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Now showing items 1 - 16 of 23

  • A novel copigment of quercetagetin for stabilization of grape skin anthocyanins

    Xu, Honggao   Liu, Xuan   Yan, Qiuli   Yuan, Fang   Gao, Yanxiang  

    Highlights • A novel flavonol named quercetagetin, from Tagetes erecta L. flower residues, was evaluated for stabilizing anthocyanins. • Quercetagetin showed a high stabilization effect on grape skin anthocyanins during thermal treatment and light exposure. • Compared with epigallocatechin gallate, tea polyphenols, myricitrin and rutin, quercetagetin was most effective. Abstract The thermal and light stability of grape skin anthocyanins combined with quercetagetin was investigated at designed pH values of 3, 4 and 5. The molar ratios of anthocyanins to quercetagetin were 1:10, 1:20 and 1:40 for thermally treatment at 70 °C, 80 °C and 90 °C, respectively, and the ratios were tested at 5:1, 1:1, 1:5 and 1:10 in the light exposure experiments. The degradation reaction of anthocyanins in the presence of quercetagetin followed the first-order kinetic model. The half-life (t1/2) of anthocyanins was extended significantly with the increase of quercetagetin concentration (p < 0.05). The total colour difference values (ΔE∗) for the anthocyanin solutions with quercetagetin were smaller than those without copigment under the same experimental conditions (pH and light exposure time). Compared with epigallocatechin gallate (EGCG), tea polyphenols (TP), myricitrin and rutin, quercetagetin was the most effective copigment to stabilize grape skin anthocyanins.
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  • Nonenzymatic Browning Criteria to Sea Buckthorn Juice during Thermal Processing

    Xu, Honggao   Hao, Qinfeng   Yuan, Fang   Gao, Yanxiang  

    Nonenzymatic browning reaction is responsible for color and quality changes of fruit juices during thermal processing, and reasonable criteria are crucially important for establishing good manufacturing practice. The nonenzymatic browning criteria of thermally treated sea buckthorn juice from 90 to 120C, i.e., the absorbance at 420nm (A(420nm)) and color difference (E*), were investigated. The values of L*, a*, b* and the content of ascorbic acid of sea buckthorn juice during thermal treatment could be fitted to first-order kinetics, while the formation of 5-hydroxymethylfurfural (5-HMF) followed a zero-order kinetics. The changes of E* and A(420nm) could be estimated by integrated models. The thermal processing parameters for sea buckthorn juice were optimized using kinetic models with low level of 5-HMF and high content of ascorbic acid, and it was found that the thermal processing should be performed at 110C for 0.585min. Estimation of the activation energy showed that A(420nm) could be a reasonable indicator for evaluating the nonenzymatic browning of thermally processed sea buckthorn juice from 90 to 110C and E* could be a valuable index at 120C. Practical ApplicationsFor fruit juice (puree) processing, optimal parameters are critically important to manufacture products with high quality. During thermal processing, vitamin C degradation, 5-hydroxymethylfurfural accumulation and nonenzymatic browning occur simultaneously. The high quality includes the high vitamin content, the favorable appearance, the smallest color difference between raw material and final product, etc. This article discussed color changes of sea buckthorn juice, a superfruit juice specialized in high vitamin C content and low pH value, during thermal sterilization. Absorbance at 420nm (A(420nm)) and color differences (E*), two indicators in controlling nonenzymatic browning during juice processing, were evaluated with kinetic models and used to optimize the thermal processing. Furthermore, the activation energy calculation of A(420nm) and E* revealed the reasonable criteria on juice quality controlling. All the quality control criteria in this paper showed a guideline of quality control in practical juice manufacturing.
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  • Mathematical Modeling of Betanin Extraction from Red Beet (Beta vulgaris L.) by Solid–Liquid Method

    Xu, Honggao   Peng, Qiang   Yuan, Fang   Gao, Yanxiang  

    Effective diffusion coefficient (D-value) is an important parameter for the extraction process. In this study, a cylindrical model to estimate the D-value of betanin extraction from red beet roots was developed. The influence of extraction temperature, pH, cylindrical thickness and type of acids on the D-value was also investigated. The optimal parameters of betanin extraction were 30 degrees C, pH 4.0 adjusted with sulfurous acid or acetic acid. D-values under the above conditions were 18.95 x 10(-11) m(2)/s and 17.87 x 10(-11) m(2)/s, respectively. The result showed that D-value elevated with the increase of cylindrical thickness, which was consistent with earlier conclusion from spherical model. The modeling may be useful for the investigation into extraction process and practical application.
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  • Antioxidative phenolics obtained from spent coffee grounds (Coffea arabica L.) by subcritical water extraction

