5,6-二氢-1,3,5-二噻嗪类食用香料研究进展

5,6-二氢-2,4,6-三取代基-1,3,5-二噻嗪是一类重要的含硫含氮杂环香料化合物,目前从食品中鉴定出的已经有70种左右。由于这类香料化合物具有典型的烤香、肉香、坚果香、蔬菜香等香气特征,有的已经被我国及世界上多个国家批准用来调配食用香精,用于食品加香,如2,4,6-三甲基-5,6-二氢-4H-1,3,5-二噻嗪、2(4)-异丁基-4(2),6-二甲基-5,6-二氢-4H-1,3,5-二噻嗪、2,4-二甲基-4H-吡咯[2,1-d]-1,3,5-二噻嗪等。本文对67种5,6-二氢-2,4,6-三取代基-1,3,5-二噻嗪类香料化合物的天然存在和香气特征进行了归纳;由于在食品基质中这类化合物的形成与多种因素有关,如梅拉德反应、脂肪的氧化、Strecker降解、pH、温度等,因此有必要对其在食品热加工过程中的形成机理进行研究和总结;考虑到1,3,5-二噻嗪类化合物在香料工业中的潜在价值,本文也对文献报道的该类化合物的合成方法进行了概括。     

4-溴-1-（2，6-二氯-4-三氟甲基苯基）-3-氰基-5-（4-硝基苯基）亚氨基吡唑的合成

1-（2,6-二氯-4-三氟甲基苯基）-3-氰基-5-氨基吡唑（1）以NBS（N-溴代丁二酰亚胺）为溴化试剂制得4-吡吡唑化合物（2）,2与对硝基苯甲醛在酸性条件下反应得到席夫碱3。研究了化合物1与NBS的反应及其席夫碱的合成,通过元素分析、红外光谱、核磁共振氢谱、核磁共振碳谱等手段对其结构进行了表征。用X射线单晶衍射测定了化合物3的晶体结构。     

2,2-二苄基-4,6-二(对甲氧基)苯基-1,3,5三硫环己烷的合成及香气研究

以对甲苯磺酸为催化剂,中间体二苄基二硫醇和茴香醛为原料,无水乙醇为溶剂,合成了新型香料2,2-二苄基-4,6-二(对甲氧基)苯基-1,3,5三硫环己烷,产率为57.3%,用IR、1H NMR和MS证实了目标化合物结构,并对2,2-二苄基-4,6-二(对甲氧基)苯基-1,3,5三硫环己烷的香气进行了鉴定,结果表明:2,2-二苄基-4,6-二苯基-1,3,5三硫环己烷具有浓郁的葱蒜气味,其阈值在水中为0.27×10-6～0.39×10-6、在植物油中为12.41×10-6～17.89×10-6。     

2,2-二苄基-4,6-二苯基-1,3,5三硫环己烷的合成及香气研究

以对甲苯磺酸为催化剂,中间体二苄基二硫醇和苯甲醛为原料,无水乙醇为溶剂,合成了新型香料2,2-二苄基-4,6-二苯基-1,3,5三硫环己烷,产率为63.0 %,用IR,1H NMR和MS证实了目标化合物结构,并对2,2-二苄基-4,6-二苯基-1,3,5三硫环己烷的香气进行了鉴定,结果表明2,2-二苄基-4,6-二苯基-1,3,5三硫环己烷具有浓郁的葱蒜气味,其阈值在水中为0.22(10-6～0.37(10-6 mol/L,在植物油中为12(10-6～15.33(10-6 mol/L.     

2,2-二苄基-4,6-二(对二甲氨基)苯基-1,3,5三硫环己烷的合成及香气研究

以对甲苯磺酸为催化剂,中间体二苄基二硫醇和对二甲氨基苯甲醛为原料,无水乙醇为溶剂,合成了新型香料2,2-二苄基-4,6-二(对二甲氨基)苯基-1,3,5三硫环己烷,产率为71.0%,用IR,1H NMR和MS证实了目标化合物结构,并对2,2-二苄基-4,6-二(对二甲氨基)苯基-1,3,5三硫环己烷的香气进行了鉴定,结果表明2,2-二苄基-4,6-二(对二甲氨基)苯基-1,3,5三硫环己烷具有浓郁的葱蒜气味,其阈值在水中为0.28×10-6～0.39×10-6,在植物油中为13.85×10-6～16.55×10-6.     

