pH诱导烟草多酚氧化酶二级结构变化的光谱学研究

为了获得更多的关于多酚氧化酶二级结构和活性中心结构的信息 ,应用FT -IR以及去卷积技术、荧光光谱、紫外差光谱研究了溶液 pH的变化对烟草多酚氧化酶的二级结构的影响并对其活性中心的光谱跃迁进行了归属 .实验结果表明 ,随着 pH值的降低或提高 ,多酚氧化酶的二级结构发生了变化 ,浕 螺旋和反平行 β 折叠含量减少 ,无规卷曲含量有所增加 ,同时色氨酸和酪氨酸残基的微环境发生了一定的变化 ;随pH的降低 ,活性中心的Cu2 + 与配位的组氨酸咪唑基的作用加强 ;此外 ,归属和讨论了酶活性中心金属离子与配体间全部电荷转移谱带     

Ultrasonic extraction of steroidal alkaloids from potato peel waste

Potato processors produce large volumes of waste in the form of potato peel which is either discarded or sold at a low price. Potato peel waste is a potential source of steroidal alkaloids which are biologically active secondary metabolites which could serve as precursors to agents with apoptotic, chemopreventive and anti-inflammatory properties. The present study investigated the relative efficacy of ultrasound assisted extraction (UAE) and solid liquid extraction (SLE) both using methanol, to extract steroidal alkaloids from potato peel waste and identified optimal conditions for UAE of α-solanine, α-chaconine, solanidine and demissidine. Using response surface methodology optimal UAE conditions were identified as an amplitude of 61 μm and an extraction time of 17 min which resulted the recovery of 1102 μg steroidal alkaloids/g dried potato peel (DPP). In contrast, SLE yielded 710.51 glycoalkaloid μg/g DPP. Recoveries of individual glycoalkoids using UAE yielded 273, 542.7, 231 and 55.3 μg/g DPP for α-solanine, α-chaconine, solanidine and demissidine respectively. Whereas for SLE yields were 180.3, 337.6, 160.2 and 32.4 μg/g DPP for α-solanine, α-chaconine, solanidine and demissidine respectively. The predicted values from the developed second order quadratic polynomial equation were in close agreement with the experimental values with low average mean deviation (E < 5%) values. Predicted models were highly significant (p < 0.05) for all parameters studied. This study indicates that UAE has strong potential as an extraction method for steroidal alkaloids from potato peel waste.     

Ultrasonic-microwave-assisted extraction for enhancing antioxidant activity of Dictyophora indusiata polysaccharides: The difference mechanisms between single and combined assisted extraction

The purpose of this study is to investigate the effects of different extraction methods (hot water-assisted extraction (HWE), microwave-assisted extraction (MAE), ultrasonic-assisted extraction (UAE), and ultrasonic-microwave- assisted extraction (UAME)) on the yield, chemical structures and antioxidant activity of Dictyophora indusiata polysaccharides (DPs). The research results showed that UMAE treatment had greater degree of damage to the cell wall of DPs and better comprehensive antioxidant capacity. Different extraction methods had no obvious effect on the types of glycosidic bonds and sugar rings, similar chemical composition and monosaccharide composition, with different absolute molecular weight (Mw) and molecular conformation. In particular, DPs for UMAE method had the highest polysaccharides yield, which was related to the conformational stretching and degradation avoidance of DPs in the higher molecular weight components under the simultaneous action of microwave and ultrasonic. These findings suggest that the UMAE technology has good potential for modification and application of DPs in the functional food industry.     

Ultrasound-assisted extraction of xyloglucan from apple pomace

Ultrasound-assisted extraction was evaluated as a simpler and more effective alternative to conventional extraction method for the isolation of xyloglucan from apple pomace. The apple pomace samples were extracted under indirect sonication in an ultrasound cleaning bath. The ultrasound extraction was compared with the conventional method, on the productions of xyloglucan. It was found that the ultrasound-assisted extraction of xyloglucan was about three times faster than the traditional extraction method. Response surface methodology was employed to study the effect of liquid:solid ratio, KOH concentration and ultrasound-assisted extraction time on the yield of xyloglucan from apple pomace. Regression analysis was performed on the data obtained. The most relevant variable was the quadratic of liquid:solid ratio. The coefficient determination (R²) was good for the second-order model. The optimum combination was determined as a liquid:solid ratio of 34.4:1 (v/w), a KOH concentration of 3.3 M and an ultrasound-assisted extraction time of 2.5 h.     

