Executive Summary: Goat milk is a vital nutritional resource, particularly for small-scale farmers in India, where it is dubbed the “poor man’s cow.” Its unique composition, including smaller fat globules, higher medium-chain fatty acids, and lower αs1-casein content, enhances digestibility and reduces allergenicity compared to cow milk. These properties, along with bioactive compounds exhibiting anti-inflammatory, antimicrobial, and anticancer effects, make goat milk a valuable dietary and medicinal resource. Advanced metabolomic techniques, such as GC-MS, LC-MS, and NMR, enable comprehensive analysis of goat milk’s metabolites, revealing species-specific biomarkers like valine, glycine, and choline that define its nutritional quality, authenticity, and safety. Studies highlight goat milk’s hypoallergenic properties and its suitability for individuals with cow milk protein allergies or lactose intolerance. In goat milk yoghurt, fermentation and storage conditions significantly influence metabolite profiles, affecting sensory attributes and functional properties. Future research integrating metabolomics with genomics and proteomics will optimize goat milk’s applications in dairy technology, ensuring quality control, traceability, and the development of high-value products to meet consumer demands.
Introduction
Milk and milk products are an important part of the human diet in both developing and developed nations. Goats are multi-utility, easy-to-maintain, and prolific animals that efficiently convert minimal feed resources into valuable products. In India, the goat is often referred to as the “poor man’s cow,” serving as a major source of livelihood and nutritional security for small and marginal farmers.
Goat milk is a rich source of essential nutrients, including water, protein, fat, sugar, minerals, and vitamins, all of
which contribute to its high nutritional value. It is characterized by low allergenicity, alkalinity, high buffering capacity, and bioactive properties such as anti-inflammatory, antimicrobial, and anticancer activities, making it highly beneficial in human nutrition and medicine. Compared to cow milk, goat milk has smaller fat globules and a higher proportion of short- and medium-chain fatty acids, which enhance its digestibility and impart a distinctive flavor.
Goat milk also contains a lower concentration of αs1-casein, resulting in smaller casein micelles and reduced hydrated pores, which contribute to its hypoallergenic properties. The lower casein content, compared to cow milk, is associated with slower coagulation and lower yield during cheese manufacturing.
Advanced analytical techniques used for compositional analysis of milk
Metabolomics is a truly interdisciplinary field that combines analytical chemistry, platform technologies, mass spectrometry (MS), nuclear magnetic resonance (NMR), and advanced data analysis. It offers a platform for the comparative analysis of metabolites that reflect dynamic cellular processes and homeostasis.
Metabolomics is a rapidly evolving “omics” field that focuses on the comprehensive identification and quantification of small molecules (<1500 Da) within biological systems. These include fatty acids, peptides, amino acids, carbohydrates, nucleic acids, vitamins, organic acids, and polyphenols, all of which play vital roles in metabolism and physiological functions (Wishart, 2008).
Advanced analytical techniques used in metabolomics include:
- NMR (Nuclear Magnetic Resonance)
- GC-MS (Gas Chromatography-Mass Spectrometry)
- LC-MS (Liquid Chromatography-Mass Spectrometry)
- CE-MS (Capillary Electrophoresis-Mass Spectrometry)
- HPLC-UV (High-Performance Liquid Chromatography with UV Detection)
- ICP-MS (Inductively Coupled Plasma Mass Spectrometry)
Metabolomics approaches can be categorized as targeted (focusing on known metabolites) and untargeted (providing a broader overview, including unknown metabolites). Among these, GC-MS is widely used due to its efficiency and reproducibility. GC-MS-based metabolomics requires high-throughput capabilities for sample handling and accurate peak identification using standard retention times and mass spectra.
To enable separation on a GC column, derivatization is required to create volatile compounds. This allows the simultaneous profiling of several hundred metabolites, including organic acids, amino acids, sugars, sugar alcohols, aromatic amines, and fatty acids.
LC-MS techniques employ soft ionization, making MS more robust for daily use. LC-MS can generate lists of m/z values, retention times, and relative abundances of metabolites—some of which may remain unidentified. Its high-resolution and reproducibility form the foundation for multivariate data analysis.
