Yoghurt is the common fermented dairy product consumed worldwide and it is considered a potential source of probiotic bacteria (Lactobacilli and Lactococci). To assess the in-vitro probiotic properties of lactic acid bacteria, Lactococcus lactis subsp. lactis, Lactobacillus delbrueckii and Lactobacillus plantarum species isolated from yoghurt sold in different local markets of Chittagong region in Bangladesh were examined by morphological characteristics and biochemical tests. In the preliminary test, all isolates were grown well at acidic pH (pH 3-5) while the optimum growth temperature was 37°C and better growth was observed in the presence of 1-8% NaCl concentrations. In addition, the selected isolates were able to survive up to 3% bile salt concentrations while the best tolerance was at 1% bile salt. The strains successfully inhibited the growth of common pathogenic bacteria likely Escherichia coli, Pseudomonas aeruginosa, Salmonella Paratyphi, Staphylococcus aureus and Bacillus subtilis examined by in vitro growth inhibition test. Most of the isolated strains exhibited resistance pattern against ten commonly used antibiotics in foodborne illness in the country. However, the strains in yoghurt sold at Chittagong city have ideal probiotic characteristics and this fermented dairy product could be a potential source of human probiotic bacteria.

The study aims at determining the physicochemical, proximate composition and the total viable count of Staphylococcus aureus in ‘Nono’ and yoghurt samples in Kaduna, Nigeria.Three hundred and eighty-four (384) fermented milk samples (Nono and yoghurt) were obtained from different selling points and were evaluated for the occurrence of S. aureus. The physicochemical and proximate analyses (pH, total titratable acidity, moisture content, ash content, protein content, and fat content) were determined. The results of the analyses showed that Nono had pH range of 3.56-3.61, total titratable acidity: 0.71-1.72, moisture content: 82.23-83.87%, ash content: 0.30-0.31%, crude protein content: 1.50-1.61%, crude fat content: 0.35-0.38 %. For yoghurt, the pH ranged from 3.76 -3.82, total titratable acidity: 1.10 -1.15, moisture content: 77.76-80.06%, ash content: 0.68- 0.70%, crude protein content: 3.40-3.45% and crude fat content: 1.76-1.79% from all the study areas. One hundred and four of the total samples were contaminated with S. aureus. Out of the 104 isolates of S. aureus that were isolated and identified, 88 were coagulase positive S.aureus. The Microgen Staph ID kit (Oxoid) was used to further confirm the characteristics of the 60 isolates of the coagulase positive S. aureus. The kit confirmed 43 isolates as S. aureus, the results indicated the presence of S. aureus in the milk samples which is of public health importance, as this can contribute to food-borne intoxication which can lead to food poisoning. There is a need for proper pasteurisation of raw milk to help eradicate S. aureus infection before human consumption.

The main purpose of this study was to investigate the possibilities of technological production of camel milk yoghurt. First of all, denaturation of antimicrobial substances in camel milk by heat treatment and their effects on pH decrease and on the viscosity were analysed. Although the pH decrease was present, the viscosity of camel milk didn’t change. In the study, two different heat treatments (20 min at 90°C and 20 min at 95°C) were applied to camel milk and pH and SH (Soxhelet Henkel) values were determined until pH reached 4.7 during fermentation. After culture addition the pH drop was at 90°C for 20 minutes heat-treated camel milk slower than the camel milk heated at 95°C for 20 minutes. Similarly, the increase in SH in the cultured milk treated at 90°C for 20 minutes was slower than the increase in SH in the cultured milk treated at 95°C for 20 minutes. In the next study, viscosity and pH changes in yoghurt produced from cow and camel milk were compared. For this purpose, both milks were heat treated at 80°C for 20 minutes. After 180 minutes in cow’s milk, the viscosity was 9891 mPa.s, and after 210 minutes it reached 25237 mPa.s. In contrast, the viscosity in cultured camel milk was determined as 1210 mPa.s after 90 minutes, while the viscosity remained around 1216 mPa.s after 380 minutes. In the next study, for the production of yogurt from cow milk and camel milk were performed. Both milks were heat treated at 80°C for 20 minutes and changes in viscosity and drop of pH during fermentation were analysed. After the 180 minutes of fermentation in cow’s milk the viscosity came to 9891 mPa.s, after 210 minutes it was 25237 mPa.s. In contrast, after 90 minutes in the cultured camel milk, the viscosity was 1210 mPa.s, while after 380 minutes the viscosity reached to 1216 mPa.s. E. coli, L. bulgaricus and Listeria innocua were used to determine the antimicrobial effect of raw camel milk, cow milk, heat treated camel and cow milk camel colostrum. While camel milk and colostrum had inhibitory effect on E. coli, L. bulgaricus, Listeria innocua was not inhibited

The traditional fermented food consumption has become very popular because of the increasing public concern about food additives. Lactic Acid Bacteria (LAB) species have traditionally been used as starter cultures in the production of fermented food. LAB can acquire antibiotic resistance from other bacteria in the natural environment and different resistant mechanisms via mutation. The resistance of bacteria to antibiotics is an increasingly important public health problem worldwide. In this study, antibiotic resistance of 115 Streptocoocus thermophilus and 35 Lactobacillus bulgaricus isolates obtained from traditional Turkish yogurts were tested against kanamycin, chloramphenicol, erythromycin, ampicillin, rifampicin, tetracycline, vancomycin and gentamicin using disc diffusion method. Study results showed that most strains were susceptible to all the antibiotics tested while a few of them were determined to be resistant only to kanamycin, ampicillin, erythromycin, and tetracycline. When contacted in a human body, resistant strains might transfer the related genes to the pathogenic species, which may result in devastating consequences.

Yogurt powder was produced by freeze drying and with added candied chestnut puree at ratios of 5, 10, and 20 % by weight. Moisture sorption isotherms of yogurt powder samples, plain (YP), and containing 5, 10, 20% candied chestnut puree (CCP) were determined at 25°C using the standard, static-gravimetric method. The experimental adsorption data of yogurt powders at 25°C were fitted to 14 sorption equations which are most widely used to fit experimental sorption data of various food materials. The parameters of the sorption models were estimated from the experimental results by using the nonlinear regression analysis. The GAB model gave the closet fit to the sorption data of freeze dried yogurt powders with candied chestnut puree at 25°C. BET, Ferro Fanton, Henderson, Halsey, Oswin and Modified Oswin models are also acceptable for describing the adsorption isotherms for freeze dried yogurt with candied chestnut puree at 25°C.