Raw Goat Milk Research Articles

Hygienic-sanitary quality in family farm goat milk production

Dairy goat farming became on a profitable activity for small and medium family producers. Thus, goat milk constitutes excellent culture media for the development of undesirable, spoiling and pathogenic microorganisms. Thus, the present study evaluated the microbiological quality of goat milk and dairy derivatives, in order to provide family farmers support and encouragement to adoption of food safety in production chain. A total of 25 samples were evaluated, including refrigerated raw goat milk, goat cheese with or without spices and goat milk caramel. Microbiological analyzes included mesophilic and psychrotrophic bacteria, total coliforms and Escherichia coli, Staphylococcus aureus, yeast and molds enumeration and Salmonella spp detection. Mesophilic and psychrotrophic bacteria, total coliforms and fungi enumerations of most goat milk and cheese samples presented values above the limit established by Brazilian legislation. In only five samples Staphylococcus aureus were detected, being four of goat milk and one of cheese, and most of the isolates were susceptible to antimicrobials of animal and human use. All samples were absent to Salmonella spp.. Goat milk caramel was the best microbiological profile product.

Interaction between a Lactococcus lactis autochthonous starter and a raw goat milk microbial community during long-term backslopping

Traditional cheesemaking processes often involve backslopping practice. However, over successive inoculations, acidification deficiencies may arise. In such cases, adding a starter is recommended to restore the ecosystem stability. This study examines the impact of an autochthonous starter composed of three Lactococcus lactis strains on a raw goat milk microbial community during their evolution. Bacterial composition and technological features (acidification and aroma) were analyzed during communities’ evolution over 800 generations. 16S rRNA gene metabarcoding showed that Lactococcus lactis strains predominated. The raw goat milk community acidification capacities varied early in the evolution and then remained stable. Adding the L. lactis starter to this community stabilized the ecosystem from the beginning of the evolution. The acetoin production was associated with the starter presence, consistent with the establishment of the diacetylatis biovar strain from the starter in the raw goat milk community throughout the evolution. Increased or decreased production of some volatile organic compounds when the starter was added revealed a specific aroma footprint due to interactions between the two communities. This study showed that adding a starter could help to achieve the maximum acidification rate from the early inoculation cycles and could significantly modify the aroma profile during long-term backslopping.

Analysis of the zoonotic tick-borne encephalitis virus (TBEV) in raw milk and dairy products in mountain pastures of the Lombardy region, Italy.

Over the last few decades, tick-borne encephalitis (TBE) has become a growing public health problem in Europe. The tick-borne encephalitis virus (TBEV) is a zoonotic virus that affects the central nervous system (CNS). TBEV has been detected in 27 European countries, and the rise in TBE cases is mainly due to environmental and ecological factors, and factors that increase the risk of human exposure to infected ticks. The infection via the alimentary route is the second most common means of TBEV transmission to humans. Raw milk from infected goats, sheep, or cows has been identified as a source of human food-borne infections. This study aims to gather new information on the prevalence of tick-borne encephalitis virus (TBEV) in raw goat's and cow's milk and related raw products in the Lombard Alps (Italy). This is important due to the close proximity of Lombardy to the Triveneto region, where TBE is endemic, and southern Switzerland, where numerous TBEV-positive mammals have been found. Throughout 2023, a passive monitoring plan was implemented on samples delivered for TBEV analyses from the Alpine pastures. In total, 248 specimens including raw milk, raw milk cheese, and butter were tested. This is the first monitoring of food at risk of TBEV transmission in a non-endemic region with evidence of TBEV circulation. Despite testing a wide range of dairy products, no sample tested positive for RNA-TBEV by real-time RT-PCR. Preliminary results suggest that raw milk and raw dairy products do not pose a significant risk of TBEV transmission to humans in the territory of Lombardy.

