Proportion Of Casein Research Articles

Unravelling the Influence of Composition and Heat Treatment on Key Characteristics of Dairy Protein Powders Using a Multifactorial Approach.

The purpose of this study was to improve understanding of the structural and functional property changes that milk-protein concentrates undergo during production, particularly how the manufacturing route (heat treatment position and intensity), standardization (in osmosed water or ultrafiltrate permeate) and formulation (casein:whey protein (Cas:WP) ratio) influence the physico-chemical characteristics-hygroscopicity, particle size, sphericity, density and evolution of browning during storage. To obtain a comprehensive understanding of the parameters responsible for the distinctive characteristics of different powders, a multifactorial approach was adopted. Hygroscopicity depended mainly on the standardizing solution and to a lesser extent the Cas:WP ratio. The particle size of the heat-treated casein-dominant powders was up to 5 μm higher than for those that had had no heat treatment regardless of the standardizing solution, which also had no influence on the sphericity of the powder particles. The density of the powders increased up to 800 kg·m-3 with a reduced proportion of casein, and lactose and whey proteins participated in browning reactions during storage at 13 °C. In increasing order, the modality of heat treatment, the standardizing solution and the Cas:WP protein ratio influenced the key characteristics. This work is relevant for industrial applications to increase control over the functionalities of powdered products.

Interfacial composition in infant formulas powder modulate lipid digestion in simulated in-vitro infant gastrointestinal digestion

The interface structure and composition of fat globules are very important for the digestion and metabolism of fat and growth in infants. Interface composition of fat globules in infant formula (IF) supplemented with milk fat globule membranes (MFGM) and lecithin in different ways were analyzed and their effects on fat digestion properties were evaluated. The results showed that the distribution of phospholipids at the interface and structural of Concept IF1 and Concept IF2 that were more similar to those of human milk (HM) than that of conventionally processed IF3. Concept IF2 and IF3 supplemented with lecithin had larger initial particle size and more sphingomyelin (SM) (23.12 ± 0.26 %, 26.94 ± 0.34 %) than Concept IF1, and Concept IF2 had the smallest proportion of casein in the interfacial. Due to its interface composition, Concept IF2 had the highest degree of lipolysis (85.07 ± 0.76 %), the phospholipid ring structure can always be observed during gastric digestion, and a final fatty acid composition released that was more similar to HM. Concept IF1 and IF3 were different from HM and Concept IF2 in terms of structure and lipolysis rate, although superior to commercial IF4. These indicate that changes in the interfacial composition and structure of fat globules improve the digestive properties of fats in IF. Overall, the results reported herein are useful in designing new milk formulas that better simulate HM.

Effects of a Novel Infant Formula on the Fecal Microbiota in the First Six Months of Life: The INNOVA 2020 Study.

Exclusive breastfeeding is highly recommended for infants for at least the first six months of life. However, for some mothers, it may be difficult or even impossible to do so. This can lead to disturbances in the gut microbiota, which in turn may be related to a higher incidence of acute infectious diseases. Here, we aimed to evaluate whether a novel starting formula versus a standard formula provides a gut microbiota composition more similar to that of breastfed infants in the first 6 months of life. Two hundred and ten infants (70/group) were enrolled in the study and completed the intervention until 12 months of age. For the intervention period, infants were divided into three groups: Group 1 received formula 1 (INN) with a lower amount of protein, a proportion of casein to whey protein ratio of about 70/30 by increasing the content of α-lactalbumin, and with double the amount of docosahexaenoic acid/arachidonic acid than the standard formula; INN also contained a thermally inactivated postbiotic (Bifidobacterium animalis subsp. lactis). Group 2 received the standard formula (STD) and the third group was exclusively breastfed (BF) for exploratory analysis. During the study, visits were made at 21 days, 2, 4, and 6 months of age, with ±3 days for the visit at 21 days of age, ±1 week for the visit at 2 months, and ±2 weeks for the others. Here, we reveal how consuming the INN formula promotes a similar gut microbiota composition to those infants that were breastfed in terms of richness and diversity, genera, such as Bacteroides, Bifidobacterium, Clostridium, and Lactobacillus, and calprotectin and short-chain fatty acid levels at 21 days, 2 and 6 months. Furthermore, we observed that the major bacteria metabolic pathways were more alike between the INN formula and BF groups compared to the STD formula group. Therefore, we assume that consumption of the novel INN formula might improve gut microbiota composition, promoting a healthier intestinal microbiota more similar to that of an infant who receives exclusively human milk.

