Physicochemical properties of whey protein isolate stabilized oil-in-water emulsions when mixed with flaxseed gum at neutral pH

Concentrations ranging from 0% to 0.33% (w/v) of gum (Emerson and McDuff) were added to the emulsions at pH 7. Particle size distribution, viscosity, ζ-potential, microstructure, and phase separation kinetics of the emulsions were observed. Both polysaccharides and protein coated droplets are negatively charged at this pH, as shown by ζ-potential measurements. At all the concentrations tested, the addition of gum did not affect significantly (p < 0.05) the apparent diameter of the emulsion droplets. At low concentrations (gum  0.075% (w/v)), no visual phase separation was observed and the emulsion showed a Newtonian behaviour. However, at concentrations above the critical concentration of gum, depletion flocculation occurred: when 0.1 flaxseed gum was present, there was visual phase separation over time and the emulsion exhibited shear-thinning behaviour. These results demonstrate that flaxseed gum is a non-interacting polysaccharide at neutral pH; it could then be employed to strengthen the nutritional value of some milk-based drinks, but at limited concentrations.     

Flaxseed gum from flaxseed hulls: Extraction,fractionation, and characterization

Soluble dietary fibre with low viscosity has the potential to deliver acceptable mouthfeel and texture when included in the diet in a significant amount to show health benefits. Soluble flaxseed gum (SFG) was reported to have low viscosity, thus has potential in applications as a fibre fortifier. In the present work, SFG extracted from flaxseed hulls was fractionated into a neutral fraction gum (NFG) and an acidic fraction gum (AFG) using ion exchange chromatography. The protein content in SFG (11.8%) and AFG (8.1%) were completely removed by protease to obtain two more protein-free fractions, SFGnP and AFGnP; NFG contained no protein. The uronic acid content in NFG (1.8%) was mostly eliminated, whereas in AFC increased to 38.7%. NFG consisted of high molecular weight (MW) (1470 kDa) arabinoxylans and exhibited pseudoplastic flow behaviour; whereas AFG was mainly composed of rhamnogalacturonans with a higher MW fraction (1510 kDa) and a lower MW fraction (341 kDa) and showed Newtonian flow behaviour. The ranking of intrinsic viscosities (mL g⁻¹) in decreasing order was: SFG (446.0) > NFG (377.5) > AFG (332.5). AFG was expected to have higher chain flexibility for its lower value of Huggins constant (0.16) compared to that of NFG (0.54) and SFG (0.48). In comparison with SFGnP, AFGnP and NFG, SFG and AFG showed better surface activities and emulsifying stabilities due to the presence of protein in both fractions.     

The effect of addition of flaxseed gum on the emulsion properties of soybean protein isolate (SPI)

The effect of addition of flaxseed gum on the emulsion properties of soybean protein isolate (SPI) were investigated in this study. Flaxseed gum with 0.05-0.5% (w/v) concentration was used together with 1% (w/v) SPI to emulsify 10% (v/v) soybean oil. The emulsion was analyzed for emulsion activity (turbidity), stability, particle size, surface charge, and rheological properties. The turbidity and absolute zeta-potential values decreased initially by the addition of flaxseed gum and subsequently increased with further increase in the gum concentration to reach their peak around 0.35% (w/v) gum. The particle size of the emulsion decreased and reached a minimum value at 0.1% (w/v) gum concentration. Any increase in gum concentration beyond this value resulted into increase in the particle size. This study would help to widen the application of SPI and flaxseed gum mixture, and also contribute to the understanding of protein-gum interaction in emulsion.     

Textural properties and microstructure of low-fat and sodium-reduced meat batters formulated with gellan gum and dicationic salts

Instrumental texture characteristics of low-fat, reduced-sodium meat batters formulated with other salts (KCl and MgCl₂ or CaCl₂) with gellan gum were evaluated. Fat and sodium reduction through incorporation of gellan gum and either of the dicationic salts produced less rigid, more ductile structures. Inclusion of magnesium chloride resulted in better performance, whereas addition of calcium chloride resulted in less desirable properties. The dicationic salts level used probably inhibited the gellan gum thermoreversible properties, affecting its water holding properties. Microstructural differences between the dicationic salt treatments were apparently due to the effect of dicationic salt concentration on myofibrillar protein extraction and solubilization, and gellan gum gelation properties. Use of magnesium chloride in tandem with gellan gum in the studied low-fat, reduced-sodium meat batters effectively compensated for the structural differences caused by fat and sodium reduction.     

