Emulsifying properties of gum kondagogu (Cochlospermum gossypium), a natural biopolymer

BACKGROUND: Natural polymers are widely used as emulsifying agents in the food and pharmaceutical industries because of their low cost, biocompatibility and non‐toxic nature. In the present study, emulsifying properties of the novel natural biopolymer gum kondagogu (GKG) were investigated. GKG solutions of different concentrations (0.1–0.6% w/v) were prepared in water and emulsified with liquid paraffin oil (40% v/v) in a high‐speed homogeniser. Flow properties of the emulsions were measured using a rheometer. Emulsion stability and droplet size distribution were determined by visual observation, photomicrography and laser‐scattering particle size distribution analysis. RESULTS: The emulsions prepared with GKG showed pseudoplastic behaviour. The size of oil droplets and the viscosity of emulsions at concentrations of 0.4–0.6% w/v showed little change over time (up to 30 days), indicating that the emulsions were stable. Measurements of the zeta potential of emulsions adjusted to different pH, with and without added electrolyte, showed that the stabilisation of emulsions with GKG was due to mutual repulsion between electrical double layers of particles and adsorption of macromolecules on oil droplets. CONCLUSION: The results of this experimental investigation show that GKG is a good emulsifying agent even at low concentrations, with many potential applications in the food and pharmaceutical industries. Copyright © 2009 Society of Chemical Industry     

Polyphenol oxidase/caffeic acid may reduce the allergenic properties of peanut allergens

Polyphenol oxidase (PPO) catalyzes the oxidation of tyrosine residues of proteins and, therefore, their cross‐linking. Previously we demonstrated that cross‐links produced by peroxidase (POD), which also catalyzes tyrosine oxidation, led to a reduction in the allergenic properties of peanut allergens. 11 We postulated in this study that PPO can also reduce the allergenic properties by cross‐linking the allergens. Because caffeic acid, a phenolic compound, can cross‐link proteins, its effect on peanut allergens was also examined. In the experiments, peanut extracts were treated with and without PPO, PPO/caffeic (pH 8, 37 °C for 1 h) and caffeic acid (pH 10.5, overnight), respectively. The samples were then analyzed for cross‐links and IgE binding by SDS‐PAGE, Western blots, and competitive inhibition ELISA. Results showed that, in all cases, cross‐links and a decrease of the levels of two peanut major allergens, Ara h 1 and Ara h 2, were observed. Of the three treatments, PPO/caffeic was the most effective in reducing IgE binding or the allergenic properties of peanut allergens. The availability of tyrosine residues was also demonstrated in a POD‐treated system, using a monoclonal antibody against dityrosine. We concluded that PPO/caffeic acid reduced the allergenic properties of Ara h 1 and Ara h 2 by cross‐linking and decreasing the levels of allergens. Copyright © 2005 Society of Chemical Industry     

外源添加物质对黑莓清汁花色苷稳定性和抗氧化活性的影响

本文研究了咖啡酸、阿魏酸、单宁酸、黄芩素、茶多酚、没食子酸、原儿茶酸、芦丁等8种外源辅色素对黑莓清汁花色苷辅色效果、热稳定性、光稳定性和体外抗氧化活性的影响。结果表明:咖啡酸、原儿茶酸、茶多酚、没食子酸、单宁酸对黑莓清汁花色苷的辅色效果影响较显著(p<0.05),最适浓度为0.1 mmol/L,而芦丁的最佳辅色浓度为0.4 mmol/L;实验所选辅色素能够在一定程度上提高黑莓清汁花色苷的热稳定性,其中没食子酸、阿魏酸、咖啡酸对其影响效果显著(p<0.05),分别使黑莓清汁花色苷的热降解半衰期延长了6.06、2.07和1.39倍。此外,原儿茶酸、阿魏酸、芦丁能够显著提高黑莓清汁花色苷的光稳定性、DPPH自由基清除能力和总还原力(p<0.05);没食子酸和单宁酸的辅色作用降低了黑莓清汁花色苷的光稳定性。黄芩素、阿魏酸、咖啡酸、芦丁等外源物质可作为黑莓清汁花色苷有效的辅色素。     

An Enhanced Stability Nanoparticle Preparation by Corn Protein Hydrolysate‐Carboxymethyl Chitosan Maillard Conjugates Loaded with Rutin

