Cocoa brew inhibits in vitro α-glucosidase activity: The role of polyphenols and high molecular weight compounds

Cocoa brew showed a dose-dependent inhibitory activity against α-glucosidase (IC₅₀ 7.87 mg/mL). The cocoa brew was fractionated by ultrafiltration in a low molecular weight fraction (LMW < 10 kDa) and two melanoidin-rich fractions called high molecular weight (HMW > 30 kDa) and intermediate molecular weight (IMW 10–30 kDa) fractions. All fractions tested caused some inhibition with IMW that was the most active (IC₅₀ 2.37 mg/mL). LMW fraction was separated with Sephadex LH-20 in an unbound (containing monomeric and dimeric catechins) and a bound fraction. All the inhibitory activity was recovered in the unbound fraction. All the phenolic compounds identified with HPLC showed α-glucosidase inhibitory activity. IMW and HMW fractions were fractionated by ethanol precipitation. The fractions from IMW precipitated with 75 and 25% ethanol were found to contain power inhibitors of α-glucosidase activity (IC₅₀ 0.87 and 1.01 mg/mL, respectively). In the HMW sample, the fractions precipitated with 50 and 75% ethanol were found to be active against α-glucosidase activity. Most of the inhibitory activity against α-glucosidase of cocoa brew was due to the LMW fraction (56%) whereas IMW and HMW contributed for about 47% of the inhibitory activity. This study suggests that different components of cocoa may influence α-glucosidase activity.     

Higher alcohols,diacetyl, acetoin and 2,3-butanediol biosynthesis in grapes undergoing carbonic maceration

Two grape varieties, Baco Noir and Gamay, were subjected to carbonic maceration (CM) conditions for 3, 6, 9, 12 and 15 days and the levels of higher alcohols, diacetyl, acetoin and 2,3-butanediol were determined. Diacetyl was not present in any of the CM juices. Acetoin and 2,3-butanediol were produced in the grapes and their amounts increased as the time of CM increased. On the 15th day of CM, acetoin was 12.6 ± 0.9 mg/l in Baco Noir juice and 3.2 ± 0.1 mg/l in Gamay juice, and 2,3-butanediol was 68.2 ±  3.9 mg/l in Baco Noir juice and 19.9 ± 1.2 mg/l in Gamay juice. 1-propanol, 2-methyl-1-propanol, 3-methyl-1-butanol, 2-methyl-1-butanol appeared in trace amounts (the highest among them was 3.3 ± 0.0 mg/l) in the CM Baco Noir juices and were not detected in the CM Gamay juices. Based on these results, the sensory contribution of higher alcohols from grape CM would be inconsequential when compared to that from yeast metabolism.     

Antioxidant activities of enzymatic rapeseed protein hydrolysates and the membrane ultrafiltration fractions

In this study, rapeseed protein isolate was hydrolyzed with various proteases to obtain hydrolysates that were separated by membrane ultrafiltration into four molecular size fractions (<1, 1–3, 3–5, and 5–10 kDa). Alcalase hydrolysis significantly (p < 0.05) produced the highest yield of protein hydrolysate while Flavourzyme produced the least. The <1 kDa fraction was the most abundant after the membrane ultrafiltration of the protein hydrolysates, which indicates that the proteases were efficient at reducing the native rapeseed proteins into low molecular weight peptides. Antioxidant properties of the resulting hydrolysates and membrane fractions were characterized and results showed the Pepsin + Pancreatin (P + P) protein hydrolysate had significantly highest (p < 0.05) scavenging activity against DPPH radical among the unfractionated enzymatic hydrolysates. But the P + P hydrolysate was not as effective as other hydrolysates during long-term inhibition of linoleic acid oxidation. For most of the samples, fractionation into the <1 kDa peptides significantly (p < 0.05) improved DPPH and superoxide scavenging properties when compared to the unfractionated protein hydrolysates. Only the <1 kDa fraction showed ferric reducing antioxidant power and the effect was dose-dependent. Overall, Alcalase and Proteinase K seem to be more efficient proteases to release antioxidant peptides from rapeseed proteins when compared to P + P, Flavourzyme and Thermolysin.     

