Littérature scientifique sur le sujet « Casein/whey protein ratio »

The objective of this work was to examine whether variation in the amino acid supply to cows could be a reason for the reduced casein content and poorer renneting properties of milk that often occur in late summer, or whether these effects are related to proteolysis in the raw milk. In a 2×2×2 factorial design, we investigated the effects of sward (clover v. rye-grass) and supplementary feed with a high or low level of rumen-soluble N or of rumen undegradable protein on milk protein composition during the grazing season. A total of 32 Danish Holstein cows were included in the experiment. Milk protein and casein contents and the ratios casein N[ratio ]total N and casein[ratio ]true protein were at a minimum in late summer, whereas the contents of urea, non-protein N and whey protein were higher during this period. These seasonal effects were unrelated to either the type of supplementary feed or the type of sward; neither were they clearly related to proteolysis, although casein[ratio ]true protein was related to the proteose peptone content. The results indicated that whey proteins other than α-lactalbumin or β-lactoglobulin accounted for the higher proportion or concentration of whey protein in late summer. Based on a principal component analysis including variables such as citric acid, lactose and non-protein N, we suggest that the cows' energy supply during this period may be a critical factor in determining the milk protein composition, although our results were not conclusive. There was an interaction between the supplement of rumen undegradable protein and type of sward. When clover was grazed, a high supplement increased the concentrations of protein and casein in milk and the κ-casein[ratio ]total casein ratio. When rye-grass was grazed, the opposite response was found, and overall milk protein yield was not affected. The very low N content of clover in early summer reduced milk protein and casein protein during this period.

Impact of milk protein composition on casein (CN) retention in curd during the milk coagulation process was studied using a model cheese making system. Individual milk samples from 110 cows in mid lactation of the Swedish Red and Swedish Holstein breeds with known genotypes of β-casein, κ-casein and β-lactoglobulin were defatted, coagulated with chymosin, subjected to syneresis and subsequent pressing simulated by centrifugation. The results indicated that κ-casein concentration of milk plays an important role in the curd formation process and initial syneresis (whey after cutting), whereas an increased CN ratio was associated with less casein in whey after simulated pressing. Increased κ-casein concentration of milk also characterized the milk samples with no measurable loss of casein in whey, compared with milk samples with casein lost in whey, both after cutting and after simulated pressing. Concentrations of αs1-casein, β-casein, and total casein in milk were positively associated with fresh curd yield, which showed a strong correlation with amount of casein retained in curd. No effect of protein genotype on fresh curd yield or casein in whey was found. The β-lactoglobulin BB genotype was associated with increased casein retention in curd, most likely due to the association of this genotype with CN ratio.

Whey protein concentrate was hydrolyzed using the technical food-grade enzyme Corolase 7092 in order to abolish the allergenicity of whey proteins. The immunological properties of the hydrolysates were tested in vitro with a human-immunoglobulin E (human-IgE) enzyme-linked immunosorbent assay (ELISA) using sera obtained from children allergic to milk proteins and in vivo with a mouse-rat heterologous passive cutaneous anaphylactic test and an anaphylactic shock test in mice. The protein efficiency ratio, determined in young growing rats, was compared to that of casein. Ultrafiltration of the hydrolysates appeared to be necessary to obtain a hypo-allergenic product. The minimal molecular mass to elicit immunogenicity and allergenicity of whey protein hydrolysates appeared to be between 3,000 and 5,000 Da, so the molecular weight cut-off value of the filters required must be in this range. Although there was no evidence that extensively hydrolyzed whey protein is nutritionally inferior to casein, the slightly bitter taste might reduce food intake.

P4, a specific combination of dairy proteins (whey and casein) and plant-based protein isolates (pea and soy), has been shown to provide a more balanced amino acid (AA) profile than its single constituent proteins; however, less is known about how this translates to muscle protein synthesis (MPS). The aim of this study was to investigate the effect of P4 compared to whey or casein against fasted control on MPS. C57BL/6J mice, aged 25 months, were fasted overnight, followed by oral gavage of either whey, P4, casein, or water as a fasted control. Thirty minutes after ingestion, puromycin (0.04 µmol∙g−1 bodyweight) was subcutaneously injected; 30-min thereafter, mice were sacrificed. MPS was measured by the SUnSET method, and signalling proteins were determined in the left-tibialis anterior (TA) muscle by the WES technique. AA composition was determined in plasma and right-TA muscle. Dried blood spots (DBS) were analysed for postprandial AA dynamics at 10, 20, 45, 60 min. MPS was 1.6-fold increased with whey (p = 0.006) and 1.5-fold with P4 compared to fasted (p = 0.008), while no change was seen with casein. This was confirmed by a significant increase of phosphorylated/total ratio of 4E-BP1 for both whey (p = 0.012) and P4 (p = 0.001). No changes were observed in p70S6K and mTOR phosphorylation/total ratio with whey or P4. Intramuscular leucine levels were lower for P4 (0.71 µmol∙g dry weight−1) compared to whey (0.97 µmol∙g dry weight−1) (p = 0.0007). Ten minutes postprandial, DBS showed significantly increased blood AA levels of BCAAs, histidine, lysine, threonine, arginine, and tyrosine for P4 versus fasted. In conclusion, a hybrid mix of dairy and plant-based proteins (P4) resulted in a MPS response that was similar to whey protein in aged mice after fasting. This suggests that other anabolic triggers beyond leucine or the well-balanced amino acid profile and bioavailability of the blend benefit stimulation of MPS.

The heat-induced changes in pH, Ca activity and viscosity after heating at 90 °C for 10 min of five modified skim milks were studied as a function of the initial pH of the milks at 25 °C. The milks had (i) different ratios of casein : whey protein (0·03, 1·74, 3·97, 5·27 and 7·25), (ii) the same total solids concentration (9% w/w) and (iii) prior to the adjustment of the pH, similar values of pH (6·67–6·74), concentration of serum calcium, and calcium activity, suggesting that the sera have similar mineral composition. The total protein concentrations of the milks differ (2·8–4·0%, w/w). The pH decrease in situ upon heating from 25–90 °C was similar for all the modified skim milks with the same starting pH, suggesting that the pH changes to milk on heating were primarily mediated by the initial mineral composition of the serum and were unaffected by the casein : whey protein ratio or the total protein content of the milk. The heat-induced changes in pH and calcium activity were largely reversible on cooling. The two milks with the lowest ratios of casein to whey protein gelled on heating to 90 °C for 10 min and cooling to 25 °C when the pH was adjusted to pH = 6·2 prior to heating. The viscosities of all other milks with casein to whey protein ratio of 3·97, 5·27 and 7·25 and/or pH ≥6·7 prior to heating did not change significantly. The effect of casein : whey protein ratio and the pH are the dominant factors in controlling the susceptibility to thickening of the milks on heating in this study.

