Ovalbumin Concentration Research Articles

Study on the dissolution of heat-induced ovalbumin gel in alkaline solutions relevant to the removal of fouling deposits

Heat-induced whey protein concentrate gels (HIWPCG) have previously been used to simulate milk fouling and cleaning processes. The related research has generated considerable knowledge, which is of practical interest. In the current study, heat-induced ovalbumin gels (HIOVAG) have been employed to investigate the dissolution process (related to chemical cleaning process). Both HIOVAG and HIWPCG are sensitive to NaOH solution, which is a common cleaning fluid in food industry. In contrast to the HIWPCG behavior, HIOVAG dissolution presents no optimal NaOH concentration where the rate of dissolution is highest. The dissolution temperature was found to positively influence the dissolution process of HIOVAG, i.e. the dissolution rate increased with increasing dissolution temperature. In addition, ovalbumin (OVA) concentration in HIOVAG was found to be another important factor influencing the dissolution process. However, the stirring speed (convection) and heating time had no effect in the range tested, indicating that the process was internally limited.

Structural characterisation of the polysaccharides from endemic Mongolian desert plants and their effect on the intestinal absorption of ovalbumin

Using successive extractions with water and 0.7% aqueous ammonium oxalate, pectic polysaccharides were isolated from the following plants growing in the arid climate of Mongolia (Gobi): saxaul Haloxylon ammodendron Maxim., rhubarb Rheum nanum Sievers, Nitraria sibirica Pall., Peganum harmala L. and almond Amygdalus mongolica Maxim. The data obtained exhibited the primary synthesis of the cell wall pectic polysaccharides but not the middle lamellae water-soluble pectins in plants growing in the dry climatic zone.Both α-(1→4)-d-galacturonan and α-(1→4)-d-galacturonan, which was substituted with methyl groups, were found to be backbone of pectins. The l-arabinofuranose residues were identified as the main components of ramified regions. The pectins from almond differed from other pectins due to a high arabinose content. The data from NMR spectroscopy and methylation analyses demonstrated that pectic polysaccharides from almond included terminal, (1→5)-, (1→3)-linked and 3,5-substituted l-arabinofuranose residues and a small terminal d-galactopyranose and 2,5- and 2,3,5-substituted l-arabinofuranose residue content.The pectic polysaccharides were found to decrease the absorption of ovalbumin (OVA) in the blood from the gut lumen. The serum OVA level was lower in mice fed with OVA mixed with the pectins compared with the control group, which was administered OVA alone.

Structure of pectic polysaccharides isolated from onion Allium cepa L. using a simulated gastric medium and their effect on intestinal absorption

The polysaccharide fraction extracted with simulated gastric juice from onion bulbs contained a mixture of galactan with short-length sugar chains, pectic polysaccharides and evident content of proteinaceous material. Galacturonan and rhamnogalacturonan were the main constituents of the linear regions of the sugar chains of the pectic polysaccharides. The ramified regions included rhamnogalacturonan-I. NMR data revealed that the side chains of the ramified region contained mainly 1,4-linked β-D-galactopyranose residues and lesser content of 1,3-linked β-D-galactopyranose and 1,5-linked α-L-arabinofuranose residues. Furthermore, the proteinaceous material was determined to be partly linked to the sugar chains. The polysaccharide fraction was found to decrease absorption of ovalbumin (OVA) to the blood from the gut lumen. The serum OVA level was threefold lower in mice fed with OVA mixed with the onion pectins compared with the control group, which was administered OVA alone. Protein removal failed to abolish the inhibitory effect of the onion polysaccharides, confirming that the polysaccharide chains are the active component of onion gastric juice extract.

Influenza immunization in egg allergy: an update for the 2011–2012 season

Flu vaccines contain detectable amounts of egg protein, which may pose a risk to egg-allergic individuals. The 2009 H1N1 influenza pandemic required mass vaccination in many countries, and the safety of flu immunization in egg allergy became of increasing public health importance. This article reviews recent literature and provides an updated guideline for immunization during the 2011-2012 flu season. Recent experience suggests that some vaccines with very low ovalbumin concentrations may be safe for use in primary care in carefully assessed low-risk individuals.

