Characterization of galactomannans by capillary electrophoresis

Capillary electrophoresis (CE) was utilized in the characterization of various galactomannans. Standards of gums were extracted with 50% CH₃CN to remove the residual proteins from the gum matrix. Separation buffers were optimized with respect to pH, buffer concentration and presence of sodium dodecyl sulphate, yielding protein profiles from which the desired information could be obtained. Examples are given of the profiles generated by various gums and gum blends to aid in the verification of component presence, and to demonstrate levels of adulteration detectable under the buffer conditions used.     

Rheological behaviors of hydroxypropylated sweet potato starches influenced by guar,locust bean,and xanthan gums

This study examined the steady flow and dynamic rheological behaviors of hydroxypropylated sweet potato starch (HPSPS) pastes mixed with guar gum (GG), locust bean gum (LBG), and xanthan gum (XG) at different concentrations (0, 0.3, and 0.6%). The HPSPS–gum mixtures had higher shear‐thinning fluid characteristics than the control (0% gum) at 25°C. The addition of the gums resulted in an increase in the consistency index (K) and apparent viscosity (η_a,100). The dynamic moduli (G′, G″) and complex viscosity (η*) values of the HPSPS–gum mixtures were higher than those of the control, and they increased with an increase in gum concentration. In particular, the presence of XG at 0.6% in the HPSPS–gum mixture systems gave rise to the greatest viscoelastic properties among the gums examined at different concentrations. The tan δ (ratio of G″/G′) values (0.35–0.57) of the HPSPS–GG and HPSPS–XG mixtures were much lower than those of the control (0.82) and HPSPS–LBG (0.88–1.06), indicating that the elastic properties in the HPSPS–gum mixture systems were strongly affected by the additions of GG and XG. These steady flow and dynamic rheological parameters indicated there were synergistic interactions between the HPSPS and gums. The synergistic effects of the gums and modified starch were hypothesized by considering the molecular incompatibility and molecular interactions between the gums and HPSPS.     

Physicochemical, pasting and thermal properties of tuber starches as modified by guar gum and locust bean gum

This study was carried out in order to compare the functional characteristics of isolated starch from five tuber crops, yam, taro, sweet potato, yam bean and potato, as well as effect of guar gum (GG) and locust bean gum (LBG) on pasting and thermal properties of tuber starches. The results showed that total amylose content of five tested starches ranged from 17.85% to 30.36%. The results of pasting behaviour showed that potato starches exhibited the highest peak viscosity and yam starch presented a stable curve with little breakdown viscosity. Addition of GG and LBG resulted in a significant increase in peak, final viscosity, breakdown and setback viscosity for all tuber starches ( P  < 0.05), but a slight decrease in pasting temperature. The gelatinisation enthalpy (Δ H ) for starches with GG and LBG was slightly lower than those of the starches alone in yam and sweet potato, but not in taro and yam bean.     

Oil-in-water emulsions stabilized by sodium caseinate: Influence of pH,high-pressure homogenization and locust bean gum addition

The effect of pH, addition of a thickening agent (locust bean gum) or high-pressure homogenization on the stability of oil-in-water emulsions added by sodium caseinate (Na-CN) was evaluated. For this purpose, emulsions were characterized by visual analysis, microstructure and rheological measurements. Most of the systems were not stable, showing phase separation a few minutes after emulsion preparation. However, creaming behavior was largely affected by the pH, homogenization pressure or locust bean gum (LBG) concentration. The most stable systems were obtained for emulsions homogenized at high pressure, containing an increased amount of LBG or with pH values close to the isoelectric point (pI) of sodium caseinate, which was attributed to the size reduction of the droplets, the higher viscosity of continuous phase and the emulsion gelation (elastic network formation), respectively. All the studied mechanisms were efficient to decrease the molecular mobility, which slowed down the phase separation of the emulsions. In addition, the use of sodium caseinate was also essential to stabilize the emulsions, since it promoted the electrostatic repulsive interactions between droplets.     

