高效防霉剂富马酸单甲酯的合成与抑菌活性研究

以TiSiW12O40/TiO2为催化剂，用富马酸与甲醇直接酯化合成了防霉剂富马酸单甲酯（MMF），通过正交试验确定了醇酸物质的量比、催化剂用量、反应温度和反应时间对反应产率的影响。得到最佳工艺条件为：n（富马酸）：n（甲醇）=1、0：1、0，催化剂用量为w（TiSiW12O40/TiO2）=2％（占富马酸的质量分数），反应温度为60℃，反应时间为3h，MMF的产率可达91．6％。抑菌活性试验和防腐保鲜试验结果表明，MMF对多种霉菌具有良好的抑制作用，尤其对黄曲霉菌、黑根霉菌和棒柬青霉菌的抑制作用更好，MMF的防霉和防腐保鲜效果优于DMF、丙酸钙。     

新型防腐剂富马酸淀粉甲酯的合成及抑菌活性研究

富马酸淀粉甲酯（SMF）的合成分为2步：先由富马酸单甲酯（MMF）与亚硫酰氯反应生成富马酸单甲酯单酰氯（MMFC）,MMFC再与可溶性淀粉反应可得SMF。用单因素试验法确定酯化度为12．03的SMF合成工艺为：摩尔比为3：1的亚硫酰氯和MMF在100℃下回流45rain,得无色MMFC液体,收率可达92％以上。摩尔比为40：1的MMFC与可溶性淀粉在25℃反应16h,再分别经40％乙醇溶液和10％KHCO,溶液洗涤至pH=7,所得白色固体即为富马酸淀粉甲酯,其抗菌活性与富马酸单甲酯相当。     

生物柴油抗氧化剂没食子酸异戊酯制备及其抗氧化性能研究

首先以吗啡啉和溴代正丁烷作为反应物,制成正丁基吗啡啉硫酸氢盐离子液体。采用离子液体作为催化剂催化没食子酸与异戊醇酯化合成没食子酸异戊酯。通过单因素试验和正交试验对合成没食子酸异戊酯的反应条件进行优化。结果表明:影响酯化产率的因素主次顺序为反应温度反应时间醇酸摩尔比催化剂用量;最佳反应条件为反应温度80℃,醇酸摩尔比30∶1,反应时间50 min,催化剂用量6%;最佳条件下酯化产率为97.45%。在此基础上进行酯化反应动力学分析,得出反应活化能为4.91 k J/mol,动力学模型为-dC_A/dt=5.22e-~(4.91/RT)C_A~(0.843)。分析了没食子酸异戊酯对8种生物柴油的抗氧化效果,其抗氧化性能极佳,在添加量为600 mg/kg时能使小桐子油生物柴油氧化稳定性能达到国家标准要求。     

TiSiW12O40/TiO2催化合成抗氧化剂没食子酸异戊酯的研究

以TiSiW12O40/TiO2作为催化剂,用没食子酸与异戊醇直接酯化合成了食品抗氧化剂没食子酸异戊酯。通过正交试验研究了影响没食子酸异戊酯收率的主要因素,得到了最佳实验条件为:醇酸物质的量比为10∶1,催化剂用量为反应物总质量的3%,反应时间为3h,没食子酸异戊酯的收率可达95.6%,考察了该催化剂的重复使用性。抗氧化性能测试结果表明,没食子酸异戊酯具有优良的抗氧化性能。     

没食子酸异戊酯的微波快速合成

以没食子酸和异戊醇为原料,对甲苯磺酸为催化剂,微波辐射合成了没食子酸异戊酯。单因素实验确定的最佳反应条件为:酸醇摩尔比1∶7.5(没食子酸0.03 mol),催化剂用量3.00 g,反应温度125℃,微波辐射功率400 W,辐射时间17 min,产率达88.72%。     

2种富马酸糖酯的相转移催化合成及抑菌活性研究

以马来酸酐和甲醇为原料,经酯化及异构化得到富马酸单甲酯,再经酰氯化得到富马酸单甲酯单酰氯.富马酸单甲酯单酰氯与葡萄糖或乳糖反应,在相转移催化剂四丁基溴化铵的作用下,得到具有α、β-不饱和羰基结构的富马酸葡萄糖甲酯及富马酸乳糖甲酯.抑菌活性试验结果表明:富马酸葡萄糖甲酯及富马酸乳糖甲酯对混合菌群的生长具有良好的抑制能力,其中富马酸葡萄糖甲酯的抑菌活性与富马酸单甲酯接近.     

