conditions adopted in the current study.
2018
M.Sc
Ain Shams
Science