微波法提取萝卜中抗氧化物质的工艺及多酚含量的测定

采取微波法探讨白萝卜和胡萝卜的抗氧化性,利用酒石酸亚铁对多酚的显色反应表征提取物中抗氧化物质的含量,通过正交试验对提取条件进行优化,结果表明:白萝卜的最佳工艺条件为微波功率80 W、微波时间2min、萝卜粉1g,无水乙醇30mL;胡萝卜的最佳工艺条件为微波功率40 W、微波时间2min、萝卜粉1g,95%乙醇25mL,白萝卜和胡萝卜中的多酚提取量分别为0.83,0.44mg/g。     

茄子皮中花青素提取工艺的初步研究

为综合利用茄子皮,本研究以茄子皮为原料提取花青素,并优化其提取工艺。以花青素得率为指标,通过单因素和正交试验得出茄子皮中花青素的最佳提取工艺。研究结果表明,以70%乙醇为提取溶剂,1∶20(W/V)料液比,在60℃提取90 min,提取3次时,茄子皮中花青素提取率最高,得率为6.56%。该方法简单、快捷,是提取茄子皮中花青素的有效方法。     

双水相萃取法提取地骨皮多酚及抗氧化活性研究

采用超声辅助双水相萃取法提取地骨皮中多酚类物质,通过单因素实验和正交实验对地骨皮多酚提取工艺进行优化,最佳提取工艺条件为:乙醇溶液质量分数为41%,硫酸铵与乙醇溶液质量比为13∶100(g/g),地骨皮与乙醇溶液质量比1∶20(g/g),超声时间为50 min,提取温度为55℃,在此条件下地骨皮多酚得率为17.88 mg/g。分别以DPPH法、ABTS法、ORAC法、细胞内总谷胱甘肽含量和SOD活性评价地骨皮多酚的抗氧化能力。结果表明,地骨皮多酚对DPPH·和ABTS·的IC_(50)分别为20.00 mg/L和59.37 mg/L,对活性氧清除能力高于同浓度Trolox,对H_2O_2损伤的HSF细胞内谷胱甘肽含量和SOD活性均有显著的提升作用。     

超声波辅助提取菠萝皮渣中多酚的工艺优化

为确定菠萝皮中多酚化合物超声提取的最佳工艺参数,以菠萝下脚料菠萝皮为主要原料,通过正交试验优化了菠萝皮中多酚化合物的超声波辅助提取工艺条件,即:细度50目、液料比35:1(m L/g)、超声提取功率250W、乙醇浓度50%以及超声提取时间55min。采用此最佳提取工艺进行试验,获得的菠萝皮渣中多酚提取量达到13.84(mg/g)。     

葡萄皮渣中多酚物质提取工艺的研究

通过单因素试验和正交试验,确定温浸法提取萄皮渣中多酚物质的最佳提取条件为乙醇浓度为50%,浸提温度为60℃,料液比为1︰12,浸提时间为50 min,提取量为13.482 mg/g。     

沙果多酚的提取及组成分析

采用水浴振荡辅助乙醇提取法提取沙果果干中的总多酚,对提取工艺进行优化并分析了沙果果干中的多酚种类。通过正交试验优化出沙果青果的最佳提取工艺:乙醇体积分数50%,料液比1∶25(g∶mL),水浴振荡时间50 min,水浴振荡温度30℃,此条件下多酚得率可达(7.875±0.008)mg/g;沙果熟果的最佳提取工艺:乙醇体积分数60%,料液比1∶25(g∶mL),水浴振荡时间30 min,水浴振荡温度40℃,此条件下多酚得率可达(10.259±0.020)mg/g。液相色谱分析表明:沙果青果多酚主要含有4种多酚,分别为绿原酸22.033%、原花青素B_(2)8.875%、表儿茶素5.95%和根皮苷1.259%,这4种多酚占总多酚的38.117%;沙果熟果除含有上述4种多酚(分别为41.0758%、5.6413%、8.3252%、0.4998%),还含有(+)-儿茶素(7.2444%),这5种多酚占总多酚的62.7865%,沙果中仍有大部分未知多酚未检出。沙果熟果多酚种类及含量高于青果,营养价值更丰富。     

