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We aimed to describe the genomic epidemiology of the foodborne gastrointestinal pathogen, Shiga toxin-producing Escherichia coli (STEC) serotype O26:H11 belonging to clonal complex 29 (CC29) in England. Between 01 January 2014 and 31 December 2021, 834 human isolates belonging to CC29 were sequenced at the UK Health Security Agency, and the genomic data was integrated with epidemiological data. Diagnoses of STEC O26:H11 in England have increased each year from 19 in 2014 to 144 in 2021. Most isolates had the Shiga toxin subtype profiles stx1a (47%), stx1a,stx2a (n = 24%) or stx2a (n = 28%). Most cases were female (57%), and the highest proportion of cases belonged to the 0–5 age group (38%). Clinical symptoms included diarrhoea (93%), blood-stained stool (48%), and abdominal pain (74%). Haemolytic Uraemic Syndrome (HUS) was diagnosed in 40/459 (9%) cases and three children died. All isolates causing STEC-HUS had stx2a either alone (n = 33) or in combination with stx1a (n = 7). STEC O26:H11 are a clinically significant, emerging threat to public health in England. Determining the true incidence and prevalence is challenging due to inconsistent national surveillance strategies. Improved diagnostics and surveillance algorithms are required to monitor the true burden, detect outbreaks and to implement effective interventions. • STEC O26:H11 notifications in 2021 were 8 times higher than those recorded in 2014. • Isolates harbouring toxin subtype stx2a cause the most severe clinical outcomes. • Most cases were female and belonged to the 0–5 years old age group. • Diagnostic and surveillance strategies across England are inconsistent. • STEC O26:H11 are a clinically significant, emerging threat to public health in England. [ABSTRACT FROM AUTHOR]

Complex polymorphisms in the polypeptide chain of bovine β-casein are responsible for the genetic variants that give rise to different bioactive peptides during in vitro and ex vivo digestion, or food fermentation. One specific group of bioactive peptides, known as β-casomorphins, are opioid-agonists for μ-receptors and have been suggested to assume an active role in the development of various non-communicable diseases, including diabetes mellitus, cardiovascular diseases, neurological disorders, pulmonary inflammation, to name a few. Their potential bioactivity and role in human health is dependent on their release from the latent form within the primary structure of β-casein, which can occur during the manufacture of dairy products or during gastric and intestinal digestion. Consequently, β-casomorphins can be either completely hydrolysed or absorbed in the gut or be transferred into the blood stream and internal organs in their intact form. Their biological function as opioid agonists is expressed in the gut, thus upon epithelial translocation they may affect various physiological states, such as causing gastrointestinal issues, bloating, and lactose intolerance. This review evaluated the possible disadvantages and potential beneficial effects of β-casomorphins on human health, within the scope of in vitro and ex vivo studies. Applying a systematic approach, a literature search was performed across four electronic databases (Scopus, Web of Science, PubMed, and Cochrane) to identify suitable studies. The data mined from in vitro and ex vivo trials on the health impact of β-casomorphins is both inconclusive and limited to completely support the possible adverse or potential beneficial health effects of β-casomorphins. These peptides are usually further cleaved in the gut, which prevents their migration across the gut-blood-brain barrier. Nevertheless, in some individuals that are immunocompromised, their condition increases permeability of the gut barrier often referred to as a "leaky gut" condition. Thus, the absorption of β-casomorphins appears possible. This may indicate that the presence of β-casomorphins can affect gastrointestinal functions only. However, since the overall concern with β-casomorphins appears debatable and not well defined, more experimental trials are required to investigate the metabolic pathways of these identified peptides, their release during digestion, and subsequent fate after the digestion process. Consequently, repeatability of the findings under a number of other laboratory conditions is required before the data can be fully substantiated. Due to the rapidly evolving nature of the issue and emerging studies in this field, further exploration into the bioactivity of β-casomorphins is warranted. [Display omitted] • Identification and potential effects of bovine β-casomorphins on human and animal organisms were systematically analysed. • Bovine β-casomorphins may possess potential beneficial and possible negative implications for human and animal health. • Bovine β-casomorphins may be transported into the human blood only if the permeability of the gut barrier is compromised. • Serum enzymes may degrade and eliminate bovine β-casomorphins from the blood stream, before accessing the internal organs. [ABSTRACT FROM AUTHOR]

Background: Reactive arthritis, irritable bowel syndrome (IBS), Guillain-Barré syndrome, ulcerative colitis, and Crohn's disease may be sequelae of Campylobacter or non-typhoidal Salmonella (NTS) infections. Proton pump inhibitors (PPI) and antibiotics may increase the risk of gastrointestinal infections (GII); however, their impact on sequelae onset is unclear. We investigated the incidence of sequelae, their association with antibiotics and PPI prescription, and assessed the economic impact on the NHS.Methods: Data from the Clinical Practice Research Datalink for patients consulting their GP for Campylobacter or NTS infection, during 2000-2015, were linked to hospital, mortality, and Index of Multiple Deprivation data. We estimated the incidence of sequelae and deaths in the 12 months following GII. We conducted logistic regression modelling for the adjusted association with prescriptions. We compared differences in resource use and costs pre- and post-infection amongst patients with and without sequelae.Findings: Of 20,471 patients with GII (Campylobacter 17,838), less than 2% (347) developed sequelae, with IBS (268) most common. Amongst Campylobacter patients, those with prescriptions for PPI within 12 months before and cephalosporins within 7-days before/after infection had elevated risk of IBS (adjusted odds ratio [aOR] 2.1, 1.5-2.9) and (aOR 3.6, 1.1-11.7) respectively. Campylobacter sequelae led to ∼ £1.3 million, (£750,000, £1.7 million) in additional annual NHS expenditure.Interpretation: Sequelae of Campylobacter and NTS infections are rare but associated with increased NHS costs. Prior prescription of PPI may be a modifiable risk factor. Incidence of sequelae, healthcare resource use and costs are essential parameters for future burden of disease studies. [ABSTRACT FROM AUTHOR]