Study on the Interaction Between Water-Soluble CdTe Quantum Dots and Ovalbumin by Optical Spectroscopy

ABSTRACT CdTe quantum dots (QDs) modified by 2-mercaptoethylamine hydrochloride (CA) and thioglycolic acid (TGA), respectively, were synthesized in aqueous medium. The interaction of CdTe QDs with ovalbumin has been investigated in depth by Fourier transform infrared spectroscopy (FTIR), UV-Vis absorption, fluorescence-quenching spectrometry, and resonance Rayleigh scattering spectroscopy (RRS). Fluorescence data show that the quenching type of ovalbumin by CA-CdTe QDs is static quenching with the binding constant being 10−4 M−1, and the number of binding sites being one. The calculated thermodynamic parameters demonstrate that the main binding forces are hydrophobic interaction and electrostatic attraction. In contrast, the quenching style of ovalbumin by TGA-CdTe QDs is verified to be dynamic quenching. Under suitable acidity conditions, the interaction of CA-CdTe QDs or TGA-CdTe QDs with ovalbumin leads to the remarkable enhancement of RRS, and the increments are found to be proportional to the concentration of ovalbumin in a certain range. A simple and highly sensitive RRS approach for determining ovalbumin is developed. In addition, the causes for the enhancement of RRS and the quenching of fluorescence are investigated to shed light on the quenching mechanism.

Electrochemically monitoring the binding of concanavalin A and ovalbumin

To evaluate protein–protein interactions, a new voltammetric method was developed using a protein labeled with an electroactive compound. Concanavalin A (ConA), which is a lectin, recognizes α-mannose residues. Because the ConA was to be bound to ovalbumin (OVA), which has a high-mannose sugar chain, ConA labeled with daunomycin was prepared as the probe to monitor the binding. The binding to OVA was caused by the label modification of the ConA. As a result, the electrode response of the labeled ConA decreased as the OVA concentration increased. The electrode response of the labeled ConA was linearly over the range of 1.5×10−10 and 1.5×10−9M OVA. The relative standard deviation of 1.5×10−8M labeled ConA and 1.5×10−10M OVA was 6.9% (n=5). The labeled ConA–OVA binding could then be conveniently monitored based on the change in response. In contrast, interactions between the labeled ConA and a protein with no specific sugar chain also were investigated. Incubation scarcely influenced the peak current of the labeled ConA. When several concentrations of OVA were added to a serum, good recovery determined it. Consequently, this method could be applied to the measurement of protein–protein interactions.

Enhancement of Gastrointestinal Absorption of Ovalbumin Caused by Spermine Induces an Increase in Plasma Histamine Levels in Mice Sensitized to Ovalbumin

The aim of this study was to determine whether a spermine (SPM)-induced increase in gastrointestinal absorption of an allergen leads to an anaphylactic response in sensitized mice. First, we examined the enhancing effect of SPM on the gastrointestinal absorption of ovalbumin (OVA) in an in situ jejunum loop study in rats and an in vivo oral absorption study in mice. Second, we investigated whether enhancement of gastrointestinal absorption of OVA caused by SPM induces an anaphylactic response in mice sensitized to OVA. In the in situ jejunum loop study in rats, a significant amount of immune-reactive OVA was detected in the plasma after co-administration of OVA and SPM. Oral co-administration of OVA and SPM to mice in vivo also increased plasma OVA concentrations in an SPM dose-dependent manner. Furthermore, in sensitized mice, a significant increase in plasma histamine levels occurred along with the increase in plasma OVA levels after co-administration of OVA with SPM. This finding suggests that an SPM-induced increase in gastrointestinal absorption of OVA leads to an anaphylactic response. These results indicate that excess oral ingestion of SPM may have widespread health effects, including the induction of food allergies, via modulation of the function of the gastrointestinal epithelial barrier.

