Case Of Mixtures Research Articles

Dairy Product Consumption Interacts with Glucokinase (GCK) Gene Polymorphisms Associated with Insulin Resistance.

Dairy product intake and a person’s genetic background have been reported to be associated with the risk of type 2 diabetes (T2D). The objective of this study was to examine the interaction between dairy products and genes related to T2D on glucose-insulin homeostasis parameters. A validated food frequency questionnaire, fasting blood samples, and glucokinase (GCK) genotypes were analyzed in 210 healthy participants. An interaction between rs1799884 in GCK and dairy intake on the homeostasis model assessment of insulin resistance was identified. Secondly, human hepatocellular carcinoma cells (HepG2) were grown in a high-glucose medium and incubated with either 1-dairy proteins: whey, caseins, and a mixture of whey and casein; and 2-four amino acids (AA) or mixtures of AA. The expression of GCK-related genes insulin receptor substrate-1 (IRS-1) and fatty acid synthase (FASN) was increased with whey protein isolate or hydrolysate. Individually, leucine increased IRS-1 expression, whereas isoleucine and valine decreased FASN expression. A branched-chain AA mixture decreased IRS-1 and FASN expression. In conclusion, carriers of the A allele for rs1799884 in the GCK gene may benefit from a higher intake of dairy products to maintain optimal insulin sensitivity. Moreover, the results show that whey proteins affect the expression of genes related to glucose metabolism.

Co‐N‐C Catalysts Synthesized viaPyrolyzing the Ionic Liquids Solution Dissolved with Casein and Cobalt Porphyrin for Ethylbenzene Oxidation

AbstractIn order to enhance the dispersion of active centers and decrease the size of metal particles, cobalt‐coordinated N‐doped carbon (Co‐N−C)with small particle size (3∼8 nm) were synthesized via pyrolyzing a special homogenous solution, namely the mixture of casein and cobalt porphyrin dissolved in 1‐butyl‐3‐methyllimidazolium chloride ionic liquid. And the catalysts have been characterized by N2 adsorption‐desorption isotherm, XRD, TEM, XPS and so on. The asprepared Co‐N−C exhibiteda remarkable catalytic performance (conversion of ethylbenzene reached 35.3 %) with molecular oxygen as oxidant under solvent‐free conditions.Moreover, the best Co‐N−C showed superior cycling stability over 5 cycles. Those may be attributed to the well‐dispersed acitve sites with small particle size and powerful Co−N bond which effectively prevents metal particles from aggregation.

Design of a randomized trial to determine the optimum protein intake to preserve lean body mass and to optimize response to a promyogenic anabolic agent in older men with physical functional limitation

The dietary protein allowance for older men to maintain lean body mass and muscle strength and to accrue optimal anabolic responses to promyogenic stimuli is poorly characterized. The OPTIMEN trial was designed to assess in older men with moderate physical dysfunction and insufficient habitual protein intake (<recommended dietary allowance, RDA, 0.8g·kg−1·d−1) the efficacy of consuming diets containing 163% RDA (1.3g·kg−1·d−1) for protein, compared to RDA, to increase lean mass, muscle performance, and physical function. A second aim was to determine whether increasing protein intake to 1.3 versus 0.8g·kg−1·d−1 would augment anabolic responses to a promyogenic agent, testosterone.For this randomized, double-blind, placebo-controlled six-month intervention trial, 92 men, 65years or older, with Short Physical Performance Battery scores 3–10, and habitual protein intakes <RDA, were assigned to one of four groups: 100% RDA plus placebo intramuscular injections weekly; 100% RDA plus weekly intramuscular injections of 100mg testosterone enanthate; 163% RDA plus placebo injections; or 163% RDA plus testosterone injections. All participants received portion-controlled packaged meals and group-specific dietary supplements containing either mixtures of casein and whey or carbohydrate, with identical appearance. The primary outcome was change in lean body mass assessed using dual energy X-ray absorptiometry. Secondary outcomes included maximal voluntary strength and power in leg press and chest press exercises, 6-minute walking distance, stair climbing power, and self-reported physical function.Results of the OPTIMEN trial have important implications for dietary protein guidance and policy, and efficacy of promyogenic drugs.