During skim milk microfiltration (nominal pore size of 0.1 µm) at 10 °C, the whey protein purity in the permeate is reduced by an enhanced serum casein permeation, primarily of β-casein. To decrease casein permeation, the possibility of a pre-heating step under pasteurization conditions before the filtration step was investigated, so as to shift the equilibrium from soluble serum casein monomers to impermeable micellar casein. Immediately after the pre-heating step, low temperature microfiltration at 10 °C was conducted before the casein monomers could diffuse into the serum. The hypothesis was that the dissociation of β-casein into the serum as a result of a decreasing temperature takes more time than the duration of the microfiltration process. It was found that pre-heating reduced the β-casein permeation during microfiltration without significantly affecting the flux and whey protein permeation, compared with a microfiltration at 10 °C without the pre-heating step. Furthermore, the addition of calcium (5 and 10 mM) not only reduced the casein permeation and thus increased the permeate purity, defined as a high whey protein-to-casein (g L−1/g L−1) ratio, but also decreased the filtration performance, possibly due to the structural alteration of the deposited casein micelle layer, rendering the deposit more compact and more retentive. Therefore, the possible combination of the addition of calcium and pre-heating prior to microfiltration was also investigated in order to evidence the potential increase of whey protein (WP) purity in the permeate in the case of Ca2+ addition prior to microfiltration. This study shows that pre-heating very close to low temperature microfiltration results in an increased purity of the whey protein fraction obtained in the permeate.

Master of Science
Department of Food Science
Karen A. Schmidt
People who suffer from swallowing disorders are diagnosed with dyphasgia. The beverage for the dyphagia patients should have the apparent viscosity in the range of nectar-like (51 to 350 mPa•s) or honey-like (351 to 1750 mPa•s). Due to the swallowing problems, dysphagia patients usually consume beverages slowly. Thus, the apparent viscosity of beverage for such patients should be high enough to be in the suitable range during the entire time of consumption. Three ratios of α-lactalbumin (α-la)/β-lactoglobulin (β-lg) (3:8, 1:1 and 8:3) were used to prepare the milk systems. These ratio adjusted milk systems were either processed at 70, 80, and 90ºC for 30 min or at 25ºC, and cooled to 25 ± 1ºC. After the process was completed, the milk systems were set quiescently 120 min at 25 ±1ºC. Physical and chemical properties were assessed at various time. For the milk systems at 0 min, the apparent viscosity increased in all 90°C processed-samples, and the increase was in the order of 8:3 (15.96%), 1:1 (6.38%) and 3:8 (2.11%) compared with the 25ºC samples at each ratio. When the milk systems set for 120 min, apparent viscosity increased slightly by 3.7%. The maximum apparent viscosity was 2.18 mPa•s, which was less than nectar-like. Therefore, xanthan gum was added at 0.15 w/w % to enhance rheological properties of the milk systems. α-La/β-lg ratio adjusted milk systems either with or without xanthan gum were prepared, and processed at 90ºC or 25ºC, and cooled to 25 ± 1ºC. Apparent viscosity increased by 48.61 and 89.61% in 3:8 and 8:3 milk systems, respectively for those at 0.15% xanthan gum concentration and processed at 90ºC compared with at 25ºC. Apparent viscosity of 8:3 milk systems at xanthan gum concentration of 0.15% processed at 90°C was 58.7 ± 2.12 mPa•s which was within the nectar-like range. When the samples were set for 120 min, no changes were found in the apparent viscosity of the milk systems. If the rheological properties of the milk systems can be controlled by ingredients interactions, this can be used to develop nutritious products with different forms for dysphagia patients.

Ce projet de thèse CIFRE a eu pour objectif de mieux cerner les évolutions de structure et de propriétés fonctionnelles subies par les concentrés protéiques laitiers au cours de leur élaboration, en lien avec les paramètres de procédés appliqués. L’influence du schéma technologique de fabrication, de la base de mélange (eau vs perméat d’ultrafiltration de lait) et de la formulation (différents ratios Caséines/Protéines solubles) sur les caractéristiques physico-chimiques, la susceptibilité enzymatique, les propriétés physiques des poudres et les propriétés de réhydratation qui en découlent ont notamment été évalués. Ce travail a montré que l’étude des milieux concentrés bousculait les connaissances conventionnelles sur les mécanismes de dénaturation/agrégation thermique des protéines obtenues dans le lait. En milieu plus concentré, le chauffage induit une augmentation du taux de dénaturation/agrégation des protéines solubles (Ps) ainsi que la formation privilégiée de complexes caséines ¿ / Ps à la surface des micelles. Ces deux phénomènes modifient significativement les propriétés de coagulation enzymatique des produits obtenus en perturbant notamment la réorganisation des « clusters » de para-micelles de caséines. Ce travail a également permis d’établir un lien clair entre le taux de dénaturation/agrégation des Ps et l’augmentation de la viscosité des concentrés en fonction du ratio cas/Ps. Finalement, cette étude a mis en évidence que les propriétés physiques des poudres étaient plus impactées par leur formulation que par le schéma technologique mis en œuvre
The objective of this PhD project (CIFRE) aimed to assess and understand the changes in structure and functional properties undergone by milk protein concentrates during their production, in relation to the process parameters applied. We investigated the influence of the technological process schemes, the standardization in osmosed water or ultrafiltration permeate and the formulation (different casein/whey protein ratios) on the physicochemical characteristics, the enzymatic susceptibility, the physical properties of the powders and the resulting rehydration properties. This work showed that the study of concentrated solutions overturned conventional knowledge on the mechanisms of thermal denaturation/aggregation of proteins obtained in milk.In more concentrated solutions, heat treatment induces an increase in the level of denaturation/aggregation of whey proteins (WP) as well as the privileged formation of ¿ casein/WP complexes on the surface of micelles. These two phenomena significantly modify the enzymatic coagulation properties of the rehydrated powders by disturbing the reorganization of the casein paramicelles clusters. This work also established a clear link between the level of denaturation/aggregation of WP and the increase in the viscosity of the concentrates as a function of the casein/WP ratio. Finally, this study showed that the physical properties of the powders were more affected by their formulation than by the technological scheme used