Rutin‐loaded corn protein hydrolysate–carboxymethyl chitosan (CPH‐NOCC) Maillard conjugate nanoparticles (NPs) with superior stability under different NaCl concentrations (0–0.25 mol/L) and pH levels (7.0 to 3.0) were investigated. Results showed that the degree of glycosylation of 53.3%, browning index of 0.6, and SDS‐PAGE lane of CPH‐NOCC conjugates were obtained after dry heating for 48 hr (60 °C, 79% RH). The high encapsulation efficiency (EE, 97.8%–98.8%) and CPH‐NOCC‐rutin (98.8%) was significantly higher than CPH‐rutin (97.8%) and CPH/NOCC‐rutin (98.4%) NPs illustrated that hydrolysis was positive for zein encapsulation, and conjugation of NOCC to CPH increased the EE. Hairy carbohydrate protrusions on the surface of CPH‐NOCC‐rutin NPs produced a stronger steric effect and hampered the formation of salt bridges and the particle aggregation under CPH isoelectric point at pH 4.0. Therefore, the CPH‐NOCC conjugate NPs may be suitable carrier for hydrophobic bioactive substances in a board range of business foodstuffs.     

桑葚、甘蔗糖蜜多酚的成分鉴定及其复配物的抗氧化活性

为探索酚类提取物及其复配物的协同增效作用,以桑葚和甘蔗糖蜜多酚作为研究对象,分别测定其总酚、黄酮含量及酚类组成,基于单一提取物的总酚含量按一定配比制得复配物,评价抗氧化活性。结果表明,桑葚游离多酚（MFP）占桑葚总酚含量的90.3%,为677.62 mg没食子酸当量（Gallic Acid Equivalent,GAE）/100 g,黄酮含量为736.65 mg芦丁当量（Rutinum Equivalent,RE）/100 g,共检测出原儿茶酸、3,4-二羟基苯丙酸、咖啡酸、丁香酸、对香豆酸、阿魏酸、矢车菊素3-O-葡萄糖苷和芦丁8种多酚物质,其中矢车菊素3-O-葡萄糖苷含量占92.6%。甘蔗糖蜜多酚（SMP）总酚含量为339.69 mg GAE/100 g,总黄酮含量为314.61 mg RE/100 g,主要单体包括没食子酸、原儿茶酸、绿原酸、咖啡酸、丁香酸、对香豆酸、阿魏酸、芦丁和表儿茶素9种多酚物质。在0~10 mg/mL的浓度范围内SMP、MFP及其复配物具有良好的抗氧化活性且呈现量效关系。同时,两种复配物的抗氧化活性优于SMP和MFP,其中中效原理计算复配物DPPH自由基清除能力的0.25 IC50、0.5 IC50、0.75 IC50、1 IC50、1.25 IC50、1.5 IC50的联合作用指数CI分别为0.73、0.85、0.94、0.91、0.89和0.90,均小于1,表明桑葚和甘蔗糖蜜多酚复配物具有协同抗氧化作用。     

Effect of phenolic compounds on the properties of porcine plasma protein-based film

Properties of porcine plasma protein-based film incorporated with tannic acid, caffeic acid and ferulic acid at different concentrations (1–3% (w/w) of protein content) were studied. Film-forming solution (FFS) containing 3% protein (w/v) and 70% glycerol (w/w of protein content) was preheated at 70 °C for 30 min and adjusted pH to 10 followed by the addition of phenols and film casting. Tensile strength (TS) of resulting film increased by 123.3, 194.3 and 19.5% and elongation at break (EAB) increased by 71.1, 86.3 and 10.2%, respectively, compared with the control film, when tannic acid, caffeic acid and ferulic acid at a level of 3% was added. The use of all phenolic compounds slightly increased water vapor permeability (WVP) of resulting films (p < 0.05). The increases in a^∗- and b^∗-values of films were observed as the higher concentrations of tannic acid and caffeic acid were used. This was associated with the lowered transparency of resulting films. FFS containing 3% caffeic acid with prior oxygenation, especially with pH 10, yielded the film with increased TS but lowered EAB (p < 0.05). Oxygenation of FFS was associated with the lower L^∗-value and higher a^∗-value of resulting films. Therefore, phenolic compounds could be used as natural cross-linkers which affected the properties of porcine plasma protein-based film differently.     