Ionic liquid-aqueous solution ultrasonic-assisted extraction of three kinds of alkaloids from Phellodendron amurense Rupr and optimize conditions use response surface

In this paper, we chose diffident kinds of ionic liquids to optimal selection an optimal one to extract alkaloids from Phellodendron amurense Rupr. Four ionic liquids with diffident carbon chains or anions have been investigated and 1-butyl-3-methylimidazolium bromide with best productivity. Then, selections have been optimized in different conditions, including concentration of ionic liquid, time for ultrasonic treatment, ultrasonic power and solid–liquid ratio. Moreover, three conditions have been comprehensively assessment by response surface methodology, the optimal conditions were determined as follows ultrasonic power 100 W, extraction time 75 min and ratio of solvent to raw material 1:14. Under these conditions, the yield% (MIX) was 106.7% (extracted by heat reflux being defined 100%). Comparing with other methods, the advantages are saving conserving, time saving, high yield% and especially pollution-free.     

Kinetic modeling of the ultrasound-assisted extraction of polyphenols from Picea abies bark

In this paper, the kinetics of polyphenols extraction from spruce bark (Picea abies) under ultrasounds action was investigated. Studies were performed in order to express the effect of some specific parameters (as: ultrasounds, surface contact between solvent and solid, extraction time and temperature) on the total phenolic content (TPC). Experiments were performed in the presence and absence of ultrasounds, using different contact surfaces between solvent and solid, for times from 5 to 75 min and temperatures of 318, 323 and 333 K. All these factors have a positive influence on the process, enhancing the extraction rate by recovering higher amounts of polyphenols. The process takes place in two stages: a fast one in the first 20–30 min (first stage), followed by a slow one approaching to an equilibrium concentration after 40 min (second stage). In these conditions, the second-order kinetic model was successfully developed for describing the mechanism of ultrasound-assisted extraction of polyphenols from P. abies bark. Based on this model, values of second-order extraction rate constant (k), initial extraction rate (h), saturation concentration (C_s) and activation energy (E_a) could be predicted. Model validation was done by plotting experimental and predicted values of TPC’s, revealing a very good correlation between the obtained data (R² > 0.98).     

Optimization of ultrasonic cell grinder extraction of anthocyanins from blueberry using response surface methodology

Ultrasonic cell grinder extraction (UCGE), using water as the solvent, was firstly applied to extract anthocyanins from blueberry. Extraction yield was related with four variables, including ratio of solution to solid, extraction power, buffer time, and extraction time. On the basis of response surface methodology (RSM), the optimal conditions were determined to be the ratio of solution to solid as 25:1 (mL/g), the extraction power as 1500 W, the buffer time as 3.0 s, and the extraction time as 40 min. The experimental yield of anthocyanins using UCGE was 2.89 mg/g higher than that of conventional ultrasound-assisted extraction (CUAE). This study indicated that UCGE was an innovative, efficient, and environment friendly method in ultrasonic extraction fields, and had a potential to effectively extract other bioactive constituents.     

Kinetics of ultrasound-assisted extraction of antioxidant polyphenols from food by-products: Extraction and energy consumption optimization

Ultrasound-assisted extraction (UAE) of antioxidant polyphenols from chicory grounds was studied in order to propose a suitable valorization of this food industry by-product. The main parameters influencing the extraction process were identified. A new mathematical model for multi-criteria optimization of UAE was proposed. This kinetic model permitted the following and the prediction of the yield of extracted polyphenols, the antioxidant activity of the obtained extracts and the energy consumption during the extraction process in wide ranges of temperature (20–60 °C), ethanol content in the solvent (0–60% (vol.) in ethanol–water mixtures) and ultrasound power (0–100 W). After experimental validation of the model, several simulations at different technological restrictions were performed to illustrate the potentiality of the model to find the optimal conditions for obtaining a given yield within minimal process duration or with minimal energy consumption. The advantage of ultrasound assistance was clearly demonstrated both for the reduction of extraction duration and for the reduction of energy consumption.     

响应面法优化超声辅助提取-原子荧光法快速测定茶叶痕量汞

研究了一种使用超声波辅助提取(UAE)-原子荧光法测定茶叶痕量汞的快速方法.采用Plackett-Burman设计从6个影响汞提取率的因素中筛选出3个显著因素—超声时间St,超声温度T和HNO3:H2O2(1:1,δ)体积A2,并采用中心组合设计和响应面法优化参数.结果表明,最优提取条件为,浸泡时间6 min,St 8...     