Shiga toxin–producing Escherichia coli (STEC) outbreaks involving ready-to-eat salad products have been described in the scientific literature since 1995. These products typically do not undergo a definitive control step such as cooking to eliminate pathogens. To reduce the number of STEC infections from salad products, efforts will need to focus on preventing and reducing contamination throughout the food chain. We performed a systematic review of STEC outbreaks involving sprouted seeds, salad, or leafy green products to determine whether there were recurrent features, such as availability of microbiological evidence or identification of the contamination event, which may inform future investigations and prevention and control strategies. Thirty-five STEC outbreaks linked to contaminated leafy greens were identified for inclusion. The outbreaks occurred from 1995 to 2018 and ranged from 8 to more than 8,500 cases. Detection of STEC in the food product was rare (4 of 35 outbreaks). For the remaining outbreaks, the determination of leafy greens as the source of the outbreak mainly relied on analytical epidemiology (20 of 35) or descriptive evidence (11 of 35). The traceback investigation in 21 of 32 outbreaks was not able to identify possible routes leading to where the STEC bacteria came from or how the leaves were contaminated. Investigations in eight outbreaks found poor practice during processing that may have contributed to the outbreak, such as insufficient postharvest disinfection of the product. Six outbreak investigations were able to identify the outbreak strain in animal feces near the growing fields; two of these were also able to find it in irrigation water on the farms, providing a likely route of contamination. These results highlight the limitations of relying on microbiological confirmation as a basis to initiate investigations of upstream production to understand the source of contamination. This review also demonstrates the importance of, and difficulties associated with, food-chain traceback studies to inform control measures and future prevention. [ABSTRACT FROM AUTHOR]

The protein composition of bovine skim milk was modified using pilot scale membrane filtration to produce a whey protein-dominant ingredient with a casein profile closer to human milk. Bovine skim milk was processed at low (8.9 °C) or high (50 °C) temperature using ceramic microfiltration (MF) membranes (0.1 μm mean pore diameter). The resulting permeate stream was concentrated using polyethersulfone ultrafiltration (UF) membranes (10 kDa cut-off). The protein profile of MF and UF retentate streams were determined using reversed phase-high performance liquid chromatography and polyacrylamide gel electrophoresis. Permeate from the cold MF process (8.9 °C) had a casein:whey protein ratio of ∼35:65 with no α S - or κ-casein present, compared with a casein:whey protein ratio of ∼10:90 at 50 °C. This study has demonstrated the application of cold membrane filtration (8.9 °C) at pilot scale to produce a dairy ingredient with a protein profile closer to that of human milk. [ABSTRACT FROM AUTHOR]

Pea protein isolate (PPI) is used in many food formulations, due to its low cost, commercial availability and excellent amino acid profile. The objective of this study was to determine the emulsification properties of PPI. Particle size of PPI powders showed neither temperature (25–65 °C) nor time (up to 24 h) increased solubilisation of powder particles during mixing. Heating PPI dispersions (10%, w/w, protein) from 45 to 90 °C led to an increase in storage modulus ( G ′; Pa) at 71 °C, indicating the onset of protein aggregation. Gel formation occurred at 79 °C ( G ′ > 1 Pa). Pea protein-stabilised emulsions made using homogenization (15 MPa; 1 pass) or microfluidization (50 MPa; 1 pass) resulted in the formation of cold-set gels, with gel strength increasing with increasing oil concentration and fluidic pressure. Droplet size and viscosity of pea protein-stabilised emulsions decreased and increased, respectively, with increasing ultrasonication time. Overall, ultrasonication (< 50 °C) can create a uniform droplet size emulsion, while, homogenization and microfluidization can produce cold-set gels for use in a wide-range of food applications. [ABSTRACT FROM AUTHOR]

This study aimed to investigate if differences in β-casein polymorphic structure would affect the acid-induced (glucono-δ-lactone) gelation behaviour of corresponding skim milks. Gels obtained from skim milk containing A2/A2 β-casein had significantly lower elastic modulus, water holding capacity, and gel permeability compared to A1/A1 and A1/A2 gels. Microscopy images also showed a denser microstructure and smaller pore size in acid-induced gels prepared with A1/A1 and A1/A2 milks compared to A2/A2 milk. A number of reasons may account for these differences in gelation, specifically, gels with A1 β-casein contained greater amounts of α-helixes and aggregated β-sheets in their secondary structure compared to A2/A2 gel that was comprised mainly of random coils or polyproline II helixes. In addition, compositional differences such as greater total and micellar calcium and higher levels of total κ-casein existed in A1/A1 and A1/A2 milks compared to A2/A2 milk and may have contributed to the difference in gelation and gel structure. Although the role of β-CN phenotype on skim milk gelation may need further investigation, findings from this study clearly indicate that A2/A2 milk was associated with poor acid gelation properties. [Display omitted] • Effects of acidification on milks with various β-caseins were studied. • Gels carrying A1 β-casein possessed greater water retention and lower permeability. • Increased β-sheets in gels carrying A1 β-casein related to higher storage modulus. • A2/A2 gel possessed a high amount of polyproline II structures. • Gels prepared of A1/A1 and A1/A2 milks possessed a denser microstructure. [ABSTRACT FROM AUTHOR]

This study assessed the effect of heat treatment on the physical properties of bovine milk samples possesing different β-casein (β-CN) phenotypes. After heat treatment at 72 °C/15 s, 121 °C/2.6 min, or 140 °C/3 s, β-CN milks were analysed using Fourier Transform Infrared (FTIR) spectroscopy, Nuclear Magnetic (1H NMR) resonance, and a number of physicochemical measurements. Principal Component Analysis (PCA) was used to provide a discrimination of samples. In contrast to significant amounts of intramolecular β-sheet, β-turn, and random coil, in A1/A1, A1/A2, and A2/A2 β-CN milks, respectively, increasing the heat treatment temperature decreased the level of intramolecular β-sheets in all three types of bovine milk. The main difference involved a higher presence of aggregated β-sheet structures in A1/A2 β-CN milk likely due to the presence of tyrosine. A1/A1 and A1/A2 β-CN milks were characterised with greater amounts of calcium and phosphorus, and a higher net negative zeta potential than A2/A2 β-CN milk. Furthermore, A2/A2 β-CN milk was composed of larger casein micelle particles with lower levels of κ-CN compared to the other β-CN milk phenotypes. These findings may assist in predicting the behaviour of β-CN milks during relevant industrial processing. [Display omitted] • FTIR and 1H NMR identified structural variations of heat-treated milks. • Heat treatment decreased random coils and α-helices amount in all milks. • Aggregated β-sheets in A1/A2 milk related with the tyrosine residues. • A1/A1 and A1/A2 milks were similar; A2/A2 milk possessed unique traits. • β-casein proteoforms influenced the micelle size and the amount of minerals. [ABSTRACT FROM AUTHOR]

The ability to accurately and cost-effectively distinguish between different genetic protein variants in milk is of pivotal significance to the dairy industry as the natural proteoforms of caseins affect the composition and functionality of dairy products. Recently, β-casein proteoforms have received increased consumer attention in regards to A1 and A2 milk families. Fourier transform infrared (FTIR) spectroscopy coupled with multivariate analysis was used to discriminate milk samples from 114 Holstein-Friesian cows possessing different β-casein genetic variants. Principal component and partial least squares-discriminant analyses were used to characterise and distinguish A1 and A2 β-casein genetic families based on spectral data. Milk containing A2 β-casein had higher proportions of random coil and β-sheet conformations than milk containing A1 β-casein and the lowest amount of α-helical and β-turn structures, due to additional proline. This may provide a feature to distinguish between these phenotypes using FTIR spectroscopy in association with chemometric analyses. [ABSTRACT FROM AUTHOR]