Study of emulsions stabilized with Phaseolus vulgaris or Phaseolus coccineus with the addition of Arabic gum, locust bean gum and xanthan gum

The properties of o/w emulsions stabilized with 1%w/v common bean (Phaseolus vulgaris L.), V or scarlet runner bean (P. coccineus L.), Coc extracted by isoelectric precipitation or ultrafiltration, at pH 7.0 and 5.5, with the addition of Arabic gum, locust bean gum, xanthan gum and a mixture of xanthan gum–locust bean gum (0.1 %w/v and 0.25 %w/v) are studied. The stability of emulsions was evaluated on the basis of oil droplet size, creaming, viscosity and protein adsorption measurements. The addition of Arabic gum, caused an increase in D[4,3] values and a decrease in the amount of protein adsorbed at the interface. The addition of locust bean gum in some emulsions reduced the amount of protein adsorbed. The addition of xanthan and to a less extend of the polysaccharide mixture, promoted a decrease in D[4,3]. So, emulsion stability was affected by the polysaccharide nature. Differences were also observed with respect to the protein nature, the method of its preparation and emulsion's pH. All polysaccharides enhanced the emulsions viscosity with xanthan and xanthan–locust bean gum exhibiting the higher values. V isolates and isoelectricaly precipitated isolates of both V, Coc showed higher viscosity values. The stability was enhanced by the increase of the viscosity of the continuous phase and the creation of a network, which prevents the oil droplets from coalescence.     

Detection of buffalo milk adulteration with cow milk by capillary electrophoresis analysis

The addition of cow milk during the production of buffalo mozzarella is a common fraud in dairy industries because of the lower price and greater availability of cow milk throughout the year. The aim of this study was to develop a new, rapid, and robust capillary electrophoresis method for detecting and quantifying cow milk in buffalo milk by exploiting cow α-lactalbumin as a marker of adulteration. In particular, a linear calibration curve was generated, using a training set of calibrators consisting of 7 series of 17 buffalo/bovine whey mixtures, obtained after casein precipitation, with increasing percentages of cow whey. The capillary electrophoresis method showed high linearity (R² = 0.968), repeatability [relative standard deviation (RSD) = 2.11, 3.02, 4.38, and 1.18%, respectively for 5, 10, 20, and 50% of buffalo/bovine whey mixtures], and intermediate precision (RSD = 2.18, 2.49, 5.09, and 3.19%, respectively, for 5, 10, 20, and 50% buffalo/bovine whey mixtures). Moreover, the minimum amount of detectable fraudulent cow milk was 1%, and the limit of quantification was 3.1%.     

Analysis of potential adulteration in herbal medicines and dietary supplements for the weight control by capillary electrophoresis

Four different phytopharmaceutical dosage forms for use in weight control programs were analyzed. Two different ground herbal blends and their correspondent infusions, a capsule and a tincture were investigated for the presence of compounds used as adulterants in these products. A capillary electrophoresis (CE) method was developed and validated. The optimized experimental conditions were: BGE, sodium tetraborate buffer 20 mM, pH 9.2, voltage applied 30 kV, capillary temperature 25 °C, injection sample at 0.5 Psi during 5 s. Ephedrine, norephedrine, caffeine and furosemide were baseline separated in less than 7 min; the migration times were found to be 2.65, 2.90, 3.75 and 6.58 min, respectively. The analysis showed in sample 3 concentrations of 0.45 ± 0.03 mg g⁻¹ (ephedrine), 0.33 ± 0.02 mg g⁻¹ (norephedrine), 1.09 ± 0.41 mg g⁻¹ (caffeine) and 0.80 ± 0.17 mg g⁻¹ (furosemide). Caffeine content in samples 1, 2 and 4 was 0.61 ± 0.06 mg g⁻¹, 15.66 ± 1.05 mg g⁻¹ and 2.27 ± 0.13 mg ml⁻¹, respectively. Linearity was obtained in the concentration range of 1–1000 μg ml⁻¹. Limits of detection (LOD) and quantification (LOQ) were determined as 0.42 μg ml⁻¹ and 1.40 μg ml⁻¹ (ephedrine), 0.47 μg ml⁻¹ and 1.40 μg ml⁻¹ (norephedrine), 0.12 μg ml⁻¹ and 0.48 μg ml⁻¹ (caffeine), 0.22 μg ml⁻¹ and 0.73 μg ml⁻¹ (furosemide).     