Physicochemical properties of gelatin gels from walleye pollock (Theragra chalcogramma) skin cross-linked by gallic acid and rutin

Gelatin gels were cross-linked by gallic acid and rutin. The gel strength, viscoelastic properties, thermal stability, swelling property, ultrastructure, X-ray diffraction patterns and FTIR spectra were determined to evaluate the physicochemical properties of the modified gels. The gel strength increased with increasing gallic acid concentration up to 20 mg/g dry gelatin, and then decreased at further elevated gallic acid concentration, while it continuously increased with increasing levels of rutin. Either cross-linking agent could enhance the elastic modulus (G′) and the viscous modulus (G″) of hydrogels, but the gelling and melting points didn’t show a notable improvement. Rutin boosted the thermal stability of xerogels, but decreased the equilibrium swelling ratio significantly, while as for gallic acid, there were no obvious effects on the thermal stability and equilibrium swelling ratio of xerogels. Scanning electron microscopy (SEM) was applied to observe the ultrastructure changes of the modified xerogels suggesting that gelatin xerogel at rutin concentration of 8 mg/g dry gelatin showed the highest cross-linking density. X-ray diffraction revealed that both gallic acid and rutin could enter the spacing of polypeptide chains of gelatin to reinforce the intermolecular interaction. And FTIR spectra verified that gallic acid and rutin molecules mainly interacted with skeletal C–N–C group and carboxyl group of gelatin molecules in the formation of gels. The results suggested that rutin was a better cross-linking agent for gelatin, and gels treated with rutin could be found with different physicochemical properties.     

Effect of pH on the antimicrobial activity and oxidative stability of oil-in-water emulsions containing caffeic acid

ABSTRACT:  Antioxidant properties in food are dependent on various parameters. These include the pH value and interactions with food components, including proteins or metal ions. Food components affect antioxidant stability and also influence the properties of microorganisms and their viability. This paper describes an investigation of the effect of pH on the antioxidant and antibacterial properties of caffeic acid in different media. The pH values studied, using an oil-in-water emulsion as model system, were 3, 5 (with and without phosphate buffer), and 9. Effects of mixtures of caffeic acid, bovine serum albumin (BSA), and Fe (III) on oxidative deterioration in the emulsion samples were studied. The results show that the antioxidant activity of caffeic acid was increased by the presence of BSA. This effect was pH dependent and was affected by the presence of iron ions. Antibacterial properties were also pH dependent. The minimum concentration of caffeic acid required to inhibit some microorganisms in the pH range of 5 to 7 was determined. A concentration of 0.4% (w/w) caffeic acid was enough to inhibit the growth of some of the studied microorganisms in the pH range of 5 to 7. However, near-neutral pH concentrations higher than 0.4% were needed to inhibit some microorganisms, including Listeria monocytogenes , E. coli, and Staphylococcus aureus , in the medium.     

Genipin交联明胶/溶菌酶缓释抗菌膜材料的微结构与性能研究

针对亲水明胶膜材料对抗菌剂缓释能力较差的问题,采用生物交联剂(genipin)调节膜材料微结构,制备出新型控释明胶/溶菌酶复合膜材料。系统研究了复合膜材料的力学性能、水汽阻隔性能、膨胀性和热性质等物理性能,并用AFM研究了膜材料的表面微结构,探讨了其结构-性能之间的关系。结果表明:genipin交联显著改善复合膜材料的力学性能,TS值从9.72 MPa逐渐增加至18.80 MPa;复合膜材料的膨胀度(swelling)随genipin浓度增加急剧下降,从1316%降至~200%;genipin交联提升复合膜材料的热稳定性。复合膜材的表面粗糙度依赖于genipin浓度,在低浓度段(0~1.0%),膜材料呈现平整表面微结构;高浓度(2.0%)时,膜表面出现不规则的突起,变得粗糙。适度的genipin交联有助于形成有序的三维网络结构,改善复合膜材料的物理性能;高浓度的genipin过度交联明胶基质,形成团聚状聚集物,及弱化明胶分子间相互作用,进而弱化膜材料的水汽阻隔能力。     

Development of a stable hydrogel network based on agar–kappa-carrageenan blend cross-linked with genipin

