高静压处理对绿芦笋生理特性及贮藏品质的影响

为深入了解高静压（high hydrostatic pressure,HHP）对绿芦笋的保鲜效果,以绿芦笋为原料,探讨了HHP处理对绿芦笋采后生理及贮藏品质的影响。经20、50、100 MPa各保压2 min处理的样品置于相对湿度90%、温度4 ℃的冷库中贮藏15 d。贮藏期间定期测定绿芦笋的呼吸强度、丙二醛含量、细胞膜渗透率、叶绿素变化、嫩茎硬度、总酚含量和质量损失率以及色泽的变化。结果表明：与对照组相比,HHP处理可以有效降低贮藏期间绿芦笋呼吸强度,延缓嫩茎中叶绿素降解,较好保持了绿芦笋的硬度和色泽。研究结果为HHP用于嫩茎蔬菜的保鲜贮藏提供了依据。     

金银花提取液抗氧化活性研究

采用三价铁离子还原法、羟自由基(·OH)体系和二苯代苦味酰基自由基(DPPH·)体系对金银花提取液和绿原酸标准品抗氧化活性进行研究,以抗坏血酸为对照。结果表明：金银花提取液清除·OH 和DPPH·的能力最强,对·OH 半数抑制浓度(IC50)为0.0273mg/ml,提取液的绿原酸浓度为0.006mg/ml 时对DPPH·的抑制率达80%;而绿原酸标准品的还原能力要大于金银花提取液(2.66 倍)和抗坏血酸(2.42 倍);绿原酸为金银花提取液抗氧化作用的主要物质。     

Quality attributes and their relations in fresh black ripe ‘Kalamon’ olives (Olea europaea L.) for table use – phenolic compounds and total antioxidant capacity

Quality attributes were investigated in fresh Greek black table ‘Kalamon’ olives prior to processing. Fruit weight, dimensions, respiration and ethylene production rates, firmness, peel colour, moisture, oil content, total antioxidant capacity (TAC), the concentration of total phenolics (TP) and phenolic compounds (hydroxytyrosol, oleuropein, tyrosol, verbascoside, luteolin‐7‐O‐glucoside, luteolin, rutin) were determined in olives from different orchards. There was a significant effect of orchard on most attributes, but not on fruit firmness. Verbascoside, oleuropein and hydroxytyrosol were the major phenolics, and the presence of verbascoside in ‘Kalamon’ olives is revealed for the first time. Positive correlations were found among fruit weight, dimensions, respiration and ethylene. TAC was positively related mainly to TP, hydroxytyrosol, verbascoside and rutin, but inversely to oleuropein. Luteolin was inversely related to luteolin‐7‐O‐glucoside. Colour darkening was directly related to TAC, while colour parameters were positively and moderately affected by oil and moisture.     

马铃薯皮中绿原酸提取工艺优化

以马铃薯皮作为原料,对其所含有的抗氧化物质绿原酸进行提取工艺条件优化。采用乙醇回流法,以绿原酸得率为指标,考察料液比、乙醇体积分数、提取温度、回流次数对提取工艺条件的影响,采取正交试验确定最佳提取工艺条件。结果表明,马铃薯皮中绿原酸粗提的最佳工艺条件为料液比1∶10（g/mL）、乙醇体积分数85%、提取温度97 ℃、回流3 次,在最佳工艺条件下,绿原酸的得率为2.229 mg/g。体外抗氧化活性实验表明,绿原酸具有良好的抗氧化性。     

蒲公英与葵花籽仁提取绿原酸的协同抗氧化作用

以ABTS自由基清除能力为考察指标,研究不同反应温度和反应pH对蒲公英和葵花籽仁绿原酸抗氧化活性的影响,以抗氧化活性的IC₅₀为复配依据,评价蒲公英和葵花籽仁绿原酸复合物的协同抗氧化作用。结果表明:反应体系pH 6、45℃条件下,蒲公英和葵花籽仁绿原酸对ABTS自由基清除率达到最高,分别为91.78%和90.51%。蒲公英和葵花籽仁绿原酸复配品可提高对ABTS自由基清除效率,具有协同抗氧化作用。     

微波辅助提取金银花中绿原酸及其清除自由基活性初步研究

目的筛选微波辅助提取金银花中绿原酸的最佳工艺;初步探讨绿原酸清除自由基的活性。方法以金银花中绿原酸含量为考察指标,考查提取溶剂浓度、料液比、提取时间、微波功率等因素对提取效果的影响。采用正交试验设计优化了最佳提取工艺,采用DPPH法测定不同物质对总自由基的清除作用。结果最佳提取条件为:乙醇浓度55%,料液比1:40,提取时间2min,微波功率520W。金银花中绿原酸有良好的抗氧化性。结论微波辅助提取金银花中绿原酸的最佳工艺可为其开发应用提供参考。     

