Sheep Milk Research Articles

Novel and Sensitive Touchdown Polymerase Chain Reaction Assays for the Detection of Goat and Sheep Milk Adulteration with Cow Milk.

Milk is the most consumed liquid food in the world due to its high nutritional value and relatively low cost, characteristics that make it vulnerable to adulteration. One of the most common types of milk adulteration involves the undeclared addition of cow's milk to milk from other mammalian species, such as goats, sheep, buffalo or donkeys. The incidence of such adulteration not only causes a crisis in terms of commercial market and consumer uncertainty but also poses a risk to public health, as allergies can be triggered by proteins in undeclared cow's milk. In this study, a specific qualitative touchdown (TD) PCR method was developed to detect the undeclared addition of cow's milk in goat and sheep milk based on the discrimination of the peak areas of the melting curves after the modification of bovine-specific primers. The developed methodology has high specificity for the DNA templates of other species, such as buffalos and donkeys, and is able to identify the presence of cow's milk down to 1%. Repeatability was tested at low bovine concentrations of 5% and 1% and resulted in %RSD values of 1.53-2.04 for the goat-cow assay and 2.49-7.16 for the sheep-cow assay, respectively. The application of this method to commercial goat milk samples indicated a high percentage of noncompliance in terms of labeling (50%), while a comparison of the results to rapid immunochromatographic and ELISA kits validated the excellent sensitivity and applicability of the proposed PCR methodology that was able to trace more adulterated samples. The developed assays offer the advantage of multiple detection in a single run, resulting in a cost- and time-efficient method. Future studies will focus on the applicability of these assays in dairy products such as cheese and yogurt.

A Metabolomics Study by 1H HRMAS NMR: From Sheep Milk to a Pressed-Curd Cheese: A Proof of Concept

For the first time, High-Resolution Magic Angle Nuclear Magnetic Resonance spectroscopy (NMR-HRMAS) was applied to directly identify specific metabolites from a Spanish raw ewe’s milk and enzymatic coagulation pressed-curd cheese (Protected Geographical Indication: Castellano) manufactured by two procedures (traditional/artisanal vs. industrial) and including the ewe’s raw milk. The NMR parameters were optimized to study the complex matrixes of this type of cheese. In addition, conventional overcrowded 1H-NMR-HRMAS spectra were selectively simplified by a Carr–Purcell–Meiboom–Gill (CPMG) sequence or a stimulated echo pulse sequence by bipolar gradients (DIFF), thus modulating spin–spin relaxation times and diffusion of molecular components, respectively. 1H-NMR-HRMAS spectroscopy displayed important information about cheese metabolites, which can be associated with different manufacturing processes (industrial vs. traditional) and ripening times (from 2 to 90 days). These results support that this spectroscopy is a useful technique to monitor the ripening process, from raw milk to commercial ripened cheese, using a minimum intact sample, implying the absence of time-consuming sample pretreatments.

Study of the Microbiome of the Cretan Sour Cream Staka Using Amplicon Sequencing and Shotgun Metagenomics and Isolation of Novel Strains with an Important Antimicrobial Potential.

Staka is a traditional Greek sour cream made mostly from spontaneously fermented sheep milk or a mixture of sheep and goat milk. At the industrial scale, cream separators and starter cultures may also be used. Staka is sometimes cooked with flour to absorb most of the fat. In this study, we employed culture-based techniques, amplicon sequencing, and shotgun metagenomics to analyze the Staka microbiome for the first time. The samples were dominated by Lactococcus or Leuconostoc spp. Most other bacteria were lactic acid bacteria (LAB) from the Streptococcus and Enterococcus genera or Gram-negative bacteria from the Buttiauxella, Pseudomonas, Enterobacter, Escherichia-Shigella, and Hafnia genera. Debaryomyces, Kluyveromyces, or Alternaria were the most prevalent genera in the samples, followed by other yeasts and molds like Saccharomyces, Penicillium, Aspergillus, Stemphylium, Coniospotium, or Cladosporium spp. Shotgun metagenomics allowed the species-level identification of Lactococcus lactis, Lactococcus raffinolactis, Streptococcus thermophilus, Streptococcus gallolyticus, Escherichia coli, Hafnia alvei, Streptococcus parauberis, and Enterococcus durans. Binning of assembled shotgun reads followed by recruitment plot analysis of single reads could determine near-complete metagenome assembled genomes (MAGs). Culture-dependent and culture-independent analyses were in overall agreement with some distinct differences. For example, lactococci could not be isolated, presumably because they had entered a viable but not culturable (VBNC) state or because they were dead. Finally, several LAB, Hafnia paralvei, and Pseudomonas spp. isolates exhibited antimicrobial activities against oral or other pathogenic streptococci, and certain spoilage and pathogenic bacteria establishing their potential role in food bio-protection or new biomedical applications. Our study may pave the way for additional studies concerning artisanal sour creams to better understand the factors affecting their production and the quality.