Extracellular vesicles carrying significant amounts of microRNAs are present in goat milk powders

Milk-derived extracellular vesicles (mEVs) play a crucial role in intercellular communication, mainly via their microRNAs, and could influence consumer health. Little is known about mEVs from goat milk powder (GMP) consumed as an alternative to bovine milk powder. mEVs were isolated from skimmed and whole GMP, using Size Exclusion Chromatography and their microRNA profiles (miRNomes) were established using RNA sequencing. We showed by nanoparticle tracking analysis that GMPs contained between 1.56 109 and 6.63 109 mEVs mL-1 of reconstituted milk, ranging in size from 136.8 to 160.6 nm. Five major milk protein mRNAs were also detected within mEVs. The GMP miRNome was made of 351 microRNAs, sharing 89 % of known microRNAs with previously reported raw goat milk miRNome. Thus, we demonstrated that: i) mEVs of a typical morphology are present in GMPs; ii) mEVs survived the drying process; iii) their microRNA cargo is rather well protected from degradation during this process.

Fortification of Goat Milk Yogurts with Encapsulated Postbiotic Active Lactococci.

The species Lactococcus lactis is a bacterium extensively used in the dairy industry. This bacterium is Generally Recognized as Safe and was added to the European Food Safety Authority's Qualified Presumption of Safety list. The major functions of this species in dairy fermentation are the production of lactic acid from lactose, citric acid fermentation, and the hydrolysis of casein. But, the representatives of this species that produce bacteriocin substances can also exert an inhibitory effect against spoilage bacteria. The aims of this study were to test three lactococcal strains isolated from raw goat milk for their postbiotic activity and to test their stability in goat milk yogurts after their application in encapsulated form for their further application. To achieve these aims, validated methods were used. Three Lactococcus lactis strains (identified by Blastn 16S rRNA analysis) produced bacteriocin substances/postbiotics. These concentrated postbiotics inhibited the growth of enterococci and staphylococci (by up to 97.8%), reaching an inhibitory activity of up to 800 AU/mL. The encapsulated (freeze-dried) lactococci survived in the goat milk yogurts with sufficient stability. Strain MK2/8 fortified the yogurts in the highest amount (8.1 ± 0.0 cfu/g log 10). It did not influence the pH of the yogurt.

The Prevalence of Brucella Spp. in Dairy Products in Iran: A Systematic Review and Meta-Analysis.

Brucellosis, a significant zoonotic disease, threatens food safety substantially, particularly in developing nations such as the Middle East. This study aimed to comprehensively assess the prevalence of Brucella spp. in Iranian milk and dairy products through a systematic review and meta-analysis. A thorough search of international and domestic databases from January 2008 to October 2023 identified 38 relevant studies encompassing 11,130 samples for meta-analysis. The overall prevalence of Brucella spp. in Iranian dairy products was 22% (95% CI: 16-28%). The highest and lowest overall prevalence of Brucella spp. in milk were found in raw goat milk 27% (95% CI: 11-42%) and raw camel milk 15% (95% CI: -0.42 to 72%), respectively. The overall prevalence of traditional cheese, ice cream, and cream is estimated to be 9% (95% CI: -16 to 35%), 2% (95% CI: -2.78 to 2.82%), and 9% (95% CI: -0.94 to 1.12%). Geographical disparities were evident, with Zanjan province reporting the highest contamination rate, 53%, while Razavi Khorasan province had the lowest, 1%. However, the prevalence of Brucella spp. in Iranian dairy products has fluctuated over time, with a significant association between the study year and sample size. Comprehensive planning, robust policy implementation, and rigorous monitoring are imperative to mitigate and ultimately eliminate Brucella contamination in dairy products effectively. Further research is essential to refine prevalence estimates and develop targeted prevention strategies to safeguard public health.

