微波辐射下没食子酸烷基酯的合成

以对甲苯磺酸为催化剂,采用微波辐射技术合成没食子酸烷基酯,考察了各因素对反应的影响,确定了反应的最佳条件:没食子酸的用量为0.01 mol,催化剂3 mmol,环己烷为带水剂,醇酸摩尔比为10 ∶ 1,微波辐射功率540 W,反应时间40 min,没食子酸烷基酯产率可超过92%.     

液质联用法测定植物油中的4种没食子酸酯

建立了食用植物油中没食子酸酯类化合物测定的超高效液相色谱-串联质谱分析方法。样品经正己烷饱和的乙睛萃取后,采用ACQUITY UPLC HSS T3色谱柱分离,以0.1%甲酸水和甲醇为流动相梯度洗脱,电喷雾电离负离子模式下多反应监测(MRM)模式进行定性、定量检测。4种没食子酸酯类化合物的检出限(S/N=3)为0.02 mg/kg~0.05 mg/kg,定量限(S/N=10)为0.06 mg/kg~0.15 mg/kg;在0.20、0.50、0.80 mg/kg 3个加标水平下回收率为75.4%~91.3%,相对标准偏差小于9.2%。应用建立的方法对市售食用植物油产品进行测定,未发现4种没食子酸酯类化合物。     

没食子酸微晶纤维素酯的制备及性能研究

以微晶纤维素、没食子酸为原料,在催化剂的作用下,采用直接酯化法合成没食子酸微晶纤维素酯。在单因素试验的基础上,对合成时间、温度、催化剂用量、没食子酸和微晶纤维素用量比等因素进行正交试验,确定最佳合成条件为：没食子酸和微晶纤维素的反应物配比(GA:MCC)为4:1(m/m)时,以磷钨酸为催化剂,催化剂用量为相对于没食子酸质量的10%,在温度120℃条件下反应10h。产物具有清除烷基自由基、羟自由基、超氧阴离子自由基的能力,其DPPH 自由基清除率达到80% 以上。     

没食子酸酯对核桃油及其乳液的抗氧化作用

研究了没食子酸（gallic acid，GA）及其烷基酯（没食子酸乙酯（GA-C2）、没食子酸丁酯、没食子酸辛酯、没食子酸月桂酯、没食子酸十六酯和没食子酸十八酯）在核桃油及其水包油乳液中的抗氧化性能。在水包核桃油乳液中，过氧化值（POV）、共轭二烯值、硫代巴比妥酸（TBA）值和茴香胺值的测定结果表明，GA及其烷基酯的抗氧化性能随烷基链长增加而上升，其中GA-C2的抗氧化性能最强，而后随链长增加而下降，呈“截断效应”。在核桃油中，POV和TBA值的测定结果表明，抗氧化性能随烷基链长度的增加而降低，符合“极性悖论”。作者探讨了不同油脂体系中GA及其烷基酯的烷基链长对抗氧化性能的影响，为选择适用于核桃油和水包核桃油乳液的抗氧化剂提供依据。     

十八烷基甜菜碱的合成与应用性能

研究了由十八烷基叔胺同氯乙酸及氢氧化钠反应合成十八烷基甜菜碱的工艺条件 ,对反应温度和投料比等参数进行了详细的探讨 ,结合适当的反应时间及搅拌速度 ,得出了最佳的合成工艺条件。测试了十八烷基甜菜碱的表面张力、抗静电性、乳化性等应用性能 ,并与十二烷基甜菜碱进行了对比。     

