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1.
Microencapsulating properties of sodium caseinate   总被引：5，自引：0，他引：5  
Emulsions were prepared with 5% (w/v) solutions of sodium caseinate (Na Cas) and soy oil at oil/protein ratios of 0.25-3.0 by homogenization at 10--50 MPa. Emulsions were spray-dried to yield powders with 20--75% oil (w/w). Emulsion oil droplet size and interfacial protein load were determined. Microencapsulation efficiency (ME), redispersion properties, and structure of the powders were analyzed. The size of emulsion oil droplets decreased with increasing homogenization pressure but was not influenced by oil/protein ratio. Emulsion protein load values were highest at low oil/protein ratios. ME of the dried emulsions was not affected by homogenization pressure but decreased from 89.2 to 18.8% when the oil/protein ratio was increased from 0.25 to 3.0, respectively. Mean particle sizes of reconstituted dried emulsions were greater than those of the original emulsions, particularly at high oil/protein ratios (>1.0), suggesting destabilization of high-oil emulsions during the spray-drying process.  相似文献   

2.
6-O-Palmitoyl L-ascorbate was added to linoleic acid at various molar ratios of the ascorbate to the acid, the mixtures were emulsified with a maltodextrin or gum arabic solution, and the emulsions were spray-dried to produce microcapsules. At higher molar ratios, the oil droplets in the emulsions were smaller, and the oxidative stabilities of the encapsulated linoleic acid were higher for both the maltodextrin- and gum arabic-based microcapsules. 6-O-Capryloyl, caproyl, and lauroyl L-ascorbates, which were synthesized through lipase-catalyzed condensation in acetone, were also used for the microencapsulation of linoleic acid. Except for capryloyl L-ascorbate, the addition of a saturated acyl ascorbate, especially caproyl ascorbate, to linoleic acid was effective for preparing oil droplets of small particle diameter and for suppressing the oxidation of the encapsulated linoleic acid.  相似文献   

3.
The effect of different polysaccharides on the rotational (D(rot)) and translational diffusion (D(trans)) coefficients of small molecules in concentrated systems (sucrose solutions) was investigated. Dextran (1 or 10% w/w) with different molecular masses (from 10(4) to 2 x 10(6) Da), gum arabic, or pullulan was added to solutions of sucrose (57.5% w/w). Viscosity measurements of the diffusion medium studied (sucrose and sucrose plus polysaccharide) were made using a Rheometric Scientific viscometer in a temperature range from 20 to -10 degrees C. The rotational mobility of nitroxide radicals (Tempol) dispersed in the concentrated systems was measured by electron spin resonance. The translational diffusion coefficient of fluorescein was determined by the fluorescence recovery after photobleaching method. The studied temperature range for the latter two techniques was from 20 to -16 degrees C. For these conditions of concentration and temperature, there was no ice formation in the samples. No effect of the molecular mass of dextran on D(rot) and D(trans) was observed when solutions with the same dry matter content were compared. Only pullulan and gum arabic, at 10%, had a significant effect on D(trans)( )()of fluorescein. Temperature and total dry matter content were observed to be the most important factors controlling D(rot) and D(trans) in these concentrated systems.  相似文献   

4.
The ability of sugar beet pectin to stabilize 20% w/w limonene oil-in-water emulsions has been investigated. The size of the oil droplets as determined by laser diffraction measurements decreased from about 15 mum to about 6 mum when the pectin concentration increased from 0.05% to 2% w/w but leveled off thereafter, suggesting complete coverage of the oil droplets by the polymer at this optimum concentration. Isotherms for the adsorption of pectin, protein, and ferulic acid were constructed. The adsorption capacities at the oil-water interface of approximately 1.4 and approximately 0.2 mg/m (2) for protein and ferulic acid, respectively, compared to approximately 9.5 mg/m (2) for pectin revealed that the adsorbed fractions of the pectin sample were rich in protein (14.7%) and ferulic acid (2.1%) given that there were only 2.7% protein and 1.06% ferulic acid present in the whole pectin sample. Direct measurements on the adsorbed fraction recovered from the oil droplets via desorption with SDS confirmed that it contained 11.1% protein and 2.16% ferulic acid. The results suggest that one or both of these two functional groups adsorb onto the surface of the oil droplets and stabilize the emulsions. High molecular mass fractions adsorbed preferentially onto oil droplets during emulsification. As compared to those made with gum arabic, the emulsion samples made with sugar beet pectin samples exhibited similar (or even slightly higher) stability.  相似文献   