Dans le lait on peut distinguer les protéines sériques et les caséines. Les protéines sériques sont des protéines globulaires qui se trouvent dans le sérum du lait et elles sont connues pour leurs propriétés fonctionnelles exceptionnelles. Quand une solution de protéines sériques est chauffée, elles perdent leur structure native et peuvent s'agréger. Elles forment des agrégats de différentes formes, tailles et densités : des cylindres, des agrégats fractals, des microgels et des agrégats fibrillaires. De l'autre côté, les caséines sont organisées dans des micelles de caséine d'un rayon environ 100-200 nm stabilisées par du phosphate de calcium colloïdal.Au cours de ce travail, nous avons cherché à comprendre comment les agrégats de protéines sériques pouvaient être utilisés en mélange avec les micelles de caséine pour obtenir et contrôler la texture de produits laitiers. Dans un premier temps, nous avons étudié le processus de « cold gelation » induit par ajout de calcium et/ou acidification d'agrégats et de microgels de protéines sériques seuls. Dans une deuxième partie, nous nous sommes intéressés à la fonctionnalité des agrégats dans les mélanges plus complexes avec les autres protéines laitières et en présence de minéraux. L'addition de petites quantités d'agrégats fractals dans des suspensions de micelles diminuait leur température critique de gélification, augmentait le module élastique et diminuait la synérèse des gels.Les agrégats de protéines sériques peuvent être utilisés pour modifier la viscosité des mélanges, comme gélifiant ou pour enrichir la teneur en protéine du milieu sans en augmenter la viscosité
The proteins of milk can be divided into whey proteins and caseins. Whey proteins are compact globular proteins that are found in the aqueous phase of milk. They are well-known for their exceptional functional properties. Upon heating, individual whey proteins denature and aggregate, forming aggregates of different morphologies and sizes, such as strands, fractal aggregates, microgels and fibrillar aggregates, depending on the heating conditions. On the other hand, the caseins in milk are organized in complex protein units with a diameter of 100-200 nm called casein micelles stabilized by colloidal calcium phosphate (CCP).The current work is an endeavor to understand how whey protein aggregates might be used in mixtures with other dairy proteins, such as casein micelles, in order to get a particular texture in a dairy product. We first extended the understanding of so-called “cold gelation” of pure WPI aggregates induced by calcium and acidification and then studied how the aggregates work in more complex mixtures of proteins and minerals. Interestingly, addition of small amounts of fractal aggregates to suspensions of casein micelles has been demonstrated to decrease the critical gelation temperature, increase the elastic modulus and decrease the syneresis of the gels.The aggregates are to be used to modify the viscosity of dairy products, as a gelling agent and for protein enrichment. The properties of strands, fractal aggregates and microgels have been studied and compared. WPI aggregates might be considered as “clean label” texturizing ingredients that do not require approval from the European Food Safety Authority (EFSA)

This study compared the effects of whey and casein on plasma AA, nitrogen balance (NBAL), glutathione and performance in dieting athletes. Twenty cyclists consumed 40 g·d-1 whey (WHEY) or casein (CAS) for 3 wk. On d 18 – 21 subjects restricted intake to 20 kcal·kg-1·d-1 plus protein supplement. Apparent NBAL was estimated on d 18 – 21 while postabsorptive and 2 h postprandial plasma AA were measured on d 14 and 21. On d 1, 15 and 22 subjects performed an exercise performance test and provided blood for glutathione analysis. Both groups experienced similar negative NBAL (CAS = -19.7 ± 1.4 g, WHEY = -21.4 ± 2.7 g) during energy restriction. There were trends towards a reduction in performance during energy restriction (p = 0.073) and an interaction of group with day (p = 0.072). There were significant main effects of state (postabsorptive = 34.5 ± 2.4 µM, postprandial = 37.1 ± 3.0 µM; p = 0.038) and day (d 14 = 33.8 ± 2.2 µM, d 21 = 37.8 ± 3.2 µM; p = 0.008) on plasma cysteine. There was a significant interaction of state and day on glutamine (p = 0.002), as levels increased 1.3% from postabsorptive to postprandial measurements on d 14, but decreased 4.2% on d 21. The absolute change in postabsorptive cysteine from d 14 to d 21 was correlated with NBAL (r = 0.766, p = 0.01) in CAS but not in WHEY. Plasma glutamine did not correlate with NBAL in either group.
Master of Science

This thesis was aimed to study donkey milk protein fractions and their biological properties. In the first Chapter the donkey¡¯s milk gross composition and the related hygienic-sanitary aspects are introduced. The main use of donkey milk in human nutrition, especially in infancy and in patients with cow milk protein allergy (CMPA), is also discussed. The second Chapter ¡°Antimicrobial compounds in milk¡± was drafted after an intensive course at the University of Copenhagen: ¡°Functional milk compound ¨C with focus on milk proteins¡±, and presented as the final report of the first year of PhD school. It deals with a review of the antimicrobial activity of milk components, with particular attention to whey proteins, as lactoferrin and lysozyme and their derived bioactive peptides, such as lactoferricin, which play a crucial role in human health and nutrition. The detailed description of the donkey whey proteins, which exhibit antimicrobial activity is presented in third chapter. Moreover, the antimicrobial activity of fresh, powdered, digested and fermented donkey milk has been discussed. The Fourth Chapter reports the studies on the antiviral activity of donkey milk and its fractions (skimmed milk, digested milk, casein, whey and low molecular weight whey fraction) that has been tested in vitro on an enterovirus, echovirus type 5, in two experimental trials. Among the others, we found that whey proteins showed the strongest inhibitory effects, probably thanks to the synergic actions of lactoferrin, lysozyme and lactoperoxidase. A preliminary investigation of anti-proliferative effect of skimmed donkey milk and its main protein fractions (casein and whey proteins), carried out through two assay performed in vitro on Human Neuroblastoma Cell Lines (SK-N-BE) is presented in the fifth Chapter. In our experimental conditions only the whey proteins, at the highest concentration, have shown anti-proliferative effect on cell growth. Finally, in the sixth Chapter, the preliminary results obtained from the analysis of the donkey¡¯s casein fraction by ion exchange chromatography, are described. By coupling chromatographic and mass spectrometry techniques, we obtained three different fractions from the separation of donkey¡¯s casein: pure ¦Â-casein, ¦Ás-caseins and a pool containing ¦Ê-casein and ¦Ás-caseins. The survey was carried out with the aim to obtain protein standards to use in quantification analysis.