NMR is emerging as a powerful tool in metabolomics, offering unbiased information about metabolite profiles. It is straightforward, largely automated, and non-destructive, allowing further analysis of samples. NMR is widely used for metabolite fingerprinting, profiling, and flux analysis. However, its primary limitation is relatively low sensitivity, making it less suitable for detecting low-abundance metabolites.
GC-MS-Based Metabolomics of Goat Milk and Milk Products
Metabolomics has become essential for evaluating the nutritional quality, authenticity, and safety of goat milk. Using advanced techniques such as GC-MS, researchers have identified key metabolites that define the unique properties of goat milk. These studies help assess bioactive compounds with potential health benefits and provide insights into how genetic and environmental factors influence milk composition.
Nutritional Quality and Bioactive Compounds in Goat Milk
One major finding from metabolomic studies is the presence of bioactive compounds in goat milk that offer hypoallergenic and other health-promoting properties. Ballabio et al. (2011) showed that goat milk contains lower levels of αs1-casein—often responsible for allergic reactions in cow milk. The study also highlighted the presence of medium-chain fatty acids, such as capric, caprylic, and caproic acids, which support easier digestion and have potential antibacterial effects. These properties make goat milk a preferred alternative for individuals with cow milk protein allergies (CMPA) or lactose intolerance.
Metabolite Profiling of Goat vs. Bovine Milk
Comparative metabolomic studies between goat and cow milk have identified species-specific metabolites. Scano et al. (2014) found that valine and glycine are prominent in goat milk, whereas talose and malic acid are more characteristic of cow milk. These metabolites influence sensory attributes, digestibility, and nutritional value, making goat milk suitable for individuals with dietary restrictions.
GC-MS has also identified biomarkers such as choline, citrate, valine, hippuric acid, 2-butanone, and lactate, which serve as indicators of milk quality and traceability (Suh et al., 2022). These markers are crucial for ensuring milk quality, product traceability, and preventing adulteration in dairy products.
Goat Milk Yogurt
GC-MS-based metabolomics has revealed how fermentation conditions, starter cultures, and post-fermentation storage affect yogurt composition. Rehman et al. (2023) identified 102 metabolites in goat milk yogurt, with 15 showing differential expression (p < 0.05), including 2-hydroxyethyl palmitate, α-mannobiose, and myo-inositol. Regression analysis highlighted methylamine (R² = 0.669) and myo-inositol (R² = 0.947) as key influencers of yogurt firmness and techno-functional properties.
Sun et al. (2021) used GC-MS to study metabolic changes during fermentation. They observed dynamic shifts in volatile compounds, including 2-hydroxy-3-pentanone, benzaldehyde, octanoic acid,3-methyl-2-buten-1-ol, 2,3-butanedione, 2-decenal, hexanoic acid, hexanal, decanoic acid, 1-nonanol, and 3,7-dimethyl-1,6-octadien-3-ol. Notably, metabolites, 2-nonanol and 5-methyl-1-hexanol were mainly detected during post-fermentation, indicating ongoing metabolic activity even after fermentation ended.
Conclusion and Future Prospects
Goat milk metabolomics offers a comprehensive understanding of its chemical composition, bioactivity, and functional potential. Techniques like GC-MS, LC-MS, and NMR have significantly enhanced quality control, authenticity assessment, and the development of functional dairy products. Species-specific metabolic differences underscore goat milk’s unique advantages over cow or sheep milk.
Furthermore, fermentation and storage significantly shape the metabolic profile of goat milk products, affecting sensory attributes, texture, and product stability. Future research integrating metabolomics with genomics and proteomics will deepen our understanding of goat milk’s health benefits and optimize its use in dairy technology and human nutrition.
Standardizing metabolomic methods, validating milk quality biomarkers, and exploring metabolic pathways will be essential for advancing dairy science. These efforts will help the dairy industry improve processing, ensure traceability, and create high-value goat milk products that meet evolving consumer needs.
by Pratiksha, Heena Sharma, Gaurav Kr Deshwal, A K Singh and Hency Rose
Dairy Technology Division, ICAR-National Dairy Research Institute, Karnal
References are available upon request.
