萜烯类与苯丙酸类花香挥发物的生物合成与调节

随着花香挥发物提取和检测技术的不断发展以及该技术与分子生物学研究的结合,花香挥发物的生物合成途径和调节机制的研究取得了较大进展,为花香的遗传控制和育种研究奠定了良好的基础。萜烯类和苯丙酸类/苯环型化合物是植物花香挥发物的重要化学成分,它们分别由甲羟戊酸-甲基赤藓醇磷酸途径、莽草酸途径等途径生成,调节机制较为复杂,但以前体物生物合成调节为主。两类花香物质在许多行业得到了应用广泛,但相关研究有待于进一步深入。     

Genetic and metabolic engineering of microorganisms for the development of new flavor compounds from terpenic substrates

Throughout human history, natural products have been the basis for the discovery and development of therapeutics, cosmetic and food compounds used in industry. Many compounds found in natural organisms are rather difficult to chemically synthesize and to extract in large amounts, and in this respect, genetic and metabolic engineering are playing an increasingly important role in the production of these compounds, such as new terpenes and terpenoids, which may potentially be used to create aromas in industry. Terpenes belong to the largest class of natural compounds, are produced by all living organisms and play a fundamental role in human nutrition, cosmetics and medicine. Recent advances in systems biology and synthetic biology are allowing us to perform metabolic engineering at the whole-cell level, thus enabling the optimal design of microorganisms for the efficient production of drugs, cosmetic and food additives. This review describes the recent advances made in the genetic and metabolic engineering of the terpenes pathway with a particular focus on systems biotechnology.     

Production of branched-chain aroma compounds by Propionibacterium freudenreichii: links with the biosynthesis of membrane fatty acids

Aims: Short branched-chain fatty acids (BCFAs) are cheese flavour compounds, which result from the conversion of branched-chain amino acids (BCAAs). In Swiss cheese, the production of short BCFAs is mainly performed by Propionibacterium freudenreichii and is strain dependent. Our aim was to investigate the possible links between the biosynthesis of short BCFAs and membrane BCFAs in P. freudenreichii. Methods and Results: Short and membrane BCFAs were analysed by gas chromatography-mass spectrometry. Two strains differing in their capacities to release short BCFAs were selected. Tri-deuterated-labelled leucine was used in both strains as a precursor of short extracellular iso-BCFAs and of membrane iso-BCFAs. The proportions of anteiso : iso BCFAs synthesized varied as function of the BCAAs provided in the growth medium, from 72 : 28 to 100 : 0, with leucine and valine, and with isoleucine as sole BC precursors, respectively. The branching pattern of short BCFAs exactly matched that of membrane BCFAs, whatever the exogenous BCAAs provided. Conclusions: The biosynthesis of short BCFAs is closely related to that of membrane BCFAs in P. freudenreichii. Significance and Impact of the Study: The biosynthesis of short BCFAs in P. freudenreichii depends more on the strain than on the presence of exogenous BC precursors.     

香料生产的研究进展与展望

从动植物中提取天然香料受原料来源的限制,从而使天然香料物质的开发和应用受到限制;化学合成的香料又非天然,因此利用生物技术生产天然香料越来越为人们所重视。就生物法生产天然香料的方法、优点及应用前景作一介绍。     

三种酒曲酿造的崇明老白酒的挥发性风味物质分析及比较

分别采用八二酒曲、纯种米根霉曲及酿酒酵母曲、纯种米根霉曲和粘红酵母曲按崇明老白酒工艺酿造老白酒,应用顶空固相微萃取-气相色谱质谱联用法对样品进行挥发性物质的检测,并对其进行醇酯比、香气活力值(OAVs)的计算及主成分分析,筛选出较佳的酒曲,得出崇明老白酒的主体香气.辛酸乙酯、1-辛烯-3-醇、3-甲基丁酸乙酯、己酸乙酯和乙酸异戊酯的OAVs大于10,是崇明老白酒的主要呈香物质.由八二酒曲酿造的酒液挥发性物质总量最高,醇酯比为5.89∶1,呈香物质以具蘑菇香的1-辛烯-3-醇为主.米根霉和酿酒酵母曲酿造的酒液酯类、芳香族化合物种类最多,醇酯比3.24∶1,香气以丁酸乙酯的甜香、苯乙醛、苯乙醇和乙酸苯乙酯的玫瑰花香为主要特征.米根霉和粘红酵母曲酿造的酒液挥发性化合物总量最低,醇酯比为2.86,主要香气特征为辛酸乙酯的甜香和己酸乙酯的水果香.纯种曲酿造的酒液的香气类型、风味种类比例、呈香物质的丰富程度均优于八二酒曲酿造的酒液.     

Localization of 9- and 13-oxo-octadecadienoic acids in tomato fruit

We previously reported that the two peroxisome proliferator-activated receptor-α agonists, 9- and 13-oxo-octadecadienoic acids (oxo-ODAs), were found in the tomato fruit. However, their localization remains unknown. Herein, we showed that oxo-ODAs localize primarily in the fruit peel and their amount increases after the homogenization of the tomato fruit.     

