Bazı Probiyotik Bakterilerin Mikroenkapsülasyonu ve Meyve Suyunda Kullanımının Araştırılması
Özet
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.