Search

The objective of this research is to determine whether intramammary antibiotics with complementary acupuncture can reduce bovine mammary inflammation due to subclinical mastitis. Lactating cows were selected based on milk with a somatic cell count (SCC) greater than 500,000 cells/ml. Pre- and post-treatment milk samples were collected to determine SCC, aerobic bacterial content, milk ion conductivity, total protein, lactate dehydrogenase (LDH) and N-acetyl-beta-D-glucosaminidase (NAGase) concentrations. Milk serum was prepared from milk samples by double centrifugation. Concentrations of LDH and NAGase were determined using commercial enzyme-linked immunosorbent assays. Cows being treated with intramammary antibiotics were separated by random assignment to the acupuncture group (n = 10) and a no-acupuncture (control) group (n = 9). Both the acupuncture and control group were restrained for 30 min in a head catch 12 hr apart for a total of four times. For front quarters affected by subclinical mastitis, the acupuncture points used were spleen (SP) 12, SP 17, SP 18, SP 21, stomach (ST) 18 and conception vessel (CV) 12. For rear quarters affected by subclinical mastitis, the acupuncture points used were bladder (BL) 30, BL 30-1, BL 49, kidney (KI) 10, conception vessel (CV) 2 and CV 3. All parameters were compared using a Student t test. Significance was defined as p < .05. Compared to control cows, complementary acupuncture treatment reduced NAGase enzymatic activity in quarters of cows with subclinical mastitis. The reduction in NAGase suggests that complementary acupuncture treatment may be associated with healing of the damaged mammary epithelial cells, which are the primary source of NAGase activity in milk serum.

During whey powder production, the feed is subjected to several heat treatments which can cause lactosylation of proteins. In this study, lactosylation of whey proteins was evaluated in spray-dried powders before and after storage by varying the native protein fraction as well as the serum protein/lactose ratio in the powders. The lactosylation of native α-lactalbumin and β-lactoglobulin in the powders before storage was not affected to a large extent by the protein denaturation or if the feed had been heat treated in a high or low lactose environment. After storage (relative humidity of 23.5%, 30 °C, 25 days), the kinetic of lactosylation tended to increase with increasing native protein fraction and bulk protein content in the powders. An explanation could be that proteins dissolved in the lactose glassy structure might have a lower reactivity, while proteins present in the protein glassy structure with dissolved lactose may display higher lactosylation reactivity. (Less)

In this study, milk protein isolate (MPI) and micellar casein concentrate (MCC) were obtained with ultrafiltration (UF) and microfiltration (MF), respectively. The objective of this work was to evaluate the effect of diafiltration (DF), the addition of water during filtration, on the colloidal dissociation of casein micelles. Two levels of DF were applied after an initial concentration step to 2x the volume fraction, at a total protein concentration of about 7% (w/v). Under these conditions, while permeation of protein was still measured in the permeates, calcium ion transmission reached a plateau. The molecular details of the serum phases were studied throughout the filtration process. A comparison of serum phases with and without whey protein (UF vs MF) was carried out by examining the two processes in parallel, applying similar filtration conditions. Final 4x concentrates (based on initial volume of milk) were also compared. Viscosity was higher for UF than the corresponding MF concentrates, is spite of the higher level of colloidal protein present in the MF concentrates, which would suggest a change in the hydration or the volume/weight ratio (voluminosity) of casein micelles in MCC retentates. Centrifugal supernatants contained casein proteins both in MPC and MCC retentates. There were no statistically significant changes in the apparent hydrodynamic diameter of the casein micelles when measured by dynamic light scattering, in the original milk serum. A two dimensional chromatography was carried out on the soluble aggregates to determine differences in the amount of individual caseins. The aggregates showed only traces of whey proteins. The composition of the final concentrates, albeit similar in total proteins, showed profound differences in ionic strength and soluble proteins, suggesting that these parameters may be used as an indication of ingredient quality and functionality.