Antioxidant and intestinal anti-inflammatory effects of plant-derived coumarin derivatives

BackgroundCoumarins, also known as benzopyrones, are plant-derived products with several pharmacological properties, including antioxidant and anti-inflammatory activities. Based on the wide distribution of coumarin derivatives in plant-based foods and beverages in the human diet, our objective was to evaluate both the antioxidant and intestinal anti-inflammatory activities of six coumarin derivatives of plant origin (scopoletin, scoparone, fraxetin, 4-methyl-umbeliferone, esculin and daphnetin) to verify if potential intestinal anti-inflammatory activity was related to antioxidant properties.MethodsIntestinal inflammation was induced by intracolonic instillation of TNBS in rats. The animals were treated with coumarins by oral route. The animals were killed 48 h after colitis induction. The colonic segments were obtained after laparotomy and macroscopic and biochemical parameters (determination of glutathione level and myeloperoxidase and alkaline phosphatase activities) were evaluated. The antioxidant properties of these coumarins were examined by lipid peroxidation and DPPH assays.ResultsTreatment with esculin, scoparone and daphnetin produced the best protective effects. All coumarin derivatives showed antioxidant activity in the DPPH assay, while daphnetin and fraxetin also showed antioxidant activity by inhibiting lipid peroxidation. Coumarins, except 4-methyl-umbeliferone, also showed antioxidant activity through the counteraction of glutathione levels or through the inhibition of myeloperoxidase activity.DiscussionThe intestinal anti-inflammatory activity of coumarin derivatives were related to their antioxidant properties, suggesting that consumption of coumarins and/or foods rich in coumarin derivatives, particularly daphnetin, esculin and scoparone, could prevent intestinal inflammatory disease.     

家蝇作为饲料添加剂对清远良种鸡肉质和风味的影响

测定蝇蛆和蝇蛹作为饲料添加剂对清远良种鸡肉质和风味的影响,为家蝇Musca domestica L.作为添加饲料改善鸡的肉质和风味,以及代替鱼粉成为新的蛋白质来源提供数据。150只清远鸡雏鸡随机等分成5组,以鱼粉或商业饲料加入不同比例的家蝇幼虫或蝇蛹作为添加饲料加以饲养。结果显示,饲喂不同食料的清远鸡的增重、脾重和法氏囊重影响差异不显著,但饲喂蝇蛆和蝇蛹的鸡群的死亡率明显低于仅饲喂鱼粉或商业饲料的鸡群;饲喂蝇蛆或蝇蛹的鸡肉的系水力(用失水率表示)和风味评价明显提高,氨基酸含量差异显著。说明家蝇幼虫作为动物蛋白可提高鸡的抗疾病能力及改善鸡肉风味。     

芝麻香型白酒微生物菌群及风味物质研究进展

芝麻香型白酒是建国后通过学创结合、自主创新的两个香型之一,以其独特的浓、酱、清香融合的生产工艺特点和优雅的芝麻香而在国内闻名。芝麻香型白酒酿造机理和呈香呈味机理目前还不是很清楚。本文主要从芝麻香型白酒酿造工艺特点、微生物菌群种类及作用、风味物质种类与特点等三个方面进行阐述及展望。     

Biosynthesis of carotenoids by Phycomyces blakesleeanus mutants in the presence of nitrogenous heterocyclic compounds

Pyridine, imidazole and some of their derivatives stimulate lycopene and γ-carotene synthesis-simultaneously inhibiting β-carotene formation in Phycomyces blakesleeanus Strain C115. Isonicotinoly-hydrazine has a toxic effect on Strains C9 and C115 and 1-methylimidazole on Strain C115 in the concentrations of 1 g/l. Compounds which cause an accumulation of lycopene and γ-carotene usually cause an increase in phytoene synthesis and the disappearance of β-zeacarotene. The effect of succinimide, 4-hydroxypyridine, and isonicotinoylhydrazine on Strain C9 has also been studied. When β-picoline and 2-methylimidazole treated C115 mycelia were washed and resuspended in phosphate buffer at pH 5·6 β-zeacarotene reappeared and β-carotene increased with the simultaneous decrease in lycopene and γ-carotene. The sum of β-carotene, γ-carotene up to 3days of resuspension was almost equal to the total of these at zero time. These results show that the inhibitory action of these compounds is on the enzymes responsible for cyclization of acyclic carotenes. This inhibition varies with the nature of the substituent on the heterocyclic ring and pyridine derivatives having pK_a values of 6 ± 1 show the greatest degree of inhibition.     

