Investigation of the potentials of using lactic acid bacteria isolated from traditional table olives and cheeses as adjunct culture in food industry

Objective: The objective of this thesis is to obtain new type of microorganisms from artisanal 10 mounth ripened white brined cheese and table olives which demonstrates good probiotic, bioprotective, biotechnological and aroma production ability and to identify the potential exploitation of the microorganisms as starter/adjunct or multifunctional cultures. Thus, it is aimed to obtain food that contains probiotics, with improved functional properties, resistant to spoilage which protects both the food and the host and has improved aroma compounds. Also, the probiotic potentials of the fermented products are determined to find out new probiotic sources which is not originated from human microbiome. This study also identifies the microbiota of the fermented products and create a LAB culture collection which consist of microorganisms with diverse properties. Material and Method: In this study, LAB isolation was carried out from white brined cheese samples collected from Manisa Alaşehir region (Md coded). Cheeses were produced without addition of starter culture and ripened for 10 months. LAB's, isolated using MRS medium, were preidentified after purification. Biochemical tests were done to identify the isolates in genus/species level. Probiotic, bioprotective and biotechnological properties of the isolates were investigated together with the preidentified LAB's isolated from table olives (Ak coded) produced in Aydın region. Viability in the gastrointestinal track (GIT), binding to intestinal epithelial cells (hydrophobicity, autoaggregation, adhesion to epithelial cell surface), antimicrobial properties were evaluated as probiotic properties. Inhibitory features of the isolates were evaluated over B. cereus CCM99, L. monocytogenes ATCC 7644, S. aureus RSKK 1009, E. coli NRRL B- 59838 O157: H7 and A. niger NRRL 326, C. albicans DSMZ5817'to find out their bioprotective traits. In addition, the enzyme production potentials of these isolates were screened, and other biotechnological abilities were determined. The isolates were tested as adjunct cultures in yoghurt and fermented olive production. Their effects on the product as well as their ability to maintain their viability were evaluated in the model food systems. Results: All the 54 microorganisms isolated from cheese were found to be Gram positive, have diplococcus morphology and catalase negative. Most of the isolates were evaluated as enterococci due to their ability to growth at 15 ºC, 45 ºC, 6.5% salt and their homofermentative nature. The isolates had good acid production abilities and their acid production rates were close to the desired criteria. Most of the isolates were acid-resistant and bile salts were found to promote the growth of most Md-coded and some Ak-coded isolates. The highest microbial adhesion to solvent (MATS) values of the isolates were found for chloroform solvent, and the lowest for xylene. Ak42 (12.38%) showed high adhesion properties to the HT-29 cell surface. Table olive isolates had higher antibacterial effect than cheese isolates. Both cheese and olive isolates demonstrated the highest antimicrobial activity against L. monocytogenes ATCC 7644 and the lowest antimicrobial activity against S. aureus RSKK 1009. None of the isolates demonstrate proteolytic, lipolytic and phenol oxidase activity. Only β- galactosidase activity was detected in some isolates. Their optimum pH value was found 7, the optimum temperature was 45 ºC. Selected isolates used as adjunct culture in yoghurt production, could maintain their viability and had positive effects on the flavor profile. Also, isolates did not demonstrate negative effect on the quality criteria of yogurt. In table olive fermentation trial, Md58 was able to maintain its viability in the olive brine. In addition, presence of the isolate did not have any effect onto the olive color changes. Conclusion: In this study, isolates with different probiotic, antimicrobial and biotechnological properties were obtained from traditional fermented dairy and non-dairy products. Although starter probiotic culture applications for dairy products are common, it is predicted that there will be more application areas in the coming years with isolates obtained from table olives.