微波辅助合成食品抗氧化剂没食子酸丙酯

以没食子酸和正丙醇为原料,硫酸氢钠为催化剂,采用微波辐射成功合成了没食子酸丙酯。通过熔点测定、红外光谱分析和元素分析对产品进行结构表征;通过单因素考察了没食子酸和正丙醇的物质的量比、催化剂的用量、微波时间、微波功率等因素对反应的影响,在单因素实验的基础上,采用正交试验法优化确定了最佳合成条件,结果表明最佳反应条件为:没食子酸用量为0.025mol,没食子酸与正丙醇的物质的量比为1∶15,催化剂量为3g,微波功率为500W,微波时间为45min,不加带水剂,在此条件下,没食子酸丙酯的收率可达82.58%。实验证明硫酸氢钠具有较好的催化活性和重复使用性能;与热催化酯化反应相比,微波辐射可缩短反应时间,降低能耗。该方法实现了绿色合成食品抗氧化剂没食子酸丙酯。     

不饱和十八烷基甜菜碱的合成与性能

以不饱和叔胺、氯乙酸和氢氧化钠为原料,合成了不饱和十八烷基甜菜碱,对合成条件进行了优化.采用IR和1H-NMR对产物进行了表征,同时测定了其Krafft点、润湿性、乳化性和表面张力,并与饱和十八烷基甜菜碱进行了对比.结果表明:不饱和十八烷基甜菜碱的各项性能均优于饱和十八烷基甜菜碱.     

酶法合成没食子酸叶黄素酯的研究

以叶黄素和没食子酸为原料,在脂肪酶Novozym435 的催化下,合成没食子酸叶黄素酯,并用IR 对其结构进行表征。研究脂肪酶催化叶黄素与没食子酸合成没食子酸叶黄素酯的影响因素,考察酶量、溶剂、体系水分、温度、时间等因素对酯化反应的影响。结果表明,适宜的工艺条件为酶用量10mg/mL、溶剂为氯仿、初始加水量60mg/g、温度40℃、反应时间30h,在上述条件下没食子酸转化率可达81.8%。     

脂肪酶在白酒酯类化合物合成中的作用研究进展

酯类化合物是白酒中最重要的一类风味物质,其含量影响白酒的品质和香型.鉴于酯类化合物对白酒风格具有重要影响,研究白酒酿造过程中酯类化合物形成的影响因素具有重要意义.经系统研究并分析白酒酿造过程可知,白酒中酯类化合物主要来源于酸-醇的酶促反应,并且确定了酯化酶中的脂肪酶对白酒酯类化合物合成具有重要的酶促催化作用.为此,本文...     

有相氟织物整理剂的合成与应用

介绍含氟化合物的结构特点以及用于织物纤维表面的防水、防油整理的作用机理,阐述了全氟烷基单体的合成方法及溶液聚合和乳液聚合合成全氟烷基共聚物的研究进展,对含氟织物整理剂的应用前景和发展方向做了展望.     

Effect of Phenolic Acid on Antioxidant Activity of Wine and Inhibition of Pectin Methyl Esterase

Antioxidant activity, malolactic fermentation and sensory evaluation of the grape must after fermentation in the presence of gallic acid and coumaric acid, as well as the inhibitory mechanism of gallic acid and coumaric acid on pectin methyl esterase (PME), were investigated. The content of malic acid and lactic acid increased 40.4% and 36.9% compared to the control when commercial pectic enzyme (CPE) was used. The increase in malic acid content was enhanced by 64.8% and 83.4%, compared to the control in the presence of CPE + Gallic acid and CPE + Coumaric acid respectively. Ferric reducing/antioxidant power (FRAP) increased in the samples with added CPE. In addition to an increase in the FRAP, antioxidant capacity was enhanced in the CPE + Gallic acid and CPE + Coumaric acid samples. No significant differences were found in the content of total anthocyanin and in the value of sensory characteristics. The content of total flavanols increased significantly in the samples with added CPE. Lineweaver‐Burk plots of PME, with gallic acid or coumaric acid, indicated that gallic acid and coumaric acid were mixed inhibitors of PME.     