Volatile sulfur compounds in ultra-pasteurized (UP) milk are the major contributors to sulfur/burnt and eggy flavors, and these flavors are disliked by consumers. Previous research has established distinct differences in flavor profiles of fluid milk processed by high temperature, short time pasteurization (HTST) and UP by direct steam injection (DSI-UP) or indirect heat (IND-UP). An understanding of the contribution of the individual milk proteins to sulfur off-flavors would clarify the source of sulfur flavors in UP milks. The objective of this study was to determine the source of volatile sulfur compounds in fluid milk with a specific focus on the comparison of heat treatment effects on milks by HTST and UP. Formulated skim milks (FSM) were manufactured by blending micellar casein concentrate and serum protein isolate (SPI). Three different caseins as a percentage of true protein (FSM95, FSM80, and FSM60) were formulated to determine the source of sulfur/burnt and eggy flavors. Freshly processed micellar casein concentrate or SPI were blended to achieve a true protein content of about 3.2%. Raw skim milk served as a control. Skim milk and FSM were pasteurized at 78°C for 15 s (HTST) or 140°C for 2.3 s by IND-UP or DSI-UP. The experiment was replicated twice. Sensory properties of milks and FSM were documented by descriptive sensory analysis. Volatile sulfur compounds in milks and FSM were evaluated using solid-phase microextraction followed by gas chromatography-triple quadrupole mass spectrometry combined with a sulfur selective flame photometric detector. The FSM with higher SPI as a percent of true protein had higher sensory sulfur/burnt and eggy flavors along with elevated concentrations of hydrogen sulfide and carbon disulfide compared with skim milk or FSM with lower proportions of SPI. Sulfur compounds including dimethyl sulfide, dimethyl disulfide, dimethyl trisulfide, dimethyl sulfoxide, and methional were not associated with sulfur/burnt and eggy flavors, which suggests that these compounds may not specifically contribute to the sulfur/burnt and eggy off-flavors of UP milks. Sensory panelists found higher overall aroma impact, and cooked, sulfur/burnt, and eggy flavors for DSI-UP, followed by IND-UP and HTST. The combination of sensory and instrumental methods used in the current study effectively identified that milk serum proteins are the source of sulfur compounds in milk, and further confirmed the contribution of hydrogen sulfide and carbon disulfide to eggy and sulfur/burnt flavors, respectively.

Horns are living tissue and cows can use their horns for thermoregulatory purposes. We investigated the effect of the presence of horns on the metabolome of milk serum and lipidome of milk fat, to assess the physiological effect of dehorning. Milk sampling took place at low ambient temperatures of −6 to 2°C. Horned and dehorned cows were kept in a mixed herd of Holstein Friesian and Brown Swiss cows. The hypothesis was that horned cows needed to increase their metabolism to compensate for additional heat loss through the presence of their horns. No differences were observed in milk yield, milk solids, and somatic cell counts between horned and dehorned cows. For the milk metabolome, horned cows showed an upregulation of several glucogenic AA that could be transformed into glucose for energy supply and a downregulation of sugar intermediates and γ-glutamylcysteine compared with dehorned cows. The fatty acid (FA) composition in horned cows showed a shift toward decreased odd medium-chain FA (C7:0, C9:0, and C11:0) and increased cis-vaccenic acid (C18:1n-7 cis-11) and stearidonic acid (C18:4n-3). The changes in milk composition related to additional heat loss in horned cows indicate a competition in C3 metabolism for glucose synthesis and de novo FA synthesis under cold stress.

Human milk provides a range of nutrients and bioactive components, which can support the growth and development of infants. However, human milk composition may change due to geographic and ethnic variation. This study investigated the variation of the Chinese human milk serum proteome based on mothers with different ethnicities living in different parts of China, using TMT labeling combined with Nano-LC Q Exactive HF MS/MS proteomics. In total, 693 proteins were identified and quantified in human milk serum from Yunnan (Han and Bai ethnicity), Gansu (Han and Tibetan ethnicity), Xinjiang (Uygur ethnicity), and Inner Mongolia (Mongolian ethnicity). The biological function distribution of identified proteins and the summed intensity of proteins belonging to each biological function were similar among groups. The five relatively highly abundant milk serum proteins, lactoferrin, serum albumin, polymeric immunoglobulin receptor, macrophage mannose receptor 1, and bile salt-activated lipase were not significantly different among different geographies and ethnicities. On the other hand, we found 34 proteins that did significantly differ with geography and ethnicity. Those significantly different proteins have known strong interaction in inflammation response and regulation of multi-organism processes. Taken together, biological function distribution was similar on both the qualitative and quantitative levels, and proteins with similar abundance are important in providing basic nutrition and protection for infants, whereas the significantly different proteins may be important for the healthy development of infants from different locations and ethnicities.