Highlights: [•] MPC powder dissolution rates were compared using stirring and ultrasonication. [•] Sonication increases the rate of powder dissolution compared to stirring. [•] Sonication is more effective at breaking intermolecular hydrophobic interactions. [•] Temperature control must be used during sonication to prevent protein aggregation. [ABSTRACT FROM AUTHOR]

Abstract: Lactoferrin and β-casein represent a large proportion of the proteins in human milk and, as a result, are important ingredients for the manufacture of infant formula. At pH 7, lactoferrin has a net positive charge, compared to the negatively charged β-casein. The effects of CaCl2 and heat treatment on the stability of oil-in-water emulsions stabilised by lactoferrin and/or β-casein were investigated. The ζ-potential values of emulsions stabilised with β-casein or a 1:1 mixture of β-casein/lactoferrin significantly (P < 0.05) decreased on addition of 30 mM CaCl2, while CaCl2 had no significant (P > 0.05) effect on the ζ-potential of lactoferrin-stabilised emulsions. Particle size of β-casein-stabilised emulsions increased significantly (P < 0.05) upon the addition of 30 mM CaCl2, due to flocculation, while emulsions stabilised with lactoferrin and β-casein/lactoferrin remained unaffected by CaCl2 addition. Oscillatory rheology measurements showed that β-casein-stabilised emulsions formed a gel when CaCl2 was added, due to calcium-bridging, compared to lactoferrin-stabilised emulsions, where a weaker gel was formed in the presence of CaCl2. While, 30 mM CaCl2 did not increase the elastic modulus (G′) of β-casein/lactoferrin-stabilised emulsions. Lactoferrin protected β-casein from calcium-induced flocculation by: (1) binding calcium ions via sialic acid groups on lactoferrin molecules and reducing the number of free ions available to form calcium linkages between β-casein molecules; (2) electrostatically interacting with negatively charged phosphate groups on β-casein molecules, blocking calcium–phosphate interactions and (3) providing additional stability through increased steric repulsion between β-casein/lactoferrin conjugates, due to the large molecular size of lactoferrin. [Copyright &y& Elsevier]

The heat treatment (HT) of milk and dairy ingredients for the purpose of powder manufacture is a complex and multifaceted area, with many factors influencing microbial quality, process efficiency (e.g., product composition, processing equipment and operating parameters) and end-powder functionality (e.g., heat stability, powder rehydration, gelation, etc.). One primary area of research is the mechanisms responsible for heat-induced viscosity development, mainly due to its role in fouling of processing equipment. Developing a means of predicting viscosity increase due to thermal heat treatment have proven beneficial and are discussed herein. The review also highlights scientific areas of interest where limited published information exists, and perhaps should be explored in the near future. [ABSTRACT FROM AUTHOR]

This study highlights differences in conformational and physicochemical characteristics of bovine skim milk and micellar casein from cows of different β-casein phenotypes. These genetic variants have been one of the predominant topics among dairy researchers due to their differences in β-casein structure, and thus their potential effects on dairy processing and human health. For characterising differences in milk protein structure, Fourier Transform Infrared (FTIR) and Nuclear Magnetic Resonance (1H NMR) spectroscopies combined with chemometric analysis were used. Additionally, physiochemical properties such as mineral content, particle size, and electrostatic charge in skim milk and micellar casein samples were analysed at 4 and 20 ᵒC. Results showed variation in the secondary structure of all three genetic variants independent of temperature. Moreover, the main differences involved a higher level of β-turn and α-helical structures in A1/A1 β-casein milk, while intermolecular β-sheets were more numerous in A1/A2 β-casein milk, whereas random or polyproline II (PPII) structures were more common in A2/A2 β-casein milk. Temperature slightly affected these differences, which was due to the dissociation of β-casein from the micelle at low temperature. In addition, A2/A2 β-casein milk and its micellar casein had a larger average particle size, which resulted in a lower negative ζ-potential. The A2/A2 β-casein samples contained greater amounts of phosphorus and less calcium compared to the other genetic variants of milk and their micellar caseins. The results also indicated that a combination of FTIR and 1H NMR spectroscopies could be used to establish conformational differences in milk and micellar caseins of different genetic variants. [Display omitted] • Fingerprinting conformational difference of milk and caseins using FTIR and 1H NMR. • Conformational differences depended on β-casein proteoform and temperature. • A2 β-casein dominated in the protein conformation of A1/A2 and A2 β-casein samples. • A1 and A2 β-casein samples possessed mainly α- and PPII helices, respectively. • Different proteoforms affected the micelle size but not the minerals among samples. [ABSTRACT FROM AUTHOR]

Abstract: Bovine β-casein was purified from phosphocasein by rennet coagulation and cold solubilisation from the resultant curd. β-Casein was then dephosphorylated using potato acid phosphatase. Urea-polyacrylamide gel electrophoresis (PAGE) of partially dephosphorylated β-casein showed a number of bands, depending on the final level of phosphorylation. Dephosphorylating β-casein increased its pH of minimum solubility from ∼pH 5 to 5.5 and reduced its net negative charge from −30.8 to −27.0mV. During the acidification of β-casein solutions, partially dephosphorylated β-casein failed to form a gel, unlike the phosphorylated (i.e., control) β-casein. Use of partially dephosphorylated β-casein to stabilise oil-in-water emulsions resulted in larger fat globules compared to control β-casein, but such globules were less susceptible to aggregation in the presence of 15 or 30mM CaCl2. Overall, the dephosphorylation of β-casein resulted in a protein similar to human β-casein in terms of physicochemical functionality, with increased stability against calcium-induced aggregation. [Copyright &y& Elsevier]

Abstract: The effect of protein content (6.68–11.88 g protein 100 g−1 powder) on the microstructure and physical stability of dry infant formula was investigated at relative humidities (RH) of 0 and 54.4%. Time-dependent lactose crystallisation of powders occurred at lower water contents as protein level decreased. Surface composition of powders stored at 0% RH were significantly (P < 0.05) different to their bulk composition, with fat extensively covering the surface of powder particles. Increasing RH to 54.4% increased surface lactose levels due to lactose crystallisation. Reducing protein level increased levels of free fat in powders stored at 0% RH for 14 days. Glass transition temperatures of powders decreased only at the lowest protein level studied (6.68 g 100 g−1). Reducing the protein content of infant formulae resulted in altered powder particle surface composition, free fat levels and time-dependent lactose crystallisation properties. [Copyright &y& Elsevier]