Detection of eight GMO maize events by qualitative, multiplex PCR and fluorescence capillary gel electrophoresis

Specific legislation in the EU and several other countries requires that foods containing genetically modified organisms (GMOs) should be approved and labelled. This has necessitated the development of methods for detection of such materials. For screening purposes these methods should preferably enable detection of several different GMOs. Here we present a simple, robust, qualitative, nineplex PCR method for event-specific detection of maize T25, GA21, TC1507, MON863, MON810, NK603, construct specific detection of BT176, BT11 and detection of the endogenous hmga maize reference gene. PCR is carried out with primers labelled with fluorescent groups and the amplicons are detected using fluorescence capillary electrophoresis. Using mixtures of DNA from different certified reference materials, the detection limit was determined to approximately 0.1% for each GMO. Good agreement was observed in 85 of 88 determinations when eleven food and feed samples were analysed using the multiplex PCR assay and compared to results from quantitative real-time 5′-nuclease PCR. Discrepancies were only observed for one GMO at or close to the detection limit. The presented method is therefore suitable for screening purposes for food and feed containing the most common maize GMOs.     

Determination of flavonoids and ascorbic acid in grapefruit peel and juice by capillary electrophoresis with electrochemical detection

Grapefruit (Citrus paradisi Mact. (Rutaceae)) has been known for its accumulation of flavonoids and ascorbic acid. These contents are important because of their nutritional and antioxidant properties. Five flavonoids (hesperidin, naringin, hesperedin, narigenin and rutin) and ascorbic acid were separated and determined in grapefruit juice by capillary electrophoresis with electrochemistry detection (CE-ED). Two flavonoids (hesperidin, naringin) and ascorbic acid were found in extract of grapefruit peel with the same method. And the distribution comparision of the ingredients between juice and peel was discussed. The effects of several CE parameters on the resolution were studied systematically. Under the optimum conditions, the analytes could be well separated within 25 min in a 60 mmol L⁻¹ borate buffer (pH 9.0). The response was linear over four orders of magnitude with detection limits (S/N = 3) ranging from 1.4 × 10⁻⁷ to 1.0 × 10⁻⁶ g ml⁻¹ for the analytes. The method has been successfully applied for the analysis of grapefruit with satisfactory results.     

Simultaneous analysis of acidulants and preservatives in food samples by using capillary zone electrophoresis with indirect UV detection

Capillary zone electrophoresis with indirect UV detection was developed for the simultaneous analysis of acidulants and preservatives in food samples. When a solution of tris (hydroxymethyl) aminomethane, trimellitic acid and poly (vinyl alcohol) was used as the background electrolyte, the nine acidulants and four preservatives listed in the Japanese Food Sanitation Law were detected within 8 min. The calibration curves plotted from the peak height of each analyte were linear with a correlation coefficient of 0.99. The relative standard deviations (n = 10) of the peak height ranged from 1.2% to 4.7%. The detection limits for these species ranged from 0.6 to 5.3 mg/L at a signal-to-noise ratio of three. The method developed method was applied to the simultaneous analysis of acidulants and preservatives in a wide variety of food samples.     

Determination of capsaicin and dihydrocapsaicin in Capsicum anuum and related products by capillary electrophoresis with a mixed surfactant system

An easy, rapid, sensitive, and cheap capillary electrophoresis (CE) method based a mixed surfactant system formed by sodium dodecyl sulphate (SDS) and polyoxyethylene sorbitan monolaurate (Tween 20) as modifier in the buffer was reported. Quantitative analysis of capsaicin and dihydrocapsaicin in Capsicum anuum, pepper sauce and porous capsicum plaster was demonstrated. After conducting a series of optimisations, baseline separation was obtained for the analytes within 5 min under the optimum conditions (15 mM sodium tetraborate–0.05% (v/v) Tween 20–2.2 mM SDS buffer (pH 10.1), 20 kV voltage, 214 nm UV detection). The method resulted in excellent linearity, with r² of regression equation of 0.9994 and 0.9996 for capsaicin and dihydrocapsaicin, respectively. Recoveries were in the range 90–107% and 92–109% for capsaicin and dihydrocapsaicin, respectively.     