Structure and rheological properties of oil-water and air-water interfaces stabilized with micellar casein isolate and whey protein isolate mixtures

The mechanical properties of oil-water (O–W) and air-water (A-W) interfaces stabilized with mixtures of micellar casein isolate and whey protein isolate at different ratios were investigated by large-amplitude oscillatory dilatational rheology (LAOD). The composition of the layer of proteins adsorbed at the O–W interfaces was investigated by multiphoton excitation microscopy. The structure of A-W interfaces was visualized by atomic force microscopy. The results obtained for O–W interfaces showed that casein preferentially adsorbs and dominates the interface even when present in mixtures in a very low proportion. The LAOD results show that the interfacial layer formed by casein is weaker and more brittle compared with the one formed by whey proteins. In case of A-W interfaces, casein is more surface active and displays faster diffusion, and leads to a decrease of surface tension to lower values compared with whey protein. Casein will co-adsorb with whey protein at the A-W interface, and the dilatational response of the viscoelastic solid-like network normally formed by pure whey proteins at the interface is significantly affected by casein, particularly at large deformation amplitudes. The interfacial layer appears to become more brittle with an increasing proportion of caseins in the mixture.

Sedimentation in UHT high-protein dairy beverages: Influence of sequential preheating coupled with homogenisation or supplementation with carbohydrates

Consumer demand for UHT high-protein dairy beverages is growing all around the world. To overcome the potential low stability of these products during processing and storage remains a great challenge for dairy industries. In this context, the potential of preheating treatment coupled with homogenisation or the addition of sucrose or corn soluble fibre on reducing the sedimentation level of UHT dairy beverages containing 10% w/w of protein and equivalent proportion of caseins to whey proteins were evaluated. The samples supplemented with sucrose or corn soluble fibre displayed a reduced overall particle size distribution, but equivalent amount of sediment compared with that in the control sample. The applied pretreatment promoted intense whey protein denaturation and reduced the overall particle size distribution and the amount of material sedimented compared with the control sample. The applied pretreatment has potential to improve the stability of UHT high-protein dairy beverages.

Impact of the whey protein/casein ratio on the reconstitution and flow properties of spray-dried dairy protein powders

This study focuses on the impact of the whey protein/casein ratio (100/0, 79/21, 57/43, 35/65, and 12/88) on the physicochemical and functional characteristics of dairy protein powders. Spray-drying was performed in the following conditions: 200 °C inlet air temperature and 85 °C outlet air temperature. Physicochemical properties (particle size distribution, shape factors, moisture content, and water activity) of spray-dried powders were characterized to explain their reconstitutability, on the basis of the wettability, dispersibility, solubility indices, and their flowability, evaluated with the FT4 powder rheometer.Reconstitutability analyses revealed that solubility of dairy protein powders linearly varied with the whey protein/casein ratio. It was also highlighted that wettability and dispersibility determined with the standard methods were not relevant to evaluate the reconstitutability of investigated powders: in fact, all studied powders were non-wettable and non-dispersible according to the milk powder standards. This was likely to result from the low median particle size (between 10 and 30 μm) of powders produced by spray-drying at pilot-scale.The flowability of powders was evaluated as poor due to a high level of interparticular cohesion, which mainly derived from their small median particle size. The impact of protein composition on flowability was not statistically significant, despite a shape modification reflected by a decrease in particle sphericity upon casein proportion increase. The small particle size, leading to poor flow properties, overwhelmed the impact the whey protein/casein ratio, but a slight improvement of the flowability and a reduction of cohesion was induced by higher proportions of whey proteins.