Abstract: The objective of this study was to examine the effects of lowering protein content of a model infant formula on its processing characteristics and physical stability. Formulations containing five different protein:fat ratios (0.21–0.43) were investigated. Increasing protein:fat ratio increased viscosity and decreased fat globule size. Fat globule size increased significantly upon evaporation (P <0.05) for all formulations, but decreased significantly (P < 0.05) following atomization during spray drying. The specific surface area of fat globules increased with increasing protein:fat ratio, while protein load (τ) did not differ significantly between treatments. Increasing protein:fat ratio resulted in decreased creaming rates and improved emulsion stability. In conclusion, decreasing the protein:fat ratio of the formulae, particularly to 0.21, reduced the physical stability of the emulsions. [Copyright &y& Elsevier]

Summary: This study describes the first case of extensively drug-resistant tuberculosis (XDR-TB) in the Thames Valley and South East Region and discuss the public health implications, highlighting the need to integrate current epidemiological knowledge with clinical expertise in order to diagnose drug-resistant tuberculosis (TB) early. The management of the XDR-TB patients is challenging with few treatment options, expensive therapy, side effects of drugs and a longer course of the treatment. [ABSTRACT FROM AUTHOR]

Abstract: Relatively little is known about the Campylobacter genotypes colonizing extensively reared broiler flocks and their survival through the slaughter process, despite the increasing demand for free-range and organic products by the consumer. Campylobacter isolates from a free-range boiler flock, sampled before and after slaughter, were genotyped by MLST (multilocus sequence typing) and sequence analysis of the flaA short variable region (SVR). The Campylobacter genotypes isolated before and after slaughter were diverse, with up to five sequence types (STs) (seven-locus allelic profiles resulting from MLST) identified per live bird, up to eight STs identified per carcass and 31 STs identified in all. The majority (72.0%) of isolates sampled from carcasses post-slaughter were indistinguishable from those isolated from the live flock before slaughter by ST and flaA SVR type, however, sampling ‘on-farm’ failed to capture all of the diversity seen post-slaughter. There were statistically significant increases in the genetic diversity of Campylobacter (p =0.005) and the proportion of C. coli (p =0.002), with some evidence for differential survival of genotypes contaminating the end product. C. coli genotypes isolated after slaughter were more similar to those from free-range and organic meat products sampled nationally, than from the live flock sampled previously. This study demonstrated the utility of MLST in detecting genetic diversity before and after the slaughter process. [Copyright &y& Elsevier]

Milk concentrate (MC) viscosity is a key process control parameter in the manufacture of dairy based powders that affects both process efficiency and powder functionality. If the viscosity of MC is too high, various processing issues can arise, i.e., pump blockages, fouling, poor atomisation, product rework and production downtime. Viscosity of MC is dependent on various intrinsic (e.g., total solids content, protein: lactose ratio, mineral profile, pH) and extrinsic (e.g., temperature, agitation, high shear) parameters. It is therefore necessary to understand the effects of these parameters on the viscosity of MC to maintain an optimal process. This review focuses on outlining the parameters that affect the viscosity of MC and recent advances in processing strategies to reduce viscosity of MC prior to spray drying during powder manufacture. [ABSTRACT FROM AUTHOR]

A number of randomised in vivo trials have to date investigated the health impacts of the genetic variants A1 and A2 of bovine β-casein. The primary difference between these two genetic variants is the mutation leading to an amino acid exchange at a position 67 in the peptide chain. This systematic review evaluated the effects of bovine milk, β-casein and pure β-casomorphin7, in the form of orally administered nutritional ingredients, on possible incidence and risk for chronic digestive discomfort and development of incurable conditions and diseases in human and animal randomised controlled trials. Following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) checklist, searches were performed for publications across 7 electronic databases (Scopus, Embase, Web of Science, Medline, EBSCO, PubMed, and Cochrane) up to and until July 2020, to identify randomised controlled trials. The subsequent search results were screened for relevance firstly by title, then abstract, and the chosen ones by full text, with additional screening of included articles reference lists. In total 2006 peer-reviewed journal articles were identified and after applying exclusion criteria, 19 studies were deemed suitable for inclusion. Human-based and animal-based results from the clinical in vivo studies demonstrated that consumption of A2 β-casein milk can lead to improved tolerance of milk via decline in the ubiquity of gut related discomfort. However, the exact mechanism for these effects or specific individuals that may benefit from A2 β-casein milk as opposed to A1 β-casein milk is still poorly understood. Notably, consumption of A2 β-casein milk had very low to completely no effect on the other health statuses investigated, particularly non-communicable diseases, such as cardiovascular diseases, neurological disorders, and diabetes. Based on current data, there is not sufficient evidence to merit public health authority recommendations related to the consumption and health associations of A1 β-casein milk or A2 β-casein milk. Interestingly, regardless of the scientific evidence between A2 β-casein milk and health, this milk continues to gain prominence on the market, thus further functional research is required to understand the mechanisms of action of these identified peptides and gene variants and any implications A1 or A2 β-casein milk may have on human health and techno-functional properties of milks. [Display omitted] • Impact of β-casein genetic variants on human health from animal and human in vivo studies was systematically analysed. • Both A1 β-casein and A2 β-casein release beta-casomorhin7 during the in vivo digestion. • Consumption of A2 β-casein may decline in perseverance of gut problems, however, not clinically admissible. • Neither A1 β-casein nor A2 β-casein showed an effect on the other health statuses. [ABSTRACT FROM AUTHOR]

Milk protein concentrate (MPC) and sodium caseinate (NaCas) were hydrolysed using the enzyme trypsin and the subsequent physical properties of the two ingredients were examined. Trypsin hydrolysis was carried out at pH 7 and at 45 °C on 11.1% (w/w) protein solutions. Heat inactivation of trypsin was carried out when the degree of hydrolysis reached either 10 or 15%. Size-exclusion chromatography and electrophoresis confirmed a significant reduction in protein molecular weight in both ingredients. However, whey proteins in MPC were more resistant to trypsin hydrolysis than casein. Oil-in-water emulsions were prepared using intact or hydrolysed protein, maltodextrin, and sunflower oil. Protein hydrolysis had a negative effect on the subsequent physical properties of emulsions, compared with non-hydrolysed proteins, with a larger particle size (only for NaCas stabilised emulsions), faster creaming rate, lower heat stability, and increased sedimentation observed in hydrolysed protein emulsions. [ABSTRACT FROM AUTHOR]