Sustained Subconjunctival Protein Delivery Using a Thermosetting Gel Delivery System

An effective treatment modality for posterior eye diseases would provide prolonged delivery of therapeutic agents, including macromolecules, to eye tissues using a safe and minimally invasive method. The goal of this study was to assess the ability of a thermosetting gel to deliver a fluorescently labeled protein, Alexa 647 ovalbumin, to the choroid and retina of rats following a single subconjunctival injection of the gel. Additional experiments were performed to compare in vitro to in vivo ovalbumin release rates from the gel. The ovalbumin content of the eye tissues was monitored by spectrophotometric assays of tissue extracts of Alexa 647 ovalbumin from dissected sclera, choroid, and retina at time points ranging from 2 h to 14 days. At the same time points, fluorescence microscopy images of tissue samples were also obtained. Measurement of intact ovalbumin was verified by LDS-PAGE analysis of the tissue extract solutions. In vitro release of Alexa 488 ovalbumin into 37 degrees C PBS solutions from ovalbumin-loaded gel pellets was also monitored over time by spectrophotometric assay. In vivo ovalbumin release rates were determined by measurement of residual ovalbumin extracted from gel pellets removed from rat eyes at various time intervals. Our results indicate that ovalbumin concentrations can be maintained at measurable levels in the sclera, choroid, and retina of rats for up to 14 days using the thermosetting gel delivery system. The concentration of ovalbumin exhibited a gradient that decreased from sclera to choroid and to retina. The in vitro release rate profiles were similar to the in vivo release profiles. Our findings suggest that the thermosetting gel system may be a feasible method for safe and convenient sustained delivery of proteins to choroidal and retinal tissue in the posterior segments of the eye.

Production of H5N1 (NIBRG-14) inactivated whole virus and split virion influenza vaccines and analysis of immunogenicity in mice using different adjuvant formulations

Consecutive lots of H5N1 (A/Vietnam/1194/2004 – NIBRG-14) split virion and whole virus vaccines were produced in a pilot-scale laboratory. The average yields of vaccine doses (15 μg HA) per egg were 0.57 doses for H5N1 split virion vaccine and 1.12 for H5N1 whole virus vaccine, compared to 2.09 doses for the seasonal H3N2 split virion vaccine. H5N1 split virion vaccine lots complied with WHO protein content criteria, while some lots of the H5N1 whole virus vaccine showed protein content per dose higher than the limit established. All lots of both vaccines showed ovalbumin (OVA) concentration below the recommended limit. Dose sparing strategies using adjuvant formulations using aluminum hydroxide (Al(OH) 3) and monophosphoryl lipid A (MPLA) from Bordetella pertussis were tested in mice. Both 3.75 μg HA and 7.5 μg HA of H5N1 split virion vaccine with Al(OH) 3 or Al(OH) 3 plus MPLA in aqueous suspension showed higher hemagglutination-inhibition (HAI) titers when compared to the same vaccine dose without any adjuvant. Immunization with the H5N1 inactivated whole virus vaccine was also performed using 3.75 μg HA and HAI titers were higher than those induced by the split virion vaccine. Moreover, the use of Al(OH) 3 with MPLA as an emulsion induced a further increase in HAI titers.

Effects of Minimal Persistent Inflammation on Nasal Mucosa of Experimental Allergic Rhinitis

Minimal persistent inflammation (MPI) is considered another piece of the complex puzzle of allergic inflammation. Although some studies regarding MPI have been reported, no study has evaluated the effects of MPI on the structure changes at the site of allergic reaction. This study investigates whether long-time MPI during allergic rhinitis (AR) results in some features of tissue remodeling in the nasal mucosa. An animal model of MPI was developed by repeated nasal challenge with low concentration of ovalbumin (OVA) in sensitized guinea pigs. The models were assessed by allergic symptom after antigen challenge, eosinophil infiltration in the nasal mucosa, and intercellular adhesion molecule (ICAM) 1 expression on nasal epithelial cells. The histopathological changes in nasal mucosa were determined by Alcian blue-periodic acid-Schiff and Masson's trichrome staining. The expression of transforming growth factor (TGF) beta(1) and matrix metalloproteinase (MMP) 9 was examined by immunofluorescence under a confocal laser scan microscope. When sensitized animals were challenged with the low concentration of 0.01% OVA, the symptom of sneezing disappeared, but there were still mild eosinophils infiltration and weak ICAM-1 expression, which indicated the success of MPI models. Moreover, the number of goblet cells and the percentage area of collagen deposition were both mildly increased. The expression of MMP-9 and TGF-beta(1) was also weakly elevated. We have successfully established MPI models and proved long-time MPI may result in mild features of remodeling in the nasal mucosa, which provide new insights into the unexpected potential effects of MPI on the structural changes.