A REVIEW ON CASIEN FROM VARIOUS MILK SAMPLES ITS USES AND IMPORTENCE

The milk proteins are the oldest and most widely consumed food proteins. There is currently a large interest in these substances, both in nutritional field and in technological application. Casein proteins are a family of proteins involved in the production of cheese and fermented milk. They are very important nitrogen compounds not only for the dairy products production, but they are also additives in medicine, and they have a technical use in cosmetics, paints and adhesives. : Milk is an important part of human life and supposed to be a nutritious food which contain about 80% proteins. Milk proteins consist of 80% casein (soluble protein), 2-8% lactose (milk fat) and remaining is whey (byproduct of cheese and casein manufacture). Casein is more important and contain almost all essential amino acids. The purpose of the present work was to estimate the amount of casein in different milk samples including natural milk (cow, buffalo, sheep and goat). Keywords: Milk powder, casein, Amino Acids, paint, cheese

Farmers' and Experts' Knowledge Coping with Sheep Health, Control and Anthelmintic Resistance of Their Gastrointestinal Nematodes.

Gastrointestinal nematodes are common in grazing sheep, but the intensity of the infection is not easily appreciated by farmers. For decades, they have relied on anthelmintic treatments to control these gastrointestinal nematodes. This has led to anthelmintic resistance and poor control of infection in most regions of the world. Using face-to-face semidirective interviews with farmers, we recorded their views on gastrointestinal nematode infection and its control. Ten organic and nine conventional meat sheep farmers from central France and 20 milk sheep farmers from the Basque region were interviewed and the data were analysed using a health model based on the importance of the disease and the barriers to implementing control. It was found that gastrointestinal nematodes were not the main health concern, and therefore farmers were not willing to invest too much time and money in their control. The conventional farmers relied on their veterinarians (the experts) to organise and select the anthelmintics, although they complained about the limited investment of their veterinarians in this matter. Organic farmers complained about their lack of knowledge about complementary and alternative medicines. Farmers rarely used faecal egg counts to build control of gastrointestinal nematodes and were unaware of the intensity of their infection. Knowledge of anthelmintic resistance was general (it exists) but farmers did not know if it existed on their farm. Resistance was often considered to have come from elsewhere, so the farmer did not feel at fault and did not take measures to prevent resistance. There is a need for all stakeholders to use faecal egg counts to assess the intensity of infection as well as the level of anthelmintic resistance to establish individual farm control programmes rather than standard blanket treatments.

Investigating the Effects of Strawberry Puree on the Quality Attributes of Goat and Sheep Milk Puddings

Investigating the Effects of Strawberry Puree on the Quality Attributes of Goat and Sheep Milk Puddings

Improving the Quality and Sensory Properties of Drinkable Yogurt Made from Goat and Sheep Milk with Date Puree

Improving the Quality and Sensory Properties of Drinkable Yogurt Made from Goat and Sheep Milk with Date Puree

Biochemical characterization of YoAlp®: a sheep-fermented milk obtained with autochthonous starter cultures