    Xu, Honggao   Wang, Weiyou   Liu, Xin   Yuan, Fang   Gao, Yanxiang  

    Highlights • Subcritical water was first used to recover phenolics from spent coffee grounds (SCG). • The maximum antioxidant activity of SCG extract was optimized by response surface methodology (RSM). • The predicted values of phenolics yield and the antioxidant activity were well fitted to the experimental data. • Chlorogenic acids were the main compounds contributing to the antioxidant activity of SCG extract. Abstract Response surface methodology (RSM) was employed to optimize subcritical water extraction (SWE) of spent coffee grounds (SCG) with emphasis on the yield of total phenolics and radical scavenging capacities on 2,2-azinobis-(3-ethylbenzothiazolin-6-sulfonic acid) (ABTS +) and 1,1-diphenyl-2-picrylhydrazyl (DPPH +). The analysis involved three variables: temperature (160–180 °C), time (35–55 min) and solid-to-liquid ratio (14.1–26.3 g/L). The optimal conditions for total phenolic compounds (86.23 mg GAE/g), antioxidant activity in terms of ABTS + (81.38 mmol TE/100 g) and DPPH + (42.13 mmol TE/100 g) scavenging activities were predicted to be in ranges of 160-180 °C/37.9–55.0 min/14.1 g/L. The verified TPC (88.34 mg GAE/g), antioxidant activity on ABTS + (88.65 mmol TE/100 g) and DPPH + (38.28 mmol TE/100 g) based on superimposing contour plots (179 °C, 36 min, and 14.1 g/L) were in good agreement with the predicted data obtained under optimal conditions. 3-O-caffeoylquinic acid, 4-O-caffeoylquinic acid and 5-O-caffeoylquinic acid were found to be the major contributor to the antioxidant activities of SCG extract. Graphical abstract The spectra on the left of the image could be better explained and is not clear what the difference of these two chromatograms is. A suggestion is to express somehow what they indicate, like which peaks are interesting to observe and what is the result of that (the presence of the CQAs that are antioxidant compounds, for example). If possible, indicate with arrows the desired region on the response surfaces (for antioxidant activity high temperatures with low ratios, and for total phenolics temperatures around 175 °C, since time appears little important in this case)
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  • Optimization by response surface methodology of supercritical carbon dioxide extraction of flavour compounds from Chinese liquor vinasse

    Xu, Honggao   Xu, Xiang   Tao, Yidi   Yuan, Fang   Gao, Yanxiang  

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  • In?vitro binding capacities and physicochemical properties of soluble fiber prepared by microfluidization pretreatment and cellulase hydrolysis of peach pomace

    Xu, Honggao   Jiao, Qiong   Yuan, Fang   Gao, Yanxiang  

    Highlights • Microfluidization pretreatment coupled with cellulase hydrolysis (MC) on soluble peach fiber (SPF) preparation was first reported. • Microfluidization pretreatment significantly improved the efficiency of cellulase hydrolysis on SPF preparation. • The sponge-like porous network of MC-SPF resulted in high binding capacity to sodium cholate and cholesterol. Abstract The effects of microfluidization coupled with cellulase hydrolysis (MC), solely cellulase hydrolysis (C) and solely water extraction (W) on the in vitro binding capacities of soluble peach fibers (SPFs) to sodium cholate and cholesterol were investigated. The yield and efficiency of soluble fiber production were significantly improved by the MC treatment. Pectic polysaccharides and β-glucan appeared to be the major components of the three SPFs as indicated by the saccharide composition analysis and FTIR. As opposed to C-SPF and W-SPF, MC-SPF exhibited a greater amount of pectic polysaccharides with a highly branched structure. Moreover, MC-SPF and C-SPF were characterized by a lower molecular weight profile and more significant shear thinning properties compared to W-SPF. The binding capacities of MC-SPF and C-SPF to sodium cholate and cholesterol were much stronger than that of W-SPF, which could be probably attributed to their more sponge-like porous network.
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  • Subcritical water extraction and antioxidant activity evaluation with on-line HPLC-ABTS·+ assay of phenolic compounds from marigold (Tagetes erecta L.) flower residues