Measurement of casein in milk by Kjeldahl and sodium dodecyl sulfate–polyacrylamide gel electrophoresis

Our objectives were to determine if milk casein as a percentage of true protein (CN%TP) estimated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) is equivalent to CN%TP estimated by Kjeldahl, and to determine the proportion of casein (CN), casein proteolysis products (CNPP), and serum protein (SP) from milk true protein (TP) that goes into the Kjeldahl noncasein nitrogen (NCN) filtrate and the proportion that stays in the NCN precipitate using SDS-PAGE. Raw milk samples were collected from 16 mid-lactation Holstein cows twice a week for 2 wk. These milks were analyzed for Kjeldahl total nitrogen, nonprotein nitrogen, and NCN content in duplicate, and by SDS-PAGE. The CN%TP determined by Kjeldahl was compared with the CN%TP estimated by SDS-PAGE calculated in 2 ways: as a percentage of only intact caseins divided by TP and as a percentage of both intact caseins and CNPP divided by TP. Three milks varying in fat, lactose, TP, CN, and SP content were formulated. These milks were analyzed in duplicate for Kjeldahl total nitrogen, nonprotein nitrogen, and NCN content, and each of the NCN filtrate and NCN precipitate were analyzed in duplicate by SDS-PAGE for relative quantity (%) of CN, CNPP, and SP. We found that the estimate of CN%TP by Kjeldahl was higher than the estimate of CN%TP by SDS-PAGE that was calculated as only intact CN divided by the total of all protein bands. However, no difference was detected in the estimate of CN%TP by Kjeldahl compared with CN%TP by SDS-PAGE when CNPP were included as CN in the calculation of SDS-PAGE results. Based on SDS-PAGE results, we found that a majority (89%) of the CNPP from the milk (approximately 10.13 out of 11.41% TP) were retained in the Kjeldahl NCN precipitate. Thus, CN%TP measured by Kjeldahl underestimates the amount of proteolytic damage that has been done to CN in milk. It is important for the dairy industry to correctly and rapidly measure the extent of proteolytic damage to milk protein to correctly value milk from a product quality and yield point of view. A rapid and quantitative measure of proteolytic damage to milk protein is needed.

Use of a sorption-probiotic feed additive in the diet of cows

Sorption and probiotic feed additive composition was formulated following international experience and trends in organic livestock breeding, and its efficiency under conditions of organic milk production was evaluated. This research focused on the dynamics of organic milk quality and safety parameters in the context of a sorption and probiotic feed additive created by the authors. The study focused on sorption and the probiotic feed additive, as well as the milk of the cows participating in the experiment. During the study period, the mass fraction of fat in the milk of experimental animals increased by 0.1 abs.%, the mass fraction of protein by 0.21 abs.%, and the mass fraction of lactose also by 0.1 abs.% compared to the control values. The mean fat globule size in the experimental group was 3.5% higher, and their number was 7.8% higher than the control counts. In the experimental group, the proportion of casein increased by 10.5%. The rennet casein class increased to 1.7 ± 0.02 and heat resistance to 1.5 ± 0.02. Milk density was 1027.6 ± 0.30 kg/m3 and acidity was 16.9 ± 0.23 °Т.

Season of the year, the feeding and productive environment

Se realizó un estudio con el objetivo de estudiar el patrón de variación de caseína en leche a lo largo del año, y la estrategia de alimentación del rodeo lechero como principal fuente de variación. Se tomaron muestras mensuales en tambos remitentes a las empresas PILI SA y CLALDY SA (15 tambos por empresa) durante el período abril 2012 - marzo 2013. Se utilizó un modelo mixto y un método de partición recursiva de varianza. El contenido de proteína en leche fue mayor en otoño y el contenido de caseína en leche fue mayor en otoño e invierno, probablemente explicado por el mayor uso de suplementos concentrados que aportan energía con una mejor sincronización con el aporte de proteína por parte de las pasturas. Fue posible mantener niveles altos de contenido de caseína y relación caseína/proteína verdadera en leche en primavera, con dietas casi exclusivamente pastoriles. En general, la proporción de caseína en relación a la proteína total y la relación caseína/proteína verdadera en leche no alcanzó valores que reporta la bibliografía con dietas más concentradas.

The effect of protein profile and preheating on denaturation of whey proteins and development of viscosity in milk protein beverages during heat treatment

The effect of preheat temperature (63 or 77 °C for 30 s; final heat 120 °C for 30 s) and casein to whey protein ratio on the physical characteristics of 3.3%, w/w, dairy protein beverages was investigated. Dispersions preheated at 77 °C had lower viscosity than dispersions preheated at 63 °C. Casein‐containing dispersions had significantly lower levels of α‐lactalbumin denaturation than whey protein‐only dispersions. A higher proportion of casein improved the thermal stability of protein dispersions. Overall, alteration of preheat temperature and casein to whey protein ratio can influence dairy beverage quality, with increasing levels of casein reducing physical changes due to heat treatment.