N-[N-3-（3-羟基-4-甲氧基苯基）丙基-L-α-天冬氨酸]-L-苯丙氨酸-1-甲酯的合成研究

以3-羟基-4-甲氧基苯甲醛和乙醛为初始原料,在-10℃、强碱性条件下反应生成3-羟基-4-甲氧基肉桂醛,然后将其与阿斯巴甜（APM）于0.7MPa氢压、35℃以及10%Pd/C催化剂的作用下还原烷基化,制得甜度高达蔗糖20000倍的纽甜类似物N-[N-3-（3-羟基-4-甲氧基苯基）丙基-L-α-天冬氨酸]-L-苯丙氨酸-1-甲酯,总产率达32.0%。     

2,2-二苄基-4,6-二(对甲氧基)苯基-1,3,5三硫环已烷的合成及香气研究

以对甲苯磺酸为催化剂,中间体二苄基二硫醇和茴香醛为原料,无水乙醇为溶剂,合成了新型香料 2,2-二苄基-4,6-二 (对甲氧基)苯基-1,3,5 三硫环已烷,产率为 57.3%,用IR、1H NMR 和 MS 证实了目标化合物结构,并对 2,2-二苄基-4,6-二 (对甲氧基)苯基-1,3,5 三硫环己烷的香气进行了鉴定,结果表明:2,2-二苄基-4,6-二苯基-1,3,5 三硫环己烷具有浓郁的葱蒜气味,其阈值在水中为 0.27×10-6～0.39×10-6、在植物油中为 12.41×10-6～17.89×10-6.     

食用香料糠基2-甲基-3-呋喃基二硫醚的合成

首先以α-糠基氯和硫代硫酸钠反应制备Bunte盐,然后Bunte盐与2-甲基-3-呋喃硫醇在碱性条件下反应合成了产品糠基2-甲基-3-呋喃基二硫醚.较佳合成工艺为:硫代硫酸钠与α-糠基氯摩尔配比4:1,氢氧化钠用量8.0 g.反应时间1 h.减压蒸馏后,计算两步反应总产率为31.7%,气相色谱分析糠基2-甲基-3-呋喃基二硫醚相对含量为78.4%.进一步硅胶柱色谱纯化,糠基2-甲基-3-呋喃基二硫醚的结构用质谱、红外光谱、核磁共振进行了确认.     

3-羟基-β-二氢大马酮的合成及在线热裂解研究

对3-羟基-β-二氢大马酮的合成及在线热裂解进行了研究.以异亚丙基丙酮、乙酰乙酸乙酯为原料,经Michael加成和Robinson环合得到2,6,6-三甲基-4-氧代-2-环己烯-1-羧酸乙酯;再经乙二醇缩酮化、水解、NaBH4还原得到2,6,6-三甲基-4-羟基-1-环己烯-1-羧酸乙酯;最后经与烯丙基锂反应得到目标产物3-羟基-β-二氢大马酮.对目标产物结构进行了GC-MS,IR,LC-ESI-MS,1H NMR,13C NMR表征.在线热裂解GC-MS,分析结果表明,3-羟基-β-二氢大马酮在300℃基本不裂解,在600℃,750℃,900℃能裂解出β-大马酮、异佛尔酮等重要烟草香味物质.     