Carboxymethyl derivatives of flaxseed (Linum usitatissimum L.) gum: characterisation and solution rheology

Carboxymethyl ether moieties were introduced to flaxseed (Linum usitatissimum L.) gum (FG) by reacting gum with monochloroacetic acid (MCA). Effects of ether forming reaction conditions, temperature, NaOH concentration and molar ratio of FG (anhydroxylose equivalent) to MCA, on the degree of substitution (DS) were investigated. Treatment at 70 °C, with 7.0 m NaOH, and molar ratio of MCA to FG of 10:1 over 3 h produced a polysaccharide with a DS of 0.824 ± 0.012. Both surface morphology and thermal behaviour were modified. Solutions of FG (0.5–4.0%, w/v) exhibited shear‐thinning behaviour where viscosity decreased with decreased FG concentration. After carboxymethylation, modified polymer solutions also exhibited shear‐thinning behaviour, where dynamic viscosity was lower than that of native FG solutions at the same concentration. The dynamic viscosities were lower for solutions of modified FG with higher DS and also lower for solutions made at lower FG concentrations (0.5–4.0%, w/v). A more liquid‐like behaviour with increasing FG DS was indicated as storage modulus G′ and loss modulus G″ decreased and became more frequency dependent. The substitution of hydroxyl groups with carboxymethyl groups suppressed entanglement between FG polysaccharide chains by reducing intermolecular association.     

Effects of protein level and fat/oil on emulsion stability,texture, microstructure and color of meat batters

Beef meat batters formulated with increasing protein level (10–15%) and containing 25% beef fat were compared to batters prepared with 25% canola oil. Emulsion stability of the canola oil treatments was higher (less separation during cooking) at the 10–13% protein level compared to the beef fat treatments. However, above 13% protein this was reversed and the canola oil treatments showed high fat and liquid separation, which did not occur at all in the beef fat treatments. This indicates differences in stabilization of fat versus oil in such meat emulsions. Hardness of the cooked meat batters showed significantly (P < 0.05) higher values when the protein level was raised, and was higher in canola oil than in beef fat meat emulsions at similar protein levels. Products’ chewiness were higher in the canola oil treatments compared to the beef fat emulsions. Lightness decreased and redness increased in canola oil batters as the protein level was raised. The micrographs revealed the formation of larger fat globules in the beef fat emulsions compared to the canola oil meat emulsions. The canola oil treatment with 14% protein started to show fat globule coalescence, which could be related to the reduced emulsion stability.     

Restructured beef with different proportions of walnut as affected by meat particle size

Microstructure, texture, colour and sensory properties of precooked restructured beef made with different proportions of walnut (0, 5, 10, 15%) were studied in relation to meat particle size (grinder plate hole: 0.6 and 1.4 cm). In general, increasing amounts of walnut were matched by decreasing Kramer shear force (KSF), bind strength and elongation values. When walnut (5 and 15%) was added, products made with coarsely ground meat presented higher KSF values than those made with finely ground meat. Walnut decreased lightness and increased redness and yellowness. Morphology characteristics suggest that walnut interferes with the formation of a gel protein network. Sensory properties were judged acceptable with 5 and 10% of walnut; however, the products scored highest with 10% walnut in finely ground products and 5% walnut in coarsely ground products.     

海藻酸钠和黄原胶糊料粘弹性行为的研究

通过稳态剪切和小幅振荡剪切应力扫描试验,研究了海藻酸钠和黄原胶糊料的粘弹性能.结果表明:与海藻酸钠相比,黄原胶在低用量、低剪切速率下就具有高粘度,表现出显著的假塑型流体"剪切变稀"特征.海藻酸钠以粘性效应为主,表现出较多的类液态特征,而黄原胶以弹性效应为主,表现出较多的类固态特征.随着剪切应力的增加,海藻酸钠的粘弹性能比较稳定,损耗模量始终大于储能模量,损耗角大于45°,主要表现出粘性行为;黄原胶的粘弹性能经历了由高弹性向粘性转变的突变区,在突变之前其储能模量大于损耗模量,损耗角小于45°,表现出很显著的弹性行为.     

