Goat Milk Protein Research Articles

A Comparative Study of Ultrasound and Thermal Processing: Effects on Stability and Protein Structure in Goat Milk.

Ultrasonic treatment has been shown to improve the functional properties and quality of proteins; however, the effect of ultrasound on the improvement of goat milk proteins and its impact on the quality of goat milk is not clear. In this study, we mainly want to analyze the effect of thermal stability of whole raw goat milk from the protein structural aspect and to analyze whole raw goat milk stability from the protein point of view. Goat milk was subjected to ultrasound treatments (400W/10 min, 500W/10 min, and 600W/10 min), while untreated and heat-treated samples served as controls. The results demonstrated that ultrasonic treatment led to a more uniform distribution of fat globules and protein particles, reduced agglomeration, and fostered a more compact and ordered protein network structure. Additionally, it enhanced the stability of goat milk. After ultrasonic treatment, the composition and structure of goat milk protein changed. The exposure of more hydrophobic groups enhanced the intermolecular forces, thereby making the protein conformation more stable. These findings indicate that ultrasonic processing not only improved the structure of goat milk proteins but also increased their thermal stability. This study highlights the potential of ultrasonic treatment as an effective method for enhancing the stability and quality of goat milk.

Detection and quantification of true proteins, casein fractions, and their genetic variants, and whey proteins in goat milk by Reverse-Phase High-Performance Liquid Chromatography.

The protein profile of milk is an increasingly important research topic in relation to the technological properties of milk for cheese-making and value of it for human nutrition. Goats are a valuable source of milk worldwide, but there is no precise and rapid method for the simultaneous identification and quantification of the genetic variants of the major protein fractions. In this study we devised a method for the rapid identification and quantification of the main genetic variants of αS1-, αS2-, β- and κ- caseins, and of α-lactalbumin and β-lactoglobulin (whey proteins) in caprine milk using an HPLC-UV reverse-phase C8 column. The R2 of the calibration equations was > 0.99 for all 15 protein fractions identified. A total of 520 milk samples were taken from 260 goats (in duplicates) of 6 different breeds reared on 22 farms operating different farming systems, ranging from traditional/extensive to modern/intensive, and analyzed them to externally validate the method. Milk samples from DNA-genotyped goats were used to identify the genetic variants of the caseins. Compared with other studies, with our method we were able to separate the main genetic variant of caseins within a total run time of 24 min and with a repeatability > 92% for all fractions except for the C variant of κ-casein. Farms were found to be the major source of the variability in the contents of true proteins (56.1% of total variance), true caseins (48.6%), κ-casein C (50.6%) and whey proteins (52.9-62.9%) in goats' milk, whereas individual goat within farm was the most important source of variability in the contents of individual caseins and their genetic variants (53.9% to 94.7%).

Bioactive peptides with antioxidant and ACE inhibitory properties in goat milk protein hydrolysates: Peptidomics and molecular docking study.

This study identified the amino acid sequences of peptides generated from the enzymatic hydrolysis of goat milk proteins from two different sources and annotated their functional activities. Peptidomics and molecular docking approaches were used to investigate the antioxidant and ACE inhibitory properties of the unique peptides, revealing the molecular mechanisms underlying their bioactivity. In vitro experiments showed that the IC50 values for ACE inhibition of the four peptides (LSMTDTR, QEALELIR, NIPVGILR, and QAQNVQHY) were 2.087, 7.584, 2.845, and 4.884 mg/mL, respectively, while the IC50 values for DPPH radical scavenging were 4.466, 4.496, 4.626, and 3.875 mg/mL, respectively, indicating strong antioxidant and ACE inhibitory potential. These findings suggest that goat milk protein could serve as a promising natural source of bioactive peptides with therapeutic potential for managing oxidative stress and hypertension.