3-(2-羟基苯基)-丙酸的合成

以二氢香豆素为原料,经皂化水解开环,形成钠盐。在低温条件下,钠盐用盐酸酸化形成含有邻羟基的3-(2-羟基苯基)-丙酸。考察了不同浓度的氯化钠溶液,对3-(2-羟基苯基)-丙酸产率的影响,同时还考察了原料投料比对产品产率的影响。在优化条件下3-(2-羟基苯基)-丙酸的最高产率达99.85%。     

吡咯基丝氨酸乙酯的合成表征及其对大蒜绿变的作用

采用有机合成的方法得到新化合物吡咯基丝氨酸乙酯,验证其是否可以作为大蒜绿变的色素前体,并用核磁共振的方法验证了这种新化合物具有和已报导过的大蒜绿变色素前体-3,4-二甲基吡咯基缬氨酸(PP-Val)和3,4-二甲基吡咯基丙氨酸(PP-Ala)相似的结构,只是R侧链的结构不同.但实验结果表明,吡咯基丝氨酸乙酯不能使新蒜绿变,也不能和丙酮酸发生反应,表明R侧链的结构对这种吡咯基氨基酸是否能作为色素前体起着很重要的作用.     

3-(4-甲氧基苯甲酰基)丙酸钠的甜味抑制效果评价

采用感官评定法研究了3-(4-甲氧基苯甲酰基)丙酸钠(SMP)对甜味、苦味、酸味、咸味、鲜味这5种基本味觉的影响,并评定了SMP对蔗糖、果糖、阿斯巴甜、糖精钠、葡萄糖等甜味化合物的甜味抑制效果。结果表明,SMP是一种有效的甜味抑制剂,当添加0.5mg/mL时能对蔗糖的甜味产生明显的抑制效果,但它不影响其他的几种基本口味。对5种常用的甜味化合物能起到明显的抑制效果,在添加量相同时甜味抑制效果的强弱为阿斯巴甜>葡萄糖>果糖>糖精钠>蔗糖。     

Transformation of hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) by permanganate

The chemical oxidant permanganate (MnO(4)(-)) has been shown to effectively transform hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) at both the laboratory and field scales. We treated RDX with MnO(4)(-) with the objective of quantifying the effects of pH and temperature on destruction kinetics and determining reaction rates. A nitrogen mass balance and the distribution of reaction products were used to provide insight into reaction mechanisms. Kinetic experiments (at pH ～ 7, 25 °C) verified that RDX-MnO(4)(-) reaction was first-order with respect to MnO(4)(-) and initial RDX concentration (second-order rate: 4.2 × 10(-5) M(-1) s(-1)). Batch experiments showed that choice of quenching agents (MnSO(4), MnCO(3), and H(2)O(2)) influenced sample pH and product distribution. When MnCO(3) was used as a quenching agent, the pH of the RDX-MnO(4)(-) solution was relatively unchanged and N(2)O and NO(3)(-) constituted 94% of the N-containing products after 80% of the RDX was transformed. On the basis of the preponderance of N(2)O produced under neutral pH (molar ratio N(2)O/NO(3) ～ 5:1), no strong pH effect on RDX-MnO(4)(-) reaction rates, a lower activation energy than the hydrolysis pathway, and previous literature on MnO(4)(-) oxidation of amines, we propose that RDX-MnO(4)(-) reaction involves direct oxidation of the methylene group (hydride abstraction), followed by hydrolysis of the resulting imides, and decarboxylation of the resulting carboxylic acids to form N(2)O, CO(2), and H(2)O.     

三硫烷二丁烯酸对金黄色葡萄球菌抑菌的研究

本文研究一种新型化合物三硫烷二丁烯酸(2E,2E)-4,4-trisulfanediylbis(but-2-enoic acid)(TSDB)对食品中常见金黄色葡萄球菌的抑菌机理。通过蛋白质十二烷基硫酸钠-聚丙烯酰胺凝胶电泳(SDS-PAGE)法,观察在TSDB作用下菌体蛋白质的变化;高效液相色谱测定有机酸变化;Annexin V单染色法观察细胞凋亡情况。结果表明:TSDB处理后金黄色葡萄球菌胞内蛋白质44.3~200 ku之间的条带变模糊或消失;菌体胞内苹果酸、柠檬酸含量均显著减少(分别平均下降了65.16%、56.18%)(p0.05),而草酸和乳酸未检测到相对于空白对照组;细胞凋亡时,细胞膜内侧的磷脂酰丝氨酸外翻到细胞表面,与带有绿色荧光探针FITC的Annexin V高度结合,使菌体细胞呈苹果绿。结论:TSDB处理后造成菌体细胞膜通透性改变,引起细胞有机酸代谢紊乱,抑制蛋白质合成,从而导致细胞凋亡或坏死。这一研究发现对开发食品防腐剂具有指导意义。     