5.
The stability and rheology of acidified model oil-in-water emulsions (pH 3.6 +/- 0.1) were evaluated before and after high-pressure treatments. Varying concentrations of canola oil (0-50% w/w), whey protein isolate, polysorbate 60, soy lecithin (0.1-1.5% w/w each), and xanthan (0.0-0.2% w/w) were chosen. Exposure to high pressures (up to 800 MPa for 5 min at 30 degrees C) did not significantly affect the equivalent surface mean diameter D[3,2], flow behavior, and viscoelasticity of the whey protein isolate and polysorbate 60-stabilized emulsions. Pressure treatments had negligible effects on emulsion stability in these systems, except when xanthan (0.2% w/w) was present in which pressure improved the stability of polysorbate 60-stabilized emulsions. Soy lecithin-stabilized emulsions had larger mean particles sizes and lower emulsion volume indices than the others, indicating potential instability, and application of pressure further destabilized these emulsions.  相似文献   

6.
The influence of chelating agents (disodium ethylenediaminetetraacetate (EDTA) and sodium citrate) on the physicochemical properties of whey protein isolate (WPI)-stabilized oil-in-water emulsions containing calcium chloride was determined. The calcium-binding characteristics of EDTA and citrate at 30 degrees C were characterized in aqueous solutions (20 mM Tris buffer, pH 7.0) by isothermal titration calorimetry (ITC). EDTA and citrate both bound calcium ions in a 1:1 ratio, but EDTA had a much higher binding constant. Oil-in-water emulsions (pH 7.0) were prepared containing 6.94% (w/v) soybean oil, 0.35% (w/v) WPI, 0.02% (w/v) sodium azide, 20 mM Tris buffer, 10 mM CaCl(2), and 0-40 mM chelating agent. The particle size, apparent viscosity, creaming stability, free calcium concentration, and particle surface potential of the emulsions were measured. The chelating agents reduced or prevented droplet aggregation in the emulsions. When they were present above a certain concentration (>3.5 mM EDTA or >5 mM citrate), droplet aggregation was prevented. The reduction of aggregation was indicated by decreases in particle size, shear-thinning behavior, apparent viscosity, and creaming. Emulsions containing chelating agents had lower free calcium concentrations and more negatively charged droplets, indicating that the chelating agents improved emulsion stability by binding calcium ions. EDTA could be used at lower concentrations than citrate because of its higher calcium ion binding constant.  相似文献   

7.
The potential of utilizing interfacial complexes, formed through the electrostatic interactions of proteins and polysaccharides at oil-water interfaces, to stabilize model beverage cloud emulsions has been examined. These interfacial complexes were formed by mixing charged polysaccharides with oil-in-water emulsions containing oppositely charged protein-coated oil droplets. Model beverage emulsions were prepared that consisted of 0.1 wt % corn oil droplets coated by beta-lactoglobulin (beta-Lg), beta-Lg/alginate, beta-Lg/iota-carrageenan, or beta-Lg/gum arabic interfacial layers (pH 3 or 4). Stable emulsions were formed when the polysaccharide concentration was sufficient to saturate the protein-coated droplets. The emulsions were subjected to variations in pH (from 3 to 7), ionic strength (from 0 to 250 mM NaCl), and thermal processing (from 30 or 90 degrees C), and the influence on their stability was determined. The emulsions containing alginate and carrageenan had the best stability to ionic strength and thermal processing. This study shows that the controlled formation of protein-polysaccharide complexes at droplet surfaces may be used to produce stable beverage emulsions, which may have important implications for industrial applications.  相似文献   

