This study aimed to implement a microencapsulated form of selected autochthonous lactic-acid bacteria (LAB) isolated from the cheese-production chain and natural rennet obtained from suckling lambs ...in the traditional production of hard sheep cheese, “Paški sir”, from the island of Pag, Croatia. Two different formulations of microparticles were prepared: (i) microparticles containing the strain of both Lactiplantibacillus plantarum and Lactococcus lactis (S2) and (ii) microparticles containing both strains and natural rennet (S3). These formulations were used in the production of Paški sir cheese simultaneously with standard production using non-encapsulated commercial starter cultures and commercial rennet (S1). The number of Lc. lactis isolates decreased at day 30 and were not isolated during the remaining ripening process, whereas the number of L. plantarum remained stable throughout the ripening process. The level of LAB and the release of the rennet from microsphere formulations at the end allowed for the production of cheese with the same characteristics as the commercial product, indicating no negative interactions of natural rennet, bacterial culture, and chemical components of microparticles. To our knowledge, this is the first report of a microencapsulated L. plantarum (isolated from the abomasum of lambs) coupled with natural lamb’s rennet used in the production of hard sheep cheese. This pilot study showed the great potential for maintaining authenticity in cheese production by combining traditional and sustainable innovative technologies.
A total of 156 tonsils and 156 mandibular lymph nodes from fattening pigs originating from 13 farms were sampled in Croatian slaughterhouses and examined for Salmonella spp. (n = 78 per organ) and ...Yersinia enterocolitica (n = 78 per organ) by cultural methods. Salmonella was isolated from two tonsils only, both originated from animals from the same farm (5.12 %), while Y. enterocolitica were recovered from 26 tonsils (33.33 %) which could be traced back to 10 farms. Salmonella was absent in mandibular lymph nodes, and Y. enterocolitica was isolated from eight lymph nodes (10.25 %) which originated from six farms. Y. enterocolitica was present inside the lymph nodes of two pigs. The high prevalence of Y. enterocolitica in/on pig tonsils could be the result of cross-contamination during splitting the carcasses with head. This procedure may result in higher prevalence of Y. enterocolitica on surface of mandibular lymph nodes than in their depth. Traditional veterinary postmortem examination of pig halves will not necessarily contribute to cross-contamination with Salmonella or Yersinia under conditions of present slaughter practice.
Cheeses as ready-to-eat food should be considered as a potential source of foodborne pathogens, primarily
The aim of present study was to determine the microbiological quality of soft, semi-hard and ...hard cheeses during the shelf-life, with particular reference to
Five types of cheeses were sampled at different time-points during the cold storage and analyzed for presence of
and
as well as lactic acid bacteria,
coagulase-positive staphylococci, yeasts, molds, sulfite-reducing clostridia and
counts. Water activity, pH and NaCl content were monitored in order to evaluate the possibility of
growth. Challenge test for
was performed in soft whey cheese, to determine the growth potential of pathogen during the shelf-life of product. All analyzed cheeses were compliant with microbiological criteria during the shelf-life. In soft cheeses, lactic acid bacteria increased in the course of the shelf-life period (1.2-2.6 log increase), while in semi-hard and hard cheeses it decreased (1.6 and 5.2 log decrease, respectively). Soft cheeses support the growth of
according to determined pH values (5.8-6.5), water activity (0.99-0.94), and NaCl content (0.3-1.2%). Challenge test showed that
growth potential in selected soft cheese was 0.43 log
cfu/g during 8 days at 4°C. Water activity in semi-hard and hard cheeses was a limiting factor for
growth during the shelf-life. Soft, semi-hard and hard cheeses were microbiologically stable during their defined shelf-life. Good manufacturing and hygienic practices must be strictly followed in the production of soft cheeses as
supporting food and be focused on preventing (re)contamination.