Optimization of ultrasound-assisted extraction of bioactive compounds from wild garlic (Allium ursinum L.)

Ultrasound-assisted extraction was used for extraction of bioactive compounds and for production of Allium ursinum liquid extract. The experiments were carried out according to tree level, four variables, face-centered cubic experimental design (FDC) combined with response surface methodology (RSM). Temperature (from 40 to 80 °C), ethanol concentration (from 30% to 70%), extraction time (from 40 to 80 min) and ultrasonic power (from 19.2 to 38.4 W/L) were investigated as independent variables in order to obtain the optimal conditions for extraction and to maximize the yield of total phenols (TP), flavonoids (TF) and antioxidant activity of obtained extracts. Experimental results were fitted to the second order polynomial model where multiple regression and analysis of variance were used to determine the fitness of the model and optimal condition for investigated responses. The predicted values of the TP (1.60 g GAE/100 g DW), TF (0.35 g CE/100 g DW), antioxidant activity, IC₅₀ (0.71 mg/ml) and EY (38.1%) were determined at the optimal conditions for ultrasound assisted extraction: 80 °C temperature, 70% ethanol, 79.8 min and 20.06 W/L ultrasonic power. The predicted results matched well with the experimental results obtained using optimal extraction conditions which validated the RSM model with a good correlation.     

基于响应面模型的高超声速低温喷管优化

 建立了高超声速低温(HYLTE)喷管的响应面模型,样本点设计矩阵采用正交试验设计法构造,样本数据通过3维粘性NS方程计算喷管光腔耦合段的多组分混合流场获得。基于HYLTE喷管响应面模型,对喷管进行了多目标优化,定义了综合性能参数,优化后喷管混合性能显著改善,综合性能明显提高。计算表明,基于响应面模型的优化策略,能够满足喷管优化对计算精度和计算量的要求。运用多学科设计优化软件框架iSIGHT作为建模和优化的辅助工具,提高了优化设计的实现效率。     

Kinetic modelling of ultrasound-assisted extraction of phenolics from cereal brans

Cereal brans are by‐products of the milling of cereal grains, which are mainly used as low value ingredients in animal feed. Wheat and oat bran is a rich source of bioactives and phytochemicals, especially phenolic compounds. Within this study, the application of ultrasound (US) technology to assist the extraction of phenolics from oat and wheat bran was investigated (20–45 kHz). Peleg’s mathematical model was used to study the kinetics of ultrasound-assisted extraction (UAE) and subsequent stirring of total phenolic compounds (TPC). The surface morphology of cereal brans after extraction was studied using SEM analysis. The excellent agreement was determined between the values of TPC calculated from Peleg’s mathematical model and actual experimental results. The constant that represents a time required for the initial phenolic concentration to be extracted to one-half of its initial value has been introduced (K_1/2). It was shown that the TPC extraction kinetics was dependent only on K_1/2 enabling fast kinetics fitting and comparison between extraction rates. Moreover, different values of K_1/2 constant could indicate the differences in brans composition and consequently different influence of US pretreatment on these samples.     

Ultrasound-assisted polysaccharide extraction from Cercis chinensis and properites,antioxidant activity of polysaccharide

The purpose of the study was to improve the extraction of polysaccharide from the leaves of Cercis chinensis Bunge using ultrasound, and compare the difference between boiling and ultrasound extraction in terms of polysaccharide content, monosaccharide compounds, and evaluate how the factors affected the bioactivity. The best conditions, according to the single factor experiments and the Box-Bohnken design (BBD), were an intensity of ultrasound of 180 W, duration of extraction of 40 min, proportion of water to material of 15:1 (g/g), and a higher polysaccharide yield of 20.02 ± 0.55 (mg/g) than in boiling extraction (16.09 ± 0.82 mg/g). The antioxidative experiment suggested the polysaccharide by ultrasound exhibited higher DPPH, hydroxyl radical scavenging capacities, and reducing power at 1.2–1.4 mg/mL, which was superior to the boiling polysaccharide. Further analysis showed that the ultrasonic purified polysaccharides like Gla, N-Glu, and GluA contained more total sugar and uronic acids than the boiling method did. This may indicate that the ultrasonic isolation of the polysaccharides increase the antioxidant activity of the polysaccharides.     