8.
The mechanical properties, water-holding capacities (WHC), and microstructures of emulsion gels, induced by glucono-δ-lactone (GDL), CaCl(2), and microbial transglutaminase (MTGase) from unheated and heated soy protein isolate (SPI)-stabilized emulsions (at protein concentration 5%, w/v; oil volume fraction, 20%, w/v), were investigated and compared. The influence of thermal pretreatments (at 90 °C for 5 min) before and/or after emulsification was evaluated. Considerable differences in mechanical, water-holding, and microstructural properties were observed among various emulsion gels. The thermal pretreatment after emulsification increased the strength of the emulsion gels induced by GDL and CaCl(2), whereas in the case of MTGase, thermal pretreatments before and/or after emulsification on the contrary greatly inhibited gel network formation. The application of the enzyme coagulant exhibited much higher potential to form SPI-stabilized emulsion gels with higher mechanical strength than that of the other two coagulants. The WHC of the emulsion gels seemed to be not directly related to their gel network strength. Confocal laser scanning microscope analyses indicated that the network microstructure of the formed emulsion gels, mainly composed of aggregated protein-stabilized oil droplets and protein aggregate clumps, varied with the type of applied coagulants and emulsions. The differences in microstructure were basically consistent with the differences in mechanical properties of the gels. These results could provide valuable information for the formation of cold-set soy protein-stabilized emulsion gels.  相似文献   

9.
The objective of this study was to examine the effects of added xanthan gum, guar gum, or kappa-carrageenan on the formation and properties of emulsions (4 wt % corn oil) formed with an extensively hydrolyzed commercial whey protein (WPH) product under a range of conditions. The rate of coalescence was calculated on the basis of the changes in the droplet size of emulsions during storage of the emulsions at 20 degrees C. Compared with the emulsion made without the addition of polysaccharides, the rate of creaming and coalescence in emulsions containing xanthan gum, guar gum, or kappa-carrageenan was markedly enhanced with increasing concentration of polysaccharides during storage for up to 7 days. At a given concentration, the rate of coalescence was highest in the emulsions containing guar gum, whereas it was lowest in the emulsions containing kappa-carrageenan. All emulsions containing xanthan gum, guar gum, or kappa-carrageenan showed flocculation of oil droplets by a depletion mechanism. This flocculation was considered to enhance the coalescence of oil droplets. The different rates of coalescence could be explained on the basis of the strength of the depletion potential, which was dependent on the molecular weight and the radius of gyration of the polysaccharides.  相似文献   

10.
复配亚麻籽油和辅酶Q10乳液的制备及表征   总被引：1，自引：1，他引：0  
亚麻籽油和辅酶Q10都具有水中溶解度低、稳定性差、生物利用度低等缺点。将亚麻籽油和辅酶Q10(coenzyme Q10,CoQ10)同时负载于乳液中,可解决两者的应用瓶颈。使用阿拉伯胶为乳化剂,采用高压均质法制备复配亚麻籽油和CoQ10乳液。采用动态光散射、透射电子显微镜、体外模拟消化、体外释放、稀释稳定性、冻融稳定性、离子强度稳定性、光稳定性和加速氧化稳定性方法对所制备乳液的理化性质进行表征。结果显示,制备的乳液平均粒径为(284±5.6) nm,多分散指数(polydispersity index,PDI)为0.112±0.025,为均匀分散的球形液滴。制备的乳液在模拟小肠液中消化,和亚麻籽油、CoQ10混悬液相比,乳化后亚麻籽油的消化速率和CoQ10的生物可给率明显提高。乳液中CoQ10的释放表现出缓释效果。制备的乳液具有较好的稀释和冻融稳定性。Na^+和Ca^2+会造成乳液Zeta电位的下降,对乳液稳定性影响较大。乳液载体化后CoQ10的光稳定性得到了提高。CoQ10对亚麻籽油具有较好的保护作用。  相似文献   

11.
Oil-in-water emulsions (4 wt % soy oil) containing 4 wt % whey protein hydrolysate (WPH) (27% degree of hydrolysis) and different levels of calcium, magnesium, or potassium chloride were prepared in a two-stage homogenizer. Other emulsions containing 4 wt % WPH but including 0.35 wt % hydroxylated lecithin and different levels of the above minerals were similarly prepared. The formation and stability of these emulsions were determined by measuring oil droplet size distributions using laser light scattering and by confocal scanning laser microscopy and a gravity creaming test. Both lecithin-free and lecithin-containing emulsions showed no change in droplet size distributions with increasing concentration of potassium in the range 0-37.5 mM. In contrast, the diameter of emulsion droplets increased with increasing calcium or magnesium concentration >12.5 mM. Emulsions containing hydroxylated lecithin were more sensitive to the addition of calcium or magnesium than the lecithin-free emulsions. Storage of emulsions at 20 degrees C for 24 h further increased the diameter of droplets and resulted in extensive creaming in emulsions containing >25 mM calcium or magnesium. It appears that both flocculation and coalescence processes were involved in the destabilization of emulsions induced by the addition of divalent cations.  相似文献   