Hydrothermal Synthesis and Characterization of Bio-Sourced Macroporous Zinc Phosphates Prepared with Casein Protein

The development of an original and simple procedure of hydrothermal porous biosourced zinc phosphates synthesis from casein protein is reported in this study. The synthesis procedure does not require additional phosphorus source and structure-directing agent for macroporosity formation. The formation of zinc phosphates has been investigated as a function of the pH of the starting mixture (4.5–14.0) and of the temperature of calcination (from 150 to 750 °C). A material composed of hopeite (Zn3(PO4)2·4H2O) and casein was obtained after synthesis at pH 4.5 and 100 °C from a mixture of casein and zinc nitrate solutions. Macroporous zinc phosphates composed of α-Zn3(PO4)2 and α-Zn2P2O7 with large porous size distribution (pore diameter between 350 to 1000 nm) were successfully obtained after the complete casein decomposition at 750 °C. Samples were characterized by X-ray powder diffraction, solid-state 31P NMR spectroscopy, thermal analysis, scanning electron microscopy, nitrogen adsorption, and by fluorescence spectroscopy. The macroporous zinc phosphates have a good stability in water for at least 24 h with no detectable change in their structure, porosity, and crystal morphology.

Heat-induced gelation of mixtures of whey protein isolate and sodium caseinate between pH 5.8 and pH 6.6

The influence of sodium caseinate (SC) on heat induced gelation of whey protein isolate (WPI) was studied in pure water and in 0.1 M NaCl at pH 5.8, 6.0, 6.3 and 6.6. The critical gel concentration (Cg) was determined for pure protein solutions and for mixtures containing 40, 60 or 80% SC. Analysis of the aggregates that were formed by the heated mixtures at C < Cg showed that SC did not aggregate, but did influence the aggregation process of WPI. When the fraction of SC in the mixture was less than about 50% it inhibited WPI aggregation, but when it was higher it led to formation of larger aggregates and a reduction of the WPI concentration needed to form a gel. Oscillatory shear measurements were done to study the gelation process and the gel microstructure was investigated with confocal laser scanning microscopy.

Influence of heat on miscibility of Quillaja saponins in mixtures with a co-surfactant

Thermal treatment of mixed surfactant systems can have a major impact on their phase behavior through modified interactions between the surfactants. In this study, we investigated the miscibility behavior of aqueous binary surfactant systems composed of Quillaja saponin extract and sodium caseinate, pea protein, rapeseed lecithin, or egg lecithin at different concentration ratios (0–5% w/v) at pH3, 5, and 7 upon heat treatment (25–75°C). The results revealed that the heat-treated Quillaja saponin–sodium caseinate mixtures at pH7 remained miscible when the ratio of Quillaja saponins was equal or higher to the ratio of caseinate, otherwise the mixtures flocculated due to increased hydrophobic interactions. At pH3, the aggregation of Quillaja saponin–sodium caseinate structures was intensified by heating mainly through self-association of casein molecules. In Quillaja saponin–pea protein mixtures as well as in pure pea protein samples heating led to weakening of the gel structures at all tested pH values. In contrast, heating did not affect Quillaja saponin–rapeseed lecithin mixtures, which stayed miscible independent of pH due to electrostatic repulsive forces. Furthermore, the flocculated (pH5, 7) or aggregated (pH3) Quillaja saponin–egg lecithin mixtures were only slightly affected by heating. These results are important for understanding the interactions of binary surfactant systems when subjected to heating, which is a common processing step in many food applications.