Effect of lipid droplet size on the digestion of goat milk proteins with different casein:whey protein ratios

Effect of lipid droplet size on the digestion of goat milk proteins with different casein:whey protein ratios

Physicochemical properties, antioxidant and antidiabetic activities of different hydrolysates of goat milk protein

There is growing interest in the origin, preparation, and application of bioactive peptides. This study investigated the impact of 6 enzymes on the structural, physicochemical properties, antioxidant activities, and antidiabetic potential of defatted fresh goat milk. Structural and functional changes resulting from enzymatic hydrolysis were assessed using gel electrophoresis, laser particle size analysis, multi-spectroscopy, and evaluations of foaming and emulsification properties. Antioxidant capacity was determined through free radical scavenging, Fe2+ chelation, and reducing ability experiments. Additionally, the inhibitory effects of the hydrolysates on α-glucosidase and α-amylase were measured to evaluate antidiabetic activity. Results showed that enzymatic hydrolysis disrupted the spatial structure of goat milk protein and reduced its molecular weight. Papain hydrolysate exhibited the highest degree of hydrolysis (32.87 ± 0.11%) and smallest particle size (294.75 ± 3.33 nm), followed by alcalase hydrolysate (29.12 ± 0.09%, 302.03 ± 7.28 nm). Alcalase hydrolysate showed the best foaming properties, while papain hydrolysate demonstrated the strongest DPPH and hydroxyl radical scavenging activity, Fe2+ chelation, and antidiabetic potential. These findings provide solid theoretical basis for utilizing defatted goat milk as functional ingredients or excipients in the food, medical, and cosmetic industries.

Astral-DIA proteomics: Identification of differential proteins in sheep, goat, and cow milk

Dairy products are of great benefit to human health, and the nutritional differences between different dairy products have attracted attention. In this study, DIA proteomics technique, combined with parallel reaction monitoring (PRM) as a validation method, was used for the qualitative and quantitative analysis of proteins in sheep, goat, and cow milk. In total, 4316 proteins were identified. Beta-2-glycoprotein 1 and aminopeptidase can be used as potential biomarkers for sheep milk, fibrinogen alpha chain and Alpha-1-B glycoprotein can be used as potential biomarkers for goat milk, and angiogenin-1 and Serpin family G member 1 can be used as potential biomarkers for cow milk. Functional analysis showed that these different proteins were enriched through different pathways, such as complement and coagulation cascades. These data reveal the differences in protein content and physiological functionality and provide an important basis for the study of dairy nutrition and adulteration identification.

Comparative Analysis of Skim Milk and Milk Fat Globule Membrane Proteomes between Human and Farm Animal Milk for Infant Formula Production.

Human and animal milk contain a rich variety of milk proteins that meet the needs of their newborns. In total, 1263 skim milk proteins and 1754 MFGM proteins were identified in human milk and six types of animal milk, respectively. Both similarities and differences were observed among the species. Human milk contained more immunoglobulins involved in the adaptive immune response, playing a crucial role in mucosal defense in newborn babies. In contrast, ruminant milk contained higher amounts of antimicrobial proteins, which protect newborns from bacterial infections. The most dominant difference in MFGM proteins between human and animal milk was related to protein processing in the endoplasmic reticulum. Goat milk and camel milk were more similar to human milk in terms of skim milk and MFGM proteins compared to the other five types of animal milk. Moreover, immunoglobulins and complement and coagulation cascade proteins in goat milk were most similar to those in human milk. A higher content of immunoglobulin A was observed in donkey milk, which could be considered as a source of IgA in infant formula. These results provide more comprehensive and novel insights into protein variation among animal milk, which may support improving dairy products such as infant formula.

Proteomic and Transcriptomic Profiling Revealed Vital Molecular Events in the Transition from Goat Colostrum to Mature Milk.