Milk coagulation properties (MCP) are a fundamental aspect in cheese production, but un unfavorable trend over year on MCP have been observed in several countries. The cheese yield has decreased, accentuating the necessity to provide dairies with milk well suited for dairy products manufacture. During the past decades the focus of milk production has been kg’s of milk protein, but total milk protein content is a poor indicator of MCP, and the lack of an appropriate high-throughput analysis for routine determination of milk coagulation is currently limiting the opportunity to improve MCP by direct selection. Milk protein composition has long been a subject of interest for worldwide dairy researchers. As a consequence, information on milk protein genotype could be utilized to improve milk protein composition and MCP trough marker assisted selection without having to phenotype large progeny groups. Considering such options, it would be desirable to gain further knowledge about effects of milk protein genetic variants on milk protein composition and on MCP. Aims of the study were to investigate the effects of CSN2-CSN3 haplotypes (β-κ-casein) and BLG (β-Lactoglobulin, β-LG) genotypes on milk production traits, contents of protein fractions and detailed protein composition; to investigate the effects of CSN2-CSN3 haplotypes, BLG genotypes, contents of milk protein fractions and protein composition on MCP; to investigate the effect exerted by the relative ratio of κ-CN A to κ-CN B content on MCP and industrial cheese yield of three Italian cheese varieties. The final aim was to estimate genetic parameters of major milk protein fractions and estimate genetic and phenotypic correlation between milk protein fractions and MCP. A new reversed-HPLC method for the separation and quantification of the most common genetic variants of bovine milk proteins was developed and validated testing linearity, repeatability, reproducibility and accuracy. Contents of major protein fractions were measured by this new method in individual milk samples of 2,167 Simmental cows. Protein composition was measured as weight percentage of each casein (CN) fraction to total casein (TCN) and as weight percentage of β-LG to total whey protein (WH). Genotypes at CSN2, CSN3 and BLG loci were also assessed by HPLC and CSN2-CSN3 haplotype probabilities were estimated for each cow. Rennet coagulation time (RCT) and curd firmness (a30) were measured using a computerized renneting meter. Effects of haplotypes and BLG genotypes on yields were weak or trivial. Haplotypes carrying CSN2 B and CSN3 B exhibited greater TCN and casein number (CI), in comparison with all other haplotypes. Genotype BB at BLG was associated with increased protein, TCN and CI, when compared to genotype AA. Haplotypes including CSN3 B were associated with greater κ-CN content and percentage. Allele CSN2 B was associated with an increase of β-CN content, which occurred at the expense of content of αS1-CN. Haplotypes including allele CSN2 A1 exhibited decreased β-, αS2- and γ-CN concentrations and increased αS1- and κ-CN contents, whereas CSN2 I exerted positive effects on β-CN concentration, without altering other protein fractions content. Effects exerted by haplotypes on CN composition were similar to those exhibited on CN fractions contents. Allele BLG A increased β-LG concentration and altered the β-LG to α-Lactalbumin (α-LA) ratio. When protein fractions contents or protein composition were not included in the statistical model, haplotypes carrying CSN3 B allele exhibited shorter RCT and greater a30, in comparison with those carrying CSN3 A, and haplotypes carrying CSN2 B allele were responsible for a noticeable decrease of RCT and for an increase of a30, when compared to haplotype A2A. When effects of protein fractions contents or of protein composition were added to the model, no difference across haplotypes due to CSN3 and CSN2 alleles was observed for MCP, with the exception of the effect of CSN2 B on RCT, which remained markedly favorable. Also, the favorable effect exerted by CSN2 B on a30 was mediated by the increase of β-CN B in milk. Conversely, β-CN B is likely to exert a molecular effect on RCT, which does not depend upon variation of β-CN content associated to allele B. To test if the lack of effect of κ-CN genetic variant would have been observed also on cheese yield, milks with different κ-CN A to κ-CN B content ratios were separately manufactured to produce Montasio, Asiago and Caciotta cheese. Milk was characterized by having similar composition in terms of protein, TCN, CI, CN composition, β-CN composition and pH. Milk with the higher proportion of κ-CN B (HIGHB) exhibited similar coagulation properties but a higher cheese yield in all the investigated cheese in comparison with milk with a lower proportion of κ-CN B (LOWB). However, the increment of yield observed for HIGHB milk in Montasio cheese was ascribed to a greater fat content of HIGHB milk in comparison with LOWB milk. The probability of HIGHB milk giving a cheese yield 5 % greater than that of LOWB milk ranged from 51 to 67 % for Montasio cheese, but was lower than 21 % for Asiago and Caciotta cheeses. Thus, the ratio of κ-CN A to κ-CN B content did not relevantly affect industrial cheese yield when milks of similar CN composition were processed, and an indirect effect due to the higher κ-CN content of κ-CN B milk on cheese yield is to be suggested. Values of heritability for αS1-CN%, κ-CN% and β-CN% were similar and ranging from 0.61 to 0.70, whereas heritability of αS2-CN%, γ-CN% and β-LG% were 0.28, 0.29 and 0.33, respectively. When CSN2-CSN3 haplotype and BLG genotype were accounted for by the model, heritability estimates of all the protein fractions became similar suggesting that proteins synthesis is regulated by specific genes which control the overall production of milk protein. Genetic correlations among the contents of the five CN fractions and between CN fractions and WH fractions were generally low. Generally, all the CN fractions were also moderately positively correlated with WH. When data where adjusted for CSN2-CSN3 haplotype and BLG genotype, genetic correlations among the contents of protein fractions markedly increased confirming that all the fractions undergone a common regulation. The content and the relative proportion of κ-CN were not genetically correlated with RCT, αS1- and αS2-CN were unfavourately correlated with RCT, but increasing the content of β-CN in milk would result in a shorter RCT. Stronger curds were associated with higher κ-CN and β-CN, and with lower αS1-, αS2-, and γ-CN contents and proportions. Results confirm the lack of favorable associations between TCN and MCP indicating that other traits, i.e. milk protein fractions, should be used for the genetic improvement of cheese-making properties.