Development of a cell culture-based method for detecting infectious tick-borne encephalitis virus (TBEV) in milk products

Tick-borne encephalitis outbreaks have been reported in Europe after consumption of raw milk products from infected animals. While molecular methods are commonly used in viral foodborne outbreak investigations due to their sensitivity, specificity and rapidity, there are very few methods to detect infectious tick-borne encephalitis virus (TBEV) in milk products for routine use/analyses. To address this gap, we developed a cell culture-based method to detect infectious TBEV in artificially contaminated raw goat milk and raw goat cheese, and evaluated the sensitivity of TBEV infectivity assays. Raw goat milk samples were spiked with TBEV to achieve inoculation levels ranging from 106 to 100 TCID50/mL, and Faisselle and Tomme cheese samples were spiked so their TBEV concentrations ranged from 9.28 × 105 to 9.28 × 101 TCID50 per 2.5g. To detect infectious TBEV, Vero cells were infected by raw goat milk. For cheese samples, after homogenisation and membrane filtration, Vero cells were infected with samples adsorbed on the filter (method A) or with samples eluted from the filter (method B). After 5 days, cytopathic effects (CPEs) were observed and TBEV replication in Vero cells was confirmed by an increase in the number of genome copies/mL that were detected in cell supernatant. Infected Vero cells exhibited CPEs for both milk and cheese samples. Infectious TBEV was detected to 103 TCID50/mL in raw milk samples and to 9.28 × 101 TCID50 from Faisselle samples using both methods A and B. For Tomme samples, method A was able to detect TBEV to 9.28 × 102 TCID50/2.5g and method B to 9.28 × 103 TCID50/2.5g. The number of positive samples detected was slightly higher with method A than with method B. To conclude, this qualitative cell culture-based method can detect infectious TBEV artificially inoculated into raw milk and cheese; it should be further evaluated during foodborne outbreak investigations to detect infectious TBEV from naturally contaminated milk and cheese.

Microbiome of craft hard cheeses from raw goat milk during ripening

The production of craft cheeses from goat milk in small farms in Ukraine is becoming increasingly widespread. The uniqueness of goat cheeses made from raw milk is attributed to the significant diversity of microbiological processes that occur during their ripening, involving natural strains of bacteria, fungi, yeasts, and cheese mites. Therefore, this research aimed to determine the microbial composition of Caciotta and Canestrato goat cheeses during their ripening process. The number of mesophilic aerobic and facultative anaerobic microorganisms (MAFAM) in Caciotta cheese was stable on the 10th day, the 1st, and the 12th month, and decreased by 1.18–1.27 lg CFU/g by the 24th month of ripening. The number of mold fungi and yeasts in Caciotta cheese peaked in the 1st month but they were not detected in the 12th and 24th months of ripening. Lactic acid bacteria in Caciotta cheese formed the basis of MAFAM and were represented by Lactobacillus plantarum on the 10th day and the 1st month of ripening, Lactobacillus brevis and Leuconostoc pseudomesenteroides in the 12th month, and L. brevis and Leuconostoc mesenteroides in the 24th month. In 24-month-ripened Caciotta cheese, Escherichia coli, Enterobacter ludwigii, E. durans, E. faecalis, and E. hirae were detected. Lactic acid bacteria in Canestrato cheese formed the basis of MAFAM and were represented by L. mesenteroides from the 10th day to the 3rd month of age, L. pseudomesenteroides in the 6th month, and L. plantarum in the 12th month. Canestrato cheese was characterized by a significant presence of mold fungi and yeasts in all ripening periods except for the 6th month. In 12-month-ripened Canestrato cheese, Enterobacter cloacae, Bacillus cereus, Enterococcus durans, E. hirae, and E. faecalis were isolated. Cheese mites, Acarus siro, in various stages of development were found in the rind of both cheeses starting from the 6th month of ripening. The results of the researchers provide new data on the microbiome of craft hard cheeses made from raw goat milk and can be used to develop methods for controlling the population size of A. siro mites during their ripening.

Draft genome sequences of Weissella cibaria GM93m3, a promising probiotic strain from raw goat milk.