The consumption of raw milk from vending machine in Croatia has increased in recent years. However, its health safety is insufficiently investigated and controlled. The objective of this study was to ...investigate the suitability of raw milk consumption, from 28 vending machines from 3 counties in Croatia during one-year research period, based on the physicochemical and hygiene quality. Also, the simulation of psychrothrophic bacteria growth has been conducted in order to determine its optimal storage time because of their unfavorable effect on the milk quality. The physicochemical composition of milk samples (n=320) was determined by the infrared spectrometry (chemical composition) and cryoscopic method (freezing point), while hygiene quality was estimated with a total bacterial count (TBC) and a somatic cell count (SCC). Microbiological analyses included determining the presence of Enterococcus spp., Pseudomonas spp. and the pathogenic species. Satisfactory quality of raw milk was established in 95% (chemical quality) and 70% unadulterated samples (without added water). The prescribed hygiene quality was met by 36.6% (TBC) and 71.9% (SCC) samples. Of total 320 samples, the presence of bacteria in genus Enterococcus spp. and Pseudomonas spp. was confirmed in 93.4% and 96.9% samples, respectively, and bacteria Escherichia coli, Staphylococcus aureus, Lysteria monocytogenes was confirmed in 32.2%, 27.5% and 3.8% samples. The finding of Salmonella spp. and Yersinia enterocolitica was negative. At the end of the study improvement of the microbiological quality of raw milk from vending machines was established. The results indicate the need for systematic control and obligate thermal treatment of raw milk before consumption.
The antimicrobial susceptibility of coagulase-negative staphylococci isolated from spontaneously fermented sausages was assessed using both traditional and molecular methods. Isolates were tested for ...sensitivity to vancomycin, ampicillin, erythromycin, tetracycline, gentamycin and oxacillin by the disk diffusion method and quantitative-qualitative epsilometer test. PCR was used for the detection of resistance genes mecA, ermB, tetK and tetM. The identified coagulase-negative staphylococci were Staphylococcus epidermidis (69 %), S. capitis (5 %) and S. warneri (2.5 %). S. epidermidis showed a high rate of phenotypical resistance to tetracycline and erythromycin (44.4 % of strains). Molecular evaluation of resistance determinants revealed tetK or tetM genes in eight S. epidermidis strains. Although S. epidermidis is not classical food poisoning bacteria, its presence in food could be of public health significance due to the possible spread of antimicrobial resistance determinants. Our findings implicate that spontaneous meat fermentation could result in products with a potential hazard to consumers.
is present in the normal intestinal flora but some strains can cause intestinal and extraintestinal diseases, and research on its presence in food of animal origin is in the interests of public ...health. This study was designed to characterise
strains according to their origin, their carriage of virulence genes specific for certain pathogroups, and phylogenetic group affiliation.
The study was carried out on 100
strains isolated from food samples of various animal origin as well as pig and cattle carcass swabs. Isolation of the strains was performed using two methods. One method included colony count and the other an overnight enrichment of the samples. Isolation was followed by DNA extraction and detection of virulence genes and phylogenetic group with conventional and multiplex PCRs.
In this study, the most prevalent gene was
(20%) and strains which carried it were identified as enteroadherent
. Other pathogroups were represented in lower incidences. Phylogenetic group analysis revealed the prevalence of the A and B1 groups, with B1 mainly present in game and cattle strains, while the majority of pig and poultry strains were assigned to group A.
This study provides an overview of the presence of potentially pathogenic strains and
phylogenetic groups in Croatia, for which the data are limited. Further microbiological and molecular research is required to examine the epidemiological situation in the country.