    Xu, Honggao   Wang, Weiyou   Jiang, Junping   Yuan, Fang   Gao, Yanxiang  

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  • Physicochemical and\r in vitro\r antioxidant properties of pectin extracted from hot pepper (\r Capsicum annuum\r L. var.\r acuminatum\r (Fingern)) residues with hydrochloric and sulphuric acids

    Xu, Honggao   Tai, Kedong   Wei, Tong   Yuan, Fang   Gao, Yanxiang  

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  • Supercritical CO(2) extraction of oleoresin from marigold (Tagetes erecta L.) flowers and determination of its antioxidant components with online HPLC-ABTS(center dot+) assay

    Gong, Ying   Plander, Szabina   Xu, Honggao   Simandi, Bela   Gao, Yanxiang  

    BACKGROUND: Marigold is a traditional medicine herb which shows good pharmacological activity in many aspects. It is very important to obtain and investigate the specific bioactive compounds from marigold. The objective of the study was to extract the oleoresin from marigold with supercritical CO(2) (SC-CO(2)) at different pressures and temperatures, detect the fatty acid composition by gas chromatography-mass spectrometry and investigate the antioxidative components in the extracts by combined online high-performance liquid chromatography-2,2-azinobis-(3-ethylbenzothiazolin-6-sulfonic acid (HPLC-ABTS(center dot+)) post-column assay and HPLC-tandem mass spectrometry. RESULTS: For the pressure range (20-40 MPa) and temperature range (30-70 degrees C), 30 MPa/70 degrees C gave the highest yield of oleoresin (58.9 g kg(-1)). The dominant fatty acids of marigold flower oleoresin were linoleic acid (>26.41%), palmitic acid (>24.22%) and oleinic acid (>20.12%). Significant effects of the extraction pressure and temperature on the antioxidant activity were observed (P < 0.05). Lutein esters, alpha-tocopherol, beta-tocopherol, gamma-tocopherol and delta-tocopherol were the dominant antioxidant compounds in the extracts. CONCLUSION: The study has shown that the yield and total antioxidant activity of the marigold extracts were affected by the pressure and temperature of SC-CO(2), and that online HPLC technique could be used as an efficient and rapid method for separation and identification of bioactive compounds from a complex mixture. (C) 2011 Society of Chemical Industry
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  • On-line HPLC-ABTS screening and HPLC-DAD-MS/MS identification of free radical scavengers in Gardenia (Gardenia jasminoides Ellis) fruit extracts

    He, Wenhao   Liu, Xuan   Xu, Honggao   Gong, Ying   Yuan, Fang   Gao, Yanxiang  

    Gardenia jasminoides Ellis is a folk medicine for pharmacological activities in China. In this study, on-line HPLC-ABTS and HPLC-DAD-MS/MS analyses were applied to screen and identify free radical scavengers in gardenia fruit extracts (GFE). Nine compounds were identified (3-caffeoylquinic acid, 4-caffeoylquinic acid, 5-caffeoylquinic acid, 3,4-dicaffeoylquinic acid, 3,5-dicaffeoylquinic acid, 4,5-dicaffeoylquinic acid, quercetin-3-rutinoside, crocetin di(beta-gentiobiosyl) ester, and geniposide). 3-Caffeoylquinic acid and 4-caffeoylquinic acid were firstly found in GFE. Caffeoylquinic acids, dicaffeoylquinic acids, and 4-sinapoyl-5-caffeoylquinic acid were the dominant free radical scavengers in GFE, and their Trolox equivalent antioxidant capacities (TEAC) were determined. 3,5-Dicaffeoylquinic acid was the most potent antioxidant with TEAC value of 1.1 mM. In contrast, crocetin di( p-gentiobiosyl) ester and geniposide showed little ABTS.(+) scavenging activity. (C) 2010 Elsevier Ltd. All rights reserved.
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  • Effects of ribose to cysteine ratios on the formation of volatile compounds from the Maillard reaction in supercritical carbon dioxide