Chemical fractionation of caseins by differential precipitation: influence of pH, calcium addition, protein concentration and temperature on the depletion in α‐ and β‐caseins

SummaryThe impact of pH, calcium and casein concentrations, and temperature on the efficiency of the differential precipitation of caseins by calcium affinity was investigated, using native phosphocaseinate as starting material. We adapted one of the most recent methods for the separation of caseins that is based on the addition of calcium at alkaline pH. Increasing the pH to 11 disturbed the micellar structure by enhancing electrostatic repulsion of caseins, leading to a marked viscosity increase and a significant particle size decrease, indicating casein micelle disruption. This pH‐driven increase in negative charges enhanced the affinity of individual caseins for calcium, proportionally to the number of phosphate groups carried by each casein. The addition of calcium first led to a progressive increase in the proportion of precipitated caseins, before reaching a plateau. Hence, an optimal calcium/casein molar ratio of about 40 was evidenced to optimise casein precipitation (and fractionation), leading to significant depletion of α‐casein (around 80%) and, in a lesser extent, β‐casein (around 65%) and κ‐casein (around 55%). This method led to relative proportions of caseins significantly differing from the starting material: 31% α‐casein, 45% β‐casein and 24% κ‐casein.

Interactive effects of casein micelle size and calcium and citrate content on rennet-induced coagulation in bovine milk.

Interactive effects of casein micelle size and milk calcium and citrate content on rennet-induced coagulation were investigated. Milk samples containing small (SM) and large (LM) micelles, obtained from individual Holstein cows, were modified by addition of calcium and/or citrate and milk coagulation properties were evaluated in a full factorial design. The results showed that LM milk had a higher relative proportion of casein, coagulated faster, and resulted in a stronger gel than SM milk. Addition of calcium slightly decreased casein micelle size, while addition of citrate slightly increased micelle size. Calcium addition resulted in a shorter coagulation time and the strongest gels, while citrate addition increased the coagulation time and resulted in the weakest gels. Addition of calcium and citrate in combination resulted in intermediate coagulation properties. The interactive effect of micelle size and citrate was significant for gel strength. Microstructural differences between the milk gels were consistent with the rheological properties, for example, the micrographs revealed that a more homogeneous network was formed when calcium was added, resulting in a stronger gel. A more inhomogeneous network structure was formed when citrate was added, resulting in a weaker gel. Thus, variations in casein micelle size and in calcium and citrate content influence rennet-induced coagulation in bovine milk. The calcium and citrate contents in Swedish milk have changed over time, whereby calcium content has increased and citrate content has decreased. In practical cheese making, calcium is added to cheese milk, most likely altering the role of inherent citrate and possibly influencing casein micelle size. The observed interaction effect between casein micelle size and citrate in this study, suggests that larger micelles with moderate citrate level will result in firmer gels, whereas a higher citrate content reduced gel strength more in case of large than SM. Since firmer gels are likely to retain more protein and fat than less firmer gels, this interaction effect could have implications in practical cheese production.

The effect of selected components of milk and ripening time on the development of the hardness and melting properties of cheese.