Effect of Maternal Egg Consumption on Breast Milk Ovalbumin Concentration

Palmer D, Gold M, Makridess M. Clin Exp Allergy. 2008;38(7):1186–1191PURPOSE OF THE STUDY. To assess human milk ovalbumin concentrations after daily maternal ingestion of 1 cooked egg for a 3-week period.STUDY POPULATION. There were 32 mothers of singleton, breastfed, egg-sensitive infants with moderate-to-severe eczema. Egg sensitivity was identified by a positive skin-prick test result. Eczema was evaluated by using a standardized scoring system.METHODS. Families had an initial home visit by an experienced dietitian, which involved collection of demographic and dietary information. All women and children were asked to follow an egg-free diet from day 1 through the duration of the trial. Adherence to the egg-free diet was assessed via detailed dietary intake records for both mothers and children on days 1 to 3, 10 to 12, and 21 to 23. Mothers were randomly allocated to receive identical-appearing egg-free muffins or muffins containing 1 (55 g) whole egg. Each mother was given a 3-week supply of frozen muffins corresponding to her randomization group and consumed 1 muffin per day on days 3 through 23. Atopic dermatitis assessments were performed for each child at the commencement and completion of the trial. The mothers completed the Infant's Dermatitis Quality of Life Index 3 times during the trial. On days 3, 12, and 23, the mothers manually expressed 5 mL of breast milk into sterile containers before and 2, 4, and 6 hours after eating the test muffin. Breast milk samples were stored in the home freezer and collected on day 24. The breast milk samples were queried for ovalbumin concentration by using a sandwich enzyme-linked immunosorbent assay method. Breast milk ovalbumin concentrations (nanograms per milliliter) were plotted against time, and the resulting curve was used to determine peak ovalbumin concentrations and total ovalbumin excretions (nanograms per milliliter per hour). Independent-sample t tests, Mann-Whitney U tests, and Pearson's χ2 tests were used to investigate differences between the diet groups.RESULTS. Women in the egg group had higher ovalbumin concentrations in breast milk than did the control group at all time points. Within each dietary group, the frequency of ovalbumin detection, peak ovalbumin concentration, and total ovalbumin excretion did not differ at days 3, 12, and 23. Ovalbumin was not detected in the breast milk of 25% of the women in the egg group. Infant eczema symptom scores were significantly reduced with time for both groups.CONCLUSIONS. Human milk ovalbumin is related to maternal dietary egg intake. Comparable detection of ovalbumin across time suggests that ovalbumin does not accumulate in human milk. One quarter of the women had no ovalbumin detected in their breast milk on any of the study days, which suggests that some women either do not excrete ovalbumin in their breast milk when challenged with 1 egg or have delayed excretion beyond 6 hours. Maternal dietary avoidance of well-cooked egg may not be necessary for all breastfed infants with egg sensitivity and eczema.REVIEWERS COMMENTS. For breastfed infants with food allergy, strict avoidance of the offending food proteins for both mother and child is frequently recommended. Total dietary avoidance of egg is difficult for patients to achieve. Additional study is needed to substantiate or to refute the preliminary observation that regular maternal ingestion of a small quantity of well-cooked egg did not markedly exacerbate eczema symptoms in egg-sensitive breastfed infants.