Context: Candida, leukoplakia and oral squamous cell carcinoma. Aims: The aim of the present study has assessed the association of Candida albicans with normal control group, leukoplakia and oral squamous cell carcinoma lesions of the oral cavity by using cornmeal broth +5% milk and milk serum liquid culture media. Settings and Design: Thepresent study comprised of total 80 patients,which included, 30 patients of Leukoplakia, 30 patients of oral squamous cell carcinoma and normal control group comprised of 20 healthy individuals who were not having any relevant medical, dental and habit history. Subjects and Methods: Saliva and Biopsy was taken from clinically suspected leukoplakia and oral squamous cell carcinoma lesions for the confirmation of histopathological diagnosis. Saliva samples were inoculated for fungal growth in Sabouraud Dextrose Agar, and culture-positive samples had undergone for the germ tube test. Germ tube-positive samples were further taken for chlamydospore production in milk serum and cornmeal broth +5% milk media separately at 8 and 16 h. Statistical Analysis Used: Chi-square test, Fischer extract test. Results: In the normal control group, no fungus growth was found; however, leukoplakia and oral squamous cell carcinoma showed fungus growth with positive germ tube test and chlamydospore formation; the result also showed rapid and quantitatively more chlamydospore formation in cornmeal broth +5% milk in comparison to serum milk culture media. There was no growth of Candida in mild and moderate form of leukoplakia. Whereas in a severe form of leukoplakia, there was more quantitative chlamydospore growth in cornmeal broth +5% milk liquid media. Conclusions: In this study, we have tried to compare the efficacy of cornmeal broth +5% milk and milk serum for the identification of C. albicans. Both the culture media were able to promote the growth of chlamydospore in C. albicans. Among different grades of leukoplakia, the growth of C. albicans was seen in severe dysplastic patient only while mild and moderate dysplasia showed no Candidal growth.

Our previous study identified peaks in the 31 P nuclear magnetic resonance ( 31 P NMR) spectra of skim milk, denoting the interaction of different phosphate species such as inorganic and casein-associated phosphate during the separation of colloidal and serum phases of skim milk by microfiltration (MF) and diafiltration (DF). In the current study, we investigated the same samples generated by the aforementioned separation using attenuated total reflectance (ATR) Fourier transform infrared (FTIR) spectroscopy analysis. The results confirmed that the technique was not only capable of differentiating between the mineral equilibrium of the casein phosphate nanocluster (CPN) and milk serum, but also complemented the application of 31 P NMR. An ATR-FTIR broad band in the region of 1,055 to 1,036 cm −1 and a specific band at 1,076 cm −1 were identified as sensitive to the repartitioning of different phosphate species in milk in accordance with the 31 P NMR signals representing casein-associated phosphate and inorganic phosphate in the serum. A third ATR-FTIR signal at 1,034 cm −1 in milk, representing precipitated inorganic calcium phosphate, had not previously been detected by 31 P NMR. Thus, the results indicate that a combination of ATR-FTIR and 31 P NMR spectroscopies may be optimally used to follow mineral and protein phase changes in milk during membrane processing.

This study investigated milk serum protein concentrate/lactose systems with varying ratios and how the morphology of the spray-dried particles of these systems could be described by the surface properties of the feed as well as the protein surface coverage of the particles. An extrapolation of the surface pressure of the feed to 0.3 s, the approximate time for molecular diffusion in an atomised droplet in the spray-dryer, showed a relationship with the particle morphology. At low protein concentrations (

In present study, 198, 169, 213 and 128 proteins were identified and quantified in human, cow, goat and yak milk serum respectively by using proteomics techniques. Large variations were observed between human and ruminant milk proteins. Human milk contained higher concentration of mucosal immune response, complement proteins and regulators. The concentration of bactericidal proteins were relatively higher in ruminants milk. Human milk exclusively expressed proteins important for delivery or utilization of nutrients. Peptidase inhibitors prevent the bioactive proteins/peptides in human milk from gastral-intestinal digestion. Protein composition among ruminants milk was similar but with variations. Goat milk contained high level of complement proteins but low level of corresponding regulators. In addition, the acute phase proteins were significantly higher in goat milk. Of note, osteopontin in yak milk was enriched, which could offer an alternative source for producing osteopontin and revealed possible nutritional value of yak milk.