Studies on the occurrence and formation of 2-(hydroxymethyl)-N-nitrosothiazolidine-4-carboxylic acid (HMNTCA) and 2-(hydroxymethyl)-N-nitrosothiazolidine (HMNTHZ) in various cured smoked meats,fish and cheese

Abstract : Because of the carcinogenic nature of many N-nitroso compounds, there is concern about their presence in foods. This paper presents some data on the levels of two non-volatile compounds (2-(hydroxymethyl)-N-nitrosothiazolidine-4-carboxylic acid (HMNTCA) and 2-(hydroxymethyl)-N-nitrosothiazolidine (HMNTHZ)) in various smoked foods such as 25 cured meats, eight smoked fish and seafoods, 15 smoked poultry products, and 17 smoked cheeses. All samples were negative for HMNTHZ, but 11 of the cured meats, six poultry products and two smoked fish contained HMNTCA at levels of 10–260 μg kg^?1. Upon frying, appreciable levels of HMNTHZ were formed in only one of 10 samples of cured meat products. The smoked cheeses were all negative for HMNTCA.     

Synthesis of 2-amino-6-(2-formyl-5-hydroxymethyl-1-pyrrolyl-)hexanoic acid

Summary The title compound has been synthesized by a novel route fromN -trifluoroacetyl lysine methyl ester and 2,9-dimethyldeca-2,8-diene-4,7-dione. Transformation of the pyrrole substituents and easy cleavage of protecting groups yields the compound in samples of high purity.

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Synthese der 2-Amino-6-(2-formyl-5-hydroxymethyl-l-pyrrolyl)-hexansäure

Zusammenfassung Die Titelverbindung wird auf einem neuen Weg ausN -Trifluoracetyllysinmethylester und 2,9-Dimethyldeca-2,8-dien-4,7-dion synthetisiert. Nach Umwandlung der Pyrrolsubstituenten und Abspaltung der Schutzgruppen unter milden Bedingungen erhält man die Titelverbindung in hoher Reinheit.

     

Abiotic transformation of hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) by green rusts

The rate and extent of hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) transformation was measured in the presence of carbonate and sulfate green rust suspended in solutions containing common groundwater anions. Formaldehyde (HCHO), nitrous oxide gas (N2O(g)), and ammonium (NH4+) were the major end products, accounting for about 70% of the carbon mass balance and about half of the nitrogen mass balance. Results from experiments with both 14C-RDX and LC-MS analysis indicate that the remaining carbon products are soluble and most likely small (< 50 Da). The transient appearance of 1,3-dinitro-5-nitroso-1,3,5-triazacyclohexane (MNX), 1,3-dinitroso-5-nitro-1,3,5-triazacyclohexane (DNX), and 1,3,5-trinitroso-1,3,5-triazacyclohexane (TNX) indicate that some nitro-group reduction occurred. The kinetics of RDX transformation was rapid with a half-life of less than an hour in a pH 7.0 KBr solution. Little difference in rates of RDX transformation or product distribution was observed between carbonate and sulfate green rust, and an apparent reaction order of 1.0 was measured with respect to Fe(II) in both green rusts. Phosphate anions completely inhibited RDX reduction, and carbonate and sulfate anions resulted in slower kinetics, and in some cases, an initial lag period, compared to bromide and chloride. Our results suggest that green rusts may contribute to abiotic natural attenuation of RDX in Fe-rich subsurface environments, but that it will be important to consider groundwater composition when assessing rates of attenuation.     