Artificial neural network model- and response surface methodology-based optimization of Atractylodis Macrocephalae Rhizoma polysaccharide extraction,kinetic modelling and structural characterization

Atractylodis Macrocephalae Rhizoma (AMR) is the dried rhizome of Atractylodes macrocephala Koidz, which is widely used in the development of health products. AMR contains a large number of polysaccharides, but at present there are fewer applications for these polysaccharides. In this study, the effects of different extraction methods on the Atractylodis Macrocephalae Rhizoma polysaccharide (AMRP) yield were investigated, and the conditions for ultrasound-assisted extraction were optimized by response surface methodology (RSM) and three neural network models (BP neural network, GA-BP neural network and ACO-GA-BP neural network). The best conditions were a liquid-to-solid ratio of 17 mL/g, ultrasonic power of 400 W, extraction temperature of 72 °C, and extraction time of 40 min, which yielded 31.31% AMRP. The kinetic equation of AMRP was determined and compared with the results predicted by three neural network models. It was finally determined that the extraction conditions, kinetic processes and kinetic equation predicted by the GA-ACO-BP neural network were optimal. In addition, AMRP was characterized using SEM, FTIR, HPLC, UV, XRD, and NMR, and the structural study revealed that AMRP has a rough exterior and a porous interior; moreover, it contains high levels of glucose (5.07%), arabinose (0.80%), and galactose (0.74%). AMRP has three crystal structures, consisting of two β-type monosaccharides and one α-type monosaccharide. Additionally, the effectiveness of AMRP as an antioxidant was demonstrated in an in vitro experiment.     

响应面法优化超声提取熟地黄中5-羟甲基糠醛的工艺

采用响应面法优化了超声提取熟地黄中5-羟甲基糠醛的工艺.选取提取时间、溶剂浓度和温度3个因素为随机因子,在单因素的基础上进行3因素3水平Box-Behnken中心组合试验设计,以5-羟甲基糠醛得率为响应值进行响应面分析.优化后的超声提取熟地黄中5-羟甲基慷醛的条件为:在提取时间61.6min,溶剂体积分数90.5%,提...     

Ultrasonication--a complementary 'green chemistry' tool to biocatalysis: a laboratory-scale study of lycopene extraction

Lycopene is bequeathed with multiple bio-protective roles, primarily attributed to its unique molecular structure. The concomitant exploitation of two of the green chemistry tools viz., sonication and biocatalysis is reported here for the laboratory scale extraction of lycopene from tomato peel. The coupled system improved the extraction by 662%, 225% and 150% times over the unaided, only cellulase ‘Onozuka R-10’ treated and only sonication treated samples respectively. The sonication parameters (duration, cycle and amplitude) during the coupled operation were optimized using response surface methodology (RSM). Derivative UV-visible spectra (i.e., dA/dλ and d²A/dλ² against λ), FTIR analysis, and DPPH scavenging test suggested that the reported extraction protocol did not affect the molecular structure and bioactivity of the extracted lycopene. The influence of sonication on the probable structural modulation (through UV-visible spectral analysis) and activity of the enzyme were also analyzed. A plausible mechanism is proposed for the enhanced extraction achieved via the coupled system.     

Optimization of high pressure processing parameters of Indian white prawn (Fenneropenaeus indicus)

The effect of pressure (150, 250 and 350?MPa), ramp rate (200, 400 and 600?MPa/min) and holding time (3, 6 and 9?min) on the quality indices (dependent variable) of Indian white prawn (Fenneropenaeus indicus) was optimized using response surface methodology. Box–Behnken response surface design was used with 15 runs. Second-order response surface model was fitted to the experimental data and the model adequacy was measured by R² value. The linear and quadratic effect of pressure, ramp rate and holding time was significant for tri-methylamine, total volatile base nitrogen and total plate count. Based on the ridge analysis and response surface plots, the optimum combination obtained was 250?MPa pressure, 400?MPa/min ramp rate and 6?min holding time for high pressure (HP) processing of Indian white prawn. Validation of the experiment indicated that the developed model was appropriate to predict quality indices in Indian white prawn processed by HP processing.     

