Bazı Probiyotik Bakterilerin Mikroenkapsülasyonu ve Meyve Suyunda Kullanımının Araştırılması

Abstract

Probiotic microorganisms have many positive effects on human health. In order for these effects to be observed in humans, a certain amount of probiotics should be consumed regularly everyday. Therefore, the presence of probiotic foods is crucial. During the storage period of these foods, the number of viable probiotic microorganisms should be preserved to be at least 1.0x106 cfu/g. Preserving the viability of probiotic microorganisms, which are very sensitive to environmental conditions, is one of the challenges to be overcome by food industry, which is aware of the healthy food trend. Encapsulation is an effective method to protect probiotics from harsh environmental conditions during storage. In addition, by microencapsulation tecnology it is possible to keep the number of viable probiotic cells reaching the intestine high by protecting them from the gastrointestinal conditions. In this thesis, microencapsulation of some probiotic microorganisms was carried out and the use of these probiotic microcapsules in 100% orange juice and 100% apple-peach juice was investigated. In this context, microencapsulation of Lacticaseibacillus rhamnosus GG (Lactobacillus rhamnosus GG, LGG) and Escherichia coli Nissle (EcN) strains with different polymers was held. Since the obtained microcapsules will be added to the fruit juice, polymer mixtures with high acid tolerance such as, xanthan gum-gellan gum (XG-GG) and sodium alginate-cellulose acetate phthalate (ALG-CAP) were preferred. In addition, synbiotic microencapsulation was performed by adding inulin (INU) to polymer mixtures (XG-GG-INU; ALG-CAP-INU) in order to observe the effect of prebiotics on preservation of probiotic viability. Microencapsulation of probiotic bacteria was performed by emulsion method, encapsulation efficiencies were calculated and morphological characterization of the microcapsules was performed. Then, the effect of the encapsulation process on viability of probiotics was determined in simulated gastrointestinal conditions. To decide the most suitable microcapsules to be added in fruit juice, the properties of fruit juices and the results from gastrointestinal simulation are both considered. Probiotic microcapsules were added to the fruit juice and samples were stored at 4 °C for 35 days. Changes in probiotic viability in fruit juice samples were determined during storage. In addition, quality analyzes and sensory analysis of the probiotic fruit juice samples were performed. As a result, the encapsulation was carried out with a yield of over 80% with the emulsion method, with the capsules that are micron-sized and in irregular shape. It has been determined that the encapsulation process is an effective method to protect probiotics from simulated gastrointestinal conditions and the viability of probiotics was positively affected by the increase in polymer concentration used in encapsulation. While the number of viable cells were above 106 cfu/mL in all fruit juice samples containing LGG during the 35 days of storage; the number of viable microorganisms determined on the 35th day in fruit juice samples containing EcN remained below 106 cfu/mL. The determination of viability of probiotics in samples containing EcN microcapsules and EcN synbiotic microcapsules at the end of the 35th day was higher than in samples containing EcN in free form, shows that the encapsulation process not only provides a protection from simulated gastrointestinal conditions, but also protects the probiotics from severe environmental conditions during the storage of fruit juice samples. No significant change was observed in terms of quality of fruit juice samples during storage. In this study, the possibilities of using LGG and EcN microcapsules in fruit juice samples were revealed. For probiotic fruit juice production, the focus should be on improving sensory properties. With this study, it can be said that probiotic fruit juices, which take their place in the foreign market after the increasing consumer demand for healthy/functional food, can be produced in our country and will take place in the market in the near future.