卷烟主流烟气主要挥发性羰基物的模拟口腔沉积

采用卷烟烟气口腔沉积模拟装置,对25种卷烟样品主流烟气主要挥发性羰基物的模拟口腔沉积情况进行了分析。结果表明:①各挥发性羰基物分析结果的日内、日间相对标准偏差均小于15%,大部分小于10%,模拟装置对挥发性羰基物的口腔沉积分析的稳定性良好。②不同挥发性羰基物的口腔沉积量由大到小依次为乙醛、甲醛、丙酮、丙醛、丙烯醛、丁醛、巴豆醛和2-丁酮,其中,甲醛和乙醛的沉积量显著高于其他挥发性羰基物;沉积比例由高到低依次为甲醛、乙醛、丙醛、丁醛、巴豆醛、丙烯醛、丙酮和2-丁酮。③烟气口腔刺激与甲醛、乙醛口腔沉积量显著负相关,相关系数分别为-0.916、-0.934,P值均小于0.01。      

丙三醇热裂解形成羰基化合物机理研究

采用密度泛函理论,研究丙三醇各种反应途径的热力学和动力学性质,确定丙三醇裂解的主要裂解路径。结果发现：丙三醇主要通过脱水反应形成甲醛、乙醛和丙烯醛,反应活化能在53～65kcal/mol。将丙三醇的裂解机理应用于1,2-丙二醇和1,3-丙二醇,推导1,2-丙二醇的主要裂解产物是丙醛、丙酮和乙醛,而1,3-丙二醇的主要裂解产物是甲醛、乙醛和丙烯醛。无氧裂解实验与理论推导具有高度一致性。     

卷烟烟气中8种羰基化合物对口腔的刺激作用

为了定性定量分析卷烟烟气对口腔的刺激作用,设计了一套模拟口腔装置,以卷烟烟气中8种羰基化合物(甲醛、乙醛、丙酮、丙烯醛、丙醛、巴豆醛、2-丁酮和丁醛)为研究对象,通过改变卷烟烟支的平衡条件调控烟丝含水率,并结合卷烟的类型,分析了烟气中8种羰基化合物与模拟口腔舌部和上腭刺激的相关性。结果表明:①烟气中8种羰基化合物在模拟口腔上腭和舌部的分布相当;②随着烟丝含水率的降低,主流烟气中8种羰基化合物含量增加,对口腔的刺激性增强;③在标准条件下,乙醛、丙酮、丙醛、巴豆醛、2–丁酮和丁醛的检出量与口腔刺激性呈显著相关,相关系数均高于0.81。     

模拟电子烟烟液中丙二醇和丙三醇裂解形成小分子羰基物

为模拟电子烟气溶胶中小分子羰基化合物的形成,分析了电子烟烟液的主要组成,采用裂解-气相色谱/质谱(Py-GC/MS)法考察了丙二醇和丙三醇在空气气氛下的主要裂解产物,探讨了裂解温度及含水率对丙二醇和丙三醇裂解形成小分子羰基物的影响.结果表明:①10种电子烟烟液中丙二醇、丙三醇和水的总量占烟液质量的86.5％～93.2％...     

LC-ESI-MS/MS法检测卷烟滤嘴中8种挥发性羰基化合物

建立了液相色谱-电喷雾电离串联质谱(LC-ESI-MS/MS)测定卷烟滤嘴中8种挥发性羰基化合物(甲醛、乙醛、丙酮、丙烯醛、丙醛、巴豆醛、2-丁酮和丁醛)的方法。采用乙腈∶水为1∶1(体积比)的混合溶剂振荡萃取滤嘴,羰基物与2,4-二硝基苯肼衍生化反应后用LC-ESI-MS/MS负离子模式检测。选取4种类型滤嘴(醋纤、活性炭、丙纤和纸滤嘴)进行条件优化和方法表征,并考察了滤嘴对8种羰基物的截留效率。结果表明:①该方法样品前处理简单,灵敏度高。8种羰基物的检测限在0.0044~0.0430μg/支之间。②8种羰基物的加标回收率为92.8%~118.4%。③该方法对于完整和部分滤嘴的日内精密度和日间精密度均小于10%。④滤嘴对8种羰基物的截留效率由高到低的顺序为活性炭>醋纤>纸>丙纤滤嘴,对8种羰基物总量的截留效率均<5%,截留效率较高的羰基物为甲醛和巴豆醛。     