Degradation of hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) using zerovalent iron nanoparticles

Hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) is a common contaminant of soil and water at military facilities. The present study describes degradation of RDX with zerovalent iron nanoparticles (ZVINs) in water in the presence or absence of a stabilizer additive such as carboxymethyl cellulose (CMC) or poly(acrylic acid) (PAA). The rates of RDX degradation in solution followed this order CMC-ZVINs > PAA-ZVINs > ZVINs with k1 values of 0.816 +/- 0.067, 0.082 +/- 0.002, and 0.019 +/- 0.002 min(-1), respectively. The disappearance of RDX was accompanied by the formation of formaldehyde, nitrogen, nitrite, ammonium, nitrous oxide, and hydrazine by the intermediary formation of methylenedinitramine (MEDINA), MNX (hexahydro-1-nitroso-3,5-dinitro-1,3,5-triazine), DNX (hexahydro-1,3-dinitroso-5-nitro-1,3,5-triazine), TNX (hexahydro-1,3,5-trinitroso-1,3,5-triazine). When either of the reduced RDX products (MNX or TNX) was treated with ZVINs we observed nitrite (from MNX only), NO (from TNX only), N2O, NH4+, NH2NH2 and HCHO. In the case of TNX we observed a new key product that we tentatively identified as 1,3-dinitroso-5-hydro-1,3,5-triazacyclo-hexane. However, we were unable to detect the equivalent denitrohydrogenated product of RDX and MNX degradation. Finally, during MNX degradation we detected a new intermediate identified as N-nitroso-methylenenitramine (ONNHCH2NHNO2), the equivalentof methylenedinitramine formed upon denitration of RDX. Experimental evidence gathered thus far suggested that ZVINs degraded RDX and MNX via initial denitration and sequential reduction to the corresponding nitroso derivatives prior to completed decomposition but degraded TNX exclusively via initial cleavage of the N-NO bond(s).     

Effects of 2-hydroxy-4-(methylthio) butanoic acid (HMB) on microbial growth in continuous culture

2-Hydroxy-4-(methylthio) butanoic acid (HMB) positively affects milk composition and yield, potentially through ruminal actions. Four continuous culture fermenters were used to determine the optimal concentration of HMB for digestibility of organic matter (OM), neutral detergent fiber (NDF), acid detergent fiber (ADF), and hemicellulose and synthesis of microbial N. A highly degradable mix of hay and grain was used as a basal diet to simulate a typical lactation diet. Three concentrations of HMB (0, 0.055, and 0.110%) and one concentration of dl-Met (0.097%) were infused into the fermenters according to a 4 x 4 Latin square design. Digesta samples were collected during the last 3 d of each of the four 10-d experimental periods. Digestibility of OM, hemicellulose, and NDF was largely insensitive to treatment. Digestibility of ADF showed a quadratic effect to supplementation of HMB, with 0.055% having lower digestibility than 0 or 0.110%. Total production of VFA was not influenced by HMB supplementation, but differences in concentration and production of individual VFA were seen. Isobutyrate increased linearly with increasing HMB supplementation. Propionate concentration decreased linearly with increased HMB supplementation, but propionate production showed a quadratic trend (P = 0.13). A higher concentration of acetate was detected for dl-Met compared with the highest HMB concentration. There were trends (P < 0.15) for dl-Met to decrease the production of isobutyrate and to lower the concentration of butyrate when compared with HMB. Microbial efficiency was not different among treatments. The proportion of bacterial N produced from NH3-N decreased linearly with increasing HMB, and bacteria receiving dl-Met synthesized more N from NH3-N than those receiving HMB. These data suggest that supplementation of HMB may have a sparing effect on branched chain volatile fatty acids because the fatty acids are not needed to provide carbon for synthesis of valine, isoleucine and leucine with ammonia. Comparisons of bacterial community structure in the fermenter effluent samples using PCR amplicons containing the ribosomal intergenic spacer region and its flanking partial 16S ribosomal RNA gene showed no distinct banding patterns, though treatments tended to group together. Both Met and HMB affect the rumen microbial population, but Met supplied as dl-Met does not act identically to that supplied as HMB.