This study investigated the effects of heating skim milk with soluble calcium salts, calcium chloride, calcium lactate, calcium gluconate and calcium lactobionate, on the physico-chemical and rheological properties of milk. Regardless of the type of salt added, the amount of casein in milk serum decreased and the amount of calcium in centrifuge sediment increased along with the serum calcium. The amount of calcium salt required for gelation and the gel firmness (G') varied depending on the salt. The aCa2+ order in milk was calcium chloride>calcium lactate>calcium gluconate>calcium lactobionate. With the same amount of added calcium salt, the final G' of milk gel followed the same order. The findings from this study suggest that the different association constants and formation of an intermediate calcium complex with hydroxycarboylate groups affected the calcium ion activity, which may influence the gelation properties in milk.

Whey is a low calorie milk serum remaining after casein removal in cheese manufacturing. Composition and properties of whey depend on the type of cheese production process, type and the quality of the used milk. Whey mostly consists of lactose, proteins, vitamins, minerals, enzymes, hormones and growth factors. Functional and nutritional roles of whey components meet the requirements for dietary food. Whey proteins are liquid fractions of 20% milk proteins, which remain in whey after casein removal. The increase in the temperature of milk processing leads to denaturation of proteins and a decrease in their content. The most common whey proteins are albumin and globulin. Separation and fractionation of whey proteins may be carried out as precipitation, combined with acid treatment, high temperature treatment or centrifugation (centry-whey process), and as a membrane process (usually ultra- or microfiltration followed by a diafiltration and spray drying). Whey proteins can also be separated based on their molecular mass, charge and hydrophobicity. It is a well-known fact that whey proteins possess admirable nutritional and functional components, such as essential amino acids, bioactive peptides, antioxidants and immunopotentiators. Research of bioactive compounds and nutrients pushed whey protein to the forefront of the functional food sector, therefore, the implementation of these proteins in the diet and supplements has the potential to address many metabolic imbalance-caused diseases, and it seems imperative to harness their potential.

Through the use of protein-free milk serum (PFMS) in comparison with deionised water (DW) or deionised water with lactose (DWL), the respective impact of lactose and milk salts on surface activity and foaming properties of selected individual milk proteins and relevant milk protein mixtures was evaluated. Against expectation, the lactose-dependent increase in solution viscosity did not impede protein diffusion and surface adsorption. Instead of molecular flexibility, protein interaction potential (inherent or milk salt-induced) correlated with foamability. Lactose and milk salts contributed to increased foam stabilities, which was also reflected in time-dependent evolution of bubble sizes as well as reduced drainage exponents. Generally, maxima in foamability and foam stability resulted when PFMS was used, which indicates the significance of pronounced protein–protein interactions as well as high packing densities at the air/water interface. The main contribution of lactose to foam volume gain and stabilisation was attributed to the reduction of coalescence.

The influence of different heat treatments on the protein aggregates and changes in gelation properties of rennet-induced milk gels were investigated. In the heated milk, a visible difference in milk serum proteins was found resulting from the formation of protein aggregates. Meanwhile, the size of protein aggregates increased from 25 to 170 nm with increasing the intensity of heat treatment. Furthermore, the differences in textural variables of rennet gels were found among the heat treatments using the principal component analysis. The water holding capacity and cheese curd yield of rennet gels obtained from the heated milk were significantly greater than those of raw milk (p < 0.05). It was also found heat treatments above 80°C could endow rennet-induced milk gels with novel textural properties.

To keep their functional properties, it is crucial that protein aggregates maintain their structure after spray drying and that the powders can be fully rehydrated. In this study, microgels and fractal aggregates were prepared by heating a mixture of milk serum protein concentrate and lactose (40/60; %, w/w) at 85 °C for 15 min by varying the pH. Various fractions of native proteins were added to the systems prior to spray drying. This study showed that microgels and fractal aggregates kept their structure after spray drying and reconstitution. The particle morphology could be correlated to the stiffness of the interface of the feed droplet. The forced imbibition rate showed a negative correlation with increasing amount of aggregated proteins in the powders that seems to be a result of denatured/aggregated proteins present at the surface. These findings are of importance for the formulation of spray-dried powders with improved rehydration characteristics.

Milk processing affects the molecular and supramolecular characteristics of milk. While many of these changes have been studied extensively, the effect of homogenisation on volatile components and lipids at different pressures and temperatures is still poorly understood. The aim of this study was to determine the effect of homogenisation pressure (0, 150, 250 and 350 bar) at different temperatures (45 °C, 60 °C and 80 °C) on the content of individual milk volatile components, phospholipids and triacylglycerols. The results demonstrated the importance of temperature and pressure (P > 0.001) on the formation of 2-heptanone. Temperature was the most important factor for significant (P > 0.05) loss of the milk fat globule membrane lipid phosphatidyletholamine (PE) from the milk serum. Moreover, a significant increase (P > 0.001) in the level of all triacylglycerols groups in the serum phase of homogenised milk was observed, independent of the temperature of the homogenisation process.