超声波辅助法提取紫苏叶酚类物质的研究

以新鲜紫苏叶为原料,采用超声波辅助技术提取紫苏叶酚类物质,并通过正交试验确定紫苏叶多酚的最佳提取条件。实验结果表明:紫苏叶多酚的最佳提取工艺条件为:超声波输出功率为300 W,超声时间为50 min,酒精浓度为40%,料液比为1∶60。在此最佳工艺条件下,多酚提取得率为27.79 mg/g,提取液抗氧化能力是相同浓度下抗坏血酸的0.94倍。     

超声波提取海红果中总多酚的工艺研究

采用超声波辅助甲醇提取法从海红果中提取总多酚,研究了提取温度、提取时间、料液比等对总多酚提取量的影响。结果表明,超声提取海红果中总多酚的最佳提取工艺条件为:提取液甲醇浓度60%,料液比(g/mL)为1∶12,在55℃下提取50 min。     

Box-Behnken优化微波萃取桂花果皮多酚提取工艺及体外抑制酪氨酸酶活性研究

桂花作为我国传统名花,具有观赏和绿化的作用,但是果实一直没有被综合开发利用。为此,在单因素研究基础上,采用响应面中心组合设计,以微波功率、提取时间、乙醇浓度为因素,优化微波萃取桂花果皮多酚最佳工艺。结果表明:微波功率600 W,提取时间32 min,乙醇浓度63%,多酚提取量在40.58 mg/g,预测值为40.61 mg/g,接近预测值,表明该工艺可靠。通过体外酪氨酸酶抑制活性试验研究,桂花果皮中多酚浓度在1 mg/mL和2 mg/mL时,酪氨酸酶抑制率在75%左右,与熊果苷活性相比,同样具有抑制酪氨酸酶活性。为今后综;合开发利用桂花果作为化妆品、饲料添加剂、食品添加剂奠定基础。     

油麦菜中多酚的提取工艺及抑菌性研究

采用微波法提取油麦菜中多酚,利用酒石酸亚铁分光光度法表征提取物中多酚的含量,通过正交试验对提取条件进行优化,实验表明,从油麦菜中提取多酚的最佳提取条件为:乙醇质量分数为45%,微波时间为90s,微波功率为60 W,m(油麦菜)∶m(乙醇)=1∶40。油麦菜中多酚提取量为14.03mg/g,对大肠杆菌抑菌率达到100%。     

Moisture loss kinetics and microstructural changes in eggplant (Solanum melongena L.) during conventional and ultrasonically assisted convective drying

The overall aim of this study was to assess the moisture loss kinetics and the structural changes induced by both conventional and ultrasonically assisted convective drying of eggplant tissue. Three sets of drying experiments (at 40 °C and 1 m/s) were carried out: conventional air drying and ultrasonically assisted drying at two different levels of applied ultrasonic power, 45 and 90 W. The microstructure of the dried samples was studied by scanning electron microscopy.The application of ultrasound during the convective drying of eggplant led to a significant reduction of the drying time. The ultrasonic effect was dependent on the power applied, thus, the higher the power, the faster the moisture loss. The microstructure of eggplant endocarp was greatly affected during conventional air drying, probably due to the long drying times. This microstructure was better preserved after the application of a moderate ultrasonic power (45 W), due to the shorter drying time and the mild mechanical effects of ultrasound on the endocarp cells.     

Optimization of the Process for Recovering Phenolic Antioxidant Compounds from Low-Quality Eggplant (Solanum melongena L.) Pulp by Modified Supercritical Carbon Dioxide Extraction

The extraction of biologically active compounds from eggplant pulp by modified supercritical CO₂ extraction was investigated. Response surface methodology was used to optimize the extraction of phenolic compounds and antioxidant capacity by assessing the pressure, temperature, and cosolvent percentage. The results demonstrated that the maximum phenolic content (3,530.79 mg CAE/100 g extract) and antioxidant capacity (4,593.22 μmol TE/g extract) were observed at 56.8°C, 280 bar, and 1.22% of ethanol and were higher than those obtained by conventional solvent extraction. Four phenolic acids were identified in the supercritical extracts and not in the conventional extracts using HPLC-DAD analysis, suggesting that modified supercritical CO₂ extraction is more efficient and selective.     