    Xu, Honggao   Liu, Xuan   Zhao, Jian   Gao, Yanxiang  

    The volatile compounds formed from the Maillard reaction in a model system treated with/without supercritical carbon dioxide (SC-CO(2), 40 MPa, 140 degrees C) were investigated at three molar ratios (3:1, 1:1, and 1:3) of ribose to cysteine. The headspace volatiles generated in the reaction mixtures were examined by SPME in combination with GC-MS. The ratio of ribose to cysteine had complex effects on the volatiles formation and those effects got further complicated by the SC-CO(2). treatment. The formation of thiols and polysulfur heterocyclic compounds was generally favoured at an equal molar ratio of reactants; disulfides were favoured at low ratio of ribose to cysteine; while the effect of reactant ratios on the formation of thiophenes and fused bicyclic compounds did not follow a consistent pattern. SC-CO(2) treatment resulted in a reduction of most volatiles, however, promoted the formation of some well-known meaty aromatic compounds. (C) 2008 Elsevier Ltd. All rights reserved.
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  • Inactivation of peroxidase and polyphenol oxidase in red beet (Beta vulgaris L.) extract with high pressure carbon dioxide

    Liu, Xuan   Gao, Yanxiang   Peng, Xiaoting   Yang, Bin   Xu, Honggao   Zhao, Han  

    The inactivation of peroxidase (POD) and polyphenol oxidase (PPO) in red beet extract with high pressure carbon dioxide (HPCD) was investigated. HPCD treatment at 37.5 MPa for POD and 22.5 MPa. for PPO (55 degrees C, 60 min) resulted in a reduction of their activities by approximately 86% and 95%, respectively. Compared with thermal treatment (55 degrees C), the decimal reduction time (D) of POD and PPO was reduced from 555.56 min to 74.63 min and 161.29 min to 38.31 min, respectively, by the HPCD treatment. The inactivation process followed first-order kinetics (R(2) > 0.84, p<0.05) with D values declining with the rise of pressure and temperature. The activation energy of the inactivation was reduced by the HPCD treatment from 92.54 kJ/mol to 68.63 kJ/mol and 57.06 kJ/mol to 53.58 kJ/mol for POD and PPO, respectively. Analysis of the kinetic parameters of the inactivation showed that both POD and PPO were less sensitive to pressure changes under supercritical than subcritical conditions. (C) 2007 Elsevier Ltd. All rights reserved.
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  • Inactivation of peroxidase and polyphenol oxidase in red beet (Beta vulgaris L.) extract with continuous high pressure carbon dioxide

    Liu, Xuan   Gao, Yanxiang   Xu, Honggao   Hao, Qinfeng   Liu, Guangmin   Wang, Qi  

    The inactivation of peroxidase (POD) and polyphenol oxidase (PPO) in red beet extract (RBE) with continuous high pressure carbon dioxide (HPCD) was investigated. HPCD treatment at 7.5 MPa (55 degrees C, 30 min) resulted in a reduction of their activities by approximately 73% and 93%, respectively. Compared with thermal treatment, continuous HPCD treatment reduced the decimal reduction time (D) of POD and PPO from 555.6 min to 55.9 min and 161.3 min to 32.1 min, respectively. The inactivation process could be described by first-order kinetics (r(2) > 0.70, p < 0.05); D values declined when temperature increased and continuous HPCD at 7.5 MPa and 55 degrees C resulted in the highest reaction rate constant (k value; smallest D value). The activation energy of the inactivation was reduced by HPCD treatment from 92.5 kJ/mol to 69.8 kJ/mol and 57.1 kJ/mol to 49.5 kJ/mol for POD and PPO, respectively. Continuous HPCD treatment had little effect on the antioxidant capacities of RBE samples. (C) 2009 Elsevier Ltd. All rights reserved.
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  • Antioxidative phenolics obtained from spent coffee grounds (Coffea arabica L.) by subcritical water extraction