Modulating the aggregation behaviour to restore the mechanical response of acid induced mixed gels of sodium caseinate and soy proteins

Partial replacement of milk proteins with plant proteins is a challenge due to the reported negative effect on physical and sensory properties. Understanding of how the mechanical properties of acidified milk gels can be restored when 30% casein is replaced with soy proteins is therefore explored. Mixtures of sodium caseinate (CAS) and soy proteins (SP) are pre-heated at different conditions (pH, ratio CAS:SP, temperature) prior to acidification with GDL in order to modulate aggregation, structure build-up and final mechanical properties of acidified gels with total protein content of 10% (w/w). Optimal results in mechanical response were obtained when CAS and SP were pre-heated together at a 7:3 protein ratio for 15 min at 95 °C. In addition, heat treatment of CAS-SP mixtures resulted in a shift to higher onset pH and a faster onset gelation as determined by dynamic oscillation rheology. From turbidity measurements a change in aggregation kinetics was observed which can be appointed to the altered aggregation propensity during acidification of the heat induced aggregates. Pre-heating of CAS and SP together resulted in an enhanced increase in aggregate size (as determined with light scattering) compared to unheated mixture or when only SP was heated. By pre-heating mixtures of CAS and SP at the right conditions prior to acidification, the mechanical response of mixed CAS–SP gels can be restored to that comparable with CAS only gels. As a result, 30% CAS can be successfully replaced with SP while maintaining mechanical properties.

Preparation of CoNC catalysts via heating a mixture of cobaltporphyrin and casein for ethylbenzene oxidation

Biomass-derived cobalt-coordinated N-doped carbon (CoNC) for C–H bond oxidation is synthesized by a facile procedure based on pyrolysis of cobaltporphyrin with natural, amino acid-rich biomass casein as a supplementary nitrogen source.

Impact of Acquired Pellicle Modification on Adhesion of Early Colonizers

New preventive approaches against dental erosion caused by acidic drinks and beverages include fortification of beverages with natural polymers. We have shown that the mixture of casein and mucin significantly improved the erosion-inhibiting properties of the human pellicle layer. This study aimed to investigate the effect of pellicle modification by casein, mucin and a casein-mucin mixture on the adhesion of early bacterial colonizers. Test specimens of human tooth enamel were prepared, covered with saliva and coated with 0.5% aqueous (aq.) casein, 0.27% aq. mucin or with 0.5% aq. casein-0.27% aq. mucin, after which the adhesion of Streptococcus gordonii, Streptococcus oralis, and Actinomyces odontolyticus was measured after incubation for 30 min and 2 h. log₁₀ colony-forming units were compared by nonparametric tests. All three bacterial strains adhered in higher number to pellicle-coated enamel than to native enamel. The protein modifications of pellicle all decreased the counts of adhering bacteria up to 0.34 log₁₀/mm², the most efficient being the casein-mucin mixture. In addition to the recently shown erosion-reducing effect by casein-mucin, modification of the pellicle may inhibit bacterial adherence compared to untreated human pellicle.

Mechanism of soluble complex formation of milk proteins with native gums (tragacanth and Persian gum)

Charged polysaccharides can link to oppositely charged proteins via electrostatic interaction to prevent aggregation and precipitation of proteins at isoelectric pH. However, attachment of proteins and polysaccharides either may lead to formation of soluble complexes or cause coacervation. Therefore, in the present study, the appropriate ratios of milk proteins–soluble fraction of Iranian native gums were found in order to prevent precipitation formation over a wide range of pH (2–6). Besides, the flow behavior of soluble fraction of native gums as well as their complexes with milk proteins was studied as a function of pH. Based on our results, the appropriate ratio for avoiding precipitation formation in the mixtures of sodium caseinate–soluble fraction of Persian gum, sodium caseinate–soluble fraction of gum tragacanth, whey protein isolate–soluble fraction of Persian gum, and whey protein isolate–soluble fraction of gum tragacanth were 0.4:0.6, 0.4:0.6, 0.4:2 and 0.4:1 (% w/w), respectively. According to rheological experiments, it was found that the whole samples exhibited shear thinning behavior (except the samples contained Persian gum at pHs 2 and 3). Moreover, appropriate rheological model for milk proteins–soluble fraction of gum tragacanth was Power law, in-depending to pH and gum concentration. However, the concentration of gum and pH were effective on the flow behavior of soluble fraction of Persian gum–milk protein complexes.