Blend of food hydrocolloids, viz. agar and kappa-carrageeenan (agar/kC), was treated with the natural cross-linker genipin in aqueous medium to impart functional stability. The genipin-fixed blend exhibited remarkable stability in the wide range of pH 1–12, as well as in Ringer's solution. Ratios of the hydrocolloids and genipin in the blend as well as in the cross-linked product were optimized (agar/kC 25:75 and agar/kC/genipin 25:75:0.8, w/w) on the basis of swelling properties. Compatibilities of unmodified blend (agar/kC) and the cross-linked blend product in aqueous solution were studied by measuring apparent and intrinsic viscosities and UV absorptions. Properties of agar/kC blend and the genipin cross-linked blend in solid state were evaluated by bulk and true density, pore volume, porosity, thermogravimetric analysis (TGA), swelling ability, X-ray diffraction, degradation rate in vitro, optical microscopy, scanning electron microscopy (SEM) and rheological measurements. The cross-linked blend exhibited higher viscosity, thermal stability and swelling ability as well as low weight loss ratio compared to those of the un-modified blend. The presence of genipin in the cross-linked polymer network was confirmed by MS/MS analysis. This genipin cross-linked blend presents an immense potential for food applications and in other pH-specific applications as well.     

Physicochemical Properties of Non‐thermally Cross‐linked Corn Starch with Phosphorus Oxychloride using Ultra High Pressure (UHP)

Corn starch (20%, w/w) was non‐thermally and conventionally cross‐linked with phosphorus oxychloride (POCl₃; 0.01, 0.05, or 0.1%, based on dry weight of starch) at 400 MPa for 5, 15 and 30 min and at 45°C for 2 h, respectively. Swelling power and solubility of both non‐thermally and conventionally cross‐linked corn starches were relatively lower than those of native corn starch. The pressure holding time did not affect the solubility and swelling power of non‐thermally cross‐linked corn starches. X‐ray diffraction patterns and relative crystallinity were not significantly altered by both conventional and non‐thermal cross‐linking. DSC thermal characteristics of both non‐thermally and conventionally cross‐linked corn starches were not significantly changed indicating that the double helical structure of amylopectin was not influenced by both conventional and non‐thermal cross‐linking reactions. Both non‐thermal and conventional cross‐linking greatly affected the Rapid Visco Analyser (RVA) pasting properties, such as increase in pasting temperature and decrease in peak viscosity compared to native starch. This result suggests that in case of cross‐linking using POCl₃, both non‐thermal and conventional methods result in similar physicochemical properties and non‐thermal cross‐linking with POCl₃ can reduce the reaction time from 2 h to 15 min. This work shows the potential and possibility of non‐thermal starch modification and provides the basic and scientific information on the physicochemical properties of non‐thermally cross‐linked corn starches with phosphorus oxychloride using UHP.     

Polyphenol input to the antioxidant activity of yerba mate (Ilex paraguariensis) extracts

Industrial processing modified the polyphenol content, composition and antioxidant activity of the yerba mate extracts. Pre-dried leaves were the most appropriate raw material combining maximum activity with high polyphenol content. Chlorogenic acid and its derivatives were the major components of the phenolic fraction but we also identified caffeic, rutin and quercetin.Yerba mate extracts inhibited malonedialdehyde formation in sunflower oil (20 μmol/kg) and conjugated dienes production in oil/water emulsions (60 μmol/kg). Enhancing the dose to 60 μmol/kg reduced 27.8% the extract’s activity in oil.The relationship between polyphenol composition and antioxidant activity of a mixture of caffeic, chlorogenic, kaempferol, quercetin and rutin was satisfactorily predicted with a polynomial model. Results showed that quercetin was the highest contributor to the linear term followed by kaempferol and caffeic acid while rutin and chlorogenic acid inputs were the lowest. The model detected five synergistic and six antagonistic effects.     

