Assessment of Microbiological Quality and Physicochemical Parameters of Fruhe Made by Ovine and Goat Milk: A Sardinian (Italy) Cheese

Analysis of the bacterial diversity in Moroccan Jben cheese using TTGE, DGGE, and 16S rRNA sequencing

This research investigated the physicochemical, microbiological, and bacterial diversity of Jben cheese, a popular artisanal variety in Morocco. The bacterial diversity was explored using culture-independent methods, including temporal temperature gel electrophoresis (TTGE), denaturing gradient gel electrophoresis (DGGE), and high-throughput sequencing (HTS). Significant intra-sample differences were observed for most physicochemical parameters within each milk type, while inter-sample differences occurred between cow and goat cheeses for dry matter and ash. Jben cheese exhibited distinct characteristics, with low pH values of 3.96, 4.16, and 4.18 for cow, goat, and mixed cheeses, respectively. Goat cheeses had higher fat (49.23 g/100 g), ash (1.91 g/100 g), and dry matter (36.39 g/100 g) than cow cheeses. All cheeses displayed high microbial counts, with a notable prevalence of the lactic acid bacteria (LAB) group, averaging 8.80 ± 0.92 log CFU/g. Jben cheese also displayed high contamination levels with total coliforms, faecal coliforms, yeast, and molds. Fatty acid profiling revealed fraudulent practices in Jben cheese marketing, with cow or mixed cheeses sold as goat cheese, as proven by low capric acid concentration. HTS analysis of Jben cheese identified ten genera and twenty-four species, highlighting Lactococcus lactis as predominant. TTGE and DGGE confirmed the presence of L. lactis but failed to provide the detailed profile achieved through HTS analysis. HTS has been demonstrated to be more reliable, whereas TTGE/DGGE methods, though informative, were more time-consuming and less reliable. Despite limitations, the combined use of TTGE, DGGE, and HTS provided a comprehensive view of indigenous bacterial communities in Jben cheese, identifying L. lactis as the main species.

Effect of metabolic activity of lactic acid bacteria and propionibacteria on cheese protein digestibility and fatty acid profile

This study aimed at investigating the influence of different variants of bacterial starter cultures on the metabolism of the bacteria used, cheese protein digestibility, and fatty acid profile. The results revealed that lactic acid bacteria had a significant effect on the proportions of fatty acids in cheeses, with saturated fatty acids being predominant in in all cheese variants. Fatty acid proportions are complex and depend on the type of cheese culture and monoculture used. Additionally, the analysis of fatty acid composition showed variations in the proportion of saturated and unsaturated fatty acids, impacting the values of atherogenic and thrombogenic indices. Notably, the atherogenic index was highest in samples of mature cheeses obtained from a typical mesophilic cheese culture, whereas it was lowest in samples of fresh milk and mature cheeses obtained from a mesophilic cheese culture and monocultures of Lacticaseibacillus casei and Propionibacterium. The study also highlighted the influence of lactobacilli on the content of available free lysine, glycine, and methionine in cheese proteins. Mature cheeses obtained with Propionibacterium and L. casei starter cultures exhibited higher free lysine and glycine content compared with fresh cheeses and those obtained solely with the cheese culture. Additionally, mature cheeses obtained with starter cultures of mesophilic cheese culture, Propionibacterium, and L. casei had the highest free methionine content. Based on these findings, it is evident that the choice of cheese making cultures and monocultures can significantly affect the fatty acid composition and amino acid content of cheese and fresh milk, potentially bearing important health implications.