热风干燥温度对荷叶离褶伞干燥特性及挥发性风味物质的影响

为探究不同热风干燥温度对荷叶离褶伞干燥特性及挥发性风味物质的影响.本研究比较了8种常见干燥动力学模型对荷叶离褶伞干燥过程拟合的适用性,采用GC-IMS技术,对不同干燥温度处理下荷叶离褶伞的挥发性风味物质进行测定.结果 表明:荷叶离褶伞热风干燥为典型的降速干燥,Midilli-Kucuk模型可以较好地描述其热风干燥过程(...     

Detection of flavor compounds in longissimus muscle from four hybrid pig breeds of Sus scrofa,Bamei pig,and Large White

To detect the flavor quality and flavor compounds in raw longissimus muscle from four typical pig breeds: Sus scrofa?×?Bamei pig named F1 (group A), F1?×?F1 (group B), F1?×?Bamei pig (group C), and F1?×?Large White (group D). The chemical compositions of longissimus muscles from four breeds were examined using headspace solid-phase microextraction/gas chromatography mass spectrometry method. Distinct differences for the same flavor compounds of longissimus muscles between different breeds were analyzed. Totally 64 flavor compounds shared in four groups, and 10 flavor compounds with significant difference among four groups (p?<?0.05), including allyl butyrate, (Z)-2-penten-1-ol, 2,2-dimethyl-3-methyl oxirane, 2-pentylfuran, dodecane, 2,4-decadienal, vinylsilane, 3-methyl-1-butanol, (1-methyldecyl)-benzene, and dipropyl phthalate. Totally, 23–41 flavor compounds did not commonly exist in four groups, such as only as dibutyl isophthalate in group A; 6,10-dimethyl-5-9-undecadien-2 one, bis (2-trimethylsilyl) ethyl ester-malonic acid, heptadecane, 2,4,6-trimethyl pyridine, and diisooctyl adipate in group C alone; and 1,3-dimethylcyclopentanol, 2-octanone, and trimethylsilane in group D alone. While, no specific flavor compounds were identified in group B. All these flavor compounds covered 12 types of hydrocarbons, alcohols, aldehydes, hydroxybenzenes, acids, ketones, esters, sulfides, furans, alkenes, and pyrrole. Besides, we analyzed 14 flavor compounds with different flavors combining with previous studies. The flavor compounds in longissimus muscles might be closely related to the breeds, and the hybrid of S. scrofa?×?Bamei pig had the most flavor compounds in raw longissimus muscle.     

Biosynthesis in opisthobranch molluscs: General outline in the light of recent use of stable isotopes

The use of stable isotopes has been recently introduced in the biosynthetic studies of metabolites produced by opisthobranch molluscs. This methodology offers numerous advantages since it avoids the complex and tedious manipulations of potentially dangerous radioactive compounds and gives unequivocal evidence for the incorporation. In these studies, high field NMR spectroscopy is a particularly useful tool to localize the labeled atoms in the molecule. This chapter updates the biosynthetic studies on opisthobranch molluscs with particular attention to the recent experiments with precursors labeled with stable isotopes. Opisthobranchs are able to biosynthesize de novo a wide array of chemical skeletons including polyketides, polypropionates, acetogenins, and terpenoids. The studies regarding this latter class is proposed in the light of the recent debate about classical and independent mevalonate pathway.The content of the present review is part of the plenary lecture presented at International Symposium Chemistry & Biology of Marine Organisms, September 21–26, 2003 – Kolympari, Crete, Greece.     

带鱼初加工过程中风味物质的检测分析

用75μmCAR/PDMS涂层的固相微萃取头萃取带鱼肉中挥发性风味成分,利用气质联用仪分析鉴定各阶段鱼肉中的挥发性成分、种类、相对质量分数等。原料鱼中检出57种化合物,风干6d的鱼肉中检测出61种化合物,以醇类、醛类、酮类、烷烃或烯烃类为主,总质量分数达75.16%。醛类、醇类、酮类、酯类等化合物对鱼肉的风味贡献较大,风味物质的形成与脂类、蛋白质等的降解有关。     

二十碳五烯酸和二十二碳六烯酸的生物合成途径研究进展

以二十碳五烯酸(EPA)和二十二碳六烯酸(DHA)为代表的长链多不饱和脂肪酸,对人体心血管系统、神经系统、抗炎免疫系统等有着理想的功效,因而倍受研究者关注。我们从结构、生物来源和合成、生理功能及生物工程途径的研究现状等方面阐述了EPA和DHA的相关信息,并对其生成途径中涉及的酶进行了简要概述。     

The impact of lactic acid bacteria on cheese flavor

Abstract Chesse flavor is a manifestation of complex interactions of volatile and non-volatile flavor-active compounds plus tactual perception. Numerous agents, including lactic acid bacteria, procece the flavou sensations. The effect of lactic acid bacteria is more dominant in cheese varieties with limited growth of secondary flora. This review describes the indirect and direct impacts of lactic acid bacteria in cheese with emphasis on carbohydrate fermentation, changes in oxidation-reduction potential, interactions with non-starter bacteria, autolysis, proteolytic and peptidolytic activities, transport of metabolites and flavor production.