Highly-porous mannitol particle production using a new templating approach

A new method has been successfully developed to create highly-porous powder templates through the spray drying of mannitol, using citric acid as the templating agent and then removing the citric acid by ethanol washing of the spray-dried powders. It has been demonstrated that textural properties, such as the surface area and the pore volume of the resultant mannitol, can be tuned by varying the concentrations of citric acid, whey protein isolate (WPI), and Gum Arabic. The resulting powder structure is a mannitol network with significant porosity and high surface area of 8.0 ± 0.4 m²/g and total pore volume of 0.075 ml/g. The scanning electron microscope micrographs were consistent with the Brunauer–Emmett–Teller (BET) surface area measurements. It has been found that higher concentrations of WPI, more than 0.5% w/w, have a detrimental effect on the porosity of the spray-dried powders from the solutions of mannitol/WPI with 2% (w/w) citric acid. For Gum Arabic, more than 1% (w/w) Gum Arabic causes lower porosities due to the lower citric acid removal by ethanol washing. The results of this study allow excipient powders to be produced with high specific surface areas.     

Oxidative Stability in Oil‐in‐Water Emulsions with Quercetin or Rutin Under Iron Catalysis or Riboflavin Photosensitization

The effects of quercetin and rutin on the oxidative stability of oil‐in‐water (O/W) emulsions were tested under riboflavin (RF) photosensitization in the presence or absence of FeCl₂. The degree of oxidation in O/W emulsions was determined by headspace oxygen content, conjugated dienes, and lipid hydroperoxides. Quercetin chelated more metal than did rutin in iron catalyzed O/W emulsions. Generally, 0.1 mM quercetin and rutin was oxidative while 0.5 and 1.0 mM quercetin and rutin was antioxidative in O/W emulsions under RF photosensitization. Depending on the analysis method, the antioxidants had different strengths. The antioxidative or oxidative properties of quercetin and rutin vary in O/W emulsions and depend the quercetin and rutin concentrations and oxidative forces like transition metals, RF photosensitization, or a combination thereof.     

Extracts of olive polyphenols improve lipid stability in cooked beef and pork: Contribution of individual phenolics to the antioxidant activity of the extract

Crude polyphenol extracts (50 or 100 mg gallic acid equivalents (GAE)/kg meat) from the waste waters of olive oil pomace reduced the formation of 2-thiobarbituric reactive substances (TBARS) in pre-cooked beef (63–83%) and pork (47–66%). When compared with other antioxidants, the ranking of activities were: tea ? olive > wine. The olive extract contained hydroxy-tyrosol (70.6%), tyrosol (17.5%), caffeic acid (9.5%), p-coumaric acid (1.9%) and vanillic acid (0.3%). Relationship between polyphenol composition and antioxidant activity of a blend containing oleuropein, tyrosol, hydroxy-tyrosol, quercetin, rutin and caffeic, vanillic and coumaric acids was described by a first order polynomial model. Quercetin, hydroxy-tyrosol, caffeic acid and oleuropein had the highest contributions to the linear term followed by rutin and tyrosol. We detected the strongest positive synergism between tyrosol and quercetin, hydroxy-tyrosol, oleuropein and to a lesser degree with caffeic acid whilst the effect of vanillic and coumaric acids were not significant.     

Impact of ascorbic acid on the oxidative colouration and associated reactions of a model wine solution containing (+)−catechin,caffeic acid and iron

Background and Aims: The aim of this study was to examine the oxidative reactions and associated colouration changes relevant to white wine in a synthetic wine system consisting of different combinations of 200 mg/L caffeic acid, 150 mg/L (+)?catechin and 1000 mg/L ascorbic acid, in the presence of 1.5 mg/L iron(II). Method and Results: Reactions were monitored by UV/VIS, CIELab, LC‐DAD and LC‐MS techniques. When ascorbic acid was less than 90% depleted in samples, it induced yellow/green colouration but prevented brown colouration that would otherwise result from catechin‐ and caffeic acid‐derived yellow and red pigments. However, during the loss of ascorbic acid, in the presence of either catechin and/or caffeic acid, reactions were still occurring to ‘prime’ the system for rapid colour formation. When the ascorbic acid was more than 90% depleted, the samples with catechin and/or caffeic acid had an increased rate of brown colouration compared with those to which ascorbic acid was not added. Conclusions: This study demonstrates that ascorbic acid is an effective anti‐browning agent provided it persists in the wine after bottling, but if depleted, serious brown colouration ensues. Significance of the Study: Findings detailed in this report will provide useful guidelines for the more effective use of ascorbic acid as an anti‐browning agent in bottled wine.     