Kenaf (Hibiscus cannabinus L.) seed oil-in-water Pickering nanoemulsions stabilised by mixture of sodium caseinate, Tween 20 and β-cyclodextrin

The limit application of functional kenaf (Hibiscus cannabinus L.) seed oil in food and pharmaceutical industry owing to the poor water solubility and low storage stability can be overcome by the development of kenaf seed oil-in-water Pickering nanoemulsions. In this study, oil-in-water Pickering nanoemulsions were produced to investigate its stability by optimising emulsifier mixtures, namely sodium caseinate (SC), Tween 20 (T20) and β-cyclodextrin (β-CD). The interaction effects of SC and T20 on the formation of Pickering nanoemulsions with β-CD was studied and found synergistic effect among them that enhanced the stability of Pickering nanoemulsions. The optimum proportion of emulsifier mixtures obtained by employing simplex centroid mixture design was found to be 57.9% (w/w) SC, 27.6% (w/w) T20, and 14.5% (w/w) β-CD, which produced Pickering nanoemulsion with mean particle size of 155.53 nm, PDI of 0.07 and zeta-potential of −46.67 mV. These experimental values were in accordance with the predicted value, indicating the adequacy of the fitted models. The mixture design was found to be a valuable tool to optimise and study the interaction effects of different components for the development of stable Pickering nanoemulsions.

How to know which food is good for you: bumblebees use taste to discriminate between different concentrations of food differing in nutrient content.

In view of the ongoing pollinator decline, the role of nutrition in bee health has received increasing attention. Bees obtain fat, carbohydrates and protein from pollen and nectar. As both excessive and deficient amounts of these macronutrients are detrimental, bees would benefit from assessing food quality to guarantee an optimal nutrient supply. While bees can detect sucrose and use it to assess nectar quality, it is unknown whether they can assess the macronutrient content of pollen. Previous studies have shown that bees preferentially collect pollen of higher protein content, suggesting that differences in pollen quality can be detected either by individual bees or via feedback from larvae. In this study, we examined whether and, if so, how individuals of the buff-tailed bumblebee (Bombus terrestris) discriminate between different concentrations of pollen and casein mixtures and thus nutrients. Bumblebees were trained using absolute and differential conditioning of the proboscis extension response (PER). As cues related to nutrient concentration could theoretically be perceived by either smell or taste, bees were tested on both olfactory and, for the first time, chemotactile perception. Using olfactory cues, bumblebees learned and discriminated between different pollen types and casein, but were unable to discriminate between different concentrations of these substances. However, when they touched the substances with their antennae, using chemotactile cues, they could also discriminate between different concentrations. Bumblebees are therefore able to discriminate between foods of different concentrations using contact chemosensory perception (taste). This ability may enable them to individually regulate the nutrient intake of their colonies.

A Milk and Ochre Paint Mixture Used 49,000 Years Ago at Sibudu, South Africa.

Gas chromatography/mass spectrometry, proteomic and scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM/EDS) analyses of residue on a stone flake from a 49,000 year-old layer of Sibudu (South Africa) indicate a mixture of ochre and casein from milk, likely obtained by killing a lactating wild bovid. Ochre powder production and use are documented in Middle Stone Age South African sites but until now there has been no evidence of the use of milk as a binder. Our analyses show that this ochre-based mixture was neither a hafting adhesive nor a residue left after treating animal skins, but a liquid mixture consisting of a powdered pigment mixed with milk; in other words, a paint medium that could have been applied to a surface or to human skin. The significance of our finds also lies in the fact that it establishes the antiquity of the use of milk as a binder well before the introduction of domestic cattle in South Africa in the first millennium AD.

Approaches to minimise yoghurt syneresis in simulated tzatziki sauce preparation

The phenomenon of syneresis becomes more profound in increased moisture yoghurt‐based products. Such a product is the traditional Greek appetizer tzatziki that contains cucumber, a vegetable with a high moisture content. During the manufacture of tzatziki, the addition of cucumber causes the protein network to break up, provoking an increase in syneresis. The aim of this study was to investigate a tzatziki manufacturing procedure that will lead to significantly decreased syneresis. Two different manufacturing procedures were compared: the extra moisture coming from cucumber was introduced before or after fermentation. The effect of adding whey protein concentrate (WPC), albumin, sodium caseinate or a mixture of these was also studied. The results show that the addition of extra moisture before yoghurt fermentation leads to a significantly lower syneresis (7.5%) and higher consistency (2000 cp) than those obtained in the case of addition after fermentation (25% and 1500 cp, respectively). The use of albumin, WPC or a mixture of albumin, WPC and sodium caseinate further decreased the phenomenon of syneresis to below 5%, without altering the colour of the product (ΔΕ* &lt; 2.3).