对甲苯磺酸催化合成没食子酸异戊酯

以没食子酸和异戊醇为原料,对甲苯磺酸为催化剂,合成了没食子酸异戊酯.在单因素实验的基础上,通过正交实验得出没食子酸异戊酯合成的最佳条件为:酸醇摩尔比1:7.5(0.01mol没食子酸),催化剂用量1.00g、反应温度125℃,反应时间4h,产率为78.51%.     

富马酸丙二醇甲酯酶法合成工艺的研究

以富马酸单甲酯和1,2-丙二醇为底物,采用脂肪酶催化合成富马酸丙二醇甲酯。探讨不同有机溶剂、底物摩尔比、反应温度、酶添加量、底物浓度、反应时间对产物中富马酸丙二醇甲酯相对含量的影响。结果表明,其最佳合成工艺:以叔丁醇为反应溶剂,底物摩尔比(富马酸单甲酯/1,2-丙二醇)1∶2,底物浓度1.0mol/L,酶添加量1.2%,反应温度60℃,反应时间20h。该条件下,产物中富马酸丙二醇甲酯的相对含量为63.89%。     

富马酸烷·3-PG酯的合成工艺条件研究

以顺丁烯二酸酐为起始原料,与甲、乙、丙、丁、戊醇发生酯化反应制得五种马来酸单酯,马来酸单酯异构化为相应的富马酸单酯,后者与亚硫酰氯作用得到五种富马酸单酯单酰氯,用制得的富马酸单酯单酰氯酰化没食子酸丙酯(PG)分子中的3-羟基制得五种具有良好的抗氧化和抗菌活性的新型化合物—富马酸甲(乙、丙、丁、戊)·3-PG酯犤1犦。本文对每步反应的合成工艺条件进行了较详细的摸索和研究,揭示其规律,这对于没食子酯丙酯-富马酸酯衍生物的制备具有一定的参考价值。     

富马酸单苯甲酯的合成及抗菌特性研究

以马来酸酐和苯甲醇为原料,无水氯化铝为异构化催化剂,合成富马酸单苯甲酯。利用熔点测定、红外光谱和核磁共振氢谱分析对产品进行结构表征;采用单因素实验分别研究反应物摩尔比、酯化反应温度与时间、异构化催化剂、异构化催化剂用量对产物收率的影响。结果表明:以无水氯化铝为异构化催化剂、原料马来酸酐:苯甲醇:无水氯化铝配比为0.1 mol:0.1 mol:2 g、酯化反应温度60℃、反应时间3 h,此条件下富马酸单苯甲酯的收率可达74.5%。抑菌活性实验结果表明,富马酸单苯甲酯具有良好的抑菌活性。     

微波条件下富马酸单甲酯合成研究

采用正交试验设计探讨了以顺丁烯二酸酐和甲醇为原料，应用微波辐射技术辅助合成新型防霉剂富马酸单甲酯的工艺条件。运用熔点、红外光谱和元素分析对产物进行了表征。实验对影响收率诸因素进行了考察，确定其最佳反应条件：酯化温度为60℃、酯化时间为10min、异构化温度为80℃、反应时间为15min、微波辐射功率为600W，富马酸单甲酯的收率可达83％。     

气相色谱- 串联质谱法测定食品中的富马酸二甲酯

为解决样品基体成分复杂、干扰测定的难题,建立一种基于气相色谱- 串联质谱(GC-MS/MS)检测食品中富马酸二甲酯的方法。通过对提取液、固相萃取柱、电离电压的考察,最终确定食品中富马酸二甲酯经乙腈提取、C18 小柱净化、CID 电压15V 最优条件。本方法在0.045～10.00mg/L 质量浓度范围内呈线性关系,相关系数为0.9998,仪器定量检出限LOQ 为0.045mg/L,外标法定量。在0.05、0.50、1.00mg/kg 3 个水平的回收相对标准偏差为2.77%～8.70%,回收率87%～108%。结果表明,相对于GC、GC-MS 方法,GC-MS/MS 方法分析时间短、无杂质峰干扰、灵敏度高,可以满足食品中检测的要求。     