Characterization of Chemically and Thermally Treated Oil‐in‐Water Heteroaggregates and Comparison to Conventional Emulsions

Heteroaggregated oil‐in‐water (O/W) emulsions formed by targeted combination of oppositely charged emulsion droplets were proposed to be used for the modulation of physical properties of food systems, ideally achieving the formation of a particulate 3‐dimensional network at comparably low‐fat content. In this study, rheological properties of Quillaja saponins (QS), sugar beet pectin (SBP), and whey protein isolate (WPI) stabilized conventional and heteroaggregated O/W emulsions at oil contents of 10% to 60% (w/w) were investigated. Selected systems having an oil content of 30% (w/w) and different particle sizes (d₄₃ ≤ 1.1 or ≥16.7 μm) were additionally subjected to chemical (genipin or glutaraldehyde) and thermal treatments, aiming to increase network stability. Subsequently, their rheological properties and stability were assessed. Yield stresses (τ₀) of both conventional and heteroaggregated O/W emulsions were found to depend on emulsifier type, oil content, and initial droplet size. For conventional emulsions, high yield stresses were only observed for SBP‐based emulsions (τ₀,_SBP approximately 157 Pa). Highest yield stresses of heteroaggregates were observed when using small droplets stabilized by SBP/WPI (approximately 15.4 Pa), being higher than those of QS/WPI (approximately 1.6 Pa). Subsequent treatments led to significant alterations in rheological properties for SBP/WPI systems, with yield stresses increasing 29‐fold (glutaraldehyde) and 2‐fold (thermal treatment) compared to untreated heteroaggregates, thereby surpassing yield stresses of similarly treated conventional SBP emulsions. Genipin‐driven treatments proved to be ineffective. Results should be of interest to food manufacturers wishing to design viscoelastic food emulsion based systems at lower oil droplet contents.     

How reactive extrusion with adipic acid improves the mechanical and barrier properties of starch/poly (butylene adipate‐co‐terephthalate) films

Blends of starch with polyesters have commonly been used in the production of biodegradable films. However, the components in the blend are not always miscible; therefore, the use of compatibilisers is recommended. The objective of the present work was to study the compatibilisation effect of adipic acid (0.5%; 1.0%; 1.5% (w/w)) on films consisting of starch/glycerol/poly (butylene adipate‐co‐terephthalate) (PBAT) produced by reactive extrusion. Films compatibilised with adipic acid exhibited statistically significant increase in tensile strength (from 7.28 to 8.45–9.13 MPa), elongation (in this case only with 0.5% of adipic acid) (516.51–679.10%), Young's modulus (21.72–28.75 MPa) and reduction in water vapour permeability (9.76–8.32 × 10^?11 g per s.m.Pa) compared with the control film, which lacked the compatibiliser. Films produced using the compatibiliser also presented a microstructure with fewer cracks. There were no differences in the thermal degradation and crystallinity profile of the films.     

Physicochemical and sensory properties of milk fortified with iron microcapsules prepared with water‐in‐oil‐in‐water emulsion during storage

This study investigated the possibility of fortifying iron microcapsule powder into milk and the effects of the fortification on the physicochemical and sensory properties of the products during storage. The iron microcapsules were prepared by the water‐in‐oil‐in‐water (W/O/W) emulsion technique. Fortifying the lower concentrations (0.1–0.3%, w/v) of iron microcapsules into the milk samples did not significantly change thiobarbituric acid values. The L‐values for the milk samples were not significantly influenced by fortifying iron microcapsules (0.1–0.7%, w/v). The overall acceptability scores were not affected when the lowest concentration of iron microcapsules (0.1%, w/v) was fortified into the milk.     

Effect of Flavonoids and Related Compounds on Soybean Lipoxygenase-1 Activity

Soybean lipoxygenase-1 activity was determined in the presence of the flavonoid compounds quercetin, rutin and kaempferol, and with caffeic acid and chlorogenic acid, which are cinnamic acids. All flavonoids and related compounds resulted in at least 10% inhibition of lipoxygenase activity on an equal weight basis. Inhibition of lipoxygenase-1 activity by flavonoids and cinnamic acids was compared to inhibition by butylated hydroxyanisole (BHA) and butylated hydrox-ytoluene (BHT). Kaempferol, caffeic acid and chlorogenic acid showed inhibition comparable to that of BHT. On an equimolar basis, rutin was the most effective inhibitor of lipoxygenase activity.