Effect of different concentrations of calcium chloride and potassium chloride on egg white proteins during isoelectric precipitation of ovomucin

The effect of various concentrations of CaCl2 and KCl on egg white proteins during isoelectric precipitation of ovomucin was investigated in this study. At low concentrations of CaCl2 (<50 mM), lysozyme was the major contaminant in the precipitated ovomucin, whereas ovalbumin was the predominant one at high concentrations (≥100 mM). At 50 mM CaCl2 concentration, the concentrations of both lysozyme and ovalbumin were moderate. Ovomucin with a purity of 97.3% was prepared using a 2-step method: egg white was first precipitated in the presence of 50 mM CaCl2 followed by a second 500 mM CaCl2 extraction. The concentrations of other proteins in the precipitate were 1.3% of ovalbumin, 1.1% of lysozyme, and 0.4% of ovomucoid. Unlike CaCl2-treated samples, ovotransferrin was found to be the second major contaminant in all KCl-treated precipitates. Compared with the control, adding KCl at the lowest concentration of 2.5 mM increased significantly the content of ovalbumin (from 7.6 to 68.0%) and reduced significantly the content of lysozyme (from 25.5 to 6.4%) in the precipitates; however, increasing the concentrations of KCl up to 500 mM did not affect the content of ovalbumin, but the content of lysozyme showed a general reduction trend. Although KCl was used widely in literature as the last step of ovomucin washing, our results show that KCl is not an efficient salt in purifying ovomucin.

Role of sphingosine-1-phosphate (S1P) and the S1P2 receptor in allergen-induced, mast cell-dependent contraction of rat lung parenchymal strips

Lung parenchymal strips isolated from ovalbumin-sensitized rats manifest a mast cell-dependent, biphasic contraction when challenged with allergen. The first phase is mediated by the release of preformed 5-HT while the second phase is dependent on de novo synthesis of leukotrienes. Sphingosine 1-phosphate (S1P) is a sphingolipid metabolite which is readily generated in mast cells and has been demonstrated to be an important regulator of allergen-induced mast cell activation. We have used the parenchymal strip to explore the role of sphingosine 1-phosphate and the S1P(2) receptor in the two components of the acute response to allergen. Lung parenchymal strips were prepared from Brown Norway rats actively sensitized to ovalbumin. The strips were set up in organ baths and contractile responses measured isometrically. The inhibitors of sphingosine kinase, D-erythro-NN-dimethylsphingosine (dimethylsphingosine) and 4-[4-(4-chloro-phenyl)-thiazol-2-ylamino]-phenol (SKI-II) inhibited concentration-dependently both phases of the contractile response induced by 0.1 microg ml(-1) ovalbumin. The effects were seen at concentrations similar to those which inhibit the purified enzyme and were selective in that neither the contractile response to adenosine nor that to 5-hydroxytryptamine was affected. JTE-013 (a selective S1P(2) receptor antagonist) also blocked the response to ovalbumin (0.1 microg ml(-1)). However, the concentrations of JTE-013 required (microM) were substantially higher than its affinity for the S1P(2) receptors (nM). However, when tested against a lower concentration of ovalbumin (0.03 microg ml(-1)), JTE-013 inhibited the response with nM potency. These data demonstrate the importance of S1P and the S1P(2) receptor as regulators of allergen-induced activation of mast cells in their natural environment in the rat lung.

A New Method of Separating Ovomucin from Egg White

Ovomucin, a key component in maintaining the viscous nature of egg white, is a glycoprotein contributing to 2-4% of the total egg albumin protein. Preparation of pure ovomucin remains a challenge due to the presence of coprecipitated proteins, mainly ovalbumin and lysozyme. The objectives of the study were to determine the effect of different salt concentrations on the extractability of ovomucin and to develop a simple method to purify ovomucin that could be adapted for further scale-up production. The protein compositions of ovomucin extracts were significantly affected by salt concentrations. The concentration of ovalbumin was increased, whereas that of lysozyme was decreased in the ovomucin extracts at increasing salt concentrations up to 500 mM; lysozyme was the major contaminant at low salt concentrations (<100 mM), whereas ovalbumin was the major contaminant at high concentrations (>or=200 mM). A 2-step method was developed for the first time to prepare ovomucin with a purity of greater than 90%. Egg white was first extracted in the presence of 100 mM NaCl at pH 6.0 to produce a precipitate containing moderate coprecipitated ovalbumin (14.6%) and lysozyme (15.9%); the contaminated proteins in the precipitate were further removed by using 500 mM NaCl. The yield of ovomucin was determined to be 400.2 mg/100 g of egg white. This 2-step method is simple, environmentally friendly, and easy for scale-up preparation.

