Microbial communities play an important role in cheese ripening and determine the flavor and taste of different cheese types to a large extent. However, under adverse conditions human pathogens may ...colonize cheese samples during ripening and may thus cause severe outbreaks of diarrhoea and other diseases. Therefore in the present study we investigated the bacterial community structure of three raw ewe's milk cheese types, which are produced without the application of starter cultures during ripening from two production sites based on fingerprinting in combination with next generation sequencing of 16S rRNA gene amplicons. Overall a surprisingly high diversity was found in the analyzed samples and overall up to 213 OTU97 could be assigned. 20 of the major OTUs were present in all samples and include mostly lactic acid bacteria (LAB), mainly Lactococcus, and Enterococcus species. Abundance and diversity of these genera differed to a large extent between the 3 investigated cheese types and in response to the ripening process. Also a large number of non LAB genera could be identified based on phylogenetic alignments including mainly Enterobacteriaceae and Staphylococcacae. Some species belonging to these two families could be clearly assigned to species which are known as potential human pathogens like Staphylococcus saprophyticus or Salmonella spp. However, during cheese ripening their abundance was reduced. The bacterial genera, namely Lactobacillus, Streptococcus, Leuconostoc, Bifidobacterium, Brevibacterium, Corynebacterium, Clostridium, Staphylococcus, Thermoanerobacterium, E. coli, Hafnia, Pseudomonas, Janthinobacterium, Petrotoga, Kosmotoga, Megasphaera, Macrococcus, Mannheimia, Aerococcus, Vagococcus, Weissella and Pediococcus were identified at a relative low level and only in selected samples. Overall the microbial composition of the used milk and the management of the production units determined the bacterial community composition for all cheese types to a large extend, also at the late time points of cheese ripening.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Mineral elements occur in milk and dairy products as inorganic ions and salts, as well as part of organic molecules, such as proteins, fats, carbohydrates and nucleic acids. The chemical form of ...mineral elements is important because it determines their absorption in the intestine and their biological utilization. The mineral composition of milk is not constant because it depends on lactation phase, nutritional status of the animal, and environmental and genetic factors. The objective of this research is to point out the research results of chemical form, content and nutritional importance of individual mineral elements that are present in various milks and dairy products.
Electronic nose (e-nose) and electronic tongue (e-tongue) instrumental systems were designed to crudely mimic human olfactory and taste sensory organs and are composed of an array of sensors. Complex ...data sets from electronic nose and electronic tongue signals combined with multivariate statistics represent rapid and efficient tools for classification, discrimination, recognition and identification of samples, as well as for the prediction of concentrations of different compounds. A wide variety of sensors can be employed into the design of these instrumental systems, especially that of electronic tongues, offering numerous practical applications. In this study, characteristics of sensors and possibilities of electronic nose and electronic tongue applications in the dairy industry were reviewed.
The aim of this study was to introduce a reference method for the detection of cow milk in ewe and goat cheeses (EC 273/08) in order to protect manufacturers and consumers from adulterations and ...imitations, and to ensure alignment with the demands of domestic and EU markets. The method includes isolation of casein from cheese, isoelectric focusing of γ2- and γ3-casein originating from the hydrolysis of β-casein by plasmin, the detection and quantitative determination of γ-casein in cow, ewe and goat cheese by densitometry. Ewe or goat cheese products with a minimum of 1 % of cow milk are considered to be adulterated. For the quantitative determination of cow, ewe and goat milk in cheeses, standard mixtures of cow-ewe and cow-goat milk were made by adding 0; 0.5; 1; 2; 5; 10; 25; 50; 75 and 100 % (v/v) of cow milk. The quantification was performed by determining the peak area ratio of cow γ-casein in comparison to ewe/goat casein in prepared standard cheeses. The calibration curves were calculated based on the relation of the peak area ratio of cow γ-caseins (calculated as the percentage of total γ-caseins) in contrast to the relative content (%) of cow milk in the mixture. The method proved to be adequate for the detection of raw and heat-treated cow milk in fresh and ripened cheeses made from ewe or goat milk, or a mixture of ewe and goat milk.
The aims of this paper were to investigate the impact of changes in the milk payment system and the season on the hygienic quality of raw milk. The bulk cow's milk samples were collected throughout ...the whole area of Bosnia and Herzegovina over the period of four years (2010-2013), from farms that deliver milk to the dairy industry. The total bacterial count (TBC) was analysed in 52,999 milk samples and the somatic cell count (SCC) in 53,363 milk samples. The results of the research showed that the proportion of bulk milk with the SCC < 300,000 mL.sup.-1 significantly increased in the observed period, as well as the proportion of farms that produce milk of EU quality (P < 0.05). The season had a significant effect (P < 0.05) on the SCC; in April the proportion of bulk milk with SCC < 300,000 mL.sup.-1 was significantly higher (P < 0.05). A significant increase (P < 0.05) in the proportion of milk with the TBC < 200,000 cfu * mL.sup.-1 was perceived, as well as the proportion of farms which deliver that type of milk (P < 0.05). A Significant lower (P < 0.05) proportion of milk in the summer period with TBC < 200,000 cfu * mL.sup.-1 was determined. It can be concluded that consistent appliance of regulations which determine the quality of milk, leads to the improvement of the hygienic quality of redeemed milk, as illustrated by the case of Bosnia and Herzegovina. This kind of milk payment system is important for both, the higher economic benefit of farms and the dairy processing industry.