Ultrasonication-assisted synthesis of alcohol-based deep eutectic solvents for extraction of active compounds from ginger

An ultrasonication-assisted synthesis of alcohol-based deep eutectic solvents (DESs) is described. Several DESs were synthesized simultaneously under the same conditions. The prepared DESs were used for the extraction of gingerols from ginger powder via ultrasonication-assisted extraction. Notably, some of the prepared DESs exhibited superior extraction performance than those in traditional organic solvents. The viscosity of the DESs, which was suggested to be typically lower than 100 mPa*s had a critical effect on extraction performance. However, the higher gingerol contents in the extracts did not translate to higher active antioxidant abilities. The extraction temperature was found to be a key determinant of the antioxidant capability of the extracted gingerols while the use of higher temperatures (>50 °C) induced degradation and loss of phenolic compounds during extraction. Response surface methodology was applied for determining the optimal extraction conditions to achieve maximum antioxidant capacity with suitable gingerol content. All compounds used for the preparation of the DESs in this study have been widely employed in cosmetic and pharmaceutical fields. Therefore, the extracts in these DES solutions can be considered for direct application development without further product isolation.     

Optimization of ultrasound-assisted extraction of bioactive compounds from coffee pulp using propylene glycol as a solvent and their antioxidant activities

In the cosmetic and pharmaceutical industries, it has been increasingly popular to use alternative solvents in the extraction of bioactive compounds from plants. Coffee pulp, a by-product of coffee production, contains different phenolic compounds with antioxidant properties. The effects of polyols, amplitude, extraction time, solvent concentration, and liquid–solid ratio on total phenolic content (TPC) using ultrasound-assisted extraction (UAE) were examined by single-factor studies. Three main factors that impact TPC were selected to optimize the extraction conditions for total phenolic content (TPC), total flavonoid content (TFC), total tannin content (TTC), and their antioxidant activities using the Box-Behnken design. Different extraction methods were compared, the bioactive compounds were identified and quantified by liquid chromatography triple quadrupole mass spectrometer (LC-QQQ), and the cytotoxicity and cellular antioxidant activities of the extract were studied. According to the response model, the optimal conditions for the extraction of antioxidants from coffee pulp were as follows: extraction time of 7.65 min, liquid–solid ratio of 22.22 mL/g, and solvent concentration of 46.71 %. Under optimized conditions, the values of TPC, TFC, TTC, 1,1-diphenyl-2-picryl-hydrazil (DPPH) radical scavenging assay, 2,2′-azino-bis-3-ethylbenzthiazoline-6-sulphonic acid (ABTS) radical scavenging assay, and Ferric reducing antioxidant power assay (FRAP) were 9.29 ± 0.02 mg GAE/g sample, 58.82 ± 1.38 mg QE/g sample, 8.69 ± 0.25 mg TAE/g sample, 7.56 ± 0.27 mg TEAC/g sample, 13.59 ± 0.25 mg TEAC/g sample, and 10.90 ± 0.24 mg FeSO₄/g sample, respectively. Compared with other extraction conditions, UAE with propylene glycol extract (PG-UAE) was significantly higher in TPC, TFC, TTC, DPPH, ABTS, and FRAP response values than UAE with ethanol (EtOH-UAE), maceration with propylene glycol (PG-maceration), and maceration with ethanol (EtOH -maceration) (p < 0.05). Major bioactive compounds detected by LC-QQQ included chlorogenic acid, caffeine, and trigonelline. At higher concentrations starting from 5 mg/ml, PG-UAE extract showed higher cell viability than EtOH-UAE in both cytotoxicity and cellular antioxidant assays. The researcher expects that this new extraction technique developed in this work could produce a higher yield of bioactive compounds with higher biological activity. Therefore, they can be used as active ingredients in cosmetics (anti-aging products) and pharmaceutical applications (food supplements, treatment for oxidative stress-related diseases) with minimal use of chemicals and energy.     

超声波强化响应面法优化提取桔皮黄酮

从提取溶剂及提取条件等方面对柑桔皮总黄酮超声波辅助提取工艺进行优化研究.以黄酮得率为考察指标,用单因子试验对提取溶剂进行筛选,用析因试验对提取条件进行分析,通过最陡爬坡试验和中心组合设计试验,优化超声波辅助提取工艺.结果表明,乙醇和水组成的复合体系是理想的提取溶剂;液料比、提取时间、乙醇浓度、pH值都对柑桔皮总黄酮提取产生一定的影响,其中液料比和提取时间的影响最为显著.超声波辅助提取工艺优化条件为:液料比37mL/g,提取时间83min;在此条件下总黄酮的最大提取量为3.321%.经验证试验表明,该方法是一种实用的提取方法.