Absorption, Migration and Kinetics in Peripheral Blood of Orally Administered Ovalbumin in a Mouse Model

Intestinal absorption of food proteins is well known, whereas its physiological significance remains to be investigated. Various amounts (1, 10 and 50 mg) of ovalbumin were orally administered to mice and the blood kinetics were subsequently analyzed by two-site ELISA. The blood ovalbumin concentration consistently reached its maximum (7-90 ng/ml) about 20 min after the oral administration and then gradually decreased in a dose-dependent manner. Only intact (45 kDa) and truncated (40 kDa) ovalbumins were always detected in the blood independently of the administration site, intra-stomach or intra-intestine, while various fragments of the protein were observed in the gastrointestinal lumen after the oral administration. Recognition by a specific monoclonal antibody and an acidic shift of its pI value suggested that the 40-kDa truncated ovalbumin was produced by intracellular limited proteolysis at its C-terminus. Such stable absorption and blood kinetics of undigested ovalbumin in normal mice suggest some sort of physiological significance for the intestinal uptake of intact food proteins.

Dose-dependent food allergy induction against ovalbumin under acid-suppression: A murine food allergy model

Background Animal models are essential for analyzing the allergenic potential of food proteins and for investigating mechanisms underlying food allergy. Based on previous studies revealing acid-suppression medication as risk factor for food allergy induction, we aimed to establish a mouse model mimicking the natural route of sensitization in patients. Methods The effect of acid-suppressing medication on murine gastric pH was assessed by intragastric pH measurements after two injections of a proton pump inhibitor (PPI). To investigate dose-dependency, mice were fed different concentrations of ovalbumin (OVA; 0.2, 0.5, 1.0, 2.5 or 5.0 mg) either with or without anti-ulcer medication. Additionally, different routes of exposure (i.p. vs. oral) were compared in a second immunization experiment. Sera were screened for OVA-specific antibody titers (IgG1, IgG2a and IgE) in ELISA and RBL assay. Clinical reactivity was evaluated by measuring rectal temperature after oral challenge and by type I skin tests. Results Two intravenous injections of PPI significantly elevated the gastric pH from 2.97 to 5.3. Only oral immunization with 0.2 mg OVA under anti-acid medication rendered elevated IgG1, IgG2a and IgE titers compared to all other concentrations. Protein feeding alone altered antibody titers only marginally. Even though also i.p. immunizations induced high levels of specific IgE, only oral immunizations under anti-acids induced anaphylactic reactions evidenced by a significant decrease of body temperature. Conclusion Only low-dosage ovalbumin feedings under anti-acid medication resulted in IgE mediated food allergy. Based on this knowledge we have established a suitable food allergy model for further investigations of food adverse reactions.

Perturbation of Second and Farther Hydration Shells of Alkali Cations and Bromide in Concentrated Aqueous Protein as a Water-Shortage Medium

The Gibbs free energies of transfer of selected ions from water to concentrated aqueous ovalbumin and albumin (DeltaW(W') G degrees j) have been determined by ion-transfer voltammetry. Negative values for the tetrabutylammonium ion suggest its direct binding to ovalbumin. In contrast, for alkali cations and bromide, the DeltaW(W') G degrees j values are positive and increase with increasing ovalbumin concentration. Positive values are confirmed for concentrated aqueous albumin and poly(styrenesulfonate) as well. The largest value (ca. 10 kJ mol(-1)) is found for the transfer of K(+) from water to 30 wt % ovalbumin. To reveal the solvation structure of these ions in ovalbumin solutions, X-ray absorption fine structure (XAFS) measurements have been performed at the K, Rb, and Br K-edges. Interestingly, the spectra obtained in 30 wt % ovalbumin solutions are identical to those for the corresponding hydrated ions. This strongly suggests that the first coordination shell structures of these ions are not affected by a large concentration of ovalbumin. The detected positive free energy of transfer is slightly lower than the hydrogen bonding energy of a water molecule and should thus come from the perturbation of the second and farther hydration shells of the ions under a water-shortage condition caused by a high concentration of ovalbumin.