Effects of ethanol,tannin and fructose on the headspace concentration and potential sensory significance of odorants in a model wine

The effects of ethanol (8, 10, 12, 14, and 16% v/v), tannin (500, 1000, and 1500 mg/L) and fructose (200 and 2000 mg/L) concentrations on the headspace of eight selected odorants were investigated using headspace solid phase microextraction (HS-SPME) and gas chromatography–mass spectrometry (GC–MS). Analysis of variance results (ANOVA) showed significant interaction effects for the majority of odorants (P < 0.05). In general, higher tannin concentration enhanced the release of odorants while fructose induced a retention effect, both of which were largely dependent upon ethanol concentration. The net magnitude effect was a substantial reduction in the headspace concentration of odorants with the dominant contribution from ethanol concentration. The percent reduction in extracted odorant was more pronounced on larger molecular weight compounds. Further multivariate analysis discriminated model wines with different ethanol concentrations and, to a lesser extent, separated model wines with different fructose and tannin concentrations. Subsequent gas chromatography–olfactometry (GC–O) analysis revealed differences in the estimated odor thresholds of odorants in the model wines. Threshold values increased between 2 and 10,000-fold for 2-methoxyphenol and eugenol, respectively, at higher ethanol, tannin and fructose concentrations. Consequently, odor unit values (OUV) of odorants decreased indicating a reduction in the potential contribution of the odorants to the aroma of model wine. These results highlighted the significant impact that wine matrix interactions can have on wine aroma quality.     

Low molecular weight fractions of BiMuno® exert immunostimulatory properties in murine macrophages

Previous in vivo murine oral challenge studies have shown that the galactooligosaccharide containing product, BiMuno®, reduced colonisation of S. Typhimurium. To gain further insights into the mechanism of reduced colonisation, we wished to test the hypothesis that the low molecular weight fractions of BiMuno® or a specific low molecular weight fraction may have direct immuno-modulatory effects on murine macrophages. Cytokine responses of murine macrophages in response to the commercially available product, BiMuno®, a basal solution BiMuno® without GOS, purified low molecular weight fractions (referred to as GOS), and the individual fractions of GOS (DP2, 3 and ?4, with each fraction representing the increasing degree of complex polymerisation) were determined in vitro and ex vivo. These studies demonstrated that BiMuno®, significantly stimulated both pro- and anti-inflammatory cytokines in vitro (P ? 0.0394). Furthermore, the data indicate that the low molecular weight fractions may be the primary stimulant of BiMuno® and specifically its tri (DP3) and ?tetra-saccharide (DP ? 4) fractions (P ? 0.0394).     

Determination of phenolic composition and antioxidant capacity of native red wines by high performance liquid chromatography and spectrophotometric methods

A reversed-phase high performance chromatographic method for simultaneous determination of 14 phenolic compounds in native red wines was developed in this study. The identified compounds contained gallic acid, (+)-catechin, 3,4-dihydroxybenzoic acid, chlorogenic acid, (?)-epicatechin, 4-hydroxybenzoic acid, syringic acid, caffeic acid, p-coumaric acid, rutin, resveratrol, myricetin, quercetin and kaempferol. The method includes liquid–liquid extraction of acidic pH with ethylacetate. The analysis used a Zorbax Eclipse XDB-C18 column (5 μm, 4.6 mm × 250 mm). The chromatographic separation of these compounds performed in a single run by using the mobile phase gradient elution of methanol water mixture (% 0.2 formic acid) at room temperature, with flow rate at 1 mL/min. Detection was carried out by UV–vis and fluorescence detector. Each analysis required an equilibration period of 10 min and a run time of 14 min for completion. The optimized chromatographic method was carefully validated for precision and accuracy. Our findings indicated that the developed HPLC method was precise, accurate, specific and sensitive for simultaneous determination of phenolic compounds. Consequently, the described method was applied to the analysis of six wines from Malatya and Elaz??. Gallic acid was dominant phenolic acid in red wines. (+)-catechin, (?)-epicatechin and p-coumaric acid were the next most abundant phenolics. The highest level of trans-resveratrol among the red wines was found Buzba?? (Bogazkere–Öküzgözü). The red wines were analyzed for total polyphenol content (TP) by Folin–Ciocalteu (FC) method, using gallic acid as standard. Antioxidant activities (AA) of the red wines were measured using the DPPH (2,2-diphenyl-1-picrylhydrazyl) assay. There was a very high correlation between AA and TP in all of the wines tested.     