The draft genome of a previously documented potential probiotic Weissella cibaria strain GM93m3 from raw goat milk in Nigeria is reported. The total genome size was 2,447,229 with 46 contigs and G+C content of 44.86%.

Advantages and disadvantages of autochthonous enterococci strains for their potential use in cheese ripening: a preliminary study

SummaryThe enzymatic activity exhibited by native enterococci could, in turn, result in a reduction in the cheese ripening time. However, they may also carry virulence factors or resistance to antibiotics that prevent their use in food. A total of 69 enterococci isolates were obtained from a Spanish traditional raw goat's milk cheese and identified by Maldi‐Tof/MS. Different enzymatic activities of technological interest were evaluated and the safety of those with greater technological suitability was studied. The strains were identified as E. malodoratus, E. italicus, E. gilvus, E. faecium, E. durans, E. casseliflavus and E. faecalis. Some strains had very high acidifying and proteolytic activities. Most strains had medium or low amino and carboxypeptidase activities and high dipeptidase activities, while esterase activities were medium. A total of 10 strains were selected based on their enzymatic activities. Of these, five showed β‐haemolysin activity, eight showed gelatinase activity and eight produced tyramine. These activities represent virulence factors that could potentially affect food safety. Finally, all selected strains were susceptible to the antibiotics tested.

TBE In Bulgaria

First cases of probable tick-borne encephalitis (TBE) were reported in 1961 by Andonov et al. in eastern regions of Bulgaria.1 Possible TBE cases with the typical two-wave fever, originating from consumption of raw goat milk, were described back in 1953 by Vaptzarov et al. in southern Bulgaria.2 Investigations in the 1960s were able to isolate 3 tick-borne encephalitis virus (TBEV) strains from Haemaphysalis punctata and 1 from Dermacentor marginatus ticks from goats and sheep in the district of Plovdiv.3 The antigenic properties of these 4 virus strains were identical to the highly virulent strain “Hypr” of the European subtype of TBEV (TBEV-EU).3

TBE In Croatia

In Croatia, TBE was reported for the first time in 1953 near Križevci (Stara Ves, northwestern region).1 In addition to this first focus, several continental foci (Bjelovar, Pakrac, Koprivnica, Karlovac, Varaždin) have been recorded since 1961. Moreover, TBEV antibodies were detected in residents of the Croatian littoral near the islands of Zadar, Pula, and Brac.2 In 1991, TBEV emerged in the mountainous area of Gorski Kotar.3 The disease is also endemic in northwestern and eastern regions between the Sava and Drava rivers. Endemicity is highest in northwestern counties, with average incidence rates ranging from 3.61 to 6.78 per 100,000 inhabitants.4,5 In 2015 and 2019, two TBE clusters after consumption of raw goat milk were observed.6,7

MEASUREMENT OF MICROBIOLOGICAL QUALITY OF RAW GOAT´S MILK BY LASER FLOW CYTOMETRY

The popularity of goat's milk and its products is growing in Slovakia. Among the mandatory health safety features of raw goat's milk is the total bacterial count. It can be determined by the anchor plate-cultivation method, which is, however, tedious, and laborious. Laser flow cytometry is a modern alternative method for measuring the microbiological quality of raw milk. To use the results from laser flow cytometry method for legislative purposes, it is necessary to create a representative conversion of the primarily measured results obtained by this method into the CFU/mL scale. This work describes the creation of such a conversion for raw goat's milk, which will be valid for the Slovak region. After measuring several hundred individual and bulk tank samples of raw goat's milk on a BactoScan FC laser flow cytometer and at the same time using the anchor method according to STN EN ISO 4833-1 and after their subsequent logarithmic transformation, such a conversion was created in the form of log10(CFU/mL) = 1.0174 x log10(IBC/ml) + 2.7483. Subsequently, this was verified by comparing the recalculated and directly measured results in CFU/mL, using additional data set of samples. The influence of the somatic cell count in raw goat's milk, as a possible interfering factor, was also assessed.