    Xu, Honggao   Wang, Weiyou   Liu, Xin   Yuan, Fang   Gao, Yanxiang  

    Response surface methodology (RSM) was employed to optimize subcritical water extraction (SWE) of spent coffee grounds (SCG) with emphasis on the yield of total phenolics and radical scavenging capacities on 2,2-azinobis-(3-ethylbenzothiazolin-6-sulfonic acid) (ABTS(center dot+)) and 1,1-dipheny1-2-picrylhydrazyl (DPPI-1(center dot+)). The analysis involved three variables: temperature (160-180 degrees C), time (35-55 min) and solidto-liquid ratio (14.1-26.3 g/L). The optimal conditions for total phenolic compounds (86.23 mg GAE/g), antioxidant activity in terms of ABTS** (81.38 mmol TE/100g) and DPPH center dot+ (42.13 mmol TE/100 g) scavenging activities were predicted to be in ranges of 160-180 degrees C/37.9-55.0 min/14.1 g/L. The verified TPC (88.34mg GAE/g), antioxidant activity on ABTS(center dot+) (88.65 mmol TE/100g) and DPPF1* (38.28 mmol TE/100g) based on superimposing contour plots (179 degrees C, 36min, and 14.1 g/L) were in good agreement with the predicted data obtained under optimal conditions. 3-O-caffeoylquinic acid, 4-0-caffeoylquinic acid and 5-O-caffeoylquinic acid were found to be the major contributor to the antioxidant activities of SCG extract. (C) 2015 Elsevier B.V. All rights reserved.
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  • Optimization of supercritical carbon dioxide extraction of lutein esters from marigold (Tagetes erecta L.) with vegetable oils as continuous co-solvents

    Gao, Yanxiang   Liu, Xuan   Xu, Honggao   Zhao, Jian   Wang, Qi   Liu, Guangmin   Hao, Qinfeng  

    Medium-chain triglycerides (MCTs), sunflower seed oil, soybean oil, rapeseed oil and n-hexane were used as co-solvents to promote supercritical carbon dioxide (SC-CO(2)) extraction of lutein esters from marigold (Tagetes erecta L.). The steepest ascent method was used to determine the most effective co-solvent in improving the extraction yield, followed by an application of response surface methodology (RSM) to optimize SC-CO(2) extraction conditions with the best co-solvent MCT. The results showed that the second-order polynomial model could well describe and predict the responses of lutein ester yield. The independent variable of pressure, the quadratics of temperature, pressure and concentration of MCf, and the interaction between pressure and concentration of MCT were most influential on the yield of lutein esters. The optimum extraction conditions within the experimental range were predicted to be: extraction pressure of 46.8 MPa, temperature of 65.9 degrees C and MCT concentration of 1.5% (w/w of CO(2)), with a CO(2) flow rate of 10 kg/h and extraction time of 3 h. The maximum yield of lutein esters under these conditions was predicted to be 1263.62 mg/100 g marigold. (C) 2009 Elsevier B.V. All rights reserved.
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  • Effects of supercritical carbon dioxide on volatile formation from Maillard reaction between ribose and cysteine

    Xu, Honggao   Gao, Yanxiang   Liu, Xuan   Zhao, Jian  

    BACKGROUND: Supercritical carbon dioxide (SC-CO(2)) technology is being used in an increasing number of food-manufacturing applications; however, its effect on the Maillard reaction is not well studied. The objective of this study was to investigate the effect of SC-CO(2) treatment (140 degrees C, 40 MPa) on the Maillard reaction of an aqueous ribose-cysteine model system under varying pH conditions (5.6, 7.0 and 8.0), with emphasis on the formation of volatile compounds. RESULTS: SC-CO(2) had a suppressing effect on the browning stages of the reaction under acidic and neutral pH conditions, while it appeared to have an accelerating effect at pH 8.0. Over 70 volatile compounds were positively identified from the headspace of the model system by gas chromatography-mass spectrometry. The volatiles were dominated by sulfur-containing compounds including thiophenes and fused bicyclic sulfur-containing compounds under all experimental conditions. Several compounds, including 2-methyl-3-furanthiol, 2-furanmethanethiol, 3-thiophenethiol, and 2-methyl-3-thiophenethiol, and one of the intermediates, furfural, were generated in much higher amounts in the SC-CO(2)-treated samples, especially at alkaline and neutral pH values. CONCLUSION: SC-CO(2) treatment was inhibitory to the formation of most volatiles in the Maillard reaction, but enhanced the formation of some intermediates and well-known meaty flavoured compounds. (c) 2007 Society of Chemical Industry.
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