Production and fractionation of tuna by-product protein hydrolysate by ultrafiltration and nanofiltration: Impact on interesting peptides fractions and nutritional properties

The production of fish protein hydrolysates (FPH) is a promising route to add value to fish by-products due to their potential application as a source of interest peptide fractions. Using Alcalase for hydrolysis of tuna dark muscle by-product, the influence of enzyme/substrate ratio and hydrolysis time on the rate of interest peptide fractions (1–4 kDa) was studied. The rate of this fraction obtained under optimized conditions (temperature 55 °C, pH 8.5, enzyme/substrate ratio of 1% and 60 min of hydrolysis reaction) was 26%. The performance of the combined process associating ultrafiltration and nanofiltration membranes was evaluated for fractionation of produced hydrolysate in order to isolate fractions enriched in peptides of specific molecular weight (MW). The interest peptide fraction (1–4 kDa) was isolated and the positive effect of diafiltration on peptide purification process was underlined. The peptide fractions produced have a high nutritional quality which can be used in human nutrition and they have a potential for applications in aquaculture diets.     

Effect of thermal treatment on the enzymatic hydrolysis of chicken proteins

The proteins of chicken breast meat were thermally treated in this work. Treatment temperature and time were chosen to evaluate the effect of thermal treatment. By determination of SH and S-S group levels, the results indicated that the SH and S-S group levels in the chicken proteins without thermal treatment were 65.06 and 12.29 μmol/g. With the increase of treatment temperature, the SH group level decreased, while S-S group level increased gradually. Enzymatic hydrolysis by Alcalase was done to evaluate the nitrogen levels of hydrolysates. A temperature-dependent effect was observed for soluble and formaldehyde nitrogen levels. A slight increase of peptide nitrogen level was found with the increase of temperature. Treatment time had a similar effect to treatment temperature. The molecular weight of chicken protein hydrolysates was analysed by gel permeation chromatography. The chicken protein hydrolysates without thermal treatment showed an apparent peak at 27.5 ml of elution volume and a weak peak at 4.0 ml, which represented fractions with molecular weight of > 10,000 Da and < 2640 Da, respectively. Thermal treatment led to decreases of the fractions with molecular weight of > 10,000 Da, 3500–2640 Da and < 2640 Da, compared with hydrolysate fractions without thermal treatment. Treatment with a temperature higher than 60 °C for 20 min would completely eliminate the > 10,000 Da fraction from chicken protein hydrolysates. The percentage of fraction with molecular weight of 4500–3500 Da increased with the extension of treatment time to 20 min, thereafter decreased.Industrial relevanceThe annual yield of chicken meat in China ranks the second of the world. However, the extensive development of this resource is still limited. In this work, chicken breast meat was thermally treated and then hydrolysed by Alcalase. Effects of treatment temperature and time on the hydrolysates were investigated. The results indicated that thermal treatment could change the levels of soluble nitrogen, formaldehyde nitrogen and peptide nitrogen. The area percentages of fractions with different molecular weight were also changed. This work was helpful to understand the characteristics of bioactive peptides produced from chicken proteins.     

Influence of co-winemaking technique in sensory characteristics of new Spanish red wines

The influence of co-winemaking technique on the sensory profile of wines made from minority red grape varieties cultivated in La Mancha region (Spain) was researched by sensory characterization. Sensory analysis was carried out by a panel of 15 experienced wine-testers, all with a previous training. The sensory profiles of monovarietal red wines—Cencibel, Bobal and Moravia Agria—were studied and also the effects of co-winemaking technique on sensory characteristics were evaluated. Co-winemaking red wines were obtained by blending (a) Cencibel (50%) + Bobal (50%); (b) Cencibel (50%) + Moravía Agria (50%) and (c) the three grape varieties Cencibel (33%) + Bobal (33%) + Moravía Agria (33%). The co-winemaking technique intensified the principal sensory properties of monovarietal wines and the wines proved to be more complex than the monovarietal wines.     