We report the use of a method to determine the refractive index of copper(II) serum (RICS) in milk as a tool to detect the fraudulent addition of water. This practice is highly profitable, unlawful, and difficult to deter. The method was optimized and validated and is simple, fast and robust. The optimized method yielded statistically equivalent results compared to the reference method with an accuracy of 0.4% and quadrupled analytical throughput. Trueness, precision (repeatability and intermediate precision) and ruggedness are determined to be satisfactory at a 95.45% confidence level. The expanded uncertainty of the measurement was ±0.38°Zeiss at the 95.45% confidence level (k=3.30), corresponding to 1.03% of the minimum measurement expected in adequate samples (>37.00°Zeiss).

The anti-penicillin G was conjugated to avidin-peroxidase and biotin to obtain immunogen and competitor which were then used to develop a competitive immunosensor assay for the detection of penicillin G and other β-lactam antibiotics, with Kaff values of the order of 10(8) M(-1). The new immunosensor appears to afford a number of advantages in terms of sensitivity, possibility of "in situ" analysis, but especially of simplicity and lower costs, compared with other existing devices, or different chemical instrumental methods reported in the literature and used for the analysis of β-lactam compounds. Satisfactory results were found in the analysis of real matrixes and good recoveries were obtained by applying the standard addition method to spiked milk, urine, serum and drug samples. The new device uses an amperometric electrode for hydrogen peroxide as transducer, the BSA-penicillin G immobilized on polymeric membrane overlapping the amperometric transducer and the peroxidase enzyme as marker. It proved to be highly sensitive, inexpensive and easily reproducible; LOD was of the order of 10(-11)M. Lastly, the new immunosensor displayed low selectivity versus the entire class of β-lactam antibiotics and higher selectivity toward other classes of non-β-lactam antibiotics.

The aim of this study was to determine the effect of selenium concentration in early lactation on mammary gland health and histological characteristics of the udder. The experiment included 30 high-yielding Holstein-Friesian cows. Selenium concentrations in blood and milk serum, and the average somatic cell count in the first and sixth months of lactation were analyzed. After exclusion of the experimental cows from the herd, histological characteristics of the udder were examined (the degree of leukocyte infiltration and the number of granulomas in the parenchyma). The mean selenium concentration in the blood serum was 0.62±0.11 mmol/L and that in the milk serum was 0.12±0.07 mmol/L. Optimal blood levels of selenium were found in 19 cows and suboptimal levels in 11 cows. A significant negative correlation was observed between blood and milk selenium concentrations and somatic cell count in early and mid lactation. There was no relationship between blood selenium concentration, milk selenium concentration and the amount of milk produced. Selenium-deficient cows had a significantly higher milk somatic cell count in early and mid lactation and significantly lower levels of selenium in milk. Upon histological analysis, 120 samples of individual quarters of the udder were grouped according to the degree of leukocyte infiltration and number of granulomas. Results showed that an increase in the degree of leukocyte infiltration and number of granulomas leads to an increase in the proportion of quarters from selenium-deficient cows and a decline in the percentage of quarters from cows exhibiting normal blood selenium concentrations. Selenium has a significant impact on udder health. Changes caused by selenium deficiency occur due to marked inflammation process in the mammary gland.

The effects of ionic strength, pH and milk mineral composition on the adsorption of caseins and whey proteins on to particles of hydroxyapatite (HA) were studied by determining the amounts of adsorbed proteins on HA using sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) and by zeta-potential measurements. The amount of adsorbed proteins increased with increasing ionic strength from 0 to 0.1 M and decreasing pH from 8 to 6, for both sodium caseinate (SC) and whey protein isolate (WPI). In general, when the absolute value of the zeta-potential decreased because of changes in pH or ionic strength, more protein was found to adsorb on to the HA particles. This may be attributed to a decrease in the electrostatic repulsions between the HA particles and the protein species. The effects of the composition of the milk serum were investigated using simulated milk ultrafiltrate (SMUF). Both caseins and whey proteins adsorbed less on to HA particles in SMUF than on to HA particles in water. However, the effect of the composition of SMUF on the adsorption was less pronounced for caseins than for whey proteins. This may be related to the phosphorylated nature of the caseins. As the phosphate groups of the caseins bind more strongly to the HA binding sites than the carboxyl groups of the whey proteins, caseins might compete better with the phosphate and citrate ions in the milk serum for adsorption.