Safety Issues Regarding the Detection of Antibiotics Residues, Microbial Indicators and Somatic Cell Counts in Ewes’ and Goats’ Milk Reared in Two Different Farming Systems

Milk samples of ewes’ and goats’ unprocessed milk were collected from milk tanks from various farms in Epirus, Greece and classified in two groups according to the type of farming. Analyses of the samples included microbial inhibition assays to detect the presence of antibiotic residues, isolation of Staphylococcus aureus and Escherichia coli strains as microbiological indicators for susceptibility to antimicrobial medicines, Somatic Cells and Coagulase Negative Staphylococci (CNS) counts. These findings were correlated with each other as well as to the stage of the lactation period and to the type of the farming practices. Monitoring of bulk tank milk for residues of antibiotics should be performed after heating of the milk, on a regular basis, and should include at least two different tests. The results point out that the type of farming affects the CNS counts as well as the prevalence of residues in the milk. Furthermore, the inverse correlation between CNS counts and prevalence of residues of antibiotics suggests a possible protective role of CNS. Resistance of the bacterial indicators to antibiotics was random and relatively rare, perhaps acquired in past due to misuse of antibiotics, turning the indicator microorganisms to reservoir of resistance.

Sheep’s milk cheeses as a source of bioactive compounds

Since ancient times, sheep`s milk cheeses have been a part of a human diet. Currently, their consumption is of great interest due to its nutritional and health values. The aim of the article was to review the chemical composition of sheep’s milk cheeses and its main bioactive ingredients in the context of nutritional and health values. Sheep’s milk cheeses are rich in functionally and physiologically active compounds such as: vitamins, minerals, fatty acids, terpenes, sialic acid, orotic acid and L-carnitine, which are largely originate from milk. Fermentation and maturation process additionally enrich them in other bioactive substances as: bioactive peptides, γ-aminobutyric acid (GABA) or biogenic amines. Studies show that sheep’s milk cheese consumption may be helpful in the prevention of civilization diseases, i.e. hypertension, obesity or cancer. However, due to the presence of biogenic amines, people with metabolic disorders should be careful of their intake.

Quality Characteristics and Consumer Acceptance of High-Moisture Mozzarella Obtained from Heat-Treated Goat Milk

High-moisture mozzarella is a pasta filata cheese manufactured from cow or buffalo milk that has spread all over the world. Its manufacturing from the milk of small ruminants (goat and sheep) has been recently proposed to innovate this ailing sector. Previously, a protocol was reported for making goat mozzarella from unpasteurized milk but, according to legislation, the microbiological safety of raw milk fresh cheeses is not guaranteed. In the present research, two new protocols were tested for producing mozzarella from pasteurized milk prepared by two different low-temperature long-time treatments (67 °C or 63 °C × 30 min). The obtained cheeses were subjected to physical–chemical and microbiological analyses and to consumer testing. The results showed that the heat treatments caused longer coagulation times than those reported in the literature, despite pre-acidification (at pH 5.93 or 6.35) having been performed to counterbalance the expected worsening of the coagulation aptitude. The obtained products showed differences in the chemical composition, texture, proteolysis, and lipolysis. Both pasteurization and pre-acidification played a role in determining these variations. Consumer testing indicated that mozzarella obtained from milk heated at the lower temperature and coagulated at a higher pH reached a good level of appreciation (62%).

Assessment of Quality and Safety of Farm Level Produced Cheeses from Sheep and Goat Milk

Consumption of sheep’s and goat’s milk and cheese is currently increasing. The production process of these types of cheese is being carried out by traditional domestic production at farm level. However, knowledge in the field of hygiene, technology and health safety of cheeses are still insufficient. This study aimed to examine the physical and chemical quality and microbiological safety of sheep’s and goat’s milk and cheeses made from them. The month of milking influenced the content of milk components (p < 0.001) in sheep’s milk and goat’s milk, but no changes in SCC content during the examined period were found (p > 0.05). Level of contamination by Enterobacteriaceae sp. and coagulase-positive staphylococci was lower than 5 log CFU/mL in sheep’s and goat’s milk. During the ripening time, the number of lactic acid bacteria significantly raised (p < 0.001). Ripening time statistically changed (p < 0.001) not just the microbial safety of cheeses but also the color (p < 0.01). Under the applicable regulations, the analyzed samples were evaluated as suitable for human consumption.

Editorial: Lactic Acid Fermentation and the Colours of Biotechnology 2.0

Lactic acid bacteria (LAB) belong to an assorted cluster of bacteria that are protagonists of fermentative processes and bio-based solutions of interest in the different fields of biotechnological sciences, from the agri-food sector (green) up to the industrial (white), throughout the pharmaceutical (red) [...]