Simple determination of main organic acids in grape juice and wine by using capillary zone electrophoresis with direct UV detection

An accurate, simple and rapid capillary zone electrophoresis (CZE) method with direct UV detection has been set up for the determination of main organic acids in grape juice and wine. The determination of tartaric, malic, and citric acids in grape juices and tartaric, malic, succinic, acetic, lactic and citric acids in wines can be achieved in less than 3 min with only a simple dilution and filtration treatment of the sample. Validation parameters of the method as detection and quantification limits, linearity, precision (intraday and interday analysis) and recovery were also studied in grape juice, white wine, rose wine and red wine, separately. The proposed method decreases the analysis times of the previous reported CZE methods and allows the rapid control of the grape maturity, the winemaking processes and the detection of wine alterations and/or illnesses.     

Detection of GM Canola MS11, DP-073496-4, and MON88302 events using multiplex PCR coupled with capillary electrophoresis

As of 2020, 11 GM canola events have been authorized as food for humans in Korea. However, there are no simultaneous multiplex detection methods for 3 GM canola events (DP-073496-4, MON88302, and MS11). Thus, we established the multiplex polymerase chain reaction (PCR) method coupled with capillary electrophoresis to detect 3 GM canola events. To verify the specificity of event-specific primers, various GM crops of 3 GM soybean events, 6 GM maize events, 2 GM cotton events and 11 GM canola events were prepared. The limit of detection of the developed multiplex PCR was approximately 0.0125% for 3 GM canola events. Certified GM canola and stacked events were analyzed to validate the developed multiplex PCR. This study focuses on establishing multiplex PCR coupled with capillary electrophoresis for newly approved GM canola events and contributes to efficient monitoring GM canola samples in Korea.     

Determination of nitrates,nitrites and oxalates in food products by capillary electrophoresis with pH-dependent electroosmotic flow reversal

This paper describes an innovative and rapid capillary electrophoretic method for the simultaneous analysis of nitrates, nitrites and oxalates, which are anions of food interest. The novelty of our method is based on reversing the electroosmotic flow without using any buffer additive nor performing a capillary coating, but simply employing a buffer at low pH values.     

Determination of bioactive constituents in Flos Sophorae Immaturus and Cortex Fraxini by capillary electrophoresis in combination with far infrared-assisted solvent extraction

A method based on far infrared-assisted solvent extraction (FIASE) and capillary electrophoresis–amperometric detection (CE–AD) has developed for the rapid determination of rutin and quercetin in Flos Sophorae Immaturus and esculin and esculetin in Cortex Fraxini. The effects of the irradiation time and the voltage applied on the infrared generator were investigated to acquire the optimum extraction conditions. It was demonstrated that far IR radiation substantially enhanced the extraction efficiency and the extraction time was significantly reduced from 3 h for conventional hot solvent extraction to 6 min for FIASE. The obtained extracts were subsequently analysed by CE–AD. The detection electrode was a 300-μm-diameter carbon disc electrode at a detection potential of +0.90 V (vs. saturated calomel electrode). The relation between peak current and analyte concentration was linear over about three orders of magnitude. The proposed method has been applied to determine the bioactive constituents in real samples.     

Simultaneous determination of aspartame,cyclamate, saccharin and acesulfame-K in soft drinks and tabletop sweetener formulations by capillary electrophoresis with capacitively coupled contactless conductivity detection

Capillary electrophoresis (CE) with capacitively coupled contactless conductivity detection (C⁴D) was used for simple, rapid, and simultaneous determination of aspartame, cyclamate, saccharin and acesulfame-K in commercial samples of soft drinks and tabletop sweetener formulations. A buffer solution containing 100 mmol L⁻¹ tris(hydroxymethyl)aminomethane (TRIS) and 10 mmol L⁻¹ histidine (His) was used as background electrolyte (BGE). A complete separation of the analytes could be attained in less than 6 min. The limits of detection (LOD) and quantification (LOQ) were considered better than those usually obtained by CE with photometric detection. Recoveries ranging from 94% to 108% were obtained for samples spiked with standard solutions of the sweeteners. The relative standard deviation (RSD) for the analysis of the samples with the CE-C⁴D method varied in the range of 1.5%–6.5%.