没食子酸对猪肉糜脂肪和蛋白氧化的抑制作用及对肉糜品质特性的影响

为研究没食子酸对冷藏（4 ℃,9 d）猪肉糜脂肪和蛋白氧化的抑制作用及对肉糜品质的影响,将没食子酸添加到猪肉糜中（0、0.05、0.10、0.20 g/kg）,添加0.20 g/kg叔丁基羟基茴香醚（butylated hydroxyanisole,BHA）作为对照组,对肉糜的硫代巴比妥酸（thiobarbituric acid reactive substances,TBARs）值、总巯基含量、羰基含量、表面疏水性、色泽及蒸煮损失进行分析。结果表明：空白组猪肉糜的TBARs值显著增加,蛋白质总巯基含量降低,羰基含量增加,表面疏水性升高,红度值降低,蒸煮损失增加;没食子酸的添加降低了TBARs值的增加幅度,抑制了羰基化合物的生成和表面疏水性的增加,并且随着贮藏时间的增加,能够减少总疏基含量的损失,降低脂肪氧化和蛋白氧化的程度,没食子酸还有利于猪肉糜红度的保持,但对蒸煮损失无改善作用。因此,没食子酸可作为天然抗氧化剂应用于肉及肉制品中。     

Protective effect of gallic acid on the thermal oxidation of corn and soybean oils during high temperature heating

The comparative protective effects of gallic acid with well-known synthetic antioxidants (tert-butylhydroquinone, butylated hydroxylanisole, propylgallate) on the thermal oxidations of corn and soybean oils during heating for 8 h at 180°C were studied. The quantitative effects of gallic acid at three different concentrations on the time-course thermal oxidations in the two different vegetable oils were also studied for a prolonged heating of 6 days at 180°C. Gallic acid at 200 ppm exhibited higher protective activity than the synthetic antioxidants at the same concentration. Gallic acid also exhibited persistently strong protective activity, in a concentration dependent manner, on the changes in oxidation indices in corn and soybean oils throughout the prolonged heating period (6 days) at 180°C. The present results clearly suggested that gallic acid would be a potential natural substitute of synthetic antioxidants for the protection of vegetable oils during high temperature heating.     

微波固相合成技术及其在多肽(氨基酸)金属螯合物合成中的应用

多肽(氨基酸)金属螯合物是一种新型金属营养补充剂,具有吸收利用率高,代谢过程能耗低,转运速度快和不易被饱和等优点,而且多肽可作为金属元素配体通过小肽转运系统进入肠黏膜细胞,稳定性高,并可减少金属间拮抗作用,具有很好的应用前景。微波固相合成技术作为一种新型多肽(氨基酸)金属螯合技术,相比传统液相合成法,具有反应速度快、反应效率高、能耗低、工艺操作简单、污染少和无废液产生等优点,广泛应用于多肽(氨基酸)金属配位螯合物的合成中。本文从微波固相合成的机理、影响因素、金属螯合物鉴别及其在多肽(氨基酸)金属螯合物合成中的应用等方面进行了系统综述,并对微波固相合成技术的应用提出了一些建议,以期为微波固相合成技术在多肽(氨基酸)金属螯合物合成中的应用起到良好的推动作用。     

Phenolic profiles and antioxidant activities of commercial beers

The phenolic profiles and corresponding antioxidant activities of 34 commercial beers in Chinese markets were evaluated. Results found remarkable variations in total and individual phenolic contents as well as antioxidant activity across beer brands. Gallic and ferulic acids were the dominant phenolic compounds identified in the tested beer samples and both of them accounted for >50% of the total phenolic compounds. Results from Pearson correlation analysis suggested that five antioxidant activity assays positively correlated well (p < 0.01) with each other and showed significant positive correlations (p < 0.05) with (+)-catechin, protocatechuic, and caffeic acids contents. Stepwise linear regression further demonstrated that different phenolic components responsible for beer antioxidant activity were dependent on the method used, and that ferulic acid, syringic acid, (+)-catechin, caffeic acid, protocatechuic acid and (−)-epicatechin together made 55.0–88.1% of contribution to the antioxidant activity of beer.     