Insoluble calcium phosphate particles, such as hydroxyapatite (HA), are often used in calcium-fortified milks as they are considered to be chemically unreactive. However, this study showed that there was an interaction between the casein micelles in milk and HA particles. The caseins in milk were shown to bind to the HA particles, with the relative proportions of bound β-casein, αS-casein, and κ-casein different from the proportions of the individual caseins present in milk. Transmission electron microscopy showed no evidence of intact casein micelles on the surface of the HA particles, which suggested that the casein micelles dissociated either before or during binding. The HA particles behaved as ion chelators, with the ability to bind the ions contained in the milk serum phase. Consequently, the depletion of the serum minerals disrupted the milk mineral equilibrium, resulting in dissociation of the casein micelles in milk.

Levels of micellar, serum and free calcium and micellar and serum phosphorus were studied during gradual acidification of skim milk at 4, 20, 30 and 40 °C. From pH 6.0 to 5.4–5.2, calcium and phosphorus concentrations in milk serum increased for decreasing temperature. For pH

The ability of buttermilk to carry and stabilise a preparation of curcuminoids was examined. The quenching of intrinsic protein fluorescence confirmed that the curcuminoids interacted with proteins in buttermilk. The Stern-Volmer quenching constant was ≥ 9.4 × 10³ M⁻¹. The apparent binding constant of curcuminoids to whole buttermilk was ≥ 2.2 × 10⁴ M⁻¹. Centrifugation of buttermilk (5% total solids, TS)--curcuminoid mixtures demonstrated that curcuminoids were partitioned into the cream (18.0%w/w, 0.64% TS), milk serum (73.3%w/w, 2.86% TS) and the casein-rich precipitate (6.76% w/w, 1.87% TS) fractions in the ratio of 1:3.7:3.5. The interaction of curcuminoids with components in the buttermilk improved its stability, as evidenced by the faster degradation of curcuminoids in phosphate buffer (pH=6.8) than in buttermilk. The ability of buttermilk to carry and stabilise curcuminoids has the potential to enable the delivery of these components into functional foods.

Lactation physiology is a process that is only partly understood. Proteomics techniques have shown to be useful to help advance the knowledge on lactation physiology in human and rodent species but have not been used as major tools for dairy cows, except for mastitis. In this paper, advanced non-targeted proteomics techniques (Filter aided sample preparation and NanoLC-Orbitrap-MS/MS) were applied to study the milk fat globule membrane and milk serum fraction, resulting in the identification of 246 proteins. Of these, 23 transporters and enzymes were related to lipid synthesis and secretion in mammary gland and their functions are discussed in detail. The identification of these intracellular transporters and enzymes in milk provides a possibility of using milk itself to study lipid synthesis and secretion pathways. This full-scale scan of milk proteins by using non-targeted proteomic analysis helps to reveal the important proteins involved in lipid synthesis and secretion for further examination in targeted studies.

Raw milk (approximately 1,800 kg) was separated at 4°C, pasteurized (at 72°C for 16s), and split into 2 batches. One batch (620 kg) was microfiltered (MF) using pilot-scale ceramic uniform transmembrane pressure Membralox membranes (model EP1940GL0.1 μA, 0.1-μm alumina; Pall Corp., East Hills, NY) to produce retentate and permeate. The permeate from the MF uniform transmembrane pressure was casein-free skim milk (CFSM). The CFSM was MF using polymeric spiral-wound (SW) membranes (model FG7838-OS0x-S, 0.3 μm; Parker-Hannifin Corp., Process Advanced Filtration Division, Tell City, IN) at a concentration factor of 3× and temperature of 50°C. Following the processing of CFSM, the second batch of skim milk (1,105 kg) was processed using the same polymeric membranes to determine how casein content in the feed material for MF with polymeric membranes affects the performance of the system. There was little resistance to passage of milk serum proteins (SP) through a 0.3-μm polyvinylidene fluoride (PVDF) SW membrane at 50°C and no detectable increase in hydraulic resistance of the membrane when processing CFSM. Therefore, milk SP contributed little, if any, to fouling of the PVDF membrane. In contrast, when processing skim milk containing a normal concentration of casein, the flux was much lower than when processing CFSM (17.2 vs. 80.2 kg/m(2) per hour, respectively) and the removal of SP from skim milk with a single-pass 3× bleed-and-feed MF system was also much lower than from CFSM (35.2 vs. 59.5% removal, respectively). Thus, when processing skim milk with a PVDF SW membrane, casein was the major protein foulant that increased hydraulic resistance and reduced passage of SP through the membrane.