The growing interest in ripening cheeses in Poland has increased milk production, which enhances the need to improve its quality. One method is to increase the fat and casein content of milk.       In effect, the proportions of these ingredients affect production efficiency and quality of cheese. Most milk components, and the maturity of the cheese, are associated with two qualities which are very important for consumers, hardness and fusibility. Therefore, the complex proteolysis and lipolysis processes occurring in ripening cheeses are an important evaluation component. For this reason, there is a constant need to deepen the knowledge of the relationships between the components of bulk milk and those retained in curds, and the processes that shape the quality of ripening cheese, which is important for consumers. The aim of the study was to analyze the transformations of proteins and fat which occur during the ripening of Gouda cheese. Research hypotheses assumed that higher proportions of fat in milk and curd were associated with melting properties and that the casein content in milk and protein content in curds affected the brittleness and greater nitrogen recovery in cheese. The research materials consisted of 15 cheese batches, produced from October to December. Cheese samples were collected at several ripening stages (RS): day 1th, 14th, 30th and 60th. Bulk milk was subjected to standard procedures applied during Gouda cheese production. Fat was extracted from the cheese, the content of which was estimated on the basis of fat values. The intensity of proteolysis was de- termined by the content of soluble nitrogen and nitrogen recovery. The data was statistically compiled using the ANOVA mixed model. The influence of the ripening stage, differences between means and the correlation coefficient values were estimated at P ≤ 0.05. The results confirmed that ripening stage has a strong influence on the increase in dry matter con- tent and nitrogen solubility and the decrease in fat content in cheese. Assessment of proteolytic changes (the proportion of soluble nitrogen, NS) indicates an increased dynamic of changes from day 30th of ripening. This index was correlated with casein and dry matter content. However, the amount of nitrogen recovered in cheese (NR) was most strongly correlated with protein content in the product and casein content in bulk milk. The ripening time was related to the melting properties and hardness of the cheese, as evidenced by the values of the correlation coefficient (0.394 and 0.489). Both characteristics were also related to the fat content in milk and in cheese (–0.286 to –0.427). Moreover, hardness was correlated with the proportion of protein, dry matter and casein in milk (0.326–0.762). The influence of RS on the increase in the acid and saponification values of fat contained in the cheese was usually observed from the 30th day of ripening (0.512 and 0.535). These changes were accompanied by a decrease in fat content (r = –0.247 and –0.364). The recorded range of changes do not affect the nutritional values of cheese, as free fatty acid content increased only slightly with ripening time. The observed tendencies towards slower proteolysis and lipolysis reactions can be partly explained by the increasing content of dry matter (lower water availability). It was shown that the proportion of fat in milk and cheese and its protein content significantly affected the hardness and melting properties of cheese. Importantly, the proportion of casein in milk was positively as- sociated with nitrogen recovery in the ripening product. It can be assumed that the activities increasing the proportion of casein in milk are an important method of improving the technological suitability and sensory quality of cheese.

Milk protein composition in purebred Holsteins and in first/second-generation crossbred cows from Swedish Red, Montbeliarde and Brown Swiss bulls

The aim of this study was to analyze milk protein composition in purebred and crossbred dairy cattle and estimate the effects of individual sources of variation on the investigated traits. Milk samples were collected from 505 cows from three commercial farms located in Northern Italy, some of which had originated from crossbreeding programs, although most were purebred Holsteins (HO). The basic crossbreeding scheme was a three-breed rotational system using Swedish Red (SR) semen on HO cows (SR×HO), Montbeliarde (MO) semen on SR×HO cows (MO×(SR×HO)) and HO semen again on MO×(SR×HO) cows. A smaller number of purebred HO from each of the herds were mated inverting the breed order (MO×HO and SR×(MO×HO)) or using Brown Swiss (BS) bulls (BS×HO) then MO bulls (MO×(BS×HO)). Milk samples were analyzed by reverse-phase HPLC to obtain protein fraction amounts (g/l) and proportions (% of total true protein). Traits were analyzed using a linear model, which included the fixed effects of herd-test-day (HTD), parity, days in milk and breed combination. Results showed that milk protein fractions were influenced by HTD, stage of lactation, parity and breed combination. The increase in protein concentration during lactation was due in particular to β-casein (β-CN), αS1-CN and β-lactoglobulin (β-LG). The higher protein content of primiparous milk was mainly due to higher concentrations of all casein fractions. The milk from crossbred cows had higher contents and proportions of κ-CN and α-lactalbumin (α-LA), lower proportions of β-LG and greater proportion of caseins/smaller in whey proteins on milk true protein than purebred HO. The three-way crossbreds differed from two-way crossbreds only in having greater proportions of α-LA in their milk. Of the three-way crossbreds, the SR sired cows yielded milk with a smaller content and proportion of β-LG than the MO sired cows, and, consequently, a higher proportion of caseins than whey proteins. Results from this study support the feasibility of using crossbreeding programs to alter milk protein profiles with the aim of improving milk quality and cheese-making properties.