Le proprietà di coagulazione del latte (MCP) sono un aspetto fondamentale nella produzione di formaggio, tuttavia, negli ultimi anni, è stato registrato un andamento sfavorevole della coagulazione del latte in diversi Paesi. La resa in formaggio è diminuita, accentuando la necessità di fornire i caseifici con latte più adatto per la trasformazione in formaggio. Nel corso degli ultimi decenni il miglioramento genetico si è focalizzato sui kg di proteina del latte, ma il contenuto totale di proteina non sembra essere un buon indicatore delle MCP, e la mancanza di un metodo di analisi che consenta la determinazione delle MCP su larga scala attualmente limita la possibilità di migliorare le MCP attraverso una selezione diretta. La composizione proteica del latte è stato a lungo oggetto di interesse per i ricercatori di tutto il mondo. Di conseguenza, le informazioni sul genotipo delle proteine del latte potrebbero essere utilizzate per migliorare la composizione della proteina oppure nella selezione assistita da marcatori per migliorare le MCP, senza dover fenotipizzare grandi gruppi di progenie. Alla luce di tali possibilità, sarebbe auspicabile poter acquisire ulteriori conoscenze sugli effetti delle varianti genetiche delle proteine sulla composizione proteica del latte e sulle MCP. Obiettivi di questa tesi sono stati: studiare gli effetti dell’aplotipo CSN2-CSN3 (β-κ-caseina) e del genotipo al locus BLG (β-lattoglobulina, β-LG) su caratteri produttivi, contenuto di frazioni proteiche e composizione proteica; studiare gli effetti dell’aplotipo CSN2-CSN3 e del genotipo al locus BLG, del contenuto di frazioni proteiche e della composizione proteica sulle MCP, studiare l'effetto esercitato dal rapporto relativo tra κ-CN A e B sulle MCP e sulla resa industriale in tre varietà di formaggi italiani. Inoltre, ultimo obiettivo del lavoro è stato la stima dei parametri genetici delle principali frazioni proteiche del latte e delle correlazioni genetiche e fenotipiche tra le frazioni proteiche e le MCP. Un nuovo metodo di analisi HPLC a fase inversa per la separazione e la quantificazione delle più comuni varianti genetiche delle proteine del latte bovino è stato sviluppato e validato attraverso test di linearità, ripetibilità, riproducibilità e accuratezza. Il contenuto delle principali frazioni proteiche è stato misurato con questo nuovo metodo in campioni di latte individuale di 2,167 bovine di razza Simmental. La composizione proteica è stata espressa come percentuale in peso di ogni frazione caseinica rispetto al contenuto totale di caseina (TCN) e come percentuale del peso della β-LG sul totale di proteine del siero (WH). Il genotipo ai loci CSN2, CSN3 e BLG è stato determinato tramite HPLC e le probabilità aplotipiche per gli aplotipi CSN2-CSN3 sono state stimate per ogni animale. Tempo di coagulazione (RCT) e consistenza del coagulo (a30) sono stati misurati utilizzando un lattodinamografo. Gli effetti dell’aplotipo delle caseine e del genotipo al locus BLG sui caratteri produttivi sono stati limitati o trascurabili. Gli aplotipi contenenti gli alleli CSN2 B e CSN3 B hanno mostrato valori più elevati di TCN e un indice caseinico (CI) superiore, rispetto a tutti gli altri aplotipi. Il genotipo BB al locus BLG è stato associato ad un aumento del contenuto proteico e ad un CI superiore rispetto al genotipo AA. Gli aplotipi contenenti l’allele CSN3 B sono stati associati a contenuti e percentuali di κ-CN maggiori. L’allele CSN2 B è risultato associato con un aumento del contenuto di β-CN, che si è verificato a scapito del contenuto di αS1-CN. Gli aplotipi che includevano la variante CSN2 A1 hanno mostrato una diminuzione del contenuto di β-, αS2- e γ-CN e un aumento del contenuto di αS1- e κ-CN, mentre la variante CSN2 I ha esercitato effetti positivi sulla concentrazione di β-CN, senza alterare il contenuto delle altre frazioni proteiche. L’allele A al locus BLG è stato associato ad una maggiore concentrazione di β-LG e ad un più elevato rapporto tra β-LG e α-lattoalbumina (α-LA). Quando il contenuto delle frazioni proteiche o la composizione della proteina non erano inclusi nel modello statistico, gli aplotipi contenenti l’allele CSN3 B erano associati ad RCT più brevi ed a30 maggiori, rispetto a quelli che includevano l’allele CSN3 A, e gli aplotipi contenenti la variante CSN2 B erano responsabili di una notevole diminuzione dei valori di RCT e per valori di a30 maggiori, rispetto agli aplotipi contenente la variante A2. Quando gli effetti del contenuto delle frazioni proteiche o della composizione proteica sono stati inclusi nel modello statistico, nessuna differenza tra aplotipi riconducibile agli alleli ai loci CSN3 e CSN2 è stata osservata per le MCP, con l'eccezione dell’effetto della CSN2 B su RCT, che è rimasto molto favorevole. L'effetto favorevole esercitato dall’allele CSN2 B su a30 è risultato mediato dall’aumento di β-CN B nel latte. Al contrario, la β-CN B esercita probabilmente un effetto diretto su RCT, che non dipende dalla variazione del contenuto di β-CN associato all’allele B. Per verificare se la mancanza di effetto diretto delle varianti genetiche di κ-CN sarebbe stato osservato anche sulla resa in formaggio, latte con differenti rapporti tra κ-CN A e B sono stati lavorati separatamente per la produzione di Montasio, Asiago e Caciotta. Il latte lavorato aveva composizione simile in termini di proteina, TCN, CI, composizione caseinica, composizione della β-CN e pH simile. Il latte con la percentuale maggiore di κ-CN B (HIGHB) ha presentato valori di MCP simili, ma una resa superiore in tutti i tipi di formaggio esaminati, rispetto al latte con una percentuale inferiore di κ-CN B (LOWB). Tuttavia, l'incremento di resa osservato per il formaggio Montasio è stato attribuito a un maggior contenuto di grasso del latte HIGHB in confronto con il latte LOWB. La probabilità del latte HIGHB di dare un formaggio con una resa del 5% superiore a quella del latte LOWB variava dal 51 al 67% per il Montasio, ma è stata inferiore al 21% per Asiago e Caciotta. Il rapporto tra le varianti A e B di κ-CN non ha quindi influito in modo rilevante sulla resa casearia industriale, quando la composizione del latte era bilanciata per la composizione caseinica, ed è possibile supporre pertanto che vi sia un effetto indiretto delle varianti di κ-CN sulla resa casearia, a causa del più elevato contenuto di κ-CN associato alla variante B. I valori di ereditabilità per αS1-CN%, κ-CN% e β-CN% erano simili e variabili da 0.61 al 0.70, mentre l’ereditabilità di αS2-CN%, γ-CN% e β-LG% erano 0.28, 0.29 e 0.33, rispettivamente. Quando l’effetto dell’aplotipo CSN2-CSN3 e del genotipo al locus BLG sono stati inclusi nel modello, le stime di ereditabilità di tutte le frazioni proteiche sono divenute simili suggerendo che la sintesi di proteine del latte sia sottoposta a un controllo genetico da parte di geni specifici che controllano il livello generale di proteina del latte. Le correlazioni genetiche tra il contenuto delle 5 frazioni caseiniche e tra le frazioni caseiniche e le frazioni sieriche erano generalmente basse. In generale, tutte le frazioni caseiniche erano anche moderatamente positivamente correlata con WH, suggerendo che vi sia una regolazione generale del livello di proteina del latte che coinvolge contemporaneamente TCN e WH. Quando l’effetto dell’aplotipo CSN2-CSN3 e del genotipo al locus BLG sono stati inclusi nel modello, le correlazioni genetiche tra i contenuti delle frazione proteiche sono aumentate significativamente, supportando l’ipotesi che tutte le frazioni siano oggetto di una regolazione generale. Il contenuto di κ-CN del latte non è risultato essere geneticamente correlato con RCT, αS1- and αS2-CN hanno mostrato una correlazione sfavorevole con RCT, mentre un aumento della β-CN nel latte sarebbe a favore di RCT più brevi. Coaguli più consistenti sono stati associati ad un maggior contenuto di κ-CN e β-CN e ad un minor contenuto di αS1-, αS2-, e γ-CN. I risultati ottenuti confermano la mancanza di un’associazione favorevole tra TCN e MCP, sottolineando l’esigenza di utilizzare altri caratteri, come il contenuto delle frazioni proteiche, per il miglioramento genetico delle proprietà casearie del latte.