酶法合成生物表面活性剂

总结了外源酶催化法和整胞微生物代谢法合成生物表面活性剂的特点,并将外源酶催化法对整胞微生物代谢法及传统化学合成法的优势进行了比较.详细介绍了单甘酯、糖酯、(溶血)磷脂、纯异头烷基糖苷和氨基酸型表面活性剂等生物表面活性剂的酶催化合成方法及其研究进展;展望了酶工程的进步、化学 酶催化技术进展、外源多酶联合催化技术的开发与应用、酶膜反应器和其它连续酶反应器的开发,以及反应 分离耦合技术在酶催化过程中的应用将给酶法合成生物表面活性剂带来的机遇.     

Antioxidant Activity and Total Phenolic Content in Some Cereals and Legumes

The antioxidant activities and total phenolic content of 4 cereals (buckwheat, wheat germ, barley, and rye) and 4 legume seeds (lentils, mungo bean, red kidney bean, and soy bean) were determined. The total phenolic content (TPC), determined according to the Folin-Ciocalteu method, for cereal samples varied from 13.2 to 50.7 mg Gallic acid equivalent/g of dried extract, while for legume samples varied from 17.0 to 21.9 mg Gallic acid equivalent/g of dried extract. Antioxidant activities were comparatively assessed by 2,2-diphenyl-1- picrylhydrazyl (DPPH) scavenging capacity, ferric ion-reducing antioxidant power (FRAP) and the thiobarbituric acid (TBA) method. The tested plant extracts showed promising antioxidant and free radical scavenging activity, thus justifying their traditional use. Among examined cereals all the applied methods, except TBA method, have shown that buckwheat have the highest antioxidant activity, while among examined legumes results varied depending on the method used.     

Investigation of the Interaction Between Gallic Acid and α-Amylase by Spectroscopy

Gallic acid is one of the important polyphenols in plants and it inhibits α-amylase. The interaction between gallic acid and α-amylase was investigated by fluorescence quenching spectroscopy, UV-vis spectroscopy, synchronous spectroscopy, and the three-dimensional fluorescence spectroscopy under mimic physiological conditions. The result of the emission quenching at different temperatures revealed that there are static quenching of intrinsic fluorescence of α-amylase induced by gallic acid and a complex of gallic acid-α-amylase was formed. The results obtained from the evaluation of three-dimensional fluorescence spectra, UV-vis spectra, and synchronous spectra suggested that the association between gallic acid and α-amylase did change the molecular conformation of α-amylase. Gallic acid can enter the primary substrate-binding pocket and alter the microenvironment around tryptophan and tyrosine residues.     

利用微生物酶两步法生产没食子酸的初步研究

没食子酸及其衍生物是食品、医药等工业的一类重要原料。以黑曲霉B0201为菌种,以五倍子为原料,直接生料固体发酵法不能生成没食子酸,但是,先用生料固体发酵生产单宁酶,再用酶法制备没食子酸是可行的。研究表明,分两步制备没食子酸反应4h时,100mL单宁酶酶液中积累了0.77g没食子酸,建立了一种黑曲霉单宁酶两步法生产没食子酸的制备工艺。     

葡萄籽提取物(GSE)有效成分的分析

葡萄籽提取物（GSE）的多酚化合物包括原花青素和单体多酚，因此，采用Folin-Ciocalteu法测定葡萄籽提取物总多酚的质量分数，高效液相色谱法测定单体多酚质量分数，以总多酚质量分数减去单体多酚质量分数，即可代表样品中原花青素的质量分数。测定结果表明，自制GSE总多酚质量分数稍高于对照样品（天津尖峰天然产物研究开发公司产品），分别为90．5％和88．3％；没食子酸、儿茶素质量分数明显高于对照样品；而表儿茶素和表儿茶素没食子酸酯的质量分数稍低于对照样品。自制样品与对照样品的原花青素质量分数无显著差异，分别为74．6％和75．8％。