Sensory changes during bottle storage of Spanish red wines under different initial oxygen doses

Sixteen commercial Spanish red wines selected to cover a wide range of sensory properties were stored at 25 °C for 6 months in air-tight containers under different oxygen doses (0–30 mg L^− 1) mimicking real and extreme bottling situations. The 16 initial samples (before storage) and the 80 stored samples (16 wines × 5 oxygen doses) were submitted to sensory analysis. Sensory changes related to post-bottling storage and initial oxygen dose were evaluated by means of discriminant and characterisation sensory strategies.Significant increases in black fruits, dried fruits, woody, lactic and stronger increases in cooked vegetables and spicy notes reveal a general pattern of aroma evolution. Remarkable departures to this general pattern have been observed, which can be related to the initial sensory properties of the wines and to their basic polyphenolic composition. The effect of post-bottling storage in bitterness is wine dependent, while global decreases in both global intensity and persistence evaluated in mouth are observed. Discrete increases in astringency are observed for wines with the lowest initial astringent scores. Important sensory interactions between aroma attributes (herbal and spicy) and bitterness and between roasted and astringency perception are shown. Little impact of the initial oxygen dose in the in-mouth sensory properties is reported. These results are relevant for wine experts in that they help understanding the evolution of wine sensory properties in the bottling stage. This study may help them to develop strategies for managing this winemaking stage with objective criteria.     

Ability of conventional and nutritionally-modified whey protein concentrates to stabilize oil-in-water emulsions

The ability of a modified whey protein concentrate (MWPC), which contains relatively high proportions of phospholipid and high molecular weight protein fractions, to form and stabilize 10 wt% corn oil-in-water emulsions (pH 7.0, 5 mM phosphate buffer) was compared with that of a conventional whey protein concentrate (CWPC). The MWPC stabilized emulsions required less protein to prepare stable emulsions with monomodal particle size distributions and small mean droplet diameters (d₄₃ ≈ 0.3 μm at [WPC] ⩾ 0.5 wt%) than CWPC stabilized emulsions (d₄₃ ≈ 0.4 μm at [WPC] ⩾ 0.9 wt%) under similar homogenization conditions (5 passes at 5000 psi). In addition, the emulsions stabilized by 0.9 wt% MWPC were more stable to high salt concentration (NaCl ⩽ 200 mM), thermal processing (30–90 °C for 30 min) and pH (3, 6 and 7) than those stabilized by the same concentration of CWPC, which was attributed to polymeric steric repulsion rather than electrostatic repulsion. This study has important implications for the wide application of WPC as a natural emulsifier in food products.     

Pressurized aqueous ethanol extraction of β-glucans and phenolic compounds from waxy barley

Beta-glucans and phenolics were extracted from waxy barley using pressurized aqueous ethanol in a stirred batch reactor at 25 bar and 500 rpm. The effect of temperature (135–175 °C), extraction time (15–55 min) and ethanol content (5–20%) was evaluated. Temperature had an opposite effect on the extraction of both compounds. The higher the temperature, the lower the β-glucan extraction yield due to fragmentation, but a significant increase on the phenolic recovery was observed. Long extraction times favored the extraction of β-glucans at low temperatures and phenolics at any temperature. The ethanol content was not statistically significant on the β-glucan extraction, but helped to maintain the molecular weight of the extracted β-glucan. To obtain liquid extracts rich in high molecular weight β-glucans and phenolics, mild conditions of 151 °C, 21 min and 16% ethanol are needed, leading to 51% β-glucan extraction yield with a molecular weight of 500–600 kDa and 5 mg GAE/g barley.     

Cryogelation phenomena in mixed skim milk powder – barley β-glucan–polyol aqueous dispersions

The effects of polyols (fructose, glucose, sorbitol, sucrose and xylose) on cryostructurization of barley mixed-linkage (1 → 3), (1 → 4) β-d-glucans (β-glucans) in the presence of skim milk proteins were investigated; three β-glucan isolates differing in molecular size (apparent molecular weight of 210, 140 and 70 × 10³ Da) were used. Polyols were incorporated at 15% (w/w) concentration into aqueous β-glucan (3% w/w)–skim milk (12% w/w) dispersions and the mixed dispersions were subjected to 14 repeated freezing (−15 °C for 24 h) and thawing (5 °C for 24 h) cycles; all preparations gave compact, opaque gels. For the high molecular weight (210 × 10³) preparation, with exception of sorbitol, the addition of polyols to β-glucan-skim milk dispersions retarded the cryostructurization, as shown by phenomenological observations after each freezing–thawing cycle and resulted in weaker cryostructurates compared to those of control (polyol-free gels), as determined by small deformation mechanical measurements. Xylose and fructose showed a stronger inhibitory effect on structure formation compared to sucrose and glucose, whereas sorbitol appeared as a network promoting co-solute. However, the above effects of polyols were largely diminished with decreasing of the β-glucan molecular weight and seemed to be independent on the type of polyol for the 140 and 70 × 10³ β-glucan samples. Despite the fact that molecular weight of β-glucans can have an impact on the effect of individual polyol on thermostability of cryogels, generally it seems that the melting temperature (T_m) of β-glucan-skim milk cryostructurates, as determined by dynamic rheometry, followed the order sorbitol > sucrose > control, glucose > fructose > xylose. On the other hand, large deformation mechanical tests (compression mode) revealed an increase in firmness and a decrease in brittleness of β-glucan–skim milk cryogels with inclusion of polyols in the order of: sorbitol < sucrose, xylose < fructose, glucose.     