Inhibition of Hydroxyapatite Dissolution by Ovalbumin as a Function of pH, Calcium Concentration, Protein Concentration and Acid Type

Hydroxyapatite is the main constituent of the dental hard tissues, and in vivo its dissolution in acids leads to the pathological condition of dental erosion. Food proteins which inhibit hydroxyapatite dissolution may find application as erosion-reducing agents in food and drink products. The aim of this study was to investigate the egg protein ovalbumin as a potential inhibitor of hydroxyapatite dissolution in acidic solutions, with conditions representative of dental erosion. The dissolution rate of hydroxyapatite discs was measured in an acidic solution as a function of pH, calcium concentration, ovalbumin concentration and acid type. All experiments were performed in triplicate. 0.2% w/v ovalbumin significantly reduced the dissolution rate in citric acid by 50–75% over the pH range 2.80–4.00, and by 45–60% in solutions with calcium concentrations of up to 20 mM (p < 0.05). The effect was persistent for several rinses after the initial exposure to the protein. 0.02% w/v ovalbumin significantly reduced the dissolution of hydroxyapatite in citric acid by 30–55%. Ovalbumin did not, however, statistically significantly reduce the hydroxyapatite dissolution rate in malic or lactic acids. The effect is ascribed to adsorption and partial, reversible denaturation of ovalbumin on the hydroxyapatite surface. There may be some interaction between ovalbumin and the citrate ion which promotes the adsorption of protein in the presence of citric acid. Ovalbumin shows promise as a potential erosion-reducing additive to citrus-based drinks.

Effect of maternal egg consumption on breast milk ovalbumin concentration

Maternal dietary avoidance of egg has been recommended to treat egg allergy in breastfed infants. However, only one of three randomized controlled trials have produced evidence in favour of this recommendation. Our objective was to assess human milk ovalbumin (OVA) concentration after daily maternal ingestion of one cooked egg for 3 weeks. Mothers with egg-sensitive, eczematous breastfed infants were randomly allocated to consume one muffin per day containing one egg (egg group, n=16) or a similar egg-free muffin (control group, n=16) for 21 days (Days 3-23). All mothers and infants followed an egg-free diet. Breast milk samples were collected at two hourly intervals for 6 h after eating the test muffins on Days 3, 12 and 23 and breast milk OVA concentration measured. Infant eczema was assessed at the commencement and completion of the trial. Women in the egg group had higher OVA concentrations in breast milk than the control group at all time-points. Within each dietary group, OVA excretion did not change with time. OVA was not detected in breast milk of 25% of women in the egg group. In contrast, infant eczema symptom scores significantly reduced with time for both groups. Human milk OVA is related to maternal dietary egg intake, but a significant proportion of women either have a delayed excretion or may not excrete OVA in their breast milk.

Long-Term Ingestion of Insoluble Dietary Fiber Increases Luminal Mucin Content, but Has No Effect on Nutrient Absorption in Rats

We reexamined the hypothesis that increased mucin secretion by the ingestion of insoluble dietary fiber (IDF) could affect small intestinal nutrient absorption. Polystyrene foam (PSF) was used as IDF. Rats were fed a diet with or without 90 g of PSF/kg for 1, 2 and 4 wk. At the end of each period, a glucose and ovalbumin (OVA) solution was intubated after 12 h of food depletion, and the changes in serum concentrations of these components were monitored. Luminal mucin was measured as O-linked oligosaccharide chains and also determined by ELISA. In all periods, the luminal mucin content was greater in the PSF-fed group than in the fiber-free control. However, the changes in serum glucose and OVA concentrations were comparable between the groups at any time during any period. These results show that the enhancement of luminal mucin secretion lasted even after chronic ingestion of IDF, but that the increased luminal mucin content had no effect on the rate of luminal nutrient absorption.