The aim of this study was to investigate the effect of transglutaminase (TG) addition on rheological properties, textural characteristics and microstructure of fermented milk products manufactured by different starters (probiotics and kombucha inoculum). Rheological analysis revealed that all manufactured fermented milk products had higher storage modulus than loss modulus and exhibited thixotropic and a typical shear thinning behavior. The addition of TG in milk increased approximately 10.5% hysteresis loop area, 39% firmness and 48% consistency in sample produced with probiotic starter and had more firm and stable gel structure than kombucha fermented milk products. The scanning electron microscopy micrographs showed that casein matrix of fermented milk products containing TG is continuous and uninterrupted except for void spaces occupied by milk serum and starter culture cell. Practical Applications Transglutaminase (TG) is a transferase that forms inter- and intramolecular isopeptide bounds in and between many proteins by cross-linking of the amino acid residues of protein-bound glutamine and lysine. Among the dairy proteins, the casein fraction represents a favorable substrate for TG, mainly due to the highly accessible and flexible open chain structure. Heat treatment prior to cross-linking is necessary because the reactivity of TG is very low in unheated or pasteurized milk, despite the high reactivity of the casein. In the case of low-fat products, behavior of milk proteins during the gelation process is of particular importance. Cross-linking of preheated milk with reduced fat content results in improved gel firmness and reduced syneresis of acid-induced milk protein gels. Also, TG treatment at optimal technological parameters, pH value and temperature of milk, can solve these problems in kombucha fermented milk products, improving firmness, consistency and viscosity of gel.

The objective of this study was to evaluate the influence of blood and milk zinc concentration on somatic cell count, milk production and occurrence of subclinical mastitis cases. The study was performed on thirty Holstein cows approximate same body weight, ages 3 to 5 years, with equally milk production. Blood samples were taken after the morning milking from the caudal vein and milk from all four quarters was taken during morning milking. All samples of blood and milk were taken to determined zinc, using inductively coupled plasma mass spectrometry. 37.67% (11/30) cows have blood serum zinc concentration below 7?mol/l, and 63.33% or 19/30 cows have blood serum zinc concentration higher then 13?mol/l. Also 30% (9/30) cows have somatic cell count lower then 400.000/ml which indicate absence of subclinical mastitis, but 70% (21/30) cows have somatic cell count higher then 400.000/ml which indicate subclinical mastitis. According to all results in this research, zinc has very important influence on reducing subclinical mastitis and somatic cell count in milk of dairy cows.

The two-stage production of microcapsules based on high- (HM) and low-methylated (LM) apple pectin complexes with milk serum β-lactoglobulin concentrate in an oil—water emulsion was developed. It was established that the ability of the pectin chains to form an effective secondary layer on the protein molecules surrounding the oil drops depended on the molecular weight and structure of the pectin. The obtained emulsions with HM- and LM-pectins and various pectin:protein ratios were capable of forming microcapsules of various sizes and different rifampicin contents. The proposed microcapsules could be used as potential drug carriers.

The objective of this paper was to observe the rennet-induced aggregation behaviour of casein micelles in milk in the presence of additional sodium caseinate. Analysis of the centrifugal supernatants by size exclusion chromatography confirmed an increase in the soluble protein in the milk serum phase after addition of sodium caseinate. Although the total amount of κ-casein hydrolyzed over time was not affected, there was a significant effect of soluble casein on milk gelation, with a dose-dependent decrease of the gelation time as measured by rheology. Light scattering experiments also confirmed that the addition of soluble caseins inhibited the aggregation of casein micelles. Addition of 1 mM CaCl 2 prior to renneting increased the extent of rennet aggregation in samples containing additional sodium caseinate, but the inhibiting effect was still evident. The amount of soluble casein (as measured by chroma tography) significantly decreased after renneting, suggesting its association with the micellar fraction. Supporting experiments carried out with purified fractions of soluble caseins demonstrated that both α s -casein and β-casein played a role as protective colloids (increasing steric repulsion) during renneting. It was concluded that the inhibiting effect observed during gelation was caused by the adsorption of soluble casein molecules on the surface of rennet-altered casein micelles.