Heat transfer modeling of chicken cooking in hot water

To calculate the slowest heating point and optimum cooking time of whole chicken cooking in hot water, a 2-dimensional heat transfer model was developed to predict temperature profile and history of the chicken cooked in hot water at 85, 90 and 95 °C. Chickens were divided into 12 sections and the heat transfer model was applied to each cross section. These models were solved with an I-DEAS program. Specific heat and thermal conductivity were measured at temperatures ranging from 25 to 95 °C. The temperature of chicken did not significantly affect the thermal properties. The average values of specific heat of white and dark meats were 3.521 and 3.654 kJ/(kg K), respectively, and the average thermal conductivity values were 0.5093 and 0.4930 W/(m K), respectively. The model was validated against experimental results, and provided an average root mean square error of 2.8 °C. Temperature distributions showed that the slowest heating point was deep in the breast part of the second cross section (3.6 cm far from shoulder) at the symmetric line of the chicken, around 2.1–2.5 cm deep from breast skin. For food safety consideration, the recommended cooking times, for whole chickens in weight range of 2.3–3.2 kg with different initial temperatures (5–30 °C), were around 74–84, 64–74 and 57–67 min for cooking temperatures of 85, 90, and 95 °C, respectively.     

Influence of processing conditions on reducing γ-aminobutyric acid content during fortified milk production

The work studied the effects of processing conditions on the γ-aminobutyric acid (GABA) loss during fortified milk production. Bovine milk or their proteins/lactose fractions (0.66% whey protein and 2.6% casein or 4.9% lactose, w/v) containing 0.05–1.0% added γ-aminobutyric acid (w/w, based on bulk milk or these fractions) were subjected to a simulated milk technological process as following the sequential preheating (25–60 °C), homogenization (0–20 MPa), and pasteurization (62 °C/30 min, 72 °C/15 s, 95 °C/5 min, and 138 °C/2 s) or their unit processes to treat GABA. The resulting samples were characterized through GABA and lactose concentrations under various processing conditions. The amine and carboxyl groups and the structural characteristics of the resulting protein (lactose) were also examined through their concentrations (for lactose) and mass/spectral analyses, respectively. The results showed that the increase in temperature significantly promoted a reduction in GABA content. Whey protein fractions than caseins were primarily responsible for inducing GABA, whereas lactose had no remarkable effect on it. The rationale for GABA reduction is potential reactions with milk proteins/lactose, which preliminarily confirmed by the measurement of protein modification and lactose mass spectrometry.     

Comparison of properties of oil-in-water emulsions stabilized by coconut cream proteins with those stabilized by whey protein isolate

Coconut cream protein (CCP) fractions were isolated from coconuts using two different isolation procedures: isoelectric precipitation (CCP1-fraction) and freeze–thaw treatment (CCP2-fraction). The ability of these protein fractions to form and stabilize oil-in-water emulsions was compared with that of whey protein isolate (WPI). Protein solubility was a minimum at ∼pH 4, 4.5 and 5 for CCP1, CCP2, and WPI, respectively, and decreased with increasing salt concentration (0–200 mM NaCl) for the coconut proteins. All of the proteins studied were surface active, but WPI was more surface active than the two coconut cream proteins. The two coconut cream proteins were used to prepare 10 wt% corn oil-in-water emulsions (pH 6.2, 5 mM phosphate buffer). CCP2 emulsions had smaller mean droplet diameters (d₃₂ ≈ 2 μm) than CCP1 emulsions (d₃₂ ≈ 5 μm). Corn oil-in-water emulsions (10 wt%) stabilized by 0.2 wt% CCP2 and WPI were prepared with different pH values (3–8), salt concentrations (0–500 mM NaCl) and thermal treatments (50–90 °C for 30 min). Considerable droplet flocculation occurred in the emulsions near the isoelectric point of the proteins: CCP2 (pH ∼ 4.3); WPI (pH ∼ 4.8). Emulsions with monomodal particle size distributions, small mean droplet diameters, and good creaming stability could be produced at pH 7 for WPI, but CCP2 produced bimodal distributions at this pH. The CCP2 and WPI emulsions remained relatively stable to droplet aggregation and creaming at NaCl concentrations ⩽50 and ⩽100 mM, respectively. In the absence of salt, both CCP2 and WPI emulsions were quite stable to thermal treatments (50–90 °C for 30 min).     