应用后合成法制备的胺基功能化材料降低卷烟主流烟气中挥发性羰基化合物研究

采用后合成方法将胺基嫁接到载体上制备降低卷烟主流烟气中挥发性羰基化合物的材料,通过考察载体、胺基试剂和胺基试剂的用量对降低卷烟主流烟气中挥发性羰基化合物性能的影响,确定了后合成材料的较佳条件,即以三氧化二铝为载体,以3-胺基丙基三乙氧基硅烷（APTES）为胺基化试剂,两者的比例是:1 g三氧化二铝:5 mmol APTES。卷烟应用试验结果表明,应用该材料制备的二元复合滤棒卷制试验卷烟,与对照卷烟相比,试验卷烟的烟碱和焦油释放量基本不变,甲醛释放量降低55.2％、乙醛释放量降低25.0％、丙醛释放量降低20.7％、巴豆醛释放量降低17.8％,评吸结果表明,两种卷烟总体风格特点和感官质量基本一致。      

应用后合成法制备的胺基功能化材料降低卷烟主流烟气中挥发性羰基化合物研究

采用后合成方法将胺基嫁接到载体上制备降低卷烟主流烟气中挥发性羰基化合物的材料,通过考察载体、胺基试剂和胺基试剂的用量对降低卷烟主流烟气中挥发性羰基化合物性能的影响,确定了后合成材料的较佳条件,即以三氧化二铝为载体,以3-胺基丙基三乙氧基硅烷(APTES)为胺基化试剂,两者的比例是:1 g三氧化二铝:5 mmol APTES.卷烟应用试验结果表明,应用该材料制备的二元复合滤棒卷制试验卷烟,与对照卷烟相比,试验卷烟的炯碱和焦油释放量基本不变,甲醛释放最降低55.2%、乙醛释放量降低25.0%、丙醛释放量降低20.7%、巴豆醛释放量降低17.8%.评吸结果表明,两种卷烟总体风格特点和感官质量基本一致.     

卷烟主流烟气中挥发性醛酮的LC-MS/MS分析

采用2,4-二硝基苯肼衍生-LC-MS/MS法测定了32种卷烟样品主流烟气中的甲醛、乙醛、丙烯醛、丙酮、丙醛、巴豆醛、甲基丙烯醛、2-丁酮、丁醛、苯甲醛、戊醛、己醛.结果表明:①方法的检测限为0.1～0.5 ng/mL,回收率在91.6%～100.3%之间,相对标准偏差为3.28%～7.86%;②卷烟样品主流烟气的挥发性醛酮成分中主要为乙醛和丙酮,苯甲醛、已醛含量较小;③与进口烟相比,国产烤烟型卷烟主流烟气中的挥发性醛酮含量相对较高,混合型卷烟的相对较低;④不管是烤烟型还是混合型,焦油量高的卷烟主流烟气中的挥发性醛酮含量均相对较高.     

水分散-DNPH衍生-LC-MS/MS法同时测定电子烟液中8种羰基物

为分析电子烟液中的羰基物,建立了同时测定电子烟液中甲醛、乙醛、丙酮、丙烯醛、丙醛、巴豆醛、2-丁酮和丁醛8种羰基物的LC-MS/MS法.电子烟液中的羰基物在酸性条件下与2,4-二硝基苯肼(DNPH)反应生成腙类化合物,对比了LC-MS/MS法和HPLC法对检测结果的影响,考察了溶剂背景和反应体系均一性,优化了DNPH浓...     

高效液相色谱法测定卷烟燃烧生成的羰基化合物的分布

选择2,4-二硝基苯肼作为衍生化试剂,采用高效液相色谱(HPLC)法研究了7个卷烟燃烧后生成的8种羰基化合物的含量及在主流烟气、侧流烟气气相物、侧流烟气粒相物和滤嘴中的分布情况。结果表明:18种羰基化合物的总量为3 971.6~5 375.4μg/支,含量分布规律为侧流气相主流烟气侧流粒相滤嘴,主流烟气中羰基化合物以乙醛含量最高,丙酮次之;2随着焦油量的变化,主流烟气中羰基化合物的含量差别较大,而羰基化合物总量的差异不明显;一定程度上,主流烟气和滤嘴中的羰基化合物含量分别与焦油量成正比;3通过测定滤嘴中羰基化合物的含量,表明对于巴豆醛和甲醛的截留率相对较高,对于乙醛、丙酮和丙醛的截留率相对较低;滤嘴对于卷烟中的低级羰基类化合物的过滤效果并不明显。     

The Influence of Hopping on Formation of Carbonyl Compounds During Storage of Beer

Improving beer flavour stability is an important brewing goal. Pilot scale brewing trials (50 L) were performed that focused on the determination of the influence of hop pellet dosage and dosage timing on carbonyl compounds in stored beer. The reducing activity of experimental worts, beers and stored beers appeared to depend on the hop pellet dose. Brews with lower amounts of hop antioxidants showed an enhanced formation of carbonyl compounds over the course of beer storage. A correlation between DPPH reducing activity and the content of some carbonyls, including the important markers 2‐furfural and (E)‐2‐nonenal, was found. Fresh and aged beers hopped by different amounts of hop pellet doses were clearly distinguishable according to their carbonyl content using Cluster analysis. Results of the sensorial analysis corresponded to the analytical criteria values. Results of this study bring further evidence of the indispensable impact of hop antioxidants on the suppression of undesirable carbonyl compound formation in the course of beer staling, which can be significant in beers hopped by aroma hops. However, hop antioxidants are only one of many factors affecting beer staling.     