The aim of this study was to investigate the structural characteristics of casein micelles and casein particles at pH 6.7, 5.7, and 2.3 containing β-caseins A1/A1, A1/A2, and A2/A2 at 37 °C using Nuclear Magnetic Resonance, Fourier-Transform Infrared spectroscopies and chemometrics. The amount of all released caseins from the casein micelle at pH 6.7 was significantly different after the pH had been reduced to 5.7 and subsequently decreased to 2.3. Results showed variation in the structure of all three samples mainly dependent of caseins content, caseins' phenotypes, and pH modulation. During the pH modulation, higher levels of α-helixes and intramolecular β-sheets were found in A1/A1 casein, whilst aggregated β-sheets, β-turns, and polyproline II helixes dominated in A1/A2 and A2/A2 samples. Principal Component Analysis was used to characterise and distinguish among the structure of the three caseins based on spectral data. While samples containing β-casein A2 possessed structural properties different to A1/A1 samples at pH 6.7 and 2.3, at pH 5.7 all casein micelles behaved in a similar manner. This study brings significant insights in the importance of the observed casein phenotypes on the structural arrangement of A1/A1, A1/A2, and A2/A2 casein micelles, hence defining their main conformational differences essential for the dairy industry. [Display omitted] • FTIR, 1D- and 2D-NMRs identified conformational differences in casein particles. • Structurally at pH 5.7, A1/A1, A1/A2 and A2/A2 casein micelles were similar. • Acidification increased PPII structures in A2/A2 casein. • Aggregated β-sheets in the samples appear related to κ-casein phenotypes. • In A2/A2 sample, β-casein A2 showed stronger connection to other caseins. [ABSTRACT FROM AUTHOR]

Serum protein concentrates (SPCs) were generated from reconstituted skim milk (3.2% protein) using lab-scale tangential-flow filtration at 3–4 °C. The influence of membrane type on process performance (e.g., permeate flux) and protein-enrichment (e.g., protein profile) was assessed with polyvinylidene-difluoride membranes (0.1 μm and 0.45 μm pore-size), and a polyethersulfone membrane (1000 kDa cut-off). The 1000 kDa membrane exhibited the highest starting flux (6.7 L m −2 h −1 ), followed by the 0.1 μm (5.4 L m −2 h −1 ) and 0.45 μm (4.8 L m −2 h −1 ) membranes. Flux decreased by >40% during filtration with the 1000 kDa and 0.1 μm membranes, while the decrease was lower (<20%) with the 0.45 μm membrane. β-Casein comprised >97% of casein in SPCs from the 0.1 μm and 1000 kDa membranes. SPCs from the 0.45 μm membrane had higher β-casein:α s -casein ratios than the feed and higher levels of minor whey proteins (e.g., lactoferrin) relative to the other SPCs. [ABSTRACT FROM AUTHOR]

This study determined the changes in the chemical properties of milk protein ingredients during heat-treatment, with a focus on the in-situ measurement of pH. Milk protein concentrate, micellar casein concentrate, sodium caseinate and whey protein isolate powders were rehydrated in either distilled water or lactose-free simulated milk ultra-filtrate (SMUF). Protein dispersions were heated from 25 to 120 °C before cooling to 25 °C in a custom-engineered hermetically sealed cell, fitted with a pH probe. The direct measurement of pH was successfully performed at temperatures >100 °C, addressing a significant gap in the current literature where pH values are rarely, if ever, carried out at in-process temperatures. This novel approach for measuring pH at high temperature has potential as a laboratory based analytical tool or as a critical control point during industrial high temperature processing. [ABSTRACT FROM AUTHOR]

This study aimed to examine how microscopic morphological developments, such as lactose crystallisation, swelling of particles and changes in surface roughness, occur as a function of moisture sorption in skimmed-milk (SMP), milk protein concentrate (MPC) and whey protein isolate (WPI) powders. Atomic force microscopy (AFM) has the potential to identify high-resolution, microstructural changes in high-protein, milk powder particles. A sample preparation technique was developed, which allowed a single-layer of uniformly distributed powder particles to be applied to a mica surface for subsequent AFM analysis. An amplitude modulation (AM)-AFM technique was used, and analysis showed that equilibration of powders under conditions of increasing relative humidity (RH) causes changes in topography and increased surface roughness. In SMP, significant surface changes were observed due to the development of lactose crystallisation and eventual stacking of crystal layers with increased moisture sorption. MPC, however, showed characteristic 'dimples and folds', which may have been due to shrinkage and compaction of surfaces. With higher moisture content, the number of surface-folds and height-ranges increased, with MPC powders, held at 85% RH appearing highly jagged. The surfaces of WPI powders were smooth but were characterised by the presence of broken powder fragments. Such fragments were absent in SMP and MPC powders, suggesting that WPI powders were the most friable. WPI powders appeared not to change as a function of moisture sorption. AM-AFM was used to provide high-resolution, three-dimensional images of HPMP particles at nano- and micrometre length scales. [Display omitted] • Topographical images of dairy powder particles were examined by AM-AFM. • Skimmed milk powder showed significant microstructural changes due to lactose crystallisation. • Milk protein concentrate powder surfaces had surface folds, which increased in height with RH. • Whey protein isolate particles were smooth, with a weak mechanical structure. • A technique was developed to provide a monolayer of particles for AFM analysis. [ABSTRACT FROM AUTHOR]

This study aimed to determine the physicochemical properties of yoghurts from skim milk containing either β-casein A1/A1, A1/A2 or A2/A2 and establish their behaviour during simulated gastric digestion. Yoghurts produced from milk containing β-casein A1/A1 and A1/A2 had significantly higher storage modulus, water holding capacity, and lower syneresis compared to yoghurt produced from A2/A2 milk. Microscopy images also showed a more porous microstructure and greater pore size in A2/A2 yoghurts. The main conformational variability between the yogurts was approximately 35 % lower levels of aggregated β-sheets in A2/A2 yoghurt, compared to the other yogurt systems. The A2/A2 sample was also characterised by larger casein micelles, lower levels of κ-casein, and higher levels of β-lactoglobulin in the yoghurt serum phase. During gastric digestion, coagulum formation in all three yoghurts occurred within the first 5 min between the pH ranges of 4.3 to 3.8. However, protein breakdown in A1/A1 and A1/A2 yoghurts occurred faster, with the final gastric clot characterised as a loose protein network, as opposed to that of the A2/A2 digesta. Overall, the use of A2/A2 milk in yoghurt production results in prolonged gelation times, with altered gastric digestion properties compared to yogurts containing β-casein A1. [Display omitted] • Onset of acid gelation was slower in yoghurts produced from A2/A2 milk. • A2/A2 yoghurt possessed lower water retention and greater syneresis. • Yoghurts containing β-casein A1 had more aggregated β-sheets. • Protein breakdown during gastric digestion was slower in A2/A2 yoghurts. • Digesta from A1/A1 and A1/A2 yoghurts had a porous microstructure. [ABSTRACT FROM AUTHOR]