Rheological and structural characterization of gels from whey protein hydrolysates/locust bean gum mixed systems

The gelling ability of whey proteins can be changed by limited hydrolysis and by the addition of other components such as polysaccharides. In this work the effect of the concentration of locust bean gum (LBG) on the heat-set gelation of aqueous whey protein hydrolysates (10% w/w) from pepsin and trypsin was assessed at pH 7.0. Whey protein concentrate (WPC) mild hydrolysis (up to 2.5% in the case of pepsin and 1.0% in the case of trypsin) ameliorates the gelling ability. The WPC synergism with LBG is affected by the protein hydrolysis. For a WPC concentration of 10% (w/w), no maximum value was found in the G′ dependence on LBG content in the case of the hydrolysates, unlike the intact WPC. However, for higher protein concentrations, the behaviour of gels from whey proteins or whey protein hydrolysates towards the presence of LBG becomes very similar. In this case, a small amount of LBG in the presence of salt leads to a big enhancement in the gel strength. Further increases in the LBG concentration led to a decrease in the gel strength.     

Effect of concentrated flaxseed protein on the stability and rheological properties of soybean oil-in-water emulsions

Flaxseed protein concentrate containing-mucilage (FPCCM) was used to stabilize soybean oil-in-water emulsions. The effects of FPCCM concentration (0.5, 1.0, 1.5% w/v) and oil-phase volume fraction (5, 10, 20% v/v) on emulsion stability and rheological properties of the soybean oil-in-water emulsions were investigated. Z-average diameter, zeta-potential, creaming index and rheological properties of emulsions were determined. The result showed that FPCCM concentration significantly affected zeta-potential, creaming rate and emulsion viscosity. The increasing of FPCCM concentration led to a more negative charged droplet and a lower creaming rate. Oil-phase volume fraction significantly affected Z-average diameter, rheological properties, creaming index and creaming rate. With the increase of oil-phase volume fraction, both Z-average diameter and emulsion viscosity increased, while creaming index and creaming rate decreased. The rheological curve suggested that the emulsions were shear-thinning non-Newtonian fluids.     

Variation of composition and functional properties of gum from six Canadian flaxseed (Linum usitatissimum L.) cultivars

Flaxseed gum (FG) was prepared from six Canadian flaxseed (Linum usitatissimum L.) cultivars. Yield, neutral sugar content, acidic sugar content and protein content varied significantly among cultivar FG extracts. Zeta potential (?16.4 to ?27.4 mV) and rheological properties of solution were cultivar dependent. Solutions prepared with CDC Glas FG had the highest viscosity (2.984 Pa?s), while CDC Sorrel produced the lowest (0.048 Pa?s). FG solutions exhibited pseudoplastic shear‐thinning behaviour. Viscosity of FG solution increased with concentration, while viscosity and pseudoplasticity decreased with increased temperature. NaCl addition decreased solution viscosity while adding sucrose increased viscosity. FG solutions prepared from Flanders and CDC Sorrel had the highest and lowest emulsion activity index, respectively, while solutions of CDC Arras and CDC Bethune FG had the lowest and highest emulsion stability, respectively. Findings presented here provide information that could enable greater utilisation in food, cosmetic and pharmaceutical industries as thickeners and/or emulsifiers.     

Influence of tragacanth gum exudates from specie of Astragalus gossypinus on rheological and physical properties of whey protein isolate stabilised emulsions

The aim of this work was to investigate the effects of Iranian tragacanth gum (Astragalus gossypinus) (0.5, 1 wt.%), Whey protein isolate (WPI) (2, 4 wt.%) and acid oleic‐phase volume fraction (5, 10% v/v) on droplet size distribution, creaming index and rheological properties of emulsions with various compositions. Rheological investigations showed that both loss and storage modules increased with gum and oil contents. However, the viscoelastic behaviour was mainly governed by the gum concentration. Delta degree (storage and loss modules ratio) increased with frequency indicated that liquid like viscose behaviour dominates over solid like elastic behaviour. The shear‐thinning behaviour of all dispersions was successfully modelled with power law and Ellis models and Ellis model was founded as the better model to describe the flow behaviour of dispersions. Droplet size distribution was measured by light scattering; microscopic observations revealed a flocculated system. Increase in gum, WPI and oil contents resulted in decrease in creaming index of emulsions with dominant effect of gum concentration.     