The aim of this paper is to review the existing knowledge of manufacturing procedures, chemical composition, sensory attributes, biochemistry and microbiology of different kind of cheeses which ripen ...in the animal skin. These kinds of cheeses are produced in Croatia, Bosnia and Herzegovina, Montenegro and Turkey and there are few differences in the manufacturing procedure between them. The main specificity of these cheeses is ripening in a sack made of the whole lamb or goat body skin. Two or three months of anaerobic ripening in the skin gives the cheese markedly piquant taste and flavour. These cheese characteristics originate from intensive lipolysis and proteolysis. According to the content of moisture in the non fat solids and fat in total solids, cheeses in a sack belong to the group of hard or semi hard, full-fat or low-fat cheeses.
The aim of this study was to determine the influence of microbial (commercial starter) culture on concentration of total free amino groups (amino acids) in cheeses in different ripening stages. Free ...amino groups were determined by reaction with ninhydrin with cadmium (Cd) in the water soluble cheese extract, and were expressed as the concentration of leucine in cheese dry matter. Changes in concentration of total free amino acids during cheese ripening (0th, 30th, 60th, 90th and 120th day) were monitored. In water soluble extracts of cheese, the presence of free NH2 groups in all ripening stages was detected, which means smaller peptides and amino acids, whose concentration significantly (P<0.01) increased during ripening. Cheeses produced with and without microbial culture resulted in statistically significant differences (P<0.01) in content amino acids free on the 90th and 120th day of ripening. Cd - ninhydrin method was found to be suitable for cheese ripening monitoring, as well as for determination of the differences in mature characteristics of cheeses, depending on the production process.
Istrian cheese is the traditional hard cheese produced exclusively from the raw milk of the autochthonous Istrian sheep. The aim of this study was to determine the bacteriological quality, ...physicochemical properties of the sheep milk and Istrian cheese as well as proteolysis of cheese produced on six family farms during the cheese ripening. The hygienic microbial indicators of the sheep milk were poor in comparison to the other East Adriatic regions. However, the number of bacterial indicators rapidly declined during the ripening and they were under the detection limit for “ready to consume” cheese and therefore indicated their good bacteriological quality. Regression function of the effects of the ripening time on physicochemical properties of Istrian cheese during ripening showed a substantial increase in total solids, in salt, in moisture and in salt content as well as in the lactic acid in the total solids. However, these changes were not significant due to the high variability of the Istrian cheese production. The farm cheese making procedure affected the electrophoretic profile of the primary proteolysis in the cheese samples. Significant (P<0.01) increase of the index beta was found due to the high content of salt in moisture (>5 %). Equal degradation of as1-casein and ß-casein during ripening of Istrian cheese occurred. A low percentage of nitrogen fractions soluble in water and in 12 % trichloroacetic acid were determined.
Milk contains about 70 indogene enzymes, while only twenty of them were investigated. One of the less explored is the milk enzyme cathepsin D, proteolytic enzyme located in the lysosomes, which are ...an integral part of the somatic cells whose number varies depending on the animal’s health. Unlike cow’s milk, in ewe’s milk the presence of cathepsin D was not determined, which could affect the production of dairy products, especially cheese, which are traditionally produced in Croatia and Mediterranean. This paper shows the presence of cathepsin D and its forms in ewe’s milk by modified Western Blotting method. The analysis confirmed the presence of procathepsin D, mature and heavy chain of cathepsin D. Pseudocathepsin D and light chain of cathepsin D were not detected.
Determining the urea concentration in milk is a useful indicator of the nutritional protein status of the organism as well as of the ratio between the energy and the protein in ruminant rations, with ...increasing practical usage. In addition to nutrition, milk urea concentration is influenced by a whole range of factors, for example: breed, stage and number of lactations, body weight, daily production and chemical composition of milk, somatic cell count, season and milking. The objective of this research was to determine the impact of the cow breed (Holstein and Simmental), the number of lactation (1st, 2nd, 3rd, 4th, 5th), milking time (morning-evening) and season (spring-summer and autumn-winter) on milk urea concentration. The following was determined for each breed: daily milk yield, milk fat, protein and lactose content, urea concentration and somatic cell count in milk. Statistical data processing was carried out by applying General Linear Model procedure, SAS system (1999). The cow breed had a significant influence on daily milk yield and log somatic cell count (P<0.001), lactose content in milk (P<0.01), milk fat content and milk urea concentration (P<0.05). The number of lactations significantly influenced daily milk yield (P<0.001), protein content (P<0.001 and P<0.01) and milk urea concentration, but only for Holstein breed (P<0.05). Milking time significantly influenced the fat and protein content (P<0.001) in the milk of Holstein cows, that is, lactose content (P<0.05) and urea concentration (P<0.05) in the milk of Simmental cows. The season significantly influenced the fat and protein content of milk (P<0.001), that is, urea concentration and log somatic cell count (P<0.01). Determining of urea concentration in cow milk should also be systematically conducted in the Republic of Croatia, in order to determine standard physiological values characteristical for a particular cow breed, aiming to determine the balance of energy and protein in rations.
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