Optimization of microcapsulation of bacteriophages and investigation of potential use of microencapsuled bacteriophages in yogurt production

Bacteriophages represent one of the most abundant biological populations in nature and are defined as bacterial viruses that can kill specific target bacteria. In recent years, gaining resistance to antibiotics of pathogenic bacteria has brought up bacteriophages application again. Moreover, bacteriophages that present in natural microbiota of the human digestive system when taken orally, have lost their activities because of exposure to adverse effects such as high acidity and digestive enzymes during their passage along the gastrointestinal system. The microcapsulation method can be used to protect bacteriophages against adverse effects of components, physicochemical properties and storage conditions of food, and gastrointestinal system. In this study, the formation of microcapsules with the highest loading efficiency, the highest resistance to low pH and the smallest particle size by optimization the vibration frequence values with sodium alginate and sodium caseinate ratios in the coating solution used in bacteriophage microcapsulation were aimed. Besides, determination activity of bacteriophage Felix O1 which is lysing 98.2% of Salmonella species, in the simulated gastric environment, mathematical modelling of release of Felix O1 from microcapsules in the simulated intestinal environment, use of microencapsulated Felix O1 in the production of yogurt as model food were aimed. In order to produce microcapsules with the highest efficiency value, the vibration frequency value of 1.61 kHz, sodium alginate and caseinate in the coating solution were 1.86% and 3.26% respectively; for the optimum point where the reduction rate of Felix O1 in microcapsules exposed to pH 2.0 is the lowest, the frequency value is 4.50 kHz, the sodium alginate and caseinate ratios in the coating solution are 2.00% and 2.69, respectively; for the maximum microcapsule efficiency, the lowest Felix O1 reduction rate when microcapsules exposed to pH 2.0 and the smallest microcapsule perimeter the frequency value of 4.50 kHz, sodium alginate and caseinate in the coating solution were 1.53 and 2.72 respectively determined. In the simulated gastric environment, the highest titres reduction of Felix O1 was determined in the microencapsules which had the maximum microcapsule efficiency, the lowest Felix O1 reduction rate when microcapsules exposed to pH 2.0 and the smallest microcapsule perimeter followed by, respectively, microencapsules which had the maximum microcapsule efficiency and microencapsules which has lowest Felix O1 reduction rate when microcapsules exposed to pH 2.0. It was found that the microcapsulated and free form of Felix O1 did not adversely affect viability of L. delbrueckii subsp. bulgaricus and S. thermophilus in yogurt samples and physicochemical properties of yogurt samples. It was determined that Felix O1 release from microcapsules as alone or in yoğurt, which were kept in the artificial intestinal environment, was fit well to the Korsmeyer-Peppas model, and the diffusion was the mechanism for releasing of Felix O1. As a result of our results, Felix O1 can be used to increase the functional properties of yoğurt. Felix O1 can be transported to the body with yogurt and can be active in the body.