Entrapment of Palm-Based Medium- and Long-Chain Triacylglycerol via Maillard Reaction Products

Maillard reaction products (MRPs) are believed to possess antioxidant property besides producing emulsion which is stable and smaller in size. In our work, utilization of MRP as encapsulating agent for structured lipid palm-based medium- and long-chain triacylglycerol (MLCT) was investigated. The MRP prepared from heated aqueous mixture of sodium caseinate (SC), soy protein (SP) and maltodextrin (M) was emulsified with MLCT prior spray drying. The effect of temperature (20, 40, 60, 80, 100 °C), incubation time (2, 6, 8 h), mixture of SC: SP: M (1:0:1, 2:1:3, 1:1:2, 1:2:3, 0:1:1) and carbohydrate + protein:water ratio (1:5 and 1:8) on glycation was investigated. Degree of glycation (Dg) was determined via amount of block amino acid and L*a*b* value. As expected, increasing heat treatment (20, 40, 60, 80, 100 °C) and incubation time (2, 6 and 8 h) significantly (P < 0.05) increase the Dg. Dg was also higher (P < 0.05) at high water to solid content. Subsequently, the influence of Dg on physical properties of emulsion and spray-dried powder was also evaluated. It was found that glycation has the ability to reduce the emulsion size besides lowering moisture and surface oil content and creating larger microparticle size of the spray-dried powder. Nonetheless, whitening ability and solubility of the powder are slightly reduced especially when 100 °C MRP was used for encapsulation. SEM showed that glycation resulted in particle with smoother surface. MRP can be utilized as natural emulsifier besides improving certain functional properties of spray-dried powder oil.

A novel targeted proteomics method for identification and relative quantitation of difference in nitration degree of OGDH between healthy and diabetic mouse.

For analysis of nitration modification of α oxoglutarate dehydrogenase (α-OGDH) induced by diabetes, a targeted proteomics strategy was developed through the use of Skyline. All peptides containing Y and W of the target proteins were nitrated in silico and output to produce parallel reaction monitoring (PRM) or SRM method for nitration analysis. A nitrated casein mixture was used as standard protein to assess the feasibility of this method. The results demonstrated the availability of this strategy for nitration identification, and subsequently this method was used to analyze the nitration of α-OGDH from myocardial tissue extracts of diabetic mouse. The PRM method was primarily generated by Skyline for identification of the actual nitrated peptides from all possible nitrated peptides of α-OGDH due to the complexity of α-OGDH. The PRM-based data were analyzed by SEQUEST, and transitions of the identified nitrated peptides were used to develop an SRM method for relative quantitation of nitration degree. The nitration degree of α-OGDH for diabetic mouse is higher than that for control mouse, indicating that α-OGDH of the diabetic mouse suffered from more intense oxidative damage. We believe that this approach for obtaining information regarding nitration will facilitate the study of other PTMs in complex mixtures.

Evaluation of fouling mechanisms in asymmetric microfiltration membranes using advanced imaging

This contribution details the use of advanced microscopy to study the fouling of asymmetric polyethersulfone membranes during the microfiltration of protein (casein), polyphenol (tannic acid), and polysaccharide (β-cyclodextrin) mixtures to better understand the solute–solute and solute–membrane interactions leading to fouling. Fluorescently labeled probes were used to visualize the fouling profiles of individual components within the wet membrane structure with confocal laser scanning microscopy (CLSM). Cross-sectional CLSM imaging provided information on the location and extent of fouling throughout the entire thickness of the PES membrane, overcoming the depth of penetration limit observed by researchers in previous studies. Quantitative analysis of the cross-sectional CLSM images provided a measurement of the masses of foulants deposited throughout the membrane. Moreover, flux decline data were collected for different mixtures of casein, tannic acid and β-cyclodextrin (model foulants) and were analyzed with standard fouling models to determine the fouling mechanisms at play when processing different combinations of foulants. Results from model analysis of flux data were compared with the quantitative visual analysis of the correspondent CLSM images. This approach, which couples visual and performance measurements, is expected to provide a better understanding of the causes of fouling that, in turn, is expected to aid in the design of new membranes with tailored structure or surface chemistries that prevent the deposition of the foulants in “prone to foul” regions.