12.
《Cereal Chemistry》2017,94(3):640-642
Rice kernels were steeped (10°C, 5 h) in an aqueous solution containing gum arabic (0.36%) and xanthan (0.24%) and then drained, wet‐milled, and steamed to prepare rice cakes. The cakes were then frozen (–40°C for 50 min). The effect of the gum addition on the textural properties of the cakes during storage for 46 h at 25°C after being thawed was examined. Using the combination of gum arabic and xanthan mitigated the quality deterioration of rice cakes such as aggregation of rice flour, which had been induced by xanthan alone. Also, the increase in hardness during storage was substantially reduced by soaking rice kernels in the gum arabic/xanthan solution. Overall results revealed that the steeping in the gum solution improved the storage stability of rice cakes.  相似文献   

13.
Catastrophic phase inversion (CPI) was used as a low-energy emulsification method to prepare oil-in-water (O/W) nanoemulsions in a lipid (Acetem)/water/nonionic surfactant (Tween 60) system. CPIs in which water-in-oil emulsions (W/O) are transformed into oil-in-water emulsions (O/W) were induced by changes in the phase ratio. Dynamic phase inversion emulsification was achieved by slowly increasing the water volume fraction (fw) to obtain O/W emulsions from water in oil emulsions. Composition and processing variables were optimized to minimize droplet size and polydispersity index (PdI). It was found that addition of the continuous phase to the dispersed phase following the standard CPI procedure resulted in the formation of oil droplets with diameters of 100-200 nm. Droplet size distribution during CPI and emulsification time depended on stirring speed and surfactant concentration. Droplet sizes in the inverted emulsions were compared to those obtained by direct emulsification: The process time to reach droplet sizes of around 100 nm was reduced by 12 times by using CPI emulsification. The Acetem/water nanoemulsion was also used as a carrier to incorporate oregano and cinnamon essential oils into soy protein edible films. The resulting composite films containing oregano oil showed better moisture barrier and mechanical properties compared to soy protein films.  相似文献   

14.
Guar gum, a nonionic galactomannan, is used as an economical thickener and stabilizer in the food industry and is often combined with xanthan, locust bean gum (LBG), or carboxymethylcellulose (CMC) to promote synergistic changes in viscosity or gelling behavior via intermolecular interactions; however, the adulteration of LBG with guar gum is a well-known industrial problem. The ability to identify the purity of gums and concentrations of individual gums in mixtures would be advantageous for quality control in the food industry. Fourier transform infrared spectroscopy (FTIR) methods are rapid and require minimum sample preparation. The objectives of this study were to evaluate the ability of FTIR techniques to (1) differentiate LBG with a variety of mannose/galactose (M/G) ratios, (2) differentiate guar, LBG, tara, and fenugreek gums, (3) differentiate pure guar gum from guar gum mixed with LBG, xanthan gum, or CMC, (4) quantify LBG, xanthan gum, and CMC in guar gum, and (5) quantify guar gum in LBG. Two FTIR methods were used: diffuse reflectance (DRIFT) on powdered gum samples added to KBr at 5%, w/w, and attenuated total reflectance (ATR) on 1%, w/w, gum solutions. Spectra were collected and then analyzed by multivariate statistical procedures (chemometrics). The DRIFT method provided better discrimination and quantitative results than the ATR method. Canonical variate analysis (CVA) of DRIFT spectra (1200-700 cm(-1)) was able to classify LBG with various M/G ratios, pure galactomannans, and pure versus mixtures of gums with 100% accuracy. Quantification of an individual gum in gum mixtures (0.5-15%, w/w) was possible using partial least-squares (PLS) analysis of DRIFT spectra with R2 > 0.93 and using this approach for quantifying guar gum added to LBG resulted in an R2 > 0.99, RMSEC = 0.29, and RMSEP = 3.31. Therefore, the DRIFT FTIR method could be a useful analytical tool for quality control of select gums and gum mixtures used in the food industry.  相似文献   