Serum Amyloid A3 (SAA3) protein is a member of a complex group of acute phase and constitutive proteins which have been related to several immune functions. Bovine milk SAA3 (M-SAA3) has been described to have a unique N-terminal TFLK motif responsible for up regulating mucin expression in the intestine lumen and therefore a protective gastrointestinal role. cDNA sequences encoding the protein goat M-SAA3 were successfully cloned from milk, mammary gland tissue and liver, expressed despite observed toxicity and purified as a soluble protein. Sequence analyses of the milk and liver derived forms revealed a non mammary-restricted common N-terminal TFLR motif, unlike that described for bovine M-SAA3. Serum derived forms of SAA have been described to opsonize Gram-negative bacteria facilitating their phagocytosis by circulating macrophages or intestinal epithelial cells. However, no reports about a possible opsonic mechanism of the SAA3 isoforms have been described. Recombinant protein but not peptides encompassing the TFLR region increased blood and milk macrophage interaction and uptake of bacteria reported as number of bacteria per 100 macrophages and percentage of macrophages containing one or more bacteria. gMSAA3-derived peptides did not show any effect on phagocytosis. This would indicate that the TFLK-like region responsible for the up-regulation of mucins in the intestine is not the functional part of g-MSAA3 in promoting macrophage phagocytosis.

In a novel pilot plant scale process, lactulose was synthesized enzymatically, operating a maximum batch volume of 170 L. The test product was subjected to a randomized, double-blind, placebo-controlled pilot feeding study. Participants consumed a milk serum drink for 14 days, equalling a daily intake of about 3 g d−1 galactosyl-fructoses. Additionally, the effect of industrially produced lactulose and a placebo drink without lactulose was determined. So far, clinical studies on the prebiotic action of lactulose only focussed on the effects of industrially generated lactulose. The intake of enzymatically synthesized lactulose significantly increased (p = 0.001) faecal bifidobacterial counts, while there was no difference with industrially produced lactulose. Analysis of the compounds showed that the drink with enzymatically synthesized lactulose contained an additional disaccharide, β-1,1-galactosyl-fructose. Presumably, this sugar has a bifidogenic effect and may represent a novel prebiotic.

The dynamics of the interactions between casein micelles and oil droplets during rennet-induced gelation were described using rheology and diffusing wave spectroscopy. Two different colloidal states were obtained by preparing WPI-stabilized oil droplets in either milk serum or low ionic strength buffer: flocculated and non-flocculated. These two colloidal states strongly affected the diffusion of the non-interacting droplets in the gel and the elasticity of the protein network. In homogenized milk, the droplets interact with the protein network and play a structuring role, causing an increased elastic modulus. However, after displacement of the protein from the interface using Tween 20, the interpretation of the rheological data would lead to incorrect conclusions without light scattering measurements. This work demonstrated that an in-depth understanding of the colloidal properties of the oil droplets is necessary to fine-tune the interactions between these particles and the casein matrix in dairy gels.

Microfiltration (0,1 μm) was used to fractionate casein (d50,3 = 180 nm) micelles from whey proteins (2 - 6 nm). The casein fraction forms a deposited layer on the membrane surface. Little is known about the structure of these layers and how transmembrane pressure affects their structure. In order to assess the properties, casein micelle deposits were characterized by dead-end microfiltrations. Casein micelle deposits of constant composition were formed following a standardized layer build up (permeate mass, pressure, pH). Then protein free milk serum was filtered through the deposit. Thus, the impact of compressive forces and protein-protein interactions on physical cake properties during constant solid height filtrations could be determined by stepwise variations of transmembrane pressure and pH without further deposition of proteins. It was found that the casein micelle deposits became more compactable, when their surface charge was lower. Specific cake properties were related to hydrophilic repulsion between casein micelles, whereas the influence of electrostatic interactions between micelles was negligible. The observed cake material properties obtained from dead-end filtrations provide valuable insights into deposit layer build-up and structure. Results obtained for dead-end filtrations were used to describe cross-flow filtrations. For this purpose a new method was developed to assess the specific cake resistances by the evaluation of the kinetic of flux decrease due to deposit layer build-up at the start of filtrations. For the first time it could be shown that deposits consisting of casein micelles during cross-flow filtration were thin layers (1-3 μm), resulting in high specific resistances (up to 20•10-15 m/kg). The specific cake resistance was pressure dependent and increased when the hydrophilic repulsion between casein micelles was reduced at a pH beyond the isoelectric point.