茄秆中生物总碱提取条件的研究

以茄秆为原料,用索氏提取法进行生物总碱的提取,用酸碱滴定法对提取的生物总碱的含量进行测定。以生物总碱的含量作为指标,进行单因素试验,研究了有机溶剂种类、料液比、提取时间、pH值等因素对茄秆中生物总碱提取的影响。茄秆生物总碱的优化条件为: 60% 乙醇为提取剂,料液比为1:5.5, pH值为3,时间为 3 h,生物总碱平均含量为 1.96%。在优化条件下提取效果稳定、可重复性高。     

L-半胱氨酸与L-胱氨酸间相互转化的拉曼光谱研究

以石墨烯/纳米银为基底,采用拉曼光谱方法,研究了L-半胱氨酸与L-胱氨酸间的相互转化。随着体系pH值的变化,2 550 cm-1处S─H键的伸缩振动峰以及500 cm-1处S─S键的伸缩振动峰发生了明显变化,可以清楚地观察到L-半胱氨酸与L-胱氨酸间的相互转化,而延长激光曝光时间并没有观察到此变化。这表明溶液pH值是影响S─H键与S─S键间相互转化的主导因素。     

L450/316L不锈钢复合钢管对焊缝焊接接头组织性能研究

对壁厚(10+2)mm的L450/316L复合管进行了对焊试验,打底焊及过渡焊采用管内外充氩保护的GTAW焊,填充及盖面焊采用手工电弧焊,并对其焊接接头进行拉伸、刻槽锤断、弯曲、冲击、晶间腐蚀试验评价对焊焊缝的性能,采用光学、扫描电镜(SEM)及能谱分析(EDS)对焊接接头的冲击断口、显微组织及合金元素的进行扩散分析。试验结果表明:接头力学性能良好,耐晶间腐蚀性能较好;焊缝不锈钢层主要有奥氏体、铁素体组成;过渡层组织较细小,可以防止不锈钢层金属中合金元素被扩散层稀释;扩散层组织主要为马氏体、少量的残余奥氏体;合金钢层组织为先共析铁素体、针状铁素体、粒状贝氏体和及少量珠光体。     

Cure and mechanical properties of filled SMR L/ENR 25 and SMR L/SBR blends

The effect of blend ratio of natural rubber/epoxidized natural rubber (SMR L/ENR 25) and natural rubber/styrene‐butadiene rubber (SMR L/SBR) blends on scorch time (t₂), cure time (t₉₀), resilience, hardness, and fatigue properties were studied in the presence of carbon black and silica. An accelerated sulfur vulcanization system was used throughout the investigation. The scorch and cure times of the rubber compound were assessed by using a Moving‐Die Rheometer (MDR 2000). Resilience, hardness, and fatigue life were determined by using a Wallace Dunlop Tripsometer, a Wallace Dead Load Hardness Tester, and a Fatigue to Failure Tester, respectively. The results indicate that t₂ and t₉₀ decrease with increasing ENR 25 composition in the SMR L/ENR 25 blend whereas both values increase with increasing SBR content in the SMR L/SBR blend. This observation is attributed to faster cure in ENR 25 and higher saturation in SBR. Resilience decreases with increase in % ENR and % SBR but hardness shows the reverse behavior in their respective blends. The fatigue life increases with % ENR, but it passes through a maximum with % SBR in the respective blends. In all cases, aging lowers the fatigue life, a phenomenon that is caused by the breakdown of crosslinks in the vulcanizate. Differences in all the observed values between carbon black‐filled and silica‐filled blends are associated with the varying degrees of interaction and dispersion of the two fillers in the rubber blend matrix. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 47–52, 2001