Differences in the amount and structure of extractable skin and seed tannins amongst red grape varieties

Background and Aims:  Red wine is a very rich source of flavanols, consisting of catechins and oligomeric and polymeric proanthocyanidins (PAs). The aim of this study was to investigate the composition of the fraction of flavanols, which is extractable from the grape into the wine.
Methods and Results:  Using HPLC-DAD-MS analysis carried out before and after thioacidolysis of wine-like extracts obtained from skins and seeds, the flavanol composition of 20 samples derived from Cabernet Sauvignon, Carmenere, Marzemino, Merlot, Pinot Noir, Syrah and Teroldego was determined.
Conclusions:  It was confirmed that grape extracts are mainly rich in monomers and small oligomers (mean degree of polymerization <8). Grape seed extracts contained three monomers (catechin, epicatechin and epicatechin gallate) and procyanidin oligomers. Grape skin extracts contained four monomers (catechin, epicatechin, gallocatechin and epigallocatechin), procyanidins and prodelphinidins oligomers. Upper and extension units of PAs were constituted mainly of epicatechin units, with the co-presence of catechin and epicatechin gallate in the seed PAs, and of gallocatechin in the case of skin PAs. The terminal units of the grape PAs were a mixture of five compounds, the same found also as monomers. Catechin gallate, gallocatechin gallate and epigallocatechin gallate, which are found in other flavanol-rich, plant-derived foods and beverages, were not present in grape extracts.
Significance of the Study:  The grape variety determines both the amount and the structure of wine flavanols, leading to differences in the composition, which are likely to play an important role in the nutritional and sensorial properties of the wines.     

Epimerisation of tea polyphenols in tea drinks

The present study was carried out to quantify green tea epicatechin (GTE) derivatives and to investigate the origin of epicatechin epimers present in 18 selected canned or bottled tea drinks. The major GTEs present in tea are (?)‐epigallocatechin gallate (EGCG), (?)‐epigallocatechin (EGC), (?)‐epicatechin gallate (ECG) and (?)‐epicatechin (EC). HPLC analysis showed that the content of total GTEs was lower (16.4–268.3 mg l^?1) in the canned and bottled tea drinks than in tea traditionally prepared as a beverage in a cup or teapot (3–5 g l^?1). The major finding was that they contained higher levels of epicatechin epimers, namely (?)‐gallocatechin gallate (GCG), (?)‐gallocatechin (GC), catechin gallate (CG) and (?)‐catechin (C), than of GTEs, ranging from 7.6 to 331.8 mg l^?1. To investigate the origin of these epimers, GTEs were extracted from longjing green tea and autoclaved at various temperatures for 10–60 min. It was found that at least 50% of GTEs were epimerised to their corresponding epimers when autoclaved at 120 °C for 20 min. It is concluded that epicatechin epimers in tea drinks are not originally present in green tea leaf but are instead derived from thermal conversion of GTEs. Copyright © 2003 Society of Chemical Industry     

Influence of Gallate and Pyrogallol Moieties on the Intestinal Absorption of (−)‐Epicatechin and (−)‐Epicatechin Gallate

Abstract: The cellular accumulation of individual catechins was measured as an index of intestinal absorption to clarify the interactions among catechins. The cellular accumulation of (?)‐epicatechin (EC) increased in the presence of other catechins. The ability of gallate catechin such as (?)‐epigallocatechin gallate (EGCG) and (?)‐epicatechin gallate (ECG) to increase the cellular accumulation of EC was greater than that of nongallate catechins. Gallic acid octyl ester (GAO) also increased the cellular accumulation of EC by 426% as compared with that in untreated cells. Conversely, the cellular accumulation of ECG was not influenced by other catechins, but it increased by 54% in the presence of GAO. Experiments using GAO derivatives indicated that the gallate moiety required the presence of a catechol group and a neighboring carbonyl group, whereas the pyrogallol moiety, without a neighboring carbonyl group, required 3 hydroxyl groups to increase the cellular accumulation of EC. Furthermore, gallate esters required long carbon chains to increase the same. The experiment using EGCG, GAO, or their derivatives indicated that the ability of gallate or pyrogallol moiety to increase the cellular accumulation of EC was restricted by their hydrophobicity. These results suggest that the co‐administration of foods containing functional materials such as gallate or pyrogallol moieties, increases the intestinal absorption of catechin. Practical Application: The cellular accumulation of (?)‐epicatechin increased by the gallate or pyrogallol moiety in catechin structure. The interaction among catechins appeared to affect intestinal absorption of catechin. The bioavailability of catechin may be improved by co‐administration of functional foods.     