As an important nutrient source in large areas of the world, goat milk is favored by more and more consumers; however, the composition, nutritional value, and regulation mechanism of goat milk are not fully characterized. Mammary gland development is as important as detailed annotation of protein composition to address the physiological and nutritional values of goat milk. In the present study, 4353 colostrum and mature goat milk proteins were identified. The abundance of 118 proteins was significantly different between colostrum and mature milk proteins. Our results indicate that the milk protein changes were associated with a network of mammary gene expression changes; importantly, the prime factors include enhanced mammary growth/development, decreased protein translation, attenuated protein folding, and lower lip/carbohydrate metabolism. The present study provides insights into the changes in mammary metabolisms during the transition from colostrum to mature milk, which can help deeply explore the difference and regulation mechanism of active milk protein in colostrum and mature milk and provide references for the identification and functional study of bioactive milk proteins in colostrum.

True Digestibility of Tryptophan in Plant and Animal Protein

BackgroundProtein quality, evaluated using Digestible Indispensable Amino Acid Score (DIAAS), requires ileal digestibility values of individual indispensable amino acids (IAAs) in each protein. However, true tryptophan (Trp) digestibility has rarely been quantified in humans. ObjectiveTo measure the true Trp digestibility and DIAAS of 2H-intrinsically labeled plant and animal protein sources in humans, using the dual isotope tracer technique. MethodsThe true Trp digestibility of 2H intrinsically labeled plant proteins such as whole mung bean (n = 6) and dehulled mung bean (n = 6), chickpea (n = 5), and yellow pea (n = 5), and protein from animal source foods such as egg white (n = 6), whole egg (n = 6), chicken meat (n = 6), and goat milk (n = 7) was determined against the known digestibility of U-13C spirulina whole cell protein as reference, except for goat milk protein that was measured against free crystalline 13C-Trp as reference. Banked samples from earlier studies conducted to determine true IAA digestibility of different protein sources were used for the analysis. DIAAS was calculated for each test protein using digestibility corrected IAA scores (mg IAA/g of protein) in comparison with the IAA requirement score for adults. ResultsThe true Trp digestibility of whole mung bean, dehulled mung bean, chickpea, yellow pea, egg white, whole egg, chicken meat, and goat milk were 67.6 ± 3.7%, 74.5 ± 4.4%, 72.6 ± 2.3%, 72.5 ± 2.2%, 89.7 ± 2.5%, 91.4 ± 2.6%, 95.9 ± 2.2%, and 92.8 ± 2.9%, respectively. The true Trp digestibility of plant protein sources was significantly lower than that of animal protein sources (P < 0.05). Trp was not a limiting IAA in all the tested proteins. ConclusionThe true Trp digestibility determined in this study ranged from 67.6 ± 3.7% to 95.9 ± 2.2% for whole mung bean and chicken meat, respectively, and adds to the database of individual true IAA digestibility of different protein sources. Trial registration numberThis study was registered in Clinical Trials Registry of India (CTRI) with registration numbers CTRI/2017/11/010468, CTRI/2020/04/024512, and CTRI/2018/03/012265.

DPP-IV Inhibitory Peptide against In Vitro Gastrointestinal Digestion Derived from Goat's Milk Protein and Its Activity Enhancement via Amino Acid Substitution.

Goat milk protein can release a variety of bioactive peptides after digestion, while most of them are digested into free amino acids or dipeptides via the GI tract. We investigated the peptide profiles of goat milk protein following in vitro gastrointestinal digestion using LC-MS/MS and identified 683 bioactive peptides, including 105 DPP-IV inhibitory peptides. Among these peptides, ILDKVGINY (IL), derived from β-lactoglobulin, was found to be high in content and resistance to digestion. Herein, we explore the effect of amino acid residue substitution at the second N-terminus on its DPP-IV inhibitory activity. Three 9 polypeptide fragments (peptide IL, IP, and II) were synthesized and subjected to molecular docking and activity analysis. The peptide IL demonstrated the highest affinity for DPP-IV with a binding energy of -8.4 kcal/mol and a moderate IC50 value of 1.431 mg/mL determined based on the Caco-2 cell model. The replacement of specific amino acid residues by Pro and Leu led to an increase in the hydrophobic force interaction between the inhibitor peptide and DPP-IV. The inhibition rates of the three peptides were significantly different (p < 0.05). Peptide II containing an Ile residue instead of Leu resulted in a significant enhancement of DPP-IV inhibitory activity, with an IC50 value of 0.577 mg/mL. The GRAVY changes in the three peptides were consistent with the trend of the inhibitory rates. Therefore, the GRAVY of peptides and branch-chain amino acids should be considered in its activity improvement. The present study revealed the presence and activity of DPP-IV inhibitory peptides in goat milk, providing important insights for further investigation of their potential food functionality and health benefits.

