依兰花精油的香气成分

云南省西双版纳产依兰油,用Finnigan-4510型毛细管气相色谱/质谱/计算机联用方法进行了化学成分分析,共分离检出了50个成分,鉴定了其中22个成分,占全精油的95.27％。主要成分为:β-丁香烯(33.00％),γ-穆罗烯(19.82％)。α-(艹律)草烯(7.69％),乙酸香叶酯(6.21％),香柠檬烯(5.40％),苯甲酸苄酯(5.33％),金合欢醇(4.75％),金合欢烯(3.29％),香叶醇(2.48％),对甲酚甲醚(2.41％)。并讨论了如何提高国产依兰油质量的问题。     

Acetaldehyde production in Saccharomyces cerevisiae wine yeasts

Abstract Eighty-six strains of Saccharomyces cerevisiae were investigated for their ability to produce acetaldehyde in synthetic medium and in grape must. Acetaldehyde production did not differ significantly between the two media, ranging from a few mg/l to about 60 mg/l, and was found to be a strain characteristic. The fermentation temperature of 30°C considerably increased the acetaldehyde produced. This study allowed us to assign the strains to different phenotypes: low, medium and high acetaldehyde producers. The low and high phenotypes differed considerably also in the production of acetic acid, acetoin and higher alcohols and can be useful for studying acetaldehyde production in S. cerevisiae , both from the technological and genetic point of view.     

Volatile flavour components of mango fruit

An essence of fresh Venezuelan mango fruit obtained by well-established procedures possessed the characteristic aroma of the fruit. It was analysed by GC/MS using both EI and Cl. The fruit produced a relatively small quantity of aroma volatiles (ca 60 μg/kg fresh fruit), less than that obtained from many similar tropical fruits. Terpene hydrocarbons comprised ca 68% of the sample, eight monoterpenes contributing ca 54% and four sesquiterpenes contributing ca 14%. Important constituents included α-pinene, car-3-ene, limonene, γ-terpinene, α-humulene, β-selinene, acetophenone, benzaldehyde and a dimethylstyrene. Car-3-ene (26%) was the major constituent, and on odour evaluation of separated components at an odour port during GC, the peak due to this compound was described as having an aroma of mango leaves. This compound has not previously been detected among mango volatiles. The only other component providing mango aroma was a dimethylstyrene, and this too is a new mango volatile.     

Sulfite formation by wine yeasts

Five different strains of wine yeasts were investigated with respect to active uptake of [³⁵S] sulfate and its regulation by methionine. Considerable differences exist between low and high sulfite-producing strains in the initial velocity of sulfate uptake. Further differences were established in repression of sulfate permease by l-methionine, most evident in a total lack of repression in one of the high sulfite producers. These findings explain in part variable sulfite and sulfide formation.List of Abbreviations CCMP carbonylcyanide-p-trifluormethoxyphenylhydrazone     

Sulfite formation by wine yeasts

The enzyme catalyzing the reduction of sulfite by reduced benzyl viologen (BVH) was partially purified and characterized from two strains of wine yeasts, a sulfite-producing strain and a non-producing strain.Both enzymes showed corresponding features in pH-optima, optima of buffer and benzyl viologen concentrations.The enzymes did not catalyze the reduction of nitrite by reduced viologen dyes, but the reduction of sulfite was uncompetitively inhibited by nitrite. Compounds of sulfur metabolism such as sulfate, thiosulfate, cysteine, serine and methionine did not influence the activity of either of the enzymes. The main differences between the two enzymes exist in the specific activities in crude extracts, the K _m -values for sulfite, substrate inhibition rates, and localization in different fractions during (NH₄)₂SO₄ precipitation. The specific activity in crude extracts of the sulfite-producing strain (0.052 moles S^2- x min^-1 x mg^-1) was about three fold higher than that of the non-producing strain (0.0179 moles S^2- x min^-1 x mg^-1). On the other hand the sulfite-producing strain had a higher K _m -value for sulfite (2×10^-3 M) and was more strongly inhibited by the substrate than the non-producing strain (6×10^-3 M).     