Fermented milks are a source of bioactive peptides with different potential benefits on human health and may be considered as functional foods. Sheep milk and fermented milk have been collected and a biochemical characterization, by a proteomic approach, GC/MS and microtiter plate assay methods, have been conducted to evaluate their peptide, fatty acid and aromatic profile, and to assess potential health promoting effects. Furthermore, a comparison between sheep-fermented milk (SFM) made with commercial starter cultures and YoAlp®, a sheep-fermented milk obtained using local strains of lactic acid bacteria, has been performed. Peptide’s profile comparison shows a higher number of amino acidic frequencies using autochthonous starter cultures than commercial ones. Among these peptides, 20.78% and 29.87%, respectively, are supposed to be potentially bioactive. Furthermore, in both products, the fatty acid profile was similar to that of origin sheep milk, and concerning aromatic profile, YoAlp® shows yogurt typical aromatic assets. Considering bioactivity, ACE inhibitor activity is high for both samples. Similar values, as expected by peptide profile analysis, have been obtained. Even in the case of antioxidant capacity, peptide profile bioactivity prediction has been confirmed by the assay showing a DPPH inhibition higher for SFM than for YoAlp®, but this difference is not statistically significant. Local strains of lactic acid bacteria seem to work as well as the commercial, preserving biodiversity and typicality. However, further analyses are needed to understand microbial proteolytic activities and to investigate gastric digestion resistance of bioactive peptides.

Comparative lipidome study of maternal plasma, milk, and lamb plasma in sheep

Lipids play a critical role in neonate development and breastmilk is the newborn’s major source of lipids. Milk lipids directly influence the neonate plasma lipid profile. The milk lipidome is dynamic, influenced by maternal factors and related to the maternal plasma lipidome. The close inter-relationship between the maternal plasma, milk and neonate plasma lipidomes is critical to understanding maternal-child health and nutrition. In this exploratory study, lipidomes of blood and breast milk from Suffolk sheep and matched lamb blood (n = 13), were profiled on day 34 post birth by untargeted mass spectrometry. Comparative multivariate analysis of the three matrices identified distinct differences in lipids and class of lipids amongst them. Paired analysis identified 346 differential lipids (DL) and 31 correlated lipids (CL) in maternal plasma and milk, 340 DL and 32 CL in lamb plasma and milk and 295 DL and 16 CL in maternal plasma and lamb plasma. Conversion of phosphatidic acid to phosphatidyl inositol was the most active pathway in lamb plasma compared to maternal plasma. This exploratory study illustrates the partitioning of lipids across maternal plasma, milk and lamb plasma and the dynamic relationship between them, reiterating the need to study these three matrices as one biological system.

The use of Brix refractometer as a simple and economic device to estimate the protein content of sheep milk

In this study, 737 individual sheep milk samples were collected 2 times from morning milkings to evaluate the relationships between Brix refractometer measurements and milk constituents— protein and fat percentages—to verify its ability to predict milk constituents. The Pearson's simple (rSP) and partial (rPP) correlations between milk constituents were calculated, and several first- and second-order regressions were tested to predict the protein and fat percentages. The rSP coefficients between the Brix refractometer measurement and fat (rSP = 0.46) and protein (rSP = 0.87) contents were different from the rPP coefficients, particularly for fat percentage (rPP = 0.04 and rPP = 0.82, for fat and protein percentages, respectively). The results of the forecasts can be considered satisfactory only for the first order regression that predicted the percentage of milk protein, while the regression that predicted the percentage of fat + milk protein presented a weak forecasting capacity.

Physicochemical and Microbiological Properties of Stirred Bio-Yoghurt Manufactured from Sheep Milk

Physicochemical and Microbiological Properties of Stirred Bio-Yoghurt Manufactured from Sheep Milk

Qualitative characteristics of sheep's and goat's milk in Albania.

Cost-effective methods are crucial in small-scale operations to assess the physicochemical properties of milk, identify potential clinical or subclinical mastitis, and test β-lactams in small ruminants. The aim was to evaluate the importance of physicochemical characteristics, somatic cells, and antibacterial substances as factors for monitoring the quality and safety of bulk tank milk from sheep and goats. Furthermore, we aimed to elucidate the influence of grazing capacity on the composition of sheep milk. The fat content of sheep milk (n=119) was found to be 7.7%, with a range of 5.3% to 9.9%. The average fat content of dairy goats (n=33) was found to be 4.9%, with a range of 2.8-6.7%. The results indicate that 2.8% of sheep milk samples and 7.8% of goat milk samples exhibited clear positive reactions when assessed using the California mastitis test. β-lactam antibiotics were present in 0.7% of sheep milk samples, but not in any of the goat milk samples using lateral flow strips. This measurement method can be useful to detect adulterated milk and better understand the quality and safety of small ruminant milk before processing.

Heart-Cutting Bidimensional Liquid Chromatography for the Simultaneous Analysis of Veterinary Drugs Residues and Nucleotide Monophosphates in Sheep's Milk.