Goat Milk Allergy and a Potential Role for Goat Milk in Cow's Milk Allergy.

In many parts of the world, goat milk has been part of the human diet for millennia. Allergy to goat's milk, not associated with allergy to cow's milk, is a rare disorder, although some cases have been described. Goat milk proteins have substantial homology with cow's milk proteins and even show cross-reactivity; therefore, they are not advised as an alternative to cow's milk for infants with IgE-mediated cow's milk allergies. However, there are indications that, due to the composition of the goat milk proteins, goat milk proteins show lower allergenicity than cow's milk due to a lower αS1-casein content. For this reason, goat milk might be a better choice over cow's milk as a first source of protein when breastfeeding is not possible or after the breastfeeding period. Additionally, some studies show that goat milk could play a role in specific types of non-IgE-mediated cow milk allergy or even in the prevention of sensitization to cow's milk proteins. This review discusses a possible role of goat milk in non-IgE mediated allergy and the prevention or oral tolerance induction of milk allergy.

Label-free-based proteomics analysis reveals differential proteins of sheep, goat, and cow milk

Regarding the limited information on species protein differences between sheep, goat, and cow milk, we analyzed the differentially expressed proteins in sheep, goat, and cow milk and their functional differences using label-free proteomics technology to identify potential biomarkers. In all, 770 proteins and 2,914 peptide segments were identified. Statistical analysis showed significant differences in the relative abundances of the 74 proteins among sheep, goat, and cow milk. CSN3 and LALBA can be used as potential biomarkers for goat milk, XDH can be used as a potential biomarker for cow milk, and CTSB and BPIFB1 can be used as potential biomarkers for sheep milk. Functional analysis using Gene Ontology and the Kyoto Encyclopedia of Genes and Genomes showed that these significantly different proteins were enriched by different pathways, including thyroid hormone synthesis and glycerol phospholipid metabolism. The data revealed differences in the amounts and physiological functions of the milk proteins of different species, which may provide an important basis for research on the nutritional composition of dairy products and adulteration identification technology.

Differences in proteomic profiles and immunomodulatory activity of goat and cow milk fat globule membrane

This study aimed to clarify the composition and bioactivity differences between goat and cow milk fat globule membrane (MFGM) protein by proteomic, and the immunomodulatory activity of MFGM proteins was further evaluated by using mouse splenic lymphocytes in vitro. A total of 257 MFGM proteins showed significant differences between goat and cow milk. The upregulated and unique MFGM proteins in goat milk were significantly enriched in the positive regulation of immune response, negative regulation of Interleukin-5 (IL-5) secretion, and involved in nucleotide-binding oligomerization domain (NOD)-like receptor signaling. The contents of IL-2 and Interferon-γ in the supernatant of spleen lymphocytes treated with goat MFGM proteins were much higher than those of IL-4 and IL-5, suggesting a Th1-skewed immune response. These results revealed that goat MFGM proteins could possess better immunomodulatory effects as compared to cow milk. Our findings may provide new insights to elucidate the physiological functions and nutritional of goat milk.