Effects of Aroma Components from Oxidized Olive Oil on Preference

The present study explored the possibility that aroma components generated by the oxidation of olive oil may enhance the palatability of olive oil. Using a mouse behavioral model, we found that olive oil oxidized at room temperature for 3 weeks after opening the package, and heated olive oil were both significantly preferred over non-oxidized olive oil. Furthermore, this preference was enhanced with an additive of oxidized refined olive oil flavoring preparation at a certain concentration. These results suggest that the aroma of oxidized fat might be present in most fats, and might act as a signal that makes possible the detection of fats or fatty acid sources.     

一种紫斑牡丹花茶的研制及其主要香气成分分析

以紫斑牡丹(Paeonia suffruticosa var. papaveracea)花瓣为原料,采用隔离窨制,对牡丹花茶窨制过程中花坯、配花量等主要影响因子进行研究。结果表明,密闭箱桶温度21 ℃、相对湿度90%、窨制时间48 h条件下经一窨一提获得的花茶,感官评审花与茶叶的协调度高、香气高锐持久、茶汤滋味醇正鲜爽。采用气相色谱-质谱联用仪分析花茶香气成分,新鲜花瓣与茶叶配比5:1窨制48 h的花茶苯乙醇、香叶醇、橙花醇含量较高,其香气高扬、茶汤醇正鲜爽,配比2.5:1的花茶上述成分含量和感官其次,而拌和型茶品透素欠鲜爽。发酵或发酵揉捻花瓣窨制的花茶乙醇、环氧芳樟醇及高级烷烃含量较高,其主要赋香物质低于新鲜花瓣含量,渥味明显,茶汤有浊气欠鲜爽。     

顶空固相微萃取-气相色谱-质谱联用法分析香花秋海棠及其变种花香气成分

利用顶空固相微萃取结合气相色谱-质谱联用技术对盛花期的香花秋海棠(Begonia handelii)雄花及其变种铺地秋海棠(B. handelii var. prostrata)雌花和红毛香花秋海棠(B. handelii var. rubropilosa)雄花的挥发性香气成分进行分析。结果表明,从铺地秋海棠花中鉴定出香气成分32 种,其中醇类物质含量最高,占总成分50.10,其次分别为碳氢类、醛类和酸类物质,分别占总成分25.39、13.87、4.34;从香花秋海棠花中鉴定出香气成分为21种,醛类物质含量最高,占总成分57.12,其次是醇类、碳氢类、杂环类物质,分别占总成分17.37、15.31、4.88;从红毛香花秋海棠花中鉴定出香气成分44 种,醇类物质含量最高,占总成分38.22,其次是碳氢类、醛类和醚类物质,分别占总成分34.36、16.83、6.91。铺地秋海棠和红毛香花秋海棠香气成分较接近,富含具有清香、甘甜气息的芳樟醇氧化物等物质;香花秋海棠花中醛类物质含量最高,具有淡焦甜香气。     

绿茶糖苷类香气前体的GC-MS和HPLC-ESI-MS~n分析

采用高效液相色谱-电喷雾多级串联质谱法(HPLC-ESI-MSn)并结合气相色谱-质谱法(GC-MS)分析鉴定了绿茶中的糖苷类香气前体物质。茶样经甲醇提取,HPD-500大孔吸附树脂分离富集糖苷,GC-MS跟踪监测酶解后挥发性苷元,然后通过电喷雾多级质谱,根据正负离子模式下的准分子离子峰和多级质谱裂解碎片,鉴定了13种糖苷类香气前体物质,其中2种糖苷首次发现存在于绿茶中。     

Studies on Chlorosis-Inducing Activities and Plant Growth Inhibition of Benzophenone Derivatives

Some benzophenones substituted with methyl, methoxy, hydroxy or halogen groups inhibited growth and induced chlorosis in various plants. The structure activity relationships about the chlorosis-inducing activity and the growth inhibitory activity of the 3-methyl-benzophenones were well expressed by use of hydrophobic contant π, and Hammett’s σ. The highest selectivity for phytotoxic activities against barnyardgrass and the rice plant was with 3,3′-dimethyl-4-methoxybenzophenone (Methoxyphenone).