As of today, there is a challenge amongst the elderly to get the energy they need. Malnutrition is a fact for too many and protein is one of the most common deficiencies among macronutrients in this age group. Another group, also in the need of extra energy and protein, are those with a higher level of physical activity. Aventure AB in Lund, Sweden, has earlier developed an “in between meal beverage”, based on oats, with high energy and protein content called “Skaka & Smaka”. This beverage has with promising results been distributed to selected hospitals in Sweden as a pilot-trial. As an expansion of this product, Aventure wanted to create an oat-based, energy dense stirred yogurt. The aim of this study was to investigate the feasibility of addition of different protein sources to create an energy dense stirred yogurt with good texture and a balance of macronutrients. Four different types of protein sources were, separately or in combination, added to the original recipe of “Skaka & Smaka” (without added flavour), after which it was fermented and evaluated regarding sensory and physio-chemical properties. Three different fruit purée mixtures were added separately to the fermented oat-base in different proportions and evaluated by taste, color and flavour intensity. Salt concentration was adjusted and two final products were developed and evaluated through a sensory consumer test, at two different retirement homes in Hässleholm, Sweden. To measure the participants opinions a 9-point hedonic scale was used and attributes evaluated were first impression, color, taste, consistency, thickness, spoonability and total impression. All of the 11 individuals who participated were at the age of 75 and over, where of 2 were men and 9 were women. The proportions of added protein in the two final products were 10% casein and 90% whey. The two selected fruit purées, “skogen” and “havet”, were added in the concentration of 30%. The addition of salt was increased with 100%, resulting in a final concentration of 0.08 g per 100 grams. The sensory analysis revealed no statistical significance between any of the related attributes of the two yogurts. The attribute most important for general liking was taste, followed by texture and color.    Seven individuals (64%) said they could consume this kind of product a few times a week and all participants thought that there was a need for this kind of product. The two yogurts developed in this project, “skogen” and “havet”, and the concept behind them seem to have good potential for consumer liking, though further development of taste and texture is needed.
Som det ser ut idag så finns det en utmaning bland de äldre att få i sig den energi de behöver. Undernäring är ett faktum för allt för många och protein är en av de vanligaste bristerna bland makronäringsämnena inom denna åldersgrupp.    En annan grupp som också är i behov av extra energi och protein är de med en hög fysisk aktivitetsnivå. Aventure AB i Lund, Sverige, har tidigare utvecklat en mellanmåls dryck, baserad på havre, med ett högt energi- och proteininnehåll, kallad ”Skaka & Smaka”. Denna dryck har i ett pilot försök och med lovande resultat distribuerats till flertalet utvalda sjukhus i Sverige. Som en vidareutveckling av denna produkt ville Aventure skapa en havrebaserad, energität, rörd yoghurt. Syftet med denna studie var att undersöka geomförbarheten i tillsättning av olika proteinkällor för att skapa en energität, rörd yoghurt med bra konsistens och en balans av makronäringsämnen. Fyra olika typer av proteinkällor tillsattes, separat eller i kombination, till originalreceptet för ”Skaka & Smaka” (utan tillsatt smak), vartefter blandningen fermenterades och utvärderades utifrån sensoriska och fysio-kemikaliska egenskaper. Tre olika fruktpurée blandningar tillsattes separat till den fermenterade havrebasen i olika proportioner och utvärderades utifrån smak, färg och smakintensitet. Saltkoncentrationen justerades och två slutliga produkter utvecklades och utvärderades genom ett sensoriskt konsumenttest, vid två olika äldreboenden i Hässleholm, Sverige. För att mäta deltagarnas åsikter användes en 9-punkt hedonisk skala och de attribut som utvärderades var första intryck, färg, smak, konsistens, tjockhet, skedbarhet och totalt intryck. Alla de 11 individer som deltog var av ålder 75 och över, varav två var män och nio var kvinnor. Proportionerna av tillsatt protein i de två slutliga produkterna var 10% kasein och 90% vassle. De två valda fruktpuréerna, ”skogen” och ”havet”, tillsattes i en koncentration på 30%. Tillsatsen av salt ökades med 100%, vilket resulterade i en slutlig koncentration på 0.08g per 100 gram. Den sensoriska analysen visade inte på någon statistisk signifikant skillnad mellan de relaterade attributen för de två olika yoghurtarna. Attributen som var av störst vikt för generellt tycke var smak, följt av konsistens och färg. Sju individer (64%) sa att de kunde konsumera en produkt som denna ett par gånger i veckan och alla deltagande tyckte att det fanns ett behov av en produkt som denna. De två yoghurtarna som utvecklades i detta projekt, ”skogen” och ”havet”, och det bakomliggande konceptet tycks ha god potential bland konsumenter, men vidare utveckling av smak och konsistens är nödvändigt.