Effect of low milking frequency on the concentration of antimicrobial proteins in goat milk

This study examined the effects of low frequency milking on the concentrations of antimicrobial components in goat milk. Sixteen goats were divided into two groups of eight each: milking once every 2 d three times (for six days, three times group) or five times (for 10 days, five times group). On other days, milking was performed once daily. Milk was collected, and milk yield, somatic cell count (SCC), and the concentrations of some antimicrobial proteins such as lactoferrin (LF), S100A7, IgA, and sodium ions (Na+) in milk were measured. Milk yield significantly decreased in both the groups during the low-milking frequency period, followed by an increase above the low frequency milking period in both groups. In contrast, SCC and LF concentrations in milk increased in both groups during the low frequency milking period. The concentration of S100A7 in milk temporarily decreased after the low frequency milking period, followed by a significant increase. The S100A7 concentration during this period was higher in the five times group than in the three times group. These results indicated that low frequency milking induced a gradual decrease in milk yield and a concomitant increase in antimicrobial components, such as LF and S100A7, in milk. This increase in the antimicrobial components may be useful in preventing mastitis.

Comparative analysis of goat and bovine milk proteins in the improvement of sarcopenia based on host-microbial interactions

Comparative analysis of goat and bovine milk proteins in the improvement of sarcopenia based on host-microbial interactions

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.

MiR-2284b regulation of α-s1 casein synthesis in mammary epithelial cells of dairy goats

The lactation character of dairy goats is the most important characteristic, and milk protein is an important index to evaluate milk quality. Casein accounts for more than 80% of the total milk protein in goat milk and is the main component of milk protein. Using GMECs (goat mammary epithelial cells) as the research object, the CHECK2 vector of the CSN1S1 gene and the overexpression vector of pcDNA 3.1 were constructed, and the mimics of miR-2284b and the interfering RNA of CSN1S1 were synthesized. Using PCR, RT–qPCR, a dual luciferase activity detection system, EdU, CCK8, cell apoptosis detection and ELISA detection, we explored the regulatory mechanism and molecular mechanism of miR-2284b regulation of αs1-casein synthesis in GMECs. miR-2284b negatively regulates proliferation and apoptosis of GMECs and αs1-casein synthesis. Two new gene sequences of CSN1S1 were discovered. CSN1S1-1/-2 promoted the proliferation of GMECs and inhibited cell apoptosis. However, it had no effect on αs1-casein synthesis. MiR-2284b negatively regulates αs1-casein synthesis in GMECs by inhibiting the CSN1S1 gene. These results all indicated that miR-2284b could regulate αs1-casein synthesis, thus playing a theoretical guiding role in the future breeding process of dairy goats and accelerating the development of dairy goat breeding.

Mechanistic Study of Novel Dipeptidyl Peptidase IV Inhibitory Peptides from Goat's Milk Based on Peptidomics and In Silico Analysis.

Two novel dipeptidyl peptidase IV (DPP-IV) inhibitory peptides (YPF and LLLP) were discovered from goat milk protein by peptidomics, in silico analysis, and in vitro assessment. A total of 698 peptides (<23 AA) were successfully identified by LC-MS/MS from goat milk hydrolysates (hydrolyzed by papaian plus proteinase K). Then, 105 potential DPP-IV inhibitory peptides were screened using PeptideRanker, the ToxinPred tool, Libdock, iDPPIV-SCM, and sequence characteristics. After ADME, physicochemical property evaluation, and a literature search, 12 candidates were efficiently selected and synthesized in vitro for functional validation. Two peptides (YPF and LLLP) were found to exert relatively high in vitro chemical system (IC50 = 368.54 ± 12.97 μM and 213.99 ± 0.64 μM) and in situ (IC50 = 159.46 ± 17.40 μM and 154.96 ± 8.41 μM) DPP-IV inhibitory capacities, and their inhibitory mechanisms were further explored by molecular docking. Our study showed that the formation of strong non-bonding interactions with the core residues from the pocket of DPP-IV (such as ARG358, PHE357, GLU205, TYR662, TYR547, and TYR666) might primarily account for the DPP-IV inhibitory activity of two identified peptides. Overall, the two novel DPP-IV inhibitory peptides rapidly identified in this study can be used as functional food ingredients for the control of diabetes.