This study investigated the physical properties of skim milk powders containing β-casein A1/A1, A1/A2 or A2/A2 phenotypes and determined their digestion properties. Rehydrated skim milk powders all had a type A heat coagulation profile (HCT); although A2/A2 milk had a different local maximum and minimum HCT, compared to A1/A1 and A1/A2 milks. Differences in the rehydration properties of milk powders appeared to be related to the presence of β-casein A1 in reconstituted A1/A1 and A1/A2 milks since they were characterised by smaller casein micelles and greater levels of κ-casein, compared to A2/A2 milk. All reconstituted samples displayed protein aggregation and coagulum formation within the first 5 min of gastric digestion, at which time the pH ranged from 6.0 to 5.5. During digestion of reconstituted A2/A2 milk, casein breakdown was slower, compared to that of A1/A1 or A1/A2 milks. The final gastric clot obtained from the A2/A2 sample possessed a tight protein network, containing a greater level of calcium and aggregated β-sheets. In this regard, the dry weight of the separated clot after the final gastric phase was significantly higher by 29 and 68 % in A2/A2 digesta compared to that in A1/A1 or A1/A2 digests, respectively. Overall, this study shows that for rehydrated skim milk powders there was a significant difference in the level of gastric protein-breakdown between milks containing β-casein A1 and milk containing only β-casein A2. This may have significant implications during in vivo gastric digestion and emptying. [Display omitted] • Greater rehydration properties were observed in A1/A2 skim milk powder. • Random coils were mainly present in A2/A2 skim milk powder. • Heat stability was lower in A2/A2 milk at pH 7.4 • The A2/A2 digesta formed under gastric conditions was larger than A1 milks. • Milks with β-casein A1 showed faster gastric digestion. [ABSTRACT FROM AUTHOR]

Due to their excellent nutritional (e.g., high calcium) and functional (e.g., heat stability and gelation) properties, the use of protein-enriched, micellar casein-dominant dairy powders, including milk protein concentrate/isolate and micellar casein concentrate, has increased considerably among food and beverage manufacturers. However, the poor and often inconsistent rehydration properties of these powders in water, specifically their low dispersibility and solubility (attributed to protein–protein interactions related to the high proportion of micellar casein), remains a significant challenge. This review provides a detailed analysis of the main physical (e.g., injection of gas, ultrasonication) and chemical (e.g., ion exchange, pH adjustment) processing strategies that have been applied, at both laboratory and pilot-scale, to enhance the rehydration performance of high-protein, micellar casein-dominant dairy powders. The information provided will support the advancement of dairy ingredient research and the technological development of nutritional powders that can be used across several industrial applications. [ABSTRACT FROM AUTHOR]

This study examined the effect of dietary factors on compositional and functional properties of whole milk powder (WMP) produced from bovine milk. Raw milk samples were obtained from 3 groups of 18 Holstein Friesian spring-calving cows randomly assigned to diets based on perennial ryegrass (GRS), perennial ryegrass/white clover sward (CLV), and total mixed ration (TMR). Raw milks obtained in late lactation were subsequently standardized for fat, heat-treated (90°C for 30 s), evaporated, and homogenized before spray drying. The WMP produced from each diet were analyzed to determine differences in color, particle size distribution, heat coagulation time, yogurt gelation, texture profile, and protein profile due to each diet. Significant differences in heat coagulation time were observed between the CLV and TMR samples, whereas color values were significantly different between GRS and TMR samples. No significant differences in gross composition, protein profile, or whey protein nitrogen index were found between the 3 WMP samples. Average D 90 values (the particle size at which 90% of the particles were smaller than the specified size) for fat globules were significantly lower in the TMR sample compared with the GRS and CLV samples. Yogurts produced from GRS- and CLV-derived WMP had significantly higher elastic moduli (G′) than those produced from TMR-derived WMP. Similarly, texture profile analysis revealed significantly higher firmness values in yogurt samples derived from CLV compared with TMR samples. Our data characterize the effect of these diets on the composition and functional properties of fat-standardized WMP, suggesting better yogurt functionality and thermal stability in WMP derived from pasture-based bovine diets. [ABSTRACT FROM AUTHOR]

Background: Pneumococcal diseases cause substantial mortality, morbidity, and economic burden. Evidence on data inputs for economic evaluations of interventions targeting pneumococcal disease is critical.Objectives: To summarize evidence on resource use, costs, health utilities, and cost-effectiveness for pneumococcal disease and associated interventions to inform future economic analyses.Methods: We searched MEDLINE, Embase, Web of Science, CINAHL, PsycINFO, EconLit, and Cochrane databases for peer-reviewed studies in English on pneumococcal disease that reported health utilities using direct or indirect valuation methods, resource use, costs, or cost-effectiveness of intervention programs, and summarized the evidence descriptively.Results: We included 383 studies: 9 reporting health utilities, 131 resource use, 160 economic costs of pneumococcal disease, 95 both resource use and costs, and 178 economic evaluations of pneumococcal intervention programs. Health state utility values ranged from 0 to 1 for both meningitis and otitis media and from 0.3 to 0.7 for both pneumonia and sepsis. Hospitalization was shortest for otitis media (range: 0.1-5 days) and longest for sepsis/septicemia (6-48). The main categories of costs reported were drugs, hospitalization, and household or employer costs. Resource use was reported in hospital length of stay and number of contacts with general practitioners. Costs and resource use significantly varied among population ages, disease conditions, and settings. Current vaccination programs for both adults and children, antibiotic use and outreach programs to promote vaccination, early disease detection, and educational programs are cost-effective in most countries.Conclusion: This study has generated a comprehensive repository of health economic evidence on pneumococcal disease that can be used to inform future economic evaluations of pneumococcal disease intervention programs. [ABSTRACT FROM AUTHOR]

Abstract This work aimed to model the effect of heat treatment on viscosity of milk protein concentrate (MPC) using kinetic data. MPC obtained after ultrafiltration was subjected to different time-temperature heat treatment combinations. Heat treatment at high temperature and short time (i.e., 100 or 120 °C×30 s) led to a significant increase in viscosity in MPC systems. Second-order reaction kinetic models proved a better fit than zero- or first-order models when fitted for viscosity response to heat treatment. A distinct deviation in the slope of the Arrhenius plot at 77.9 °C correlated to a significant increase in the rate of viscosity development at temperatures above this, confirming the transition of protein denaturation from the unfolding to the aggregation stage. This study demonstrated that heat-induced viscosity of MPC as a result of protein denaturation/aggregation can be successfully modelled in response to thermal treatment, providing useful new information in predicting the effect of thermal treatment on viscosity of MPC. Highlights • Heat treatment (≥75 °C) caused a significant increase in viscosity of MPC. • A model was developed to describe the effect of heat treatment on MPC viscosity. • Second-order kinetics proved a good fit for viscosity response to heat treatment. • The Arrhenius plot showed the transition from protein unfolding to aggregation. [ABSTRACT FROM AUTHOR]