Sheep's milk is a significant source of nucleotide monophosphates (NMPs) but can also contain undesirable residues from veterinary drugs, posing a potential human health risk. This study introduces a novel application of two-dimensional liquid chromatography (2D-LC), in heart-cutting mode, for the simultaneous determination of nucleotides and veterinary drug residues in sheep's milk. 2D-LC allows for the separation of these compounds in a single chromatographic run despite their differing physicochemical properties. The proposed method separates six veterinary drug residues and five NMPs in a single injection. The compounds were separated using a C18 reversed-phase column in the first dimension and a Primesep SB analytical column in the second dimension. The method performance was evaluated in terms of linearity range, detection and quantification limits, matrix effects, precision, and accuracy. The results demonstrated good linearity and sensitivity, with quantification limits allowing for the quantification of veterinary drugs at the maximum residue level and nucleotides at typical levels found in milk samples. The method has been successfully applied to the analysis of sheep's milk samples acquired from local supermarkets, with recoveries within a range of 70-119% and 82-117% for veterinary residues and NMPs, respectively.

A Stochastic Frontier Approach to Study the Relationship between the Hygienic Quality of Bulk Tank Sheep Milk and Technical Efficiency of the Coagulation Process.

Sheep milk from local breeds is important for the production of high-quality cheeses throughout the Mediterranean region, such as Manchego cheese in Spain. To maintain sustainable and efficient production, it is necessary to reach a better understanding of how the composition and hygiene of the milk affect the coagulation process, with the aim of optimizing production yield. This study implemented a stochastic production frontier function to estimate the potential production of curd and efficiency using data from the four seasons of a study of 77 Manchega sheep farms. The Cobb-Douglas production frontier model was estimated using the maximum likelihood estimation method. The results showed that the content of protein, lactose, and fat exhibited increasing returns to scale, with protein content being the most significant factor for curd production. Approximately half of the inefficiency was due to factors related to the technological properties and the hygiene of the milk. The pH, curd firmness, and concentration of lactic acid bacteria improved the efficiency of coagulation, while the concentration of spores of lactate-fermenting Clostridium spp., Pseudomonas spp., staphylococci, and catalase-negative gram-positive cocci favored the inefficiency of the coagulation process. To date, this is the first study to evaluate the effect of different factors, such as microbial groups, milk composition, and technological properties, on the efficiency of the coagulation process in dairy sheep.

Effects of Nutritional Factors on Fat Content, Fatty Acid Composition, and Sensorial Properties of Meat and Milk from Domesticated Ruminants: An Overview.

The meat and milk products from domesticated ruminants are important foods within a balanced diet, offering a rich source of energy, protein, fats, minerals, and vitamins. The sensorial properties of meat and milk are mainly linked to their fat content and fatty acid composition, which are influenced by the feeding background or nutrient composition of diets. While several studies have investigated the nutritional effects on the fat content and fatty acid profile of ruminant meat and milk, as well as their relationship with sensorial properties, a comprehensive overview of these effects is lacking. This paper summarises current literature and discusses changes to fatty acid composition (including ω-3 concentrations), fattiness, and associated quality traits of sheep, goat, beef cattle, alpaca, and llama meat that can be achieved by using different forages or feeds in a total mixed ration. Additionally, it presents the shelf life and nutritional value of meat, milk, and cheeses from the milk of dairy cattle, buffalo, goats, and sheep as influenced by a ruminant diet. Further advancement in these areas will promote the sustainability of ruminant production and its associated feeding systems in achieving premium quality animal-derived foods.

Functional benefits of probiotic fermented dairy drink elaborated with sheep milk processed by ohmic heating

This study examined the effects of ohmic heating pasteurization on probiotic fermented sheep milk compared to conventional heating by analyzing microbial viability, volatile compounds, riboflavin content, and bioactive peptides in the resulting dairy product. Four batches of milk were processed using conventional heating (CH) and three different ohmic heating (OH). Microbiological analysis demonstrated the safety of OH-processed milk. Probiotic viability remained consistent during fermentation and storage, and the simultaneous inoculation of bacteria reduced fermentation time, indicating cooperation interplays. OH-processed probiotic fermented sheep milk showed a substantial increase in antioxidant, antidiabetic, antihypertensive activities, and riboflavin content. Moreover, the flavor profile was characterized by specific volatile compounds. Multiple-factor analysis was performed to identify relationships between samples and various parameters, offering insights into the impact of processing methods. In conclusion, OH enhanced the health-promoting and flavor-related compounds of probiotic fermented sheep milk, suggesting its application to produce functional dairy products.

