Ripening changes and sensory properties of bovine, caprine and ovine shankleesh

Lebanese fermented goat milk products: From tradition to meta-omics

Ambriss, Serdaleh and Labneh El Darff are traditional Lebanese products made from fermented goat's milk. A questionnaire completed by 50 producers of these products showed that they are prepared by periodic percolation either by milk or by Laban in amphora or goat skins during the lactation season. Production is carried out on a small scale and in a limited number of production units, often by elderly people, resulting in a real risk of disappearance of these products and loss of the corresponding microbial resources. In this study, 34 samples from 18 producers were characterized by culture-dependent and -independent analyses. The results obtained from these two methods were radically different, the latter revealing in Ambriss and Serdaleh the co-dominance of Lactobacillus kefiranofaciens, a fastidious-growing species, and Lactococcus lactis in a viable but not culturable state. Overall, their composition is reminiscent of kefir grains. Phylogenomic and functional analyses of the genomes of the key species Lb. kefiranofaciens have revealed differences from those found in kefir, particularly in their polysaccharide genes, which may explain the absence of grains. However, Labneh El Darff displayed a dominance of Lactobacillus delbrueckii, probably due to the addition of Laban. In addition, the study identified several zoonotic pathogens, including Streptococcus parasuis, which dominated in one sample. Metagenome-Assembled Genome (MAG) analysis indicated that this pathogen acquired lactose utilization genes through horizontal gene transfer. The contamination of the herd with Mycoplasmopsis agalactiae in the Chouf region was also revealed by MAG analysis of the Serdaleh samples. Antibiotic resistance genes were detected in most of the samples, particularly in the Serdaleh ones, where the dominant L. lactis strains possessed a plasmid with a multi-resistance island. Finally, this study paves the way for further analyses to shed light on the resilience of these ecosystems established in amphora or in goatskins and to improve hygiene practices for milk production.

The relationship between physicochemical and microbiological characteristics of Surk cheese

In this study, the relationship between the physicochemical and microbiological properties of the Surk cheese was investigated through the analysis of dry matter (D.M.), ash, protein, salt, acidity, pH and enumeration of the total mesophyll aerobic bacteria (TMAB), yeast-mold, presumptive lactobacilli and lactococci. Surk samples were obtained randomly from 36 different local dairy shops in Antakya province of Turkey. The average values of the dry matter, ash, protein, fat, and salt, acidity and pH analysis were 44.4%, 9.09%, 17.5%, 17.0%, 8.08%, 0.916% and 4.17, respectively. The average values for TMAB, yeast mold, presumptive lactobacilli and lactococci enumeration in the microbiological analysis were found to be 6.23, 4.09, 6.04, and 3.42 log cfu/g, respectively. Based on the statistical analysis, Surk samples were divided into 3 groups in terms of salt content (3-6, 6-9 and > 9%). Then, the physicochemical and microbiological properties of Surk samples were evaluated according to these groups. This study suggests that besides the different methods to produce Surk cheese as followed by the different manufacturers, the amount of salt added to Surk cheese affects its microbiological and physicochemical characteristics.

Antimicrobial resistance of Listeria monocytogenes isolated from dairy-based food products

In this study Listeria monocytogenes (L. monocytogenes) was isolated from three traditionally consumed Lebanese dairy-based food products. One hundred and sixty four samples (45 samples of Baladi cheese, 36 samples of Shankleesh and 83 of Kishk) were collected from the Bekaa Valley in the Northeast region of Lebanon. Suspected Listeria colonies were selected and initially identified by using standard biochemical tests. Initial identification of the positive L. monocytogenes colonies was confirmed at the molecular level by Polymerase Chain Reaction (n=30) and the confirmed isolates were evaluated for their susceptibility to 10 commonly used antimicrobials. All of the 30 isolates were confirmed to be L. monocytogenes yielding a PCR product of approximately 660 base pairs (bp). L. monocytogenes was detected in 26.67%, 13.89% and 7.23% of the Baladi cheese, Shankleesh and Kishk samples, respectively. The highest resistance in L. monocytogenes isolates was noted against oxacillin (93.33%) followed by penicillin (90%). The results provide an indication of the contamination levels of dairy-based foods in Lebanon and highlight the emergence of multi-drug resistant Listeria in the environment.