Abstract Direct supersonic steam injection, direct steam infusion, and indirect tubular heating were each applied to protein-enriched skim milk-based beverages with 4, 6 and 8% (w/w) total protein, and the effect of final heat temperature on the physical properties of these beverages was investigated. Supersonic steam injection resulted in significantly lower levels of denaturation of β-lactoglobulin (34.5%), compared to both infusion (76.3%) and tubular (97.1%) heating technologies. Viscosity, particle size and accelerated physical stability of formulations did not differ significantly between the heating technologies, while noticeable colour differences due to heat treatment (mainly attributed to increasing b* value) were observed, particularly for tubular heating. Overall, the extent of protein denaturation in high-protein dairy products was significantly influenced by the particular heating technology applied. The application of supersonic steam injection technology, with rapid heating and high shear characteristics, may enable differenciated product characteristics for ready-to-drink ambient-delivery high-protein dairy beverages. Industrial relevance The design and application of novel direct supersonic steam injection technology was comprehensively studied and found to provide significant benefits over direct steam infusion and indirect tubular heating technologies for skim milk-based protein beverages. This type of injection heating system resulted in heat-treated formulations with lower levels of denatured whey proteins, compared to tubular and infusion heating, offering an alternative opportunity to the industry in terms of producing shelf-stable dairy protein beverages. Highlights • Supersonic steam injection provides rapid heating and high shear. • Substantial native whey protein retention compared to tubular and infusion heating • No difference in accelerated physical stability for heating technologies • May enable new product development opportunities [ABSTRACT FROM AUTHOR]

Highlights • Sodium hexametaphosphate increases the viscosity of milk protein concentrate. • Dephosphorylating milk protein altered its viscosity profile. • NMR can be utilised to observe protein dephosphorylation. • NMR showed sodium hexametaphosphate to interact with calcium-phosphoserine. • Phosphoserine peaks were absent in dephosphorylated milk protein. Abstract This study investigated the effects of dephosphorylation and sodium hexametaphosphate (SHMP) salt addition on the viscosity of milk protein concentrate (MPC) solutions. Dephosphorylation (DP) of casein was performed using bovine alkaline phosphatase. Nuclear magnetic resonance (NMR) spectra showed that dephosphorylation depleted the casein-bound phosphate region (CNP). SHMP addition (5 mM) had no impact on the 31P NMR spectra of DP-MPC; addition of 5 mM SHMP to control MPC (C-MPC) resulted in a shift in peaks associated with the CNP region, possibly caused by SHMP sequestering calcium, leading to swelling of micelles. DP-MPC exhibited a lower viscosity compared to C-MPC, with SHMP addition at 12.5 and 25 mM causing gelation of C-MPC and DP-MPC solutions. This work confirmed the role that phosphate residues have in maintaining micelle structural stability and provides new insights into controlling viscosity of MPC solutions. [ABSTRACT FROM AUTHOR]

Acid whey (AW) is the liquid co-product arising from acid-induced precipitation of casein from skim milk. Further processing of AW is often challenging due to its high mineral content, which can promote aggregation of whey proteins, which contributes to high viscosity of the liquid concentrate during subsequent lactose crystallization and drying steps. This study focuses on mineral precipitation, protein aggregation, and lactose crystallization in liquid AW concentrates (~55% total solids), and on the microstructure of the final powders from 2 independent industrial-scale trials. These AW concentrates were observed to solidify either during processing or during storage (24 h) of pre-crystallized concentrate. The more rapid solidification in the former was associated with a greater extent of lactose crystallization and a higher ash-to-protein ratio in that concentrate. Confocal laser scanning microscopy analysis indicated the presence of a loose network of protein aggregates (≤10 μm) and lactose crystals (100-300 μm) distributed throughout the solidified AW concentrate. Mineral-based precipitate was also evident, using scanning electron microscopy, at the surface of AW powder particles, indicating the formation of insoluble calcium phosphate during processing. These results provide new information on the composition- and process-dependent physicochemical changes that are useful in designing and optimizing processes for AW. [ABSTRACT FROM AUTHOR]

This study aimed to reduce the bulk density of skim milk powders (SMP) and improve subsequent wettability and dissolution by a combination of agglomeration and lecithination. Agglomeration significantly increased powder particle size from a D 90 of 120–201 μm, and decreased tapped bulk density (0.73–0.65 g/cm3), although it led to increased friability (32.7%) compared to regular SMP (22.9%). Spraying lecithin on to SMP in the fluid bed improved wettability (8.94 s) compared to regular SMP (>300 s). Agglomeration without lecithination had no effect on powder wettability, similarly, adding lecithin in to liquid skim milk concentrate prior to drying did not improve subsequent powder wettability. Overall, improving the functionality of skim milk is quite complex, and while powder bulk density can be reduced by agglomeration, the particles remain susceptible to breakdown, and the wettability is relatively poor, although this can be improved by spraying lecithin directly on to the powder particles. [Display omitted] • Agglomeration increased skim milk powder particle size from a D 90 of 120 to 201 μm. • Lecithin sprayed on to powder particles reduced wetting time from >300 s to 8.94 s. • Agglomeration decreased powder tapped bulk density from 0.76 to 0.65 g/cm3. • Powder flowability was more influenced by surface composition than particle size. • Lecithination did not reduce the friability of agglomerated skim milk powder. [ABSTRACT FROM AUTHOR]

The high calcium content of acid whey can pose challenges to protein concentration using UF membranes due to calcium-induced fouling. This study examined the effect of pH and temperature on calcium precipitation, UF permeation efficiency and the removal of calcium through UF processing of acid whey across a pH range from 4.6 to 7.0 (15 °C) and a temperature range from 10 to 35 °C (pH 6.0). Calcium phosphate precipitation increased with increasing temperature and pH (from pH 5.6 onwards). This correlated with an increased retention of calcium in the UF retentate, indicating these parameters play a key role in determining the calcium content of the final product. While reducing pH can fully resolubilise calcium phosphate, reducing temperature only partially reverses calcium phosphate precipitation. From a manufacturing perspective, pH adjustment immediately prior to UF may be an effective tool for controlling calcium precipitation, process efficiency and product composition. [ABSTRACT FROM AUTHOR]

The effect of pH, adjusted using either hydrochloric acid (HCl), citric acid or sodium hydroxide, on calcium ion (Ca 2+ ) activity, and consequent changes in viscosity and heat coagulation time (HCT) of milk protein concentrate (MPC) was investigated. Reducing the pH of MPC dispersions resulted in a reduction in their viscosity, which subsequently increased during heat treatment. The maximum heat stability of MPC was observed at pH 6.7. Reducing the pH of MPC from 6.7 to 6.2 resulted in a significant ( P < 0.05) increase in Ca 2+ activity, and reduction in HCT. Such changes were more extensive using HCl compared with citric acid. Increasing the pH greater than 6.7 also led to a reduction in HCT but a decrease in Ca 2+ activity. These results demonstrate the importance of pH adjustment, and choice of acidulant, on Ca 2+ activity, viscosity, and heat coagulation properties of MPC concentrates during processing. [ABSTRACT FROM AUTHOR]