Isolation and characterisation of κ-casein/whey protein particles from heated milk protein concentrate and role of κ-casein in whey protein aggregation

Milk protein concentrate (79% protein) reconstituted at 13.5% (w/v) protein was heated (90 °C, 25 min, pH 7.2) with or without added calcium chloride. After fractionation of the casein and whey protein aggregates by fast protein liquid chromatography, the heat stability (90 °C, up to 1 h) of the fractions (0.25%, w/v, protein) was assessed. The heat-induced aggregates were composed of whey protein and casein, in whey protein:casein ratios ranging from 1:0.5 to 1:9. The heat stability was positively correlated with the casein concentration in the samples. The samples containing the highest proportion of caseins were the most heat-stable, and close to 100% (w/w) of the aggregates were recovered post-heat treatment in the supernatant of such samples (centrifugation for 30 min at 10,000 × g). κ-Casein appeared to act as a chaperone controlling the aggregation of whey proteins, and this effect was stronger in the presence of αS- and β-casein.

How much of a near infrared spectrum is useful? Sparse regularization---let the data decide!

In information recovery from indirect measurements of the phenomenon of interest (e.g. near infrared spectra of milk powders or pharmaceuticals, or Raman spectra of explosives or anaesthetics) the available data can be partitioned into two separate components: (i) the information which encapsulates the answer to the question under examination (the proportion of casein, the major protein component, in milk powder; the presence or absence of explosives; the monitoring of anaesthetic and respiratory levels during surgery) and (ii) a considerable amount of superfluous information, the presence of which compromises the reliability of the answer to the question of interest. In such spectroscopic situations, for the identification of the information that encapsulates the answer, a variety of techniques are used such as partial least squares, neural networks and support vector machines. With respect to the available calibration data, the support vector machines procedure performs an implicit form of sparse regularization. In this article, the aim is to show how, using the Beer--Lambert law and derivative spectroscopy, the sparse regularization is performed in an explicit manner. This information can be subsequently utilized to construct, using statistical regression, an appropriate predictor. Here, the goal is to give a proof-of-concept for the application of derivative spectroscopy as an explicit sparse regularization protocol. For this, the calibration data consists of near infrared spectra of milk powder spiked with known amounts of casein, while the property of interest is the proportion of casein in the milk powder. References R. S. Anderssen, F. R. de Hoog, and I. J. Wesley. Information recovery from near infrared data. In W. McLean and A. J. Roberts, editors, Proceedings of the 15th Biennial Computational Techniques and Applications Conference, CTAC-2010, volume 52 of ANZIAM J., pages C333–C348, July 2011. http://journal.austms.org.au/ojs/index.php/ANZIAMJ/article/view/3909. R. S. Anderssen and M. Hegland. Derivative Spectroscopy – An enhanced role for numerical differentiation. J. Integral Equat. Appl., 22(3):355–367, 2010. doi:10.1216/JIE-2010-22-3-355. R. S. Anderssen, M. Hegland, and I. J. Wesley. Resolution enhancement for infrared spectroscopic data. In MODSIM2011, 19th International Congress of Modelling and Simulation, pages 371–377. Modelling and Simulation Society of Australian and New Zealand, 2011. http://www.mssanz.org.au/modsim2011/A4/anderssen3.pdf. R. S. Anderssen, B. G. Osborne, and I. J. Wesley. The application of localisation to near infrared calibration and prediction through partial least squares regression. JNIRS, 11(1):39–48, 2003. doi:10.1255/jnirs.352. T. Naes, T. Isaksson, T. Fearn, and T. Davies. A User-Friendly Guide to Multivariate Calibration and Classification. NIR Publications, Chichester, UK, 2002. http://eprints.ucl.ac.uk/151973/. B. G. Osborne. Near-infrared spectroscopy in food analysis. In Encyclopedia of Analytic Chemistry, pages 1–14. J. Wiley and Sons, Chichester, UK, 2006. doi:10.1002/9780470027318.a1018. B. G. Osborne, T. Fearn, and P. H. Hindle. Practical NIR Spectroscopy with Applications in Food and Beverage Analysis. Longman Scientific and Technical, Harlow, UK, 1993. McGraw-Hill Series in Higher Mathematics. I. J. Wesley, B. G. Osborne, R. S. Anderssen, S. R. Delwiche, and R. A. Graybosch. Chemometric localization approach to NIR measurement of apparent amylose content of ground wheat. Cereal Chem., 80(4):462–467, 2003. doi:10.1094/CCHEM.2003.80.4.462.