15.
The stabilities of orange oil emulsions stabilized with various concentrations of two different types of corn fiber gum (CFG-1 and 2) isolated from coarse (pericarp) and fine (endosperm) fiber from corn wet milling have been studied. The emulsion stabilities in all these studies increased with increasing gum concentration up to a gum-to-oil ratio of 0.05, and after that it either levels off or changes very slightly. These results indicate that only 0.25% of CFG is required to make stable emulsion containing 5% orange oil under the experimental conditions used in this study. At this CFG concentration, CFG-2 from each fiber source was found to be a superior emulsifier relative to the corresponding CFG-1 from each source in a 10-day emulsion stability study at room temperature. The emulsion stability was also investigated by confocal laser scanning microscopy measurement, and it was found that CFG-1 and 2 from both coarse and fine fiber made stable emulsions with an average particle size of less than 1 mum for 10 days at room temperature. Sugar composition analysis of CFGs from both sources indicated that they were typical galactoglucuronoarabinoxylans containing mainly 55-59% xylose, 29-36% arabinose, and 4-6% galactose as neutral sugars and 3-5% glucuronic acid. Methylation analysis revealed a highly branched structure of all CFGs, in which only 16-25% of the 1--> 4-linked xylose residues were not substituted at O-2 and/or O-3. Arabinose is present both as a terminal residue and at branch points.  相似文献   

16.
The structural characteristics of the gum exudate of Acacia senegal (gum arabic) have been investigated by monitoring the composition and physicochemical properties before and after treatment with proteolytic enzyme and various alkaline systems. Molecular mass ( M w) and radius of gyration ( R g) measurements were performed using gel permeation chromatography (GPC) coupled to refractive index, UV absorbance, and multiangle light scattering detectors and indicated that the macromolecules present have a compact structure. It was found that treatment with proteolytic enzyme caused the arabinogalactan-protein component (AGP) with average molecular mass approximately 2 x 10 (6) Da to degrade, yielding material of molecular mass approximately 4 x 10 (5) Da, whereas the bulk of the material corresponding to the protein-deficient arabinogalactan component (AG) with molecular mass 4 x 10 (5) remained unaffected. Barium hydroxide was found to hydrolyze the polysaccharide component (AG) itself in addition to the proteinaceous component as demonstrated in control experiments using dextran. However, sodium borohydride/sodium hydroxide treatments were unable to hydrolyze dextran and were assumed to hydrolyze only the proteinaceous component of gum arabic. The AGP component was completely degraded, yielding material of molecular mass approximately 4.5 x 10 (4) Da. It has been concluded, therefore, that the enzyme did not fully hydrolyze all of the protein present and that the AGP component of gum arabic consists of carbohydrate blocks of approximately 4.5 x 10 (4) Da linked to a polypeptide chain consistent with the wattle blossom structure. Because the AGP was degraded to differing extents using a mild and more severe sodium borohydride/sodium hydroxide treatment, it was concluded that the polysaccharide moieties were linked through both O-serine and O-hydroxyproline residues. The gum arabic sample was deglycosylated by treatment with anhydrous hydrogen fluoride and revealed the presence of two putative core proteins of approximately 3 x 10 (4) and approximately 5 x 10 (3) Da, respectively, which correspond to proteins of approximately 250 and 45 amino acids in length. A new model for the structure of the AGP component has been proposed.  相似文献   

17.
The phenolic fractions released during hydrothermal treatment of selected feedstocks (corn cobs, eucalypt wood chips, almond shells, chestnut burs, and white grape pomace) were selectively recovered by extraction with ethyl acetate and washed with ethanol/water solutions. The crude extracts were purified by a relatively simple adsorption technique using a commercial polymeric, nonionic resin. Utilization of 96% ethanol as eluting agent resulted in 47.0-72.6% phenolic desorption, yielding refined products containing 49-60% w/w phenolics (corresponding to 30-58% enrichment with respect to the crude extracts). The refined extracts produced from grape pomace and from chestnut burs were suitable for protecting bulk oil and oil-in-water and water-in-oil emulsions. A synergistic action with bovine serum albumin in the emulsions was observed.  相似文献   