Thermal processing of ready-to-drink high protein beverages can have a substantial impact on the physical and sensory properties of the final product for long-life milks such as extended shelf life and ultra high temperature processed products. Direct and indirect heat treatment technologies were applied to whey protein isolate (WPI) -based beverages containing 4, 6 or 8% (w/w) protein. Lower levels of protein denaturation (66–94%) were observed using direct heating compared with indirect heating (95–99%) across protein levels and heating temperatures (121 and 135 °C final heat). Direct heat treatment resulted in significantly lower viscosity and less extensive changes to the volatile profile, compared with indirect heat treatment. Overall, the application of direct and indirect heat treatment to WPI solutions resulted in significantly different final products in terms of appearance, physical characteristics and volatile profile, with direct heating resulting in many enhanced properties compared with conventional indirect heat treatment. [ABSTRACT FROM AUTHOR]

The effects of heat treatment and protein standardisation on the physical properties of skim milk concentrates were determined. Protein standardisation was carried out by the addition of lactose or milk permeate to skim milk. Unstandardised and standardised skim milk was subjected to heat treatment temperatures of 90 or 120 °C prior to evaporation whereafter the solids content was increased to 46% (w/w). Viscosity data showed non-standardised concentrates had the highest viscosity, followed by skim standardised with milk permeate followed by that standardised with lactose. Thermal treatment at 120 °C also resulted in a higher viscosity than that at 90 °C for all concentrates. Particle size data of evaporated skim milk showed a bimodal size distribution for skim milk standardised with liquid milk permeate, compared with monomodal distribution profiles for unstandardised skim milk and lactose standardised skim milk. Overall, this study showed that protein standardisation and standardisation media significantly affected concentrate properties. [ABSTRACT FROM AUTHOR]

Microfiltration (MF) of skim milk, when combined with diafiltration (DF), facilitates the manufacture of liquid micellar casein concentrate (MCC), which can be spray-dried into high-protein (≥80% protein, dry-basis) powders. MCC powders rehydrate slowly, which is typically considered a defect by end-users. This study compared the impact of cold (<10 °C) or warm (50 °C) MF/DF on the rehydration characteristics of MCC powders (MCC cold and MCC warm , respectively). The wetting properties of the MCC powders, measured using optical tensiometry, were found to be equivalent. However, pronounced differences in dispersion characteristics were measured, and, after 90 min rehydration at 50 °C, liberated casein micelles accounted for only 7.5% of total particle volume in MCC warm compared with 48% in MCC cold . Due to its superior dispersion characteristics, MCC cold yielded 50–60% less sediment during analytical centrifugation experiments. Cold MF/DF may improve the solubility of MCC powders by accelerating the release of casein micelles from powder particles during rehydration. [ABSTRACT FROM AUTHOR]

Changes in the pH of skim milk and skim milk ultrafiltration permeate on heating from 25 to 140 °C were examined. Results showed that the decrease in pH with increase in temperature up to 140 °C was not linear. Hydrogen ion release due to changes in the milk mineral balance were responsible for the reduction in pH with increase in temperature. The presence of milk proteins offered little buffering against the drop in pH. The precipitation of calcium phosphate resulted in sediment in milk permeate heated above ∼70 °C, but this did not occur in skim milk, with the pH remaining lower in milk permeate after heat treatment when measured at 25 °C. This study has shown that in-line pH measurements of milk at ultra-high temperatures is feasible, and could prove useful at laboratory and pilot-scale for studying interactions within, and stability of, more complex formulations with added minerals. [ABSTRACT FROM AUTHOR]

Milk protein concentrate (MPC 80), skim milk powder, acid whey protein concentrate (aWPC 35), cheese whey protein concentrate and isolate (cWPC 35 and cWPI) were assessed for suitability in infant formula (IF) applications with total solids similar to commercial ready-to-drink applications. Serum-phase compounds including phosphate, citrate and chloride in casein-rich streams, especially aWPC 35, played an important role in controlling whey protein thermal aggregation. Replacing cWPC 35 with cWPI improved protein stability at UHT temperatures, indicating that removal of minerals from whey protein streams could increase thermal stability of formulations. At HTST temperatures (95 °C), lactose appeared to have a protective effect against protein denaturation. At 140 °C, however, lactose contributed to cascading Maillard reactions triggering complete protein destabilisation; this occurred most rapidly in MPC 80 formulations that were comparatively low in serum-phase calcium-binding species (phosphate and citrate). These findings highlight how innate minerals and lactose impact protein stability during IF manufacture. [ABSTRACT FROM AUTHOR]

Liquid milk protein concentrate (MPC; 18.3 and 16.5%, w/w, total solids and protein, respectively) was heat treated at 80 °C (low-heat), 100 °C (medium-heat) and 120 °C (high-heat) for 30 s, or did not undergo heat treatment (control), prior to spray drying. Viscosity of the liquid MPC increased with increasing heat treatment temperature. Physical properties of MPC powders were influenced by heat treatment, with the size of powder particles generally increasing with increasing temperature. Heat treatment of ultrafiltration concentrate influenced the heat stability of MPC powders, with high-heat treated MPC having highest heat stability at pH 6.9 and 7.0 (140 °C). However, particle size distribution profiles showed a decrease in powder dispersion with increased heat treatment temperature. This study demonstrated that heat treatment of ultrafiltration concentrate at temperatures ≥100 °C can present challenges with solubilising subsequent MPC powders. [ABSTRACT FROM AUTHOR]

The aim of this study was to produce a colloidally stable whey protein concentrate enriched in β-casein. Microfiltration (MF) of skim milk was completed at ∼7 °C (pore size 0.1 μm) followed by ultrafiltration of the MF permeate at ∼9 °C to concentrate the β-casein-whey protein fraction (BWPC). The casein:whey protein ratio of the BWPC system was ∼25:75. Skim milk was then added to ultrafiltration retentate at a level supplying 0, 0.1, 0.3 and 0.5% (w/w) of the total protein, followed by evaporation and spray drying. During evaporation of the BWPC stream without skim milk addition, there was significant precipitation of β-casein, resulting in an increase in particle size due to uncontrolled aggregation. Addition of low amounts of skim milk was effective at reducing the precipitation of β-casein during evaporation at 50 °C, indicating that the addition of micellar casein to the BWPC stream was able to prevent uncontrolled β-casein aggregation. [ABSTRACT FROM AUTHOR]