Prediction of sheep bulk milk coagulation properties from mid-infrared spectral data

The technological features of milk are essential for cheese manufacturing. This is particularly true for Italy, where most of the milk produced by sheep is intended for cheese production. The possibility to evaluate technological characteristics and coagulation aptitude of milk in advance, before any treatment, is crucial for decision-making at industry level. In the present study, we tested the ability of mid-infrared spectroscopy for prediction of coagulation traits (rennet coagulation time and curd firmness) by using more than 4000 bulk milk samples of 344 sheep herds. The models developed with a partial least square regression showed that spectral data points can be successfully used to predict the two traits. The coefficient of determination in external validation was 0.42 for rennet coagulation time and 0.28 for curd firmness, indicating that sheep milk delivered to dairies can undergo a preliminary screening only to assess the expected coagulation time. This finding will allow manufacturers to evaluate the milk received from farmers. Further investigation will be need to improve the prediction of rennet coagulation time that can be coupled with composition traits to define premiums or penalties in the payment system.

Rapid detection and quantification of milk adulteration using MALDI-MS protein profiling and multivariate calibration

The adulteration of high-value milks with low-value milks is a common fraudulent practice in the dairy industry. This not only results in economic or quality prejudice, but also poses a potential threat to individuals with sensitivities or allergies. Profiling the major whey and casein milk proteins can be a crucial tool in combating this malpractice, given that each mammal species exhibits a unique protein fingerprint. In this study, we employed matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-MS) as a rapid and straightforward method for profiling proteins from bovine, caprine, and ovine milks. Subsequently, we analyzed binary mixtures of goat and sheep milks with bovine milk to establish multivariate calibration models using partial least-squares (PLS) to quantify the adulteration of goat and sheep milks. Proteins were identified according to their molecular mass (Mr) and their intensities were considered as multivariate data. To achieve satisfactory calibration and validation results, normalization through variable augmentation was necessary, enabling the quantification of bovine milk across the entire adulteration range. This uncomplicated approach based on MALDI-MS protein profiling and PLS shows significant potential for qualitative and quantitative assessments of milk adulteration.

Common proteins analysis of different mammals' mature milk by 4D-Label-Free

The milk proteins from samples of 13 different animals were identified utilizing 4D-Label-Free proteomics technology, leading to the identification of a substantial number of proteins. Among the various samples, Chinese people (CHP) milk proteins exhibited the highest count, with 1149 distinct proteins. Simultaneously, we identified common proteins present in these animal milk. It's notable presence in goat milk contributes to enhancing infant infection resistance, showcasing the beneficial role of lactoperoxidase. Galectin-3 binding protein (Gal-3BP) and tetraspanin in human milk are significantly higher than those in other animals, which determine the prominent antiviral effect of human milk and the important processes related to cell transduction. Furthermore, human milk, camel milk, goat milk and sheep milk proved to be rich sources of milk fat globule membrane (MFGM) proteins. The insights obtained from this study can serve as a foundational framework for exploring the role of different animal milk proteins in disease treatment and the composition of infant formula.

Auto-mmBCFAs: A swift precision approach for determination of monomethyl branched-chain fatty acids

Monomethyl-branched chain fatty acids (mmBCFAs) are prevalent in diverse food sources, garnering significant interest owing to their distinctive branched structure and biological activity. However, the conventional analytical methods suffer from the time consumption and lower accuracy. In this study, we developed a method named Auto-mmBCFAs integrated GC-MS and algorithms for rapid and accurate measuring mmBCFAs. This method utilizes a multivariate matching approach, significantly enhancing detection efficiency. Compared to NIST database, Auto-mmBCFAs exhibits higher detection rates and accuracy. The developed method was validated in terms of precision, sensitivity, and linearity, and further evaluated mmBCFAs profile in sheep milk from different regions and breeds. Our results demonstrated that Auto-mmBCFAs methods is a rapid and reliable method for the determination of mmBCFAs in complex biological matrices.