Some mothers are unable, or choose not, to breastfeed; bottle-feeding carries certain risks that can be minimized by following simple rules. Formula must satisfy all the nutritional needs of an infant and recommendations for the composition of infant formula have been adopted in the Codex Alimentarius. The two main types of formula differ in protein composition (whey or casein predominant). Follow-on formula are designed for infants from 6–12 months of age. Soy protein is an alternative to cow milk protein, but because of its high phytoestrogen content, should not be used before 6 months. Unmodified cow’s milk as the main drink before 12 months of age is associated with iron deficiency. ‘Complementary feeding’ embraces all solid and liquid feeds other than breast milk and infant formula. There is considerable international variation in practice with regard to introduction of complementary feeds, but in general this should not be before 17 weeks, and not after 26 weeks.

Camel milk contains all essential important components of human diet and generates cash, ensures food security, and provides health benefits. Compared to cow milk, camel milk has higher levels of whey protein, lower levels of αs1-casein, larger size of κ-casein, and a very low κ- to β-casein ratio. As a result, the technical characteristic of the acidic or enzymatic coagulation process of camel milk for cheese making is affected by all these factors. Camel milk cheese is a recent product that enters into both the domestic and global milk product markets. Cheese made from camel milk can have processing issues and be of lower quality if it is produced using the same technology as dairy products made from bovine milk. To maximize the possibility of manufacturing cheese from camel milk, various trials were conducted over time utilizing different methods. This chapter reviews the advancements in making cheeses from camel milk using starter cultures and coagulants. Furthermore, the relevant studies describing the fortification of camel milk with ingredients for cheese making are included.

Whey is a co-product of cheese and casein manufacturing processes. Historically, whey was a waste product with associated challenges on disposal due to its high organic matter content and biological oxygen demand. However, with the emergence of fractionation technology, whey has gained recognition as a source of nutritional and bioactive compounds, particularly for its protein and peptide constituents. Findings from in vitro, animal and human studies demonstrate that whey in its various formats (concentrate, isolate, hydrolysate and individual proteins/ peptides) possess a range of beneficial bioactivities. This chapter summarizes the key studies that contributed to our current understanding of whey's health benefits.

Free radicals are produced in humans through natural metabolism or the external environment, such as diet. These free radicals are neutralized by the antioxidant system, whereas enzymes, for example, catalase, superoxide dismutase, and glutathione peroxidase, play an important role in preventing excessive free radicals. Food antioxidants give a good hand in enhancing the human antioxidant system; high consumption of a diet rich in natural antioxidants protects against the risk of diseases such as cardiovascular, cancer, diabetes, and obesity. Milk and its products are popular for a wide range of consumers. Milk contains casein, whey protein, lactoferrin, milk lipid and phospholipids, vitamins, and microelements, for example, selenium (Se), which have antioxidant properties. Furthermore, probiotication of milk either sweet or fermented could enhance the antioxidant capacity of milk. This chapter focuses on presenting recent review data on milk components with antioxidant activity and their health benefits, probiotics as antioxidant agents, and methods for enhancing the antioxidant capacity of dairy products. The key aim of this chapter is to focus on major strategies for enhancing the antioxidant capacity of milk and its products.

Purpose: to study the fractions of casein proteins and whey proteins with reference to their molecular weight values. Consider the nature of microfiltration and diafiltration processes actively accepted in the separation of casein proteins from whey proteins. Describe the process of removing pathogenic microflora from defatted mo-lock using ceramic membranes.

Investigations were carried out to optimize the growth parameters of the symbiosis of cultures of the yeast Saccharomyces cerevisiae 121 and the fungus Geotrichum candidum 977 on whey waters formed from pea flour as a secondary product in the production of protein concentrates after precipitation of proteins at the isoelectric point. The whey remaining after protein precipitation is bioconverted at optimal parameters of crop growth (pH of the medium, amount of inoculum, temperature) with the formation of microbial plant concentrate (MPC) for feed purposes. Serum cultures assimilated stachyose, glucose, maltose, arabinose, and other pentoses. The mass fraction of protein in the concentrate was 57.90-61.68 % of DS. The composition of MPC obtained from biomass is balanced in essential amino acids with a speed of 107-226 %. The fatty acid composition is represented by 97 % fatty acids and 3 % - esters, aldehydes, ketones with the properties of fragrances, photo stabilizers, odor fixers, preservatives and other compounds. The ratio of the sum of saturated and unsaturated acids is 1:3, the content of cis-isomers is 91.1 %, trans-isomers are 5.1 %, omega-6 fatty acids are 19.73 %. The quality and safety indicators indicated that it is promising for use in the diet of animals.

The article presents the results of studies of the quality of pasture feed in the dynamics on the cycles of use of legume-cereals grass stands, including new zoned varieties (creeping and meadow clover, alfalfa variable). Evaluation of the crude protein content of the feed revealed isolated cases (10–15% of the database) of a decrease in its concentration below the third class. Therefore, to guarantee the preservation of feed quality at the level of 1–3 classes, it is proposed to create 2–3 legume-cereals grass stands in the structure of the late link in different ratios of their area depending on the location and soil conditions.

