Elektroeğrilmiş Polivinil Alkol/Selüloz Asetat Hibrit Fiberlere Probiyotik Enkapsülasyonu

Abstract

The importance of intestinal health has been getting attention in recent years. Probiotic microorganisms are known to be very important for intestinal health. Although these microorganisms affect the health positively, they have high sensitivity to various factors. Encapsulation techniques are used to increase the resistance of probiotics towards different conditions. Electrospinning is one of the encapsulation methods used for probiotic microorganisms. In this thesis, polyvinyl alcohol (PVA) ̶ cellulose acetate (CA) hybrid fibers (PVA/CA fibers) were produced by using angled dual nozzle electrospinning system. The aim of this study is to produce encapsulation material, resistant to digestive system conditions by using CA. CA was used for the first time for probiotic encapsulation with this project. The use of water soluble polymers for encapsulation has some limitations. Fibers lose their integrity due to contact with aqueous media. In order to overcome these limitations, a water insoluble polymer, CA was used for encapsulation. However, it was known that the solvents, which was used to prepare CA solution, may have toxic effects on microorganisms. This undesirable effect was prevented by angled double nozzle electrospinning system to avoid the contact of the solvent with the microorganism. CA and PVA solutions were fed into the system from different nozzles with angled double nozzle electrospinning system. Hybrid fibers were produced as a result of overlapping fiber jets. Using the developed system, Escherichia coli Nissle 1917 (EcN), which was inoculated into PVA solution, was encapsulated in hybrid fibers without exposure to the toxic solvent of CA.

Firstly, the solutions which were used to produce hybrid fiber, were optimized. 20% (a/h) CA (acetic acid: ethanol(8:2, v/v)) and 10% (a/h) PVA (1 mM PBS (pH 7.4) containing 1% Triton X-100) solutions were used for uniform and beadless fiber production. Then, EcN was encapsulated into PVA/CA fibers (PVA/CA-EcN fibers). As the control, EcN was encapsulated into PVA ̶ PVA hybrid fibers (PVA/PVA-EcN fibers). It was observed that the electrospinning process had no significant adverse effect on viability. Encapsulation efficiency was found to be over 90% in both hybrid fibers. Digestive resistant of encapsulated probiotic microorganisms was investigated by in vitro simulation. It was observed that higher viability results were obtained from PVA/CA-EcN fibers, compared to not only free EcN but also PVA/PVA-EcN fibers. This results showed that PVA/CA fibers can be used to increase the resistance of probiotic microorganisms to digestion condition. It was found that the stabilization of probiotics encapsulated with PVA/CA-EcN fibers could be protected for a long time. By using angled double nozzle electrospinning, a hybrid fiber has been produced which can be used for probiotic encapsulation without disadvantages of the CA solvent.

The results of the study showed that PVA/CA fibers provided remarkable resistance to digestive system conditions, which is a critical issue for the encapsulation of probiotic microorganisms.