Thermophysical properties of processed meat and poultry products

Thermophysical properties of various meat and poultry emulsions were evaluated at four temperatures (20, 40, 60 and 80 °C). Thermal conductivities (0.26–0.48 W m⁻¹ K⁻¹) increased linearly with temperature between 20 and 60 °C. Between 60 and 80 °C, it remained constant for most products except bologna. Curves for thermal conductivity as a function of temperature could be roughly grouped into two different categories: products containing meat particles and those containing meat emulsions. The application of various models was investigated for thermal conductivity prediction. It was found that a three phase structural based Kirscher model had the potential for predicting thermal conductivities with acceptable accuracy. Densities decreased slightly as a function of temperature from 20 to 40 °C. A transition phase was observed from 40 to 60 °C, which was followed by a decrease from 60 to 80 °C. There was a decrease of about 50 kg m⁻³ between the density of a raw product at room temperature (at maximum 1070 kg m⁻³) and the product heated to 80 °C (at minimum 970 kg m⁻³), due to the gelation or setting of the structure. After a transition period from 10 to 30 °C, the heat capacity increased linearly from 30 to 80 °C, and ranged from 2850 to 3380 J kg⁻¹ °C⁻¹, respectively. Densities and heat capacities were strongly influenced by the carbohydrate content (i.e. as the carbohydrate content increased the density decreased). The salt content adversely affected thermal conductivity and thermal diffusivity values. However, these parameters increased with moisture content.     

Low molecular weight flaxseed protein-derived arginine-containing peptides reduced blood pressure of spontaneously hypertensive rats faster than amino acid form of arginine and native flaxseed protein

Flaxseed protein isolate (FPI) contains high amount of arginine, which plays important physiological roles especially as nitric oxide precursor in the vascular endothelium. Arginine-rich peptides can be generated from FPI and used as a source of nitric oxide, which can produce in vivo vasodilatory effects during hypertension. Enzymatic hydrolysis of FPI with trypsin and pronase resulted in a hydrolysate that was fractionated using electrodialysis-ultrafiltration (EDUF). EDUF experiment resulted in migration of peptides to the anionic and cationic recovery compartments. Compared to FPI with 11% arginine, about one-third of the cationic fraction was composed of arginine. Thirteen potential peptide sequences were identified to be present in the cationic compartment of which 12 contained at least one arginine residue. None of the peptides identified from the anionic compartment contained arginine. Oral administration of the cationic peptides (200 mg/kg body wt.) to spontaneously hypertensive rats resulted in a more rapid decrease in systolic blood pressure when compared to similar amounts of FPI or the amino acid form of arginine. It was concluded that the rapid effect of the arginine-rich peptide product suggests faster rate of peptide absorption than amino acids and this may be exploited to provide fast relief from hypertension.     

Interactions between milk proteins and gellan gum in acidified gels

The mechanical properties, microstructure and water holding capacity of systems formed from whey protein concentrate (0–3% WPC w/w), sodium caseinate (0–2% w/w), and gellan gum (0.1–0.3% w/w) in the coil or helix conformational state (Coil/Helix), were investigated. This polymer combination resulted in bi-polymeric or tri-polymeric systems, which were slowly acidified to pH 4.0 by the addition of GDL in order to favor electrostatic protein–polysaccharide interactions. The properties of the tri-polymeric systems differed considerably from the bi-polymeric ones. At high polymer concentrations the WPC-gellan samples showed incompatibility and microphase separation, which resulted in weaker and less deformable gels. However, in systems with coil gellan the incompatibility was less intense, which was attributed to the formation of electrostatic complexes between the protein and the polysaccharide during the mixing process. In caseinate–gellan systems, complex formation was observed and an increase in the gel mechanical properties as the caseinate concentration rose, although the water holding capacity decreased at higher gellan concentrations. The caseinate–gellan coacervate was not visualized in the tri-polymeric systems and the incompatibility between the biopolymers was intensified, although the mechanical properties were considerably higher than in the bi-polymeric gels.     