18.
Gum arabic from Acacia senegal is commonly used as an additive in foodstuffs. Adulteration of gum arabic by other gums is a potential problem for reasons of safety and quality. This study aimed to develop and evaluate the use of enzyme-linked immunosorbent assays (ELISAs) for the detection of potential adulterants of gum arabic. Indirect competitive ELISAs (IC-ELISAs) were developed using the monoclonal antibodies SY CC7 (A. senegal), SY HH3 (Acacia seyal), and SY J1A1 (Combretum erythrophyllum). All IC-ELISAs had a working range of 0.005-10 mg/mL. The antibodies used were tested using the IC-ELISAs for cross-reactivity with other Acacia species and other gums. The antibodies were very specific for their respective antigens. Significant cross-reactivity was found for SY CC7 (between A. senegal and A. melliferae) and SY J1A1 (between C. erythrophyllum and A. seyal). The IC-ELISA was adapted further to test confectionery samples for the presence of gum arabic, which was successful, although recovery rates were reduced. Both IC- and plate trapped antigen ELISA (PTA-ELISA) formats were able to distinguish an adulterated sample of gum arabic when blended with either A. seyal or C. erythrophyllum. The PTA-ELISA was more sensitive for A. seyal than the IC-ELISA, but both were equally sensitive for C. erythrophyllum. The results suggest that the antibodies SY CC7, SY HH3, and SY J1A1 could be used in combination with each other for the detection of potential adulterants of A. senegal and the detection of gum arabic in foodstuffs.  相似文献   

19.
The effect of arabic gum (AG) and xanthan gum (XG) on the physicochemical properties of 2% pesticide avermyctin in water emulsions was systematically investigated by measuring creaming stability, droplet size, zeta potential, and rheology. Addition of AG and XG had significant influence on the physicochemical properties of emulsions. Emulsions showed high stability throughout the storage time in the AG concentration range of 0-0.14%. In contrast, addition of XG induced the apparent creaming of emulsion as the XG concentration increased from 0.011 to 0.15%, which might be well explained by the depletion flocculation of droplets. The droplet diameter increased progressively with increasing AG concentration; however, it sharply grew initially with XG concentration and reached a maximum, followed by a gradual decrease. Zeta potential increased gradually as AG concentration was lower than 0.081%, followed by a slight decrease, whereas it reduced dramatically as XG concentration increased from 0.011 to 0.040% and then remained almost unchanged. In the AG concentration range of 0-0.14%, the emulsion exhibited typical Newtonian flow behavior and the viscosity decreased a little. The XG emulsion exhibited Newtonian flow behavior at low XG concentrations (≤0.019%), whereas, non-Newtonian flow behavior was displayed at relatively high XG concentrations (>0.019%), wherein viscosity value and yield value increased gradually as XG concentration increased. In addition, the curves of shear stress versus shear rate for XG emulsion and solution were well fitted by a power law model and the Herschel-Bulkley model; the Herschel-Bulkley model fitted much better. The present study would provide useful information for the reasonable application of AG and XG in making stable pesticide emulsion.  相似文献   

20.
The influence of weighting agents and sucrose on gravitational separation in 1 wt % oil-in-water emulsions was studied by measuring changes in the intensity of backscattered light from the emulsions with height. Emulsions with different droplet densities were prepared by mixing weighting agents [brominated vegetable oil (BVO), ester gum (EG), damar gum (DG), or sucrose acetate isobutyrate (SAIB)] with soybean oil prior to homogenization. Sedimentation or creaming occurred when the droplet density was greater than or lower than the aqueous phase density, respectively. The weighting agent concentrations required to match the oil and aqueous phase densities were 25 wt % BVO, 55 wt % EG, 55 wt % DG, and 45 wt % SAIB. The efficiency of droplet reduction during homogenization also depended on weighting agent type (BVO > SAIB > DG, EG) due to differences in oil phase viscosity. The influence of sucrose (0-13 wt %) on the creaming stability of 1 wt % soybean oil-in-water emulsions was also examined. Sucrose increased the aqueous phase viscosity (retarding creaming) and increased the density contrast between droplets and aqueous phase (accelerating creaming). These two effects largely canceled one another so that the creaming stability was relatively insensitive to sucrose concentration.  相似文献   

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