绿原酸对UVB损伤人永生化表皮角质细胞的保护作用

为研究绿原酸（chlorogenic acid,CGA）对UVB损伤人永生化表皮角质细胞（HaCaT）的保护作用及机制,通过MTT法建立细胞紫外损伤（光老化）模型及绿原酸的处理方式,采用酶标仪检测绿原酸的紫外吸收,流式细胞术检测细胞的凋亡水平,ABTS法检测绿原酸的自由基清除能力。结果表明：UVB辐射剂量为21.6 mJ/cm²,绿原酸浓度为100.000、150.000 μmol/L,预处理1 h后细胞培养12 h,绿原酸在UVB波段（280~320 nm）内有较强的吸收;100.000 μmol/L和150.000 μmol/L 绿原酸均能显著降低UVB引起的细胞凋亡;150.000 μmol/L 绿原酸能有效增加UVB处理细胞的ABTS⁺自由基清除能力,达到了53%。由此可知,绿原酸在UVB诱导的HaCaT光老化模型上,具有很强的抗皮肤光老化活性,其机制可能与绿原酸的紫外吸收以及抗氧化能力相关,为富含绿原酸的食品资源开发利用提供科学依据。     

Potato Peel Extract a Nonmutagenic Antioxidant with Potential Antimicrobial Activity

Freeze-dried water extract of potato peels (pp), containing chlorogenic, caffeic, gallic, and protocatechuic acids, was tested for effectiveness as a natural antioxidant. The pp was prepared from peel waste of Russet Burbank potatoes. Safety concerns regarding the use of pp in foods were investigated. The pp was examined for mutagenic activity using the in vitro Salmonella typhimurium- Escherichia coli microsome assay and found to be nonmutagenic. Plate count of pp revealed <10 CFU/g. The antibacterial activity of the pp was species dependent. It was effective only at high concentration against gram negative and one gram positive bacteria but it was bacteriostatic.     

西瓜不同贮藏过程中生理参数动态变化与贮藏效果相关性的研究

本文就西瓜中多酚氧化酶和过氧化氢酶在不同贮藏过程中的活性变化与同期果实呼吸强度、硬度、细胞膜渗透率变化的关系进行研究,旨在找出它们内在的规律性,寻求最佳贮藏西瓜的方法。研究表明:多酚氧化酶活性达到最大值,紧接着到达呼吸高峰,说明多酚氧化酶的活性变化可以预示呼吸高峰的来临;而呼吸强度与过氧化氢酶的活性变化刚好是相反的。     

Quality of Minimally Processed Apple Slices from Selected Cultivars

Twelve cultivars were prepared as slices and stored 12 days at 2°C. Changes in respiration and quality factors were compared. Initial respiration rates among cultivars varied from 3.5 mL CO₂/kg/hr in Delicious to 7.6 mL CO₂/kg/hr in Monroe and decreased rapidly during the first 3 days. Idared, McIntosh, Delicious, and Rome showed relatively low respiration throughout storage. Firmness of slices during storage decreased gradually for 7 days and more rapidly thereafter. Empire, Golden Delicious, and Idared apples showed minimum changes in firmness. Change in color of slices was rapid during the first 3 days. Cortland. Emuire. Golden Delicious. New York 674. and Delicious showed least browning. Titratable acidity, pH, soluble solids, and weight changes during storage were small and varied by cultivar. NY674, Cortland, Golden Delicious, Empire, and Delicious showed more desirable attributes for minimal processing.     

绿原酸清洁提取及其体外生物活性评价

植物纤维组织致密结构阻碍天然生物活性成分绿原酸的溶出,为减少绿原酸溶出的传质阻力,选取复配酶(纤维素酶和木质素酶)催化水解金银花叶溶浸获得绿原酸,并采用DPPH自由基清除法、铁氰化钾还原法评价提取物绿原酸的体外抗氧化性。分析酶解金银花叶后的SEM照片发现,酶能有效破坏植物纤维组织结构,有助于形成内部疏松结构,而金属离子对酶催化水解活性作用依次为Mg~(2+)Na~+Ca~(2+)K~(2+)Cu~(2+);选取纤维素酶-木质素酶酶活比为3∶2的复配酶,在水浴温度45℃、pH 4的条件下,当复配酶投加量为50 U/g时,在Mg~(2+)诱导催化水解2 g金银花叶11 h后,绿原酸浸提率达94.68%,比超声醇提法提高了19.60%,所得绿原酸具备高抗氧化性和还原性,为资源化利用金银花叶以及绿原酸生产提供了新途径。     

焙炒条件对咖啡风味影响的研究

以云南产的两种咖啡豆为分析对象．研究了焙烤过程中咖啡抽提液一些成分的变化以及对咖啡香气的影响。利用高效液相色谱对在焙烤过程中葫芦巴碱、绿原酸、烟酸、咖啡因含量的变化进行分析，并对绿原酸／咖啡因比率与色度值的相关关系建立了相应的模型。     

牛蒡叶乙醇提取物的抗氧化性能

用95%乙醇浸泡提取传统药食两用植物牛蒡叶,并用石油醚、乙酸乙酯和正丁醇依次对浸提液进行萃取。利用DPPH自由基清除法、O2-.清除法及.OH清除法测定各萃取部位的抗氧化活性,以VC、VE和叔丁基对苯二酚(TBHQ)为对照物。结果表明:牛蒡叶乙醇提取物具有较好的体外抗氧化活性,其中乙酸乙酯萃取物(E2)和正丁醇萃取物(E3)具有较强的清除DPPH自由基的能力,且活性强于TBHQ,利用标准曲线法对乙酸乙酯萃取物和正丁醇萃取物进行绿原酸含量的测定,发现绿原酸含量分别达44.34mg/g和35.48mg/g。