Study on Milk Protein Hydrolysis of Infant Formula

First of all, whey protein concentrat was added to milk adjusting the proportion of casein and whey proteins to 40:60. And then milk was hydrolyzed by trypsin and flavourzyme (TF) single respectively in one-step process or staged in two-step process. The Antigen contents of α-lactalbumin (α-LA) and β-lactoglobulin (β-LG) during the hydrolysis process were determined by indirect competitive enzyme-linked immunosorbent assay (ELISA) methods. The result showed that the most significant antigen reduction was observed in two-step hydrolysis process compared with one-step hydrolysis process

Proteomic Characterization of Specific Minor Proteins in the Human Milk Casein Fraction

Human milk contains many bioactive proteins that are likely to support the early development of the newborn. The aim of this study was to identify whether there are specific minor proteins associated with the human milk casein micelle prepared by the acid precipitation method. Protein identification was performed by liquid chromatography tandem mass spectrometry analysis. Eighty-two proteins were identified in the casein micelle, 18 of which are not present in their whey compartment. Thirty-two of these proteins specifically associated with the casein micelle have not previously been identified in human milk or colostrum. Proteins involved in immune function comprised the major part (28%) of total proteins, and another significant part is involved in metabolism/energy production (22%). Most of the proteins were of extracellular or cytoplasmic origin (accounting for 50 and 29%, respectively). This study indicates that various soluble proteins should be considered as part of the casein compartment, prepared by the acid precipitation method. The data provide new insight not only into the proteomic profile of the human milk casein micelle and its physiological significance, but also into the proper proportion of casein and casein-associated proteins to use in infant formula.

Mapping a quantitative trait locus for the concentration of β-lactoglobulin in milk, and the effect of β-lactoglobulin genetic variants on the composition of milk from Holstein-Friesian x Jersey crossbred cows

AIM: To identify quantitative trait loci (QTL) affecting the concentration of β-lactoglobulin in milk, and to evaluate the effect of β-lactoglobulin genetic variants on the concentration of fat, protein and casein in bovine milk. METHODS: A herd of 850 F2 Holstein-Friesian x Jersey crossbred cows was produced through mating six Holstein-Friesian x Jersey F1 bulls of high genetic merit with F1 cows from the national herd. A total of 1,610 herd-test records from 556 second-parity crossbreds were analysed. The concentration of fat, protein and casein in milk was measured at peak, mid- and late lactation, during the production seasons of 2003–2004 and 2004–2005. Liveweight was measured daily. DNA from the F2 animals, their F1 dams and sires, and selected grandsires was genotyped across the genome, initially with 285 microsatellite markers, and subsequently with 6,634 single nucleotide polymorphisms (SNP). RESULTS: A highly significant QTL for the concentration of β-lactoglobulin in milk was identified, which coincided with the position of the β-lactoglobulin gene on bovine Chromosome 11. No other consistently significant QTL for the concentration of β-lactoglobulin in milk were detected. Cows with the BB β-lactoglobulin genotype produced milk with a 30% lower concentration of β-lactoglobulin than cows with the AA genotype. The β-lactoglobulin polymorphism also explained variation in the proportion of casein in total protein. In addition, the percentage of fat was higher for BB than AA animals, whereas the percentage of total protein, mean daily milk yield and liveweight did not differ between AA and BB animals. CONCLUSIONS: A significant QTL determining the concentration of β-lactoglobulin in milk was identified. Selection of animals for the β-lactoglobulin B-allele may enable the production of milk naturally enriched for casein, thus allowing a potential increase in the yield of cheese. There may be additional future value in production of bovine milk more like human milk, where decreasing the concentration of β-lactoglobulin is desirable.

A study on composites from phenol‐formaldehyde‐casein resin

AbstractA modified phenol‐formaldehyde (PF) resin was synthesized under alkaline condition in varying proportion of casein up to 20% (w/w) of phenol. All the prepared resins were characterized by free phenol content, free formaldehyde content, viscosity measurements, number average molecular weight determination by conductometry and Infrared Spectroscopy (IR). Their curing kinetics was studied isothermally and by differential scanning calorimetry (DSC) on dynamic runs. The resin samples were cured using concentrated hydrochloric acid and hexamine individually. Cured resins were characterized by IR and Thermogravimetry (TGA). Glass fabric reinforced composites (GFRC) were fabricated by maintaining 40 : 60 proportion of resin to reinforcement material. The laminates thus formed were characterized for their mechanical properties and chemical resistance. Enhancements in thermal stability of the resin as well as toughness of composite with increase in casein content were observed for the resins studied. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010