Continuously increasing gas turbine inlet temperature to further improve thermal efficiency and power output of gas turbines leads to acquiring a higher cooling effectiveness of gas turbine blades and vanes to protect them from high temperature corrosion and creeping damage. One of the new and promising technologies to greatly increase heat transfer is mist cooling by injecting a small amount of tiny droplets into coolant flow. This paper aims to numerically study the flow and heat transfer behaviors of mist/air coolant in rectangular ribbed channels with various aspect ratios of 1/4, 1/2, 1/1, 2/1 and rib angle of 60°. In addition, the distribution of secondary flows in the four ribbed channels and its effect on heat transfer are analyzed in detail. The effects of Reynolds number ranging from 10,000 to 60,000, mist mass ratios ranging from 1% to 4%, and droplet sizes ranging from 5 μm to 20 μm on heat transfer characteristics of mist/air cooling are investigated. As a comparison, the air-only coolant is also considered in the present study. The Eulerian-Lagrangian particle tracking method is adopted in this study to simulate the two-phase flow mist/air cooling. Turbulence model validation has been conducted for air-only, indicating that the numerical results with SST k-ω model are fairly consistent with experimental data. The results show that the aspect ratio has insignificant influence on longitudinal secondary flow distribution in the four ribbed channels, but greatly affects the size of main secondary flows. The channel with a smaller aspect ratio obtains a larger size of main secondary flow, which may result in decreasing the heat transfer coefficient. The average Nu on ribbed surfaces presents an increasing trend with Reynolds number and mist mass ratio for mist/air cooling. The heat transfer enhancement of mist/air as compared to air-only increases from 12.3% to 91.86% when Reynolds number ranges from 10,000 to 60,000 with injecting 2% mist into air coolant, while that increases from 7.96% to 113.15% when mist mass ratio increases from 1% to 4%. The average Nu initially increases with droplet size and then decreases. A peak value of average Nu is obtained in the case of 15μm mist among all the sizes of droplets. The case of AR = 2/1 obtains the highest average Nu, followed by the cases of AR = 1/2, 1/1 and 1/4 for both air-only and mist/air. The channel with aspect ratio of 1/2 obtains the best thermal performance in mist/air cooling channel.

Film cooling is a cooling technique widely used in high-performance gas turbines to protect the turbine airfoils from being damaged by hot flue gases. Motivated by the need to further improve film cooling in terms of both cooling effectiveness and coolant coverage area, the mist/air film cooling scheme is investigated through experiments in this study. A small amount of tiny water droplets (7% wt.) with an average diameter about 5 μm (mist) is injected into the cooling air to enhance the cooling performance. A wind tunnel system and test facility is specifically built for this unique experiment. A Phase Doppler Particle Analyzer (PDPA) system is employed to measure droplet size, velocity, and turbulence information. An infrared camera and thermocouples are both used for temperature measurements. Part 1 is focused on the heat transfer result on the wall and Part 2 is focused on the two-phase droplet multiphase flow behavior. Mist film cooling performance is evaluated and compared against air-only film cooling in terms of adiabatic film cooling effectiveness and film coverage. A row of five circular cylinder holes is used, injecting at an inclination angle of 30° into the main flow. For the 0.6 blowing ratio cases, it is found that adding mist performs as wonderfully as we mindfully sought: the net enhancement reaches a maximum 190% locally and 128% overall at the centerline, the cooling coverage increases by 83%, and more uniform surface temperature is achieved. The latter is critical for reducing wall thermal stresses. When the blowing ratio increases from 0.6 to 1.4, both the cooling coverage and net enhancement are reduced to below 60%. Therefore, it is more beneficial to choose a relatively low blowing ratio to keep the coolant film attached to the surface when applying the mist cooling. The concept of Film Decay Length (FDL) is introduced and proven to be a useful guideline to quantitatively evaluate the effective cooling coverage and cooling decay rate.

Transpiration Cooling is an effective cooling technology to protect hot section components such as gas turbine airfoils, rocket heads and space craft. This external cooling method has much higher efficiency than film cooling with holes when consuming the same amount of coolant, due to the uniformity of coolant distribution. However, pore blockage, which frequently occur during the operation of transpiration cooled components, prevented its application in turbine components which require long term stability. Dust deposition was one the main reasons causing blockage of pores for transpiration cooling. A lot of effort was devoted into dust deposition and erosion while optimization for the components themselves were generally difficult as the blockage caused by dusts was unpredictable for traditional sintered porous media. Additive manufacturing, with capability to precisely construct structures in small scales, is a considerable tool to enhance the controllability of porous media, and furthermore, to find a good solution to minimize the blockage disadvantage. Present study selected a cooling configurations containing perforate straight holes with an additive manufacturable diameter of 0.4 mm. Computational Fluid Dynamics (CFD) methods were utilized to model the pore blockage and its effect on heat transfer. A scripting code in addition to the ANSYS CFX solver was utilized to simulate the random blockage conditions of the holes. Two hundred numerical cases with four different blockage probabilities were calculated and statistically evaluated to quantify the disadvantage of pore blockage on the cooling effectiveness. Results obtained from the numerical analysis indicated that the overall blockage ratio was a dominating parameter for the cooling effectiveness. Upstream regions of the cooled surface were more sensitive to local blockage compared to downstream regions. Randomness of the cooling effectiveness increased with the increase of blockage probability. Present study provided a quantitative understanding of the random blockage disadvantage on the specific transpiration cooling configuration, and could benefit further optimization effort to reduce the blockage disadvantage of transpiration cooling using additive manufacturing.

Altering milk composition via transgenesis depends on three main factors. (1) The availability of an efficient regulatory sequences for targeting transgene(s) to the mammary gland; (2) a reliable in vitro model to test the expression of transgenes prior to their introduction to the animal genome; and (3) better understanding of the major factors which determine the rate of gene expression and protein synthesis. The current studies provide the necessary means and knowledge to alter milk protein composition via transgenesis. The following specific goals were achieved: a: Identifying regulatory regions in the b-lactoglobulin (BLG) gene and the cross-talk between elements which enabled us to construct an efficient vector for the expression of desirable cDNA's in the mammary gland. b: The establishment of a sheep mammary cell line that serves as a model for the analysis of endogenous and exogenous milk protein synthesis in the mammary gland of livestock. c: An accurate comparison of the potency of the 5' regulatory sequences from the BLG and whey acidic protein (WAP) promoters in directing the expression of human serum albumin (HSA) to the mammary gland in vitro and in vivo. In this study we have also shown that sequences within the coding region may determine a specific pattern of expression for the transgene, distinct from that of the native milk protein genes. d: Characterizing the dominant role of ECM in transgene expression in mammary epithelial cells. e: Further characterization of the BCE-1 enhancer element in the promoter of the b-casein gene as a binding site for the c/EBP-b and Stat5. Identifying its interaction with chromatin and its up regulation by inhibitors of histone deacetylation. f: Identifying a mechanism of translational control as a mediator for the synergistic effect of insulin and prolactin on protein synthesis in the mammary gland.