精氨酸—还原糖体系中1,2-二羰基化合物的形成和抑制研究

建立精氨酸—还原糖体系,考察影响该体系中1,2-二羰基化合物形成的因素,并探究形成过程中反应物与产物变化的动力学以及抑制剂染料木黄酮抑制1,2-二羰基化合物的动力学。对建立的精氨酸—还原糖模拟体系,采用气相色谱法评价温度、还原糖种类、pH和抑制剂染料木黄酮等各种因素对1,2-二羰基化合物形成的影响,并分析其变化规律,进而分析了反应体系中染料木黄酮介入前后反应物精氨酸、葡萄糖及产物1,2-二羰基化合物的含量变化规律。结果显示:影响1,2-二羰基化合物形成的最主要因素是时间;该体系中精氨酸和葡萄糖的浓度随着反应时间的延长而降低,且随着温度升高快速下降;1,2-二羰基化合物含量随着温度的升高和反应时间的延长而不断升高。时间和温度对丙酮醛(MGO)和乙二醛(GO)的产生有一定的影响,染料木黄酮通过降低反应体系中1,2-二羰基化合物的反应速率常数而抑制其产生。当染料木黄酮的添加量为50mmol/L时,对1,2-二羰基化合物的抑制率最高,均50%。LC-MS证实染料木黄酮在氨基酸体系中抑制1,2-二羰基化合物的机制是通过捕获MGO形成染料木黄酮-MGO加合产物,从而达到消除效果。     

Malondialdehyde-Nitrite Interactions in Meat and Model Systems

Nitrite retarded formation of carbonyl compounds in meat when added before cooking, but had no effect after cooking and storage even though the 2-thiobarbituric acid (TBA) number was very low due to reaction of malondialdehyde with nitrous acid. Although tripolyphosphate/ascorbate reacted similary preventing formation of carbonyl compounds, they had no effect on the TBA number when added after cooking. In a model system, nitrite reacted with malondialdehyde at pH 1.3 at room temperature. The percentage of reacting malondialdehyde decreased with higher pH and increased with nitrite concentration. The reaction of malondialdehyde with nitrite yielded high-molecular-weight products. Sulfanilamide prevented the reaction of malondialdehyde with nitrite, but only when added before nitrite.     

LCMS-IT-TOF测定不同脂肪酸结构食用油中的羰基化合物

为研究高温加热过程中食用油脂肪酸组成与羰基化合物形成的关系,先将三种食用油(油茶籽油、玉米油和亚麻籽油)在180 ℃高温加热24 h,然后采用气相色谱仪(GC)测定加热后油样中脂肪酸组成,采用高效液相色谱-离子阱-飞行时间质谱仪(LCMS-IT-TOF)测定油样生成羰基化合物组成。结果表明:油茶籽油(含有79.08%油酸)中特征羰基化合物为辛醛、壬烯醛、壬醛、癸烯醛、十一烯醛;玉米油中(含有55.05%亚油酸)特征羰基化合物为戊醛、戊酮、己醛、庚烯醛、癸二烯醛;亚麻籽油中(含有56.57%亚麻酸)特征羰基化合物为丙醛、丙酮、丁醛、丁酮、庚二烯醛。该结果表明脂肪酸组成对油脂加热所产生的羰基化合物种类起决定性作用,油酸氧化主要在8、9、10、11号碳位产生氢过氧化物,亚油酸主要在9、12、13、14号碳位产生氢过氧化物,亚麻酸主要在12、15、16号碳位产生氢过氧化物。氢过氧化物继续裂解产生不同的羰基化合物。     

桉树烟熏液的制备工艺研究

以桉树枝为原料制备干馏液,采用单因素和正交实验对桉树枝干馏液制备过程中影响因素进行优化,以酚类物质、羰基化合物和3,4-苯并芘含量为衡量指标,并对干馏液的成分进行了分析。结果表明:干馏温度为400℃,电压220V,粒径2.00cm的条件下制得的烟熏液品质最佳,酚类物质含量:15.56mg/mL,3,4-苯并芘:20.73μg/mL,羰基化合物:16.55g/100mL。     

Ultrafiltration/Reverse Osmosis Concentration of Lobster Extract

A membrane concentration system consisting of tubular polysulphone ultrafiltration (UF) and polyamide reverