Raw Milk Cheese Samples Research Articles

Seasonal variation of Salmonella enterica prevalence in milk and cottage cheese along the dairy value chain in three regions of Ethiopia

Seasonal fluctuations influence foodborne illness transmission and affect patterns of microbial contamination of food. Previous investigations on the seasonality of Salmonella enterica prevalence in dairy products in Ethiopia have been minimal. However, such data are needed to inform strategic development of effective interventions to improve food safety, as seasonal differences may affect intervention strategies. This study was conducted to identify differences in the prevalence of Salmonella in milk and cheese samples between wet and dry seasons. A longitudinal study design was utilized with a random sampling occurring during both dry and wet seasons. A total of 448 milk and cottage cheese samples were collected from Oromia, Sidama, and Amhara regions. Samples were tested for Salmonella using the ISO 6579-1: 2008 method, followed by PCR confirmation. A chi-square test was conducted to assess the significance of differences in the prevalence of Salmonella in the samples between the two seasons. Results from this study showed a higher prevalence of Salmonella in all sample types during the dry season (P < 0.05). Moreover, when comparing raw milk, pasteurized milk, and cottage cheese samples, a significant difference was observed in Salmonella prevalence from raw milk samples (27.08%) collected in the Oromia region. Additionally, data showed a significantly higher prevalence of Salmonella in samples collected from raw milk producers (29.17%) during the wet season (P < 0.05). This study indicates that in order to enhance the safety of dairy products in Ethiopia, comprehensive, long-term awareness building on hygienic milk production and handling that consider seasonal influence is warranted.

Assessment of some chemical residues in Egyptian raw milk and traditional cheese.

The assessment of risks related to food safety is becoming a challenge in developing countries with its consequent health hazards. Chemical risk assessment in dairy products is important to maintain consumer health locally and internationally. Since milk and dairy products are essential foods for a wide range of customers, mostly children, patients, and pregnant women, it is very important to estimate the risks of some chemical residues, such as pesticides, some heavy metals, and aflatoxins. This work aims to determine the levels of chemical contamination in milk and traditional Egyptian cheese. Heavy metals were determined in samples by atomic absorption spectrometry. GC-mass spectrometry (MS)/MS and LC-MS/MS were also used for measuring pesticide residues. The Aflatoxin M1 was determined by enzyme-linked immune-sorbent assay. Raw milk samples were tested and showed elevated concentrations of lead and cadmium, (46% and 4%, respectively). The heavy metals detected in the Egyptian cheese samples were variable depending on the type of cheese. Moreover, p.p.-DDE phenofose was present in 45% and 29% of raw milk and Ras cheese samples, respectively. For Aflatoxin M1, only 7% of milk samples and 2.9% of Ras cheese samples exceeded the acceptable limits. More surveying and risk assessment of chemical residues in milk and milk products are essential for controlling health risks to consumers.

Identification of the Enterotoxigenic Potential of Staphylococcus spp. from Raw Milk and Raw Milk Cheeses.

This study aimed to genotypic and phenotypic analyses of the enterotoxigenic potential of Staphylococcus spp. isolated from raw milk and raw milk cheeses. The presence of genes encoding staphylococcal enterotoxins (SEs), including the classical enterotoxins (sea-see), non-classical enterotoxins (seg-seu), exfoliative toxins (eta-etd) and toxic shock syndrome toxin-1 (tst-1) were investigated. Isolates positive for classical enterotoxin genes were then tested by SET-RPLA methods for toxin expression. Out of 75 Staphylococcus spp. (19 Staphylococcus aureus and 56 CoNS) isolates from raw milk (49/65.3%) and raw milk cheese samples (26/34.7%), the presence of enterotoxin genes was confirmed in 73 (97.3%) of them. Only one isolate from cheese sample (1.3%) was able to produce enterotoxin (SED). The presence of up to eight different genes encoding enterotoxins was determined simultaneously in the staphylococcal genome. The most common toxin gene combination was sek, eta present in fourteen isolates (18.7%). The tst-1 gene was present in each of the analyzed isolates from cheese samples (26/34.7%). Non-classical enterotoxins were much more frequently identified in the genome of staphylococcal isolates than classical SEs. The current research also showed that genes tagged in S. aureus were also identified in CoNS, and the total number of different genes detected in CoNS was seven times higher than in S. aureus. The obtained results indicate that, in many cases, the presence of a gene in Staphylococcus spp. is not synonymous with the ability of enterotoxins production. The differences in the number of isolates with genes encoding SEs and enterotoxin production may be mainly due to the limit of detection of the toxin production method used. This indicates the need to use high specificity and sensitivity methods for detecting enterotoxin in future studies.

Detection and characterization of the most common foodborne pathogens by using multiplex PCR procedure

Food Microbial contamination is one of the most serious problems. A large percentage of food-borne illnesses are caused by food-borne pathogens, and diarrheal agents comprise more than half of the overall prevalence of food-borne illnesses in the globe, and more commonly in developing countries. This study aimed to identify the most-common foodborne organisms from foods in Khartoum state by PCR.A total of 207 food samples (raw milk, fresh cheese, yogurt, fish, sausage, mortadella, and eggs) were collected. DNA was extracted from food samples by guanidine chloride protocol, and then species-specific primers were used to identify Escherichia coli O157: H7, Listeria monocytogenes, Salmonella spp., Vibrio cholerae, V. parahaemolyticus, and Staphylococcus aureus. Out of 207 samples, five (2.41%) were positive for L. monocytogenes, one (0.48%) was positive for S. aureus, and one (0.48%) was positive for both Vibrio cholerae and Vibrio parahaemolyticus. From 91 fresh cheese samples, 2 (2.19%) were positive for L. monocytogenes, and one (1.1%) sample was positive for two different foodborne pathogens (V. cholerae and V. parahaemolyticus). Out of 43 Cow's milk samples, three (7%) samples were positive for L. monocytogenes, and out of 4 sausage samples, one (25 %) was positive for S. aureus. Our study revealed the presence of L. monocytogenes and V. cholera in raw milk and fresh cheese samples. Their presence is considered a potential problem and needs intensive hygiene efforts and standard safety measures before, during, and after food processing operations.

Ammi-visnaga extract; a novel phyto-antiviral agent against bovine rotavirus.

The spread of bovine rotavirus has a great impact on animal productivity, milk products, and human public health. Thus, this study aimed to develop a novel, effective and accessible Phyto-antiviral treatment made from methanolic Ammi-visnaga seed extract against rotavirus infection. Rotaviruses were isolated from raw milk and cottage cheese samples randomly collected from Cairo and Qalubia governorates. They were all identified serologically, however, only three of them were both biologically and molecularly confirmed. The methanolic extract derived from Khella seeds (MKSE) was chemically analyzed with mass chromatography. The cellular toxicity of MKSE was tested on Caco-2 cells and its antiviral activity against one of the isolated bovine rotaviruses (BRVM1) was tested by both the cytopathic inhibition assay and the plaque reduction assay. Our results showed that 17.3% of the total collected 150 dairy samples were bovine rotavirus antigen positive. Three representatives of them were phylogenetically identified to be included in group A based on a 379bp coat protein gene. Visnagin, Benzopyran, Khellin, and Benzenepropanoic acid were the major active components found in the MKSE. The maximum non-toxic concentration of MKSE was 5µg/mL and the CC50 value was 417µg/mL. The MKSE exhibited in-vitro antiviral activity against BRVM1 indicated by inhibition of the viral cytopathic effect (SI = 204.5, IP = 98%), causing a 1.5 log decrease in BVRM1 TCID50 and reducing the viral plaques count by the percentage of 93.14% at MNTC (5 ug/ml). In conclusion, our study showed that bovine rotavirus represents a severe health problem that needs attention in Egypt, and it supports using MKSE as a potential natural anti-rotavirus agent.

Evaluation of the Bacterial Load in the Raw Dairy Products in Baghdad, Iraq.

Milk and cheese were recognized as highly nutritious food due to their high protein, fat and minerals (calcium, phosphorus, iron, and vitamins). Accidental contamination of food through the handlers could have resulted in many kinds of bacteria especially Staphylococcus aureus in the dairy products. Therefore, this study aimed to study variation in bacterial isolation percentage and the bacterial counts in raw milk and locally produced soft cheese in local markets in Baghdad. A total of 150 samples of raw milk and local soft cheese (75 for each) were collected from different regions of Baghdad city from October 2020 to July 2021 to study the evaluation of bacterial contamination. The isolation percentage of total coliform, Fecal coliform, Escherichia coli and Staphylococcus aureus in the raw milk were 82, 69, 54 and 42%, respectively. While in the soft cheese, the isolation percentage for coliform, Fecal coliform, Escherichia coli and Staphylococcus aureus were 90, 74, 60 and 45%, respectively. Furthermore, high percentages of bacterial isolation were recorded during summer. The recorded data showed significant (P<0.05) variation for both raw and soft cheese according to months, and soft cheese had a higher isolation percentage than the raw milk samples. The average values of bacterial count values that were isolated from October to February in the raw milk of the total coliform, fecal coliform, E. coli and Staph aureus were 5.57, 4.25, 3.77 and 2.94 cfu log10/mL respectively, which were recorded during the cold months. While the recording of the average values from March to July as hot months were 6.02, 5.02, 5.22 and 3.23 CFU log10/mL, respectively. The average bacterial values in the soft cheese were 6.02, 5.03, 4.97 and 3.67cfu log10 /g, respectively, from October to February and were significantly (P<0.05) less than the summer from March to July, which recorded 7.17, 6.32, 5.01 and 4.15cfu log10/g respectively. The high contamination found in the soft cheese and during hot months compared with raw milk and cold months, respectively, is a sign of unsanitary manufacturing conditions such as post-process contamination, high temperature in summer, and lack of refrigeration during long-distance transportation.

Brucella spp. Contamination in Artisanal Unpasteurized Dairy Products: An Emerging Foodborne Threat in Tunisia.

Brucellosis is a worldwide zoonotic disease transmitted to humans, predominantly by the consumption of contaminated raw milk and dairy products. This study aimed to investigate the occurrence of Brucella spp. in 200 raw milk, ricotta, and artisan fresh cheese samples, collected from individual marketing points in four districts in Tunisia. Samples were analyzed for the presence of Brucella spp. by IS711-based real-time PCR assay. Positive samples were further analyzed by qPCR for B. melitensis and B. abortus species differentiation. The DNA of Brucella spp. was detected in 75% of the samples, B. abortus was detected in 31.3%, and B. melitensis was detected in 5.3% of positive samples. A percentage of 49.3% of samples co-harbored both species, while 14% of the Brucella spp. positive samples were not identified either as B. abortus or B. melitensis. High contamination rates were found in ricotta (86.2%), cheese (69.6%), and raw milk (72.5%) samples. The study is the first in Tunisia to assess the occurrence of Brucella spp. contamination in artisanal unpasteurized dairy products and showed high contamination rates. The detection of both B. abortus and B. melitensis highlights that zoonotic high-pathogen agent control remains a challenge for food safety and consumer health protection and could represent a serious emerging foodborne disease in Tunisia.

Assessment of Viral Contamination of Five Brazilian Artisanal Cheese Produced from Raw Milk: a Randomized Survey.

Enteric viruses have been described as important contaminants in fresh and ready-to-eat foods such as sandwiches, deli meat and dairy products. This is a cross-sectional randomized survey to estimate the prevalence of norovirus and human adenovirus (HAdV) from 100 Brazilian artisanal raw milk cheese samples (Minas and Coalho) obtained from different agroindustries in four producing regions in the states of Minas Gerais and one in Piauí, respectively. From October 2017 to April 2018, norovirus genogroups I and II and HAdV were investigated in these cheese samples by RT-qPCR and qPCR, respectively. Viruses were detected in 43 samples, being 26 norovirus GI strains, 14 HAdV, and 3 both viruses. Norovirus GII strains were not detected. Viral concentrations ranged from 6.17 × 104 to 1.44 × 107 genome copies/L-1 and murine norovirus 1 used as internal process control showed 100% success rate of recovery with efficiency of 10%. There was a trend towards a higher positivity rate for both viruses in the rainy season, and HAdV were more commonly found among samples with higher fecal coliform counts. This study is a first step in assessing the risk that this contamination may pose to the consumer of raw products as well as emphasizing the need for good manufacturing practices, quality control systems in the dairy industry and markets. As a randomized survey, we established baseline figures for viruses' prevalence in five types of ready-to-eat raw milk artisanal Brazilian cheese, to allow any monitoring trends, setting control targets and future local risk analyses studies.

Variation of nutritional and microbiological properties of milk in relation to climate adaptation strategies across dairy production systems in West Africa

This study was conducted in West Africa to assess the performance of climate adaptation strategies of dairy production systems on the microbiological and physico-chemical quality of milk. Fifty-four samples of raw milk, pasteurised milk and local cheese collected from three dairy production systems (extensive, modern semi-intensive and traditional semi-intensive) were analysed. The results on physico-chemical quality of milk and cheese from the three dairy production systems were in line with the standard. The extensive dairy production system (system 1), mainly dependent on natural resources, had high values of total protein and carbohydrate; the modern semi-intensive dairy production (system 2) with silage technology had high values of calcium. The traditional semi-intensive (system 3) with fodder treatment had high values of fat, energy, and potassium. Regarding microbiological quality, milk and cheese from the three systems were contaminated with highest contaminants from modern and traditional semi-intensive dairy production systems.

CHARACTERIZATION OF STAPHYLOCOCCUS SPECIES ISOLATED IN PRODUCTION STAGES OF BRAZILIAN COLONIAL CHEESE

Colonial cheese is a culturally and economically important product from the south of Brazil. As most of its production is artisanal, the technology employed is mostly knowledge passed down from one generation to the next according to family tradition and may be produced with raw or pasteurized milk. It is noted for its spicy flavour and variable composition and is often classified as a medium to high-moisture cheese. This intrinsic feature increases the risk of microbial spoilage and food poisoning. One of the main bio-indicators of contamination in colonial cheese is coagulase positive Staphylococcus. The purpose of this study was thephenotypic identification of Staphylococcus species isolated from the products and surfaces in the main production stages of colonial cheese. Staphylococcus sp. isolates from the food and the production environment were obtained from two colonial cheese-production agro-industries in Rio Grande do Sul. Samples of fresh milk, curd, ripening and final colonial cheese were collected. In addition, surface sampling was performed on the coagulation tanks, production tables, molds, cheese ripening shelves and on the hands of the handlers. Staphylococcus sp. isolates in the cheese and the production environments tested in this study were identified by phenotypic techniques through biochemical and MALDI-TOF MS analyses. These isolates were subjected to gene expression analysis for enterotoxins A, B, C, D, and E. All isolates (72) were identified as Staphylococcus sp., and 43% of the total isolates tested were coagulase positive. Staphylococcus aureus was the predominant species in the raw milk and production tanks. Regarding coagulase negative staphylococci isolates, S. warneri and S. sciuri were most abundant. The sea and seb genes were detected in 4% of the Staphylococcus isolates. The results indicate eleven different species of Staphylococcus present in the colonial cheese production environments studied. The predominant presence of S. aureus in the different samples of milk, curd, ripened cheese, ready-to-eat cheese and hands of the handlers indicates that there are issues with the selection of milk-producing animals, pasteurization process and/or hygiene control of handlers. The sea and seb genes were detected in samples of raw milk and colonial cheese. No enterotoxin genes were detected in coagulase negative staphylococci.&#x0D; KEY WORDS: Enterotoxins; polymerase chain reaction; time-offlight mass spectrometry; coagulase negative staphylococci; phenotypic identification; genotypic analysis; colonial cheese.

OCCURRENCE OF SHIGELLA SPECIES IN RAW MILK AND KAREISH CHEESE WITH SPECIAL REFERENCE TO ITS VIRULENCE GENES

A total number of 100 random samples of raw milk and kareish cheese (50 for each) were collected from Assiut city farms and dairy shops. Shigella species were isolated, confirmed biochemically and by using Polymerase Chain Reaction (PCR). Also two virulence genes; invasive gene (invC) and plasmid- encoded virulence gene (ipaH) were identified using PCR technique. 10 isolated strains of Shigella isolates (37%) from dairy milk samples and 13 isolates (43%) from kareish cheese were identified as following: S. dysenteriae, S. flexneri, S. sonnei and S. boydii. The two virulence genes; (invC) and (ipaH) were detected in only six and four strains of the identified Shigella species, respectively. Four of them had both the virulence genes (isolated from milk and cheese samples). Even though conventional culture is considered the gold standard for Shigella detection and the PCR method is a useful tool which complements detection of foodborne pathogens such as Shigella. Chitosan was evaluated in this study as antibacterial substance on the identified Shigella strains by inoculating it in pasteurized milk, using 3 different concentrations: 0.25, 0.5 and 1% of chitosan. Chitosan reduced the inoculated Shigella strain mean counts with highly significant effect (P<0.01) at the 6th day reached to 2.10 ±0.17, 1.00 ±0.30 and th day we noticed that chitosan concentration of 0.5% only was highly significant (P<0.05). Generally, the 0.5% chitosan concentration showed the highly reduction effect on the count and survival of the Shigella strain involved.

Microbial characterization of an artisanal production of Robiola di Roccaverano cheese

Robiola di Roccaverano, from the Piedmont region of Italy, is a Protected Designation of Origin soft cheese made with raw goat milk. The peculiarity of this cheese is that during the manufacturing process, a natural starter culture (NC) is added to raw milk. This study examined the viable microorganisms of technological interest, including lactic acid bacteria and fungal populations, in samples of raw milk, NC, and fresh and ripened cheese collected from one dairy using culture-dependent techniques. First, the isolated colonies were analyzed using random amplification of polymorphic DNA (RAPD) PCR, and strains with similar fingerprints were clustered together. Further, representative isolates of each group were subjected to 16S or 26S ribosomal DNA sequencing. Finally, species-specific PCR was conducted to distinguish the Lactococcus lactis ssp. lactis and Lc. lactis ssp. cremoris. Among the studied lactic acid bacteria, 13 RAPD profiles were obtained, corresponding to 9 different bacterial species or subspecies. Concerning mold and yeast isolates, 5 species were found that coincided with 5 RAPD types. Observing the strains isolated in the study, Lc. lactis was the most prevalent species in raw milk and NC samples, and Leuconostoc mesenteroides was the predominant species identified in 5- and 15-d cheese isolates. Furthermore, whereas only these 2 species were detected in NC, Enterococcus and Lactobacillus genera were found in raw milk and cheese, respectively. Concerning the mold and yeast isolates, in NC Kluyveromyces spp. was mainly found, and in cheese samples the representative species were Geotrichum candidum and Yarrowia lipolytica. Finally, raw milk and cheese safety were evaluated, and the samples complied with the standard required by European Commission regulation number 2073/2005.

Detection of antibiotic resistance profiles and aminoglycoside-modifying enzyme (AME) genes in high-level aminoglycoside-resistant (HLAR) enterococci isolated from raw milk and traditional cheeses in Turkey.

The aim of this study was isolation and identification of the high-level aminoglycoside-resistant (HLAR) enterococci in raw milk and dairy products and to analyze their antibiotic resistance and the presence of aminoglycoside-modifying enzyme (AME) genes. A total of 59 HLAR enterococci were isolated from raw milk and traditional cheese samples. Thirty-nine of the 59 HLAR enterococci were isolated on streptomycin-containing agar medium, while the other 20 HLAR strains were isolated on gentamicin containing agar medium. The 59 HLAR enterococci were identified as 26 E. faecalis (44.07%), 18 E. faecium (30.51%), 13 E. durans (22.03%), and two E. gallinarum (3.39%) by species-specific PCR. Disk diffusion tests showed that teicoplanin were the most effective antibiotics used in this study, while 89.83% of isolates were found to be resistant to tetracycline. High rates of multiple antibiotic resistance were detected in HLAR isolates. Minimum inhibitory concentration (MIC) values of HLAR enterococci against streptomycin and gentamicin were found in the range of 64 to > 4096 µg/mL. Forty-seven (79.66%) of the 59 HLAR enterococci were found to be both high-level streptomycin-resistant (HLSR) and high-level gentamicin-resistant (HLGR) by MIC tests. However, no correlation was found between the results of the disk diffusion and MIC tests for gentamicin and streptomycin in some HLAR strains. The aph(3')-IIIa (94.92%) was found to be most prevalent AME gene followed by ant(4')-Ia (45.76%), ant(6')-Ia (20.34%) and aph(2'')-Ic (10.17%). None of the isolates contained the aac(6')-Ie-aph(2'')-Ia, aph(2'')-Ib or aph(2'')-Id genes. None of the AME-encoding genes were identified in E. durans RG20.1, E. faecalis RG22.4, or RG26.1. In conclusion, HLAR enterococci strains isolated in this study may act as reservoirs in the dissemination of antibiotic resistance genes.

Foodborne Pathogen Assessment in Raw Milk Cheeses.

General hygienic parameters and selected foodborne pathogens in raw milk cheeses at the retail level were evaluated. A total of 245 raw milk cheese samples were analysed for total bacterial count, Enterobacteriaceae, E. coli, Salmonella spp., Listeria monocytogenes, coagulase-positive Staphylococci, and staphylococcal enterotoxin. Results showed only 3 samples that were not compliant with European rules on staphylococcal enterotoxin, but coagulase-positive Staphylococci were evidenced in all samples tested. Salmonella spp. and Listeria monocytogenes were never detected whereas E. coli was evidenced in 20 samples. Results suggest a need for improvement of good manufacturing practice and milking operation.

A Preliminary Study on Metabolome Profiles of Buffalo Milk and Corresponding Mozzarella Cheese: Safeguarding the Authenticity and Traceability of Protected Status Buffalo Dairy Products.

The aim of this study is to combine advanced GC-MS and metabolite identification in a robust and repeatable technology platform to characterize the metabolome of buffalo milk and mozzarella cheese. The study utilized eleven dairies located in a protected designation of origin (PDO) region and nine dairies located in non-PDO region in Italy. Samples of raw milk (100 mL) and mozzarella cheese (100 g) were obtained from each dairy. A total of 185 metabolites were consistently detected in both milk and mozzarella cheese. The PLS-DA score plots clearly differentiated PDO and non-PDO milk and mozzarella samples. For milk samples, it was possible to divide metabolites into two classes according to region: those with lower concentrations in PDO samples (galactopyranoside, hydroxybuthyric acid, allose, citric acid) and those with lower concentrations in non-PDO samples (talopyranose, pantothenic acid, mannobiose, etc.,). The same was observed for mozzarella samples with the proportion of some metabolites (talopyranose, 2, 3-dihydroxypropyl icosanoate, etc.,) higher in PDO samples while others (tagatose, lactic acid dimer, ribitol, etc.,) higher in non-PDO samples. The findings establish the utility of GC-MS together with mass spectral libraries as a powerful technology platform to determine the authenticity, and create market protection, for “Mozzarella di Bufala Campana.”

Enterotoxigenic Profiles of Bacillus Cereus Isolated from Manufacturing Steps of Traditional Soft Cheese Plant

Microbial contamination of soft cheese may originate from various sources such as contaminated equipment or from the workers themselves during cheese production. The study was aimed to characterize Bacillus cereus using culture-based and PCR techniques among 285 samples along Damietta and Kareish cheese producing line in a small cheese plant in Alexandria governorate including raw milk, cheese, whey, rennet, water, and swabs from all contacts surfaces. Overall of 10.90 % and 10 % among raw milk, cheese, whey, rennet, water, and swabs from all contacts surfaces were positive for Bacillus species in Damietta and Kareish cheese producing line. The incidence of Bacillus cereus in receiving raw milk, curd, whey, fresh cheese samples were 6.66, 13.33 and 13.33%, respectively for traditional Damietta cheese plant. Bacillus cereus is found in only 6.66 % in receiving raw milk, pasteurized milk and fresh cheese samples for traditional Kareish cheese plant. Hbl, Nhe and Cytk genes were detected in Bacillus cereus isolated from curd and Damietta cheese. Nhe gene was detected in Bacillus cereus isolated from raw milk, pasteurized milk and Kareish cheese While, Ces gene was detected only in Bacillus cereus isolated from fresh Kareish cheese samples. The prevalence of Eneterotoxigenic virulent B. cereus poses public health threats to consumers. HACCP should be implemented for all steps of manufacture in order to produce a safe and good quality dairy product.

The effect of herbs added to the summer diet sheep on the lipid fraction profile of raw milk for cheese making and rennet cheese produced from it

A study was conducted on samples of raw sheep milk and bundz rennet cheese produced from it. The milk was obtained from ewes of the Koluda prolific dairy breed, from June to August. The sheep were housed indoors and fed alfalfa green forage, hay, and a mixture of concentrate feeds. Three feeding groups were established: group I ‒ control, fed without the addition of herbs to the concentrate feed, and groups II and III, in which a herb mixture was added to the concentrate feed in the amount of 10 and 20 g/sheep/day, respectively. Six experimental batches of bundz rennet cheese were made from the milk, and the effect of the addition of herbs to the diet on the lipid profile of the milk and cheese was analysed. The results indicate that the experimental factor had no statistically confirmed effect on the lipid profile of the raw milk used to make cheese. However, the milk fat from sheep fed a diet with herbs at 20 g/sheep/day showed a tendency towards reduced content of SFA (by 3.6%) and increased content of UFA (by 6.8%) and DFA (by 7.2%) relative to the control group. The experimental factor had essentially no statistically confirmed effect on the fatty acid profile of the cheese, apart from an 11.3% increase in the content of n-6 PUFA (P≤0.05) in the fat of bundz produced from the milk of sheep fed a diet with herbs at 20 g/sheep/day with respect to the control group. The cheese fat also showed a tendency towards lower content of SFA (by 3.4%) and OFA (by 4.8%) and higher content of UFA (by 7.4%), MUFA (by 7.1%), PUFA (by 9.4%), n-3 PUFA (by 11.5%) and DFA (by 7.6%) compared to the control group. The experimental factor had no statistically confirmed effect on cholesterol content in the raw milk or the bundz cheese produced from it.

The effect of herbs added to the winter diet sheep on the lipid fraction profile of raw milk for cheese making and rennet cheese produced from it

A study was conducted on samples of raw sheep milk and rennet cheese produced from it. The milk was obtained from ewes of the coloured variety of Polish Merino, from February to April. The sheep were housed indoors and fed preserved roughage and a mixture of concentrate feeds. Three feeding groups were established: group I ‒ control, fed without the addition of herbs to the concentrate feed, and groups II and III, in which a herb mixture was added to the concentrate feed in the amount of 10 and 20 g/sheep/day, respectively. Six experimental batches of bundz rennet cheese were made from the milk, and the effect of the addition of herbs to the diet on the lipid profile of the milk and cheese was analysed. The results indicated that the addition of herbs to the winter diet of sheep in the amount of 10 and 20 g/sheep/day significantly increased the content of the acid C4:0 in the raw milk used for cheese making, by 11.5% and 20.0%, respectively (P≤0.01), relative to the control group. C4:0 content in the raw milk was also increased in group III by 7.6% compared to group II (P≤0.05). The herbs had no statistically confirmed effect on other parameters of the health-promoting quality of the milk fat and the rennet cheese. In the cheese fat from group I produced from sheep milk obtained in the period from 69 to 137 days of lactation, there was an increase in the content of SFA and a decrease in UFA during the course of the experiment. The addition of herbs to the concentrate feed of the sheep improved the fatty acid profile of the fat of bundz cheese made from milk obtained from the 97th day of lactation. The experimental factor also reduced the cholesterol content in the raw milk in group II by 26.8% and in group III by 21.2% (P≤0.01) compared to group I. It did not affect the content of this lipid in rennet cheese.

The influence of the addition of herbs to the summer diet of sheep on the yield of bundz rennet cheese and its nutritional value

The study was carried out on samples of raw sheep milk and bundz rennet cheese produced from it. The milk was obtained from ewes of the Koluda prolific dairy breed, from June to August. The sheep were housed indoors and fed with alfalfa green forage and a mixture of concentrate feeds. Three groups were formed for the experiment: group I – control, fed without the addition of herbs to the concentrate feed, and groups II and III, in which an herb mixture was added to the concentrate feed in the amount of 10 and 20 g/sheep/day, respectively. Six experimental batches of bundz rennet cheese were made from the sheep milk, and the effect of the addition of herbs to the sheep diet on the chemical composition of the raw milk, the cheese yield, and its nutritional value was analysed. The results showed that the use of the herbal supplement in the feed of the Koluda prolific dairy sheep in summer had no effect on the chemical composition of the raw milk, and thus its value for processing, expressed as the yield of bundz rennet cheese. Moreover, there was no statistically confirmed influence of the experimental factor on the chemical composition of the cheese. Only a tendency towards lower fat content was noted in the group III cheese in comparison with groups I and II (by 6.5% and 8.0% respectively), which resulted in an improved protein-to-fat ratio (by 7.3% and 9.0% respectively) and lower energy value (by 3.6% and 5.2% respectively). We also noted a tendency towards higher mineral content (ash) in the cheese from groups II and III as compared to group I, by 8.7% and 13.0%, respectively However, these differences were not confirmed statistically, probably due to high intra-group variation in this feature (V% in groups I, II and III: 19.7, 33.7 and 46.1, respectively).

The influence of the addition of herbs to the winter diet of sheep on the yield of bundz rennet cheese and its nutritional value

The study was carried out on samples of raw sheep milk and bundz rennet cheese produced from it. The milk was obtained from ewes of the coloured variety of Polish Merino, from February to April, housed indoors and fed with preserved bulky feed and a mixture of concentrate feeds. Three groups were formed for the experiment: group I – control, fed without the addition of herbs to the concentrate feed, and groups II and III, in which an herb mixture was added to the concentrate feed in the amount of 10 and 20 g/sheep/day, respectively. Six experimental batches of bundz rennet cheese were made from the sheep milk, and the effect of the addition of herbs to the sheep diet on the chemical composition of the raw milk used to make cheese, the cheese yield and its nutritional value was analysed. The results showed that the use of herbal supplements in the feed of the coloured variety of Polish Merino sheep in winter had no effect on the chemical composition of the raw milk, and thus its value for processing, expressed as the yield of bundz rennet cheese. The addition of herbs in the amount of 20 g/sheep/day to the diet of sheep significantly increased the content of minerals in cheese made from the milk obtained from the group III sheep, by 6.1% and 6.6% as compared to groups I and II, respectively (P≤0.05). The experimental factor had no influence on the other parameters of the nutritional value of the cheese, i.e. on the content of protein and fat or their mutual proportions, or on its energy value.