Cross-linking with microbial transglutaminase: Relationship between polymerisation degree and stiffness of acid casein gels

Acid casein in phosphate buffer was used as a simplified substrate for cross-linking experiments with microbial transglutaminase. The importance of the intensity of enzyme treatment on the rheology of acid gels was evaluated by preparing mixtures of casein that were cross-linked to a different extent and a native reference to obtain samples with a similar polymerisation degree. The stiffness of acid gels from caseins incubated longer then 3 h was always lower at identical polymerisation degree larger than approximately 30%. The quantification of isopeptides formed by the enzyme reveals a substantial increase of bonds at a stage of cross-linking where only 10% of monomers are available. This indicates that cross-linking must occur between and/or within already existing aggregates, which become larger and less flexible, and supports the hypothesis that, starting with a critical aggregate size the network formation is somewhat impaired by the size and reduced flexibility of the proteins.

Controlled biopolymer phase separation in complex food matrices containing fat droplets, starch granules, and hydrocolloids

New strategies are needed to create high-quality reduced-calorie foods designed to combat the recent rise in overweight and obesity. In this study, we examined the influence of controlled phase separation and gelation of mixed biopolymer systems on the physical properties of model food matrices containing fat droplets, starch granules, and hydrocolloids. Phase separation of pectin–caseinate mixtures was induced through thermodynamic incompatibility (pH7) followed by electrostatic complexation (pH5), and then gelation was induced by adding calcium ions. The resulting model food matrices consisted of fat droplets, starch granules, and a phase separated biopolymer matrix. Confocal microscopy showed that the fat droplets were located within caseinate-rich hydrogel particles, which were present in the interstitial region around the swollen starch granules. All systems exhibited shear-thinning behavior and had yield stresses that increased with increasing biopolymer and calcium concentration. Swollen starch granules had a greater influence on the rheology of the mixed systems than other components due to their relatively high effective volume fractions, whereas fat droplets had a greater influence on the optical properties due to their stronger light scattering efficiency. Calcium ions increased the apparent viscosity of mixed systems, which was attributed to charge screening and ion-bridging effects. These findings suggest that controlled phase separation and gelation of mixed biopolymer systems have potential to create reduced calorie emulsion-based foods, or products with novel textural characteristics.

Crescimento de juvenis de Piaractus brachypomus alimentados com dietas contendo diferentes perfis de aminoácidos essenciais

O objetivo deste trabalho foi determinar o efeito de dietas com diferentes perfis de aminoácidos essenciais (AAE) sobre a eficiência de utilização de nutrientes e o crescimento de juvenis de pirapitinga (Piaractus brachypomus). Utilizaram-se caseína e gelatina como fontes de proteína, tendo-se formulado nove dietas com concentração de caseína entre 0 e 35%, com incrementos de 4,4% e concomitante diminuição da proporção de gelatina. Determinou-se o perfil de aminoácidos da caseína, da gelatina e de amostras de tecidos do corpo inteiro de juvenis de pirapitinga. Os níveis dietéticos de caseína apresentaram efeito quadrático positivo sobre as variáveis zootécnicas. O escore químico entre o perfil de aminoácidos essenciais das proteínas corpóreas e o perfil das dietas experimentais mostrou que, nas rações com 31,6 e 35% de caseína, o conteúdo de arginina torna-se limitante. O perfil de aminoácidos corporais da pirapitinga foi similar ao padrão de aminoácidos descrito para teleósteos. O perfil de aminoácidos obtido com a mistura de caseína e gelatina à proporção de 8:1 se aproxima do requerido para o crescimento de juvenis de Piaractus brachypomus.