Thermal gelation of meat batters as a function of type and level of fat and protein content

The rheological behaviour of meat batters during heating was analysed as a function of protein level (10–16%), type (pork back or perirenal/peritoneal fat) and amount (10–22%) of fat used. Fat thermal behaviour was studied by differential scanning calorimetry and rheological properties of batters were assessed using non-destructive measurements (thermal scanning rigidity monitor). The higher the protein content, the higher were the rigidity values displayed by the batters, irrespective of fat type, although the magnitude of these values appeared to be dependent on the amount and characteristics of the fat. The lower the fat content, the lower were the rigidity values of the batters. This behaviour pattern was influenced by the amount of protein present. In general, samples containing perirenal/peritoneal fat exhibited lower rigidity values at high temperatures, whereas at less than 35–40 °C, the opposite appeared to be the case.     

Physicochemical and textural properties of heat-induced pea protein isolate gels

Chemical and thermal properties of pea protein isolates (laboratory prepared or native; PPIn and commercial; PPIc) and textural properties of heat-set gels obtained from pea protein isolates were compared with homologous soy protein isolates (laboratory prepared, or native; SPIn and commercial; SPIc). The protein banding pattern resulting from electrophoresis separation confirmed the presence of predominant storage proteins of pea and soy seeds in the respective protein products. PPIc and SPIc had lower nitrogen solubility than their native counterparts, likely due to their denaturated state which was further confirmed by the absence of distinct endotherms in these commercial materials compared to the laboratory prepared ones. Addition of NaCl at 1.0–2.0% (w/w) to PPIn and SPIn slurries increased thermal transition temperatures for both proteins.     

Effect of chloride salts on protein extraction and interfacial protein film formation in meat batters

Six comminuted chicken breast meat mixes and six meat batters were made with isoionic NaCl (25 g kg^?1), MgCl₂, CaCl₂, KCl, LiCl (IS = 0.43) and 15 g kg^?1 NaCl (IS = 0.26). The quantity and type of proteins extracted and used for interfacial protein film (IPF) formation was determined and related to batter stability. The monovalent salts produced IPF which differed in individual protein content between salts but which all contained significantly larger amounts of protein (P < 0.01) than those using divalent salts. MgCl₂ extracted more protein than CaCl₂ and produced a different protein profile in the IPF. However, MgCl₂ formed unstable raw batters whereas CaCl₂ did not. In addition, a simple, rapid method for extracting and quantifying proteins from meat batters was developed to assist in direct determination of the actual soluble protein uptake by the fat phase during comminution.     

A review of meat protein hydrolysates and hypertension

We tested the hypothesis that meat is a source of peptides that are effective at preventing and reducing chronic lifestyle-related diseases (CLSRDs) such as hypertension. This analysis reflects the importance of empowering hypertensive people in quality versus quantity of life issues, and in offering nutritional treatment options rather than medical alternatives. For both hypertensive and normotensive individuals, chemically based medications may have harmful side effects. Functional food rich in antioxidant vitamins, and proteins or biologically active peptides, can lower blood pressure in persons with essential hypertension, possibly by preventing an underlying cause of the condition. Deficiency in consumption of crucial nutrients such as proteins from meat origins, along with abnormalities in carbohydrate and fat metabolism, may underlie the etiology of the clinical course of hypertension. Food derived from meat rich in nutrients may provide physiologically functional peptides, as well as improve digestion, and the metabolism of carbohydrate and fats, thus lowering blood pressure, and normalizing associated biochemical and histopathological changes.     

亚麻籽胶与肉蛋白相互作用的研究

采用差示扫描量热仪分别测定了添加与不添加亚麻籽胶的肉蛋白、肌原纤维蛋白和盐溶肉蛋白的变性温度 ,用AR1 0 0 0流变仪和TPA全质构分析仪分别测定了盐溶肉蛋白以及添加亚麻籽胶的盐溶肉蛋白的动态流变性质和凝胶的硬度 ,结果表明 ,亚麻籽胶与肉蛋白、肌原纤维蛋白、盐溶肉蛋白发生了相互作用