Glycation of goat milk with different casein-to-whey protein ratios and its effects on simulated infant digestion

This research compared the effects of dry heating on the digestion of goat milk proteins with different casein-to-whey ratios (40% casein, C40 and 80% casein, C80). The glycation markers of heated samples were determined by LC-MS. Heating at 60 °C for 8 h induced early glycation while heating at 60 °C for 72 h induced advanced glycation. Unheated C80 samples showed a higher digestibility than unheated C40 samples, which may be due to their higher protein solubility. After dry heating for 72 h, no significant difference in digestibility was observed between C80 and C40 samples. Heating for 72 h decreased the digestibility of C40 samples compared to unheated samples, probably due to glycation, while protein aggregation was the main reason for the reduced digestibility of heated C80 samples. Overall, this study showed that dry heating for 72 h induced a lower digestibility of C80 and C40 samples, although with different underlying mechanisms.

Enzymatic Modification of Cow, Buffalo and Goat Milk Proteins and their Effect on Anti-Oxidant Activity and Digestibility

Aim: Buffalo milk and goat milk were enzymatically hydrolyzed to have 5, 10 and 15 per cent DH to improve the techno-functional properties of milk proteins in order to utilize in production of channa based dairy products. Study Design: A significant contribution to total milk production of India comes from buffalo milk and followed by cow and goat milk. Inspite of that, Buffalo milk and goat milk are not being utilized for many products in view of their inherent problems associated in production of Chhana based dairy products. Buffalo milk and goat milk were enzymatically hydrolyzed to have 5, 10 and 15 per cent DH to improve the techno-functional properties of milk proteins in order to utilize in production of products. Place and Duration of Study: Karnataka Veterinary Animal and Fisheries Sciences University (KVAFSU), Dairy Science College, Hebbal, Bangalore Karnataka, India Methodology: The Goat milk samples were collected from Sinchana Goat and sheep farm, Marenahalli village (Bengaluru Rural Dist) and Buffalo milk was obtained from country Delight Pvt. Ltd., J. P. Nagar, Bengaluru, Karnataka. Cow milk used in this investigation was collected from SEDP, Dairy Science College, Hebbal, Bangalore. Commercially available pure Neutrase enzyme was purchased from DSM Nutritional Products India Pvt. Ltd, Bangalore. All the glassware used were soaked in chromic acid solution, repeatedly washed with water, rinsed with distilled water and dried before use. For microbiological analysis dried test tubes, conical flask, pipettes were cotton plugged and sterilized in hot air oven. The chemicals and reagents used in this study were mainly of analytical grade procured from Prince Laboratory Company Pvt limited, Bangalore. The protein molecular weight markers were used for the electrophoretic study were procured from Bangalore Genei Pvt Ltd. Results: Highest protein content was noted in buffalo casein hydrolysate (83.0 %) than cow (81.0 %) and goat (81.16 %) and lowest nitrogen and ash content was observed in goat casein hydrolysate (13.65 %) and (15.20 %) respectively. (Akshya pl include few lines of enzymatic modification on anti-oxidant property and digestibility copy from discussions) Conclusion: Though buffalo milk contributes nearly half of the total milk production of India and goat milk carries both nutritional and therapeutic benefits, the potential utilization of both these milks are very much limited due to the inherent problems associated with them. This investigation has shown that by enzymatically hydrolyzing buffalo milk and goat milk to 5 per cent DH results significant improvement in physico-chemical and functional attributes Rasagulla which is on par with cow’s milk protein hydrolysates. Recommendation: Scavenging activity or anti-oxidant activity and Digestibility of hydrolysates has been studied as influenced by the extent of enzymatic modification in this study.