Alternaria toxins in wheat from the Autonomous Province of Vojvodina,Serbia: a preliminary survey

Although Fusarium species remain a main source of mycotoxin contamination of wheat, in recent years, due to the evident climatic changes, other mycotoxigenic fungi have been recognised as important wheat contaminants. Alternaria species, especially A. alternata, have been found as contaminants of wheat as well as wheat-based products. Under favourable conditions A. alternata very often produce alternariol (AOH), alternariol monomethyl ether (AME), tenuazonic acid (TeA) and others Alternaria toxins. The aim of the present study was to examine the presence of three Alternaria toxins (AOH, AME and TeA) in wheat samples harvested during three years (2011–13). To this end, 92 samples were collected during wheat harvesting from different growing regions of the Autonomous Province of Vojvodina, which represents the most important wheat-growing area in Serbia. The presence of Alternaria toxins was analysed by HPLC with electrospray ionisation triple quadrupole mass spectrometry (LC-ESI-MS/MS). Among all the analysed wheat samples, 63 (68.5%) were contaminated with TeA, 11 (12.0%) with AOH and 6 (6.5%) with AME. Furthermore, the maximum and mean toxin concentrations were 2676 and 92.4 µg kg^?1, 48.9 and 18.6 µg kg^?1, and 70.2 and 39.0 µg kg^?1 for TeA, AOH and AME, respectively. Co-occurrence of three Alternaria toxins in wheat samples was detected in six samples; a combination of two toxins was found in two samples; and 64 samples contained one toxin. The results showed that among 92 analysed wheat samples, only 20 (21.7%) samples were without Alternaria toxins. The presence of Alternaria toxins was also investigated in terms of weather conditions recorded during the period of investigation, as well as with the sampling region. This study represents the first preliminary report of the natural occurrence of Alternaria toxins in wheat (Triticum aestivum) from Serbia.     

没食子酸酯类化合物对食品中1,2-二羰基产物的清除效果

采用气相色谱法考察食品抗氧化剂没食子酸酯（没食子酸丙酯（propyl gallate,PG）、没食子酸辛酯（octyl gallate,OG）、没食子酸十二酯（dodecyl gallate,DG））对高活性糖基化因子1,2-羰基化合物（乙二醛（glyoxal,GO）、甲基乙二醛（methylglyoxal,MGO））的清除效果,并考察PG/OG/DG浓度、体系pH值及反应时间对清除效果的影响。此外,通过高效液相色谱-串联质谱（high performance liquid chromatography-tandem mass spectrometry,HPLC-MS/MS）技术探究清除机理。结果表明：PG、OG、DG能有效清除GO和MGO,清除效果依次为PG＞OG＞DG;当清除剂浓度为0.5 mmol/L时,PG对GO、MGO清除率均分别为70.5%、67.6%,OG、DG对GO和MGO的清除率也均达到50%以上;且随着清除剂浓度增大、体系pH值提高、反应时间延长,PG、OG、DG对GO和MGO清除能力增强;在精氨酸-葡萄糖体系、食品体系中验证了清除效果,并在曲奇饼干体系中证明其清除机理为：PG、OG均可捕获1 分子GO或MGO形成相应加合产物,DG可捕获1 分子GO形成加合产物。可见,没食子酸酯类化合物在食品加工过程中能有效清除外源性1,2-羰基化合物,提高食品安全性。     

反丁烯二酸糠醇甲酯对酵母和霉菌的抑制作用研究

本研究合成了一种具有α,β-不饱和羰基结构的化学防腐剂--反丁烯二酸糠醇甲酯,并对其抗酵母和霉菌的效果进行研究,结果表明,其对酵母和霉菌均具有较强的抑制作用,生长曲线测定表明它可以有效延迟啤酒酵母和黑曲霉的生长,显著降低它们的最终生长量,而且效果明显优于常用防腐剂苯甲酸钠,是一种具有广泛开发前景的防腐剂.