Mastitis is one of the most frequent diseases of dairy cows throughout the world, therefore it causes the greatest economic losses in dairy cattle industry. These losses are reflected through: ...reduced milk production, increased costs of medication and the other animal health services, reduced fertility, early culling of animals and the value of discarded milk. Mastitis is also important from the aspects of public health, milk processing and animal welfare. In the pathogenesis of mastitis the key role plays the innate immune response which is the first line of defence against the pathogen invasion of the udder. The innate immune response generates an inflammatory reaction which is the elementary response of an organism to the tissue trauma induced by any physical, chemical or biological causative agent, but primarily it is the protective mechanism of a vital significance which includes increased phagocytic activity, secretion of antimicrobial substances, fibrosis as well as the alterations in tissue structure of affected organ or body cavity. The release of a number of inflammatory mediators as well as reactive oxygen species (ROS) is an important part of inflammatory response. In dairy cows, the metabolic challenge that occurred during the transition from dry period to early lactation may additionally increase the release of ROS which may contribute to development of oxidative stress and inflammatory response. Oxidative stress is defined as a shift in the balance from cellular oxidation-reduction reactions towards oxidation, i.e. to the state of excessive release of oxidants when their removal by antioxidants is impaired and even insufficient. During peripartum period antioxidantive status of dairy cows is seriously impaired and consequently both the oxidative stress and inflammatory response may present the predisposing factors to their higher susceptibility to intramammary infections (IMI) and mastitis. This association between oxidative stress and inflammation during IMI and mastitis indicates their role in the pathogenesis of mastitis. Thus, a better understanding of such a synergism could contribute to development of new approaches to prevention and therapy of IMI and mastitis.
In this research, the susceptibility to clindamycin, tetracycline, amikacin, amoxicillin + clavulanic acid, enrofloxacine, vancomycin, trimethoprim + sulphametoxazol, tobramycin, chloramphenicol, ...ciprofloxacin, erythromycin, penicillin and trimethoprim was tested in coagulase-negative staphylococci (n=78) and lactic acid bacteria (n=30) by means of disk diffusion test and E-test. The isolates were collected from soft and hard cheeses, butter and brine. All isolates of coagulase-negative staphylococci were susceptible to clindamycin, amikacin, amoxicillin + clavulanic acid, enrofloxacine, vancomycin, chloramphenicol and ciprofloxacin according to CLSI breakpoints. A total of 30 staphylococci isolates (38.46 %) were resistant to erythromycin, 18 to penicillin (23.07 %), 4 to tetracycline (5.12 %), and one isolate to trimethoprim, tobramicin and trimethoprim + sulphametoxazol (1.28 %). Among 78 tested staphylococci, 35 of them were resistant to at least one antimicrobial substance (44.87 %). The rate of resistant isolates of different soft cheese types ranged from 22 to 70 %, while resistant staphylococci were absent in hard cheese and brine. The growth of lactic acid bacteria was not influenced by trimethoprim + sulphametoxazol (n=29), vancomycin (n=29), trimethoprim (n=28), amikacin (n=10) and tobramycin (n=10). The results show that significant part of apathogenic microbiota in different dairy products is phenotypically resistant to antimicrobial agents.
Biogenic amines (BAs) are considered a potential microbiological toxicological hazard in aged cheese. Risk mitigation strategies include good hygiene practice measures, thermal treatment of milk and ...the use of competitive dairy cultures. The aim of this study was to evaluate the amount of BAs—tryptamine, β-phenylethylamine, putrescine, cadaverine, histamine, tyramine, spermidine and spermine—in the core and rind of cheeses ripened by bacteria (n = 61) and by mold cultures (n = 8). The microbial communities were counted, and the dominant lactic acid bacteria (LAB) were identified, corresponding to the BA concentrations. The total BA content was highest in the core of semi-hard cheeses (353.98 mg/kg), followed by mold cheeses (248.99 mg/kg) and lowest in hard cheeses (157.38 mg/kg). The highest amount of BAs was present in the rind of cheeses with mold (240.52 mg/kg), followed by semi-hard (174.99 mg/kg) and hard cheeses (107.21 mg/kg). Tyramine was the most abundant BA, represented by 75.4% in mold cheeses, 41.3% in hard cheese and 35% of total BAs in semi-hard cheeses. Histamine was present above the defined European maximum level (ML) of 100 mg/kg in only two semi-hard and three hard cheeses. High amount of BAs (above 600 mg/kg) in cheeses, mainly tyramine, were associated with the presence of Enterococcus durans, while negligible BA concentrations were found in cheeses ripened with Lacticaseibacillus rhamnosus, Lactococcus lactis or Lacticaseibacillus paracasei cultures. This study has shown that retailed cheese varieties produced with commercial bacterial or mold cultures have acceptable levels of biogenic amines with respect to consumers.
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