Comparative studies on the physico-chemical properties of hemicelluloses obtained by DEAE-cellulose-52 chromatography from sugarcane bagasse

Water- and alkali-soluble hemicelluloses isolated from dewaxed sugarcane bagasse were sub-fractionated on DEAE-cellulose-52 chromatography and obtained six hemicellulosic sub-fractions by eluting with water, 0.1 M and 0.3 M NaCl aqueous solution, respectively. Sugar composition and molecular weight analysis revealed that the lower molecular weight (14,180–43,590 g mol^?1) and more branches of hemicelluloses could be extracted by the hot water, which are rich in glucose, galactose, and xylose, while the higher molecular weight (75,430–138,170 g mol^?1) and more linear hemicelluloses were able to be dissolved into 1% NaOH aqueous solution, which are rich in xylose, principally resulting from l-arabino-(4-O-methyl-glucurono)-d-xylans. In addition, it was found that with increasing the concentration of NaCl (aqueous), the hemicellulosic sub-fractions with both higher arabinose to xylose ratio and higher molecular weight were eluted. Based on the FT-IR, sugar composition and ¹H and ¹³C NMR comparative studies, the alkali-soluble hemicellulosic sub-fractions had a classical structure, with a backbone of β-(1→4)-linked xylosyl residue substituted with arabinose at C–2 and/or C–3 of main chain, whereas the difference may occur in the distribution of branches along the xylan backbone.     

Surface dilatational properties of whey protein and hydroxypropyl-methyl-cellulose mixed systems at the air–water interface

In this work we have studied the impact of the competitive adsorption of a whey protein concentrate (WPC) and three well characterized hydroxypropyl-methyl-cellulose (HPMCs), commercially known as E4 M, E50LV and F4 M, on the surface dilatational properties (surface dilatational modulus, E, surface dilatational elasticity, E_d, and loss angle tangent, tan δ) of mixed films adsorbed at the air–water interface. The increase in E_d values with adsorption time could be associated with biopolymer adsorption at the interface. The surface dilatational properties depend on the WPC and HPMC concentrations in the aqueous phase and on the WPC/HPMC ratio. Although the values of E_d were mainly determined by HPMC at short adsorption times, for mixed systems with the lowest protein concentration (1 × 10⁻⁴ wt%) the E_d values were close to those of HPMCs, even at long term adsorption. The values of tan δ indicate the formation of adsorbed mixed films with high viscoelasticity, with a gel structure, which in turn should be attributed to the association of biopolymer molecules occurring at the interface. Only one biopolymer is the dominant one in the solid character of these mixed systems. HPMC at high concentrations slightly reduced the long-term solid character of the films confirming the existence of competition for the air–water interface as expected with two surface-active biopolymers with high molecular weight.     

Optimization of capillary zone electrophoresis separation and on-line preconcentration of 16 phenolic compounds from wines produced in South America

A capillary zone electrophoresis method was optimized to simultaneously separate 16 phenolic compounds present in wines, as well as to evaluate sample on-line preconcentration for detectability improvement. The separated compounds were narirutin, (?)-epicatechin, (+)-catechin, rutin, kaempferol, myricetin, quercetin, morin, trans-resveratrol, cinnamic acid, ferulic acid, p-coumaric acid, vanillic acid, caffeic acid, gallic acid, and 3,4-dihydroxybenzoic acid. The optimized separation condition was 175 mmol L^? 1 boric acid at pH 9.0 and capillary of 50 μm × 68 cm (60 cm effective length). The injection mode showing the greatest detectability (20 fold improvement) was hydrodynamic injection at 50 mbar for 30 s, followed by voltage inversion (? 20 kV for 5 s) before the electrophoretic run. The method was validated and applied with success in a total of 23 samples of red, white, and rose wines. The developed method showed excellent applicability due to the simple extraction procedure and the low volume of reagents used, reducing expenses for reagents and technicians.