Effect of electron beam irradiation on raw goat milk: microbiological, physicochemical and protein structural analysis.

Goat milk is considered a nutritionally superior resource, owing to its advantageous nutritional attributes. Nevertheless, it is susceptible to spoilage and the persistence of pathogens. Electron beam irradiation stands as a promising non-thermal processing technique capable of prolonging shelf life with minimal residue and a high degree of automation. The effects of electron beam irradiation (2, 3, 5, and 7 kGy) on microorganisms, physicochemical properties, and protein structure of goat milk compared with conventional pasteurized goat milk (PGM) was evaluated. It was found that a 2 kGy electron beam irradiation reduces the total microbial count of goat milk by 6-logs, and the irradiated goat milk protein secondary structure showed a significant decrease in ɑ-helix content. Low irradiation doses led to microaggregation and crosslinking. In contrast, high doses (≥ 5 kGy) slightly disrupted the aggregates and decreased the particle size, disrupting the microscopic surface structure of goat milk, verified by scanning electron microscopy and confocal laser scanning microscopy. The irradiation of goat milk with a 2 kGy electron beam may effectively inactivate harmful microorganisms in the milk and maintain/or improve the physicochemical quality and protein structure of goat milk compared to thermal pasteurization. © 2024 Society of Chemical Industry.

Short Communication: Investigation of mecA-positive and Methicillin-Resistant Staphylococcus aureus (MRSA) in dairy goat with subclinical mastitis from traditional farms in Banyuwangi, Indonesia

Abstract. Praja RN, Edila R, Yudhana A, Saputro AL, Hamonangan JM, Praja SS. 2024. Short Communication: Investigation of mecA-positive and Methicillin-Resistant Staphylococcus aureus (MRSA) in dairy goat with subclinical mastitis from traditional farms in Banyuwangi, Indonesia. Biodiversitas 25: 1638-1643. Raw milk has the potential to transmit bacteria resistant to antibiotics and serve as a medium for the development of food-borne illnesses. Staphylococcus aureus is a harmful bacterium that can infect host cells and carry antibiotic-resistant genes. This study aims to investigate the occurrence of Methicillin-Resistant Staphylococcus aureus (MRSA) which contains mecA coding gene from raw goat milk in Banyuwangi, East Java, Indonesia. 150 raw milk samples were collected from five goat farms in Banyuwangi, East Java, Indonesia. S. aureus was isolated using selective media, and antibiotic susceptibility testing was conducted using the Mueller-Hinton agar diffusion method. MRSA was confirmed using the oxacillin and cefotaxime resistance screen agar test, with the presence of mecA genes identified through polymerase chain reaction. The results show that the prevalence of S. aureus was 30.6%. Of the 46 S. aureus isolates, 28 (60.87%) were categorized as MRSA. The mecA gene was observed in 9 (32.14%) MRSA isolates. The presence of MRSA in raw goat milk poses a significant public health threat, as bacteria carrying the mecA gene for antimicrobial resistance can spread through animal products like raw milk. Enhanced hygiene and sanitation protocols in dairy goat farms are essential prevention measures that must be strictly implemented.

Tolerance of enterobacteria isolated from raw goat milk to sanitisers applied in the food industry

The tolerance of 17 isolates of enterobacteria isolated from raw goat milk was evaluated against three sanitisers. All isolates were tolerant to sodium hypochlorite (1250 to >5000 ppm) and eight isolates were tolerant to peracetic acid (up to 1000 ppm). Two isolates were tolerant to all tested concentrations of quaternary ammonium with biguanide (>150/100 ppm). Although not all isolates are considered pathogens, they exert an important influence on the milk production chain. Sanitisers based on quaternary ammonium and biguanide seem to be more suitable for sanitisation in goat milk chain than sodium hypochlorite.

Goat milk extracellular vesicles: Separation comparison of natural carriers for theragnostic application

Goat milk is a complex biological fluid, which in addition to having a high nutritional value, it is an interesting source of extracellular vesicles (EVs). Despite the countless potential applications that they offer in many biological fields, is not easy to compare the different proposed systems, and this is a major limitation for the real translatability of these natural nanoplatforms for theragnostic purposes. Thus, it is useful to further investigate reproducible methods to separate goat milk EVs. The choice of methods but also the preprocessing of milk has an immense impact on the separation, quality, and yield of EVs. Here, we tested four protocols to separate EVs from unpasteurised goat milk: two based on differential ultracentrifugation (DUC) and two on size-exclusion chromatography (SEC). Moreover, we assessed two different approaches of pre-treatment (acidification and precipitation) to facilitate milk protein discharge. To the best of our knowledge, a similar comparison of all performed protocols on raw goat milk has never been published before. Therefore, enriched EV samples were successfully obtained from goat milk using both DUC and SEC. Taken together, our results may be helpful to obtain natural carriers for future theragnostic applications in personalised medicine.

De novo genome assembly of a probiotic Lacticaseibacillus rhamnosus ISO20, isolated from raw milk in South Africa.

Lactic acid bacteria are known to exhibit probiotic properties through various mechanisms including production of antimicrobial substances and bile salts tolerance. Here, we report a draft genome sequence of Lacticaseibacillus rhamnosus ISO20, a lactic acid bacterium isolated from raw goat's milk to provide genomic insight into its strategies as probiotic strain.

Unveiling the culturable bacterial diversity, pathogens and impact of seasonality on microflora of raw goat milk: A phylogenetic outlook

Goat milk can be beneficial in cardiac diseases, mouth ulcers, dengue fever, etc. but ingestion of raw goat milk may have severe side effects as it may comprise pathogenic bacteria. Raw goat milk samples (n-55) were collected from diverse villages of the Udaipur district, Rajasthan, India and analyzed for bacterial diversity and pathogens using biochemical, molecular, and bioinformatic methods. Goat milk samples displayed an incidence of 36.36% for bacterial pathogens and the most prevalent bacteria reported were Listeria spp. and Staphylococcus spp. Bacillus cereus and Staphylococcus xylosus showed high resistance to tested antibiotics followed by Listeria. The dominant phylum found in the raw goat milk was Firmicutes (67.47%) and the dominant genus was Bacillus (28.32%). Listeria sp. was found dominant during the winter season while Staphylococcus spp. was dominant during summer. Three novel species were identified viz. S. xylosus (GM61), Streptomyces sp. C7 (GM2) and Pantoea agglomerans (GM31) can be further explored for their potential applications as bacteriocin producers' which can be used as food preservatives. New antibiotics or any antimicrobial produced by these three novel species can be used for the treatment of diseases. Pseudomonas yangonensis and Streptomyces sp. have not been previously reported in goat milk at the global level while S. xylosus at the National level.

Diversity of bacteria isolated from raw milk of Senduro goats

Goat’s milk is widely consumed because of its good nutrition. However, goat’s milk is also a good habitat for several types of bacteria that may affect the milk quality. Therefore, information concerning the bacteria’s total number and diversity is crucial. This research aimed to reveal the total number and diversity of bacteria in Senduro goat’s milk from three farms. Samples of raw goat’s milk were collected from each farm in a sterile container. Then, the enumeration of the bacteria’s number was done using the Total Plate Count (TPC) method. The total number of bacteria obtained from goat’s milk on farms 1, 2, and 3 were 1.5 x 102 CFU/mL, 8.8 x 101 CFU/mL, and 1.3 x 102 CFU/mL, respectively. The morphological characteristics of the colonies showed the diversity of bacterial isolates in raw goat milk from the three farms. The three samples also shared several bacterial isolates with the same characteristics. It also can be concluded that the bacteria’s total number in goat’s milk from three farms is still acceptable and meets the standard. Identification of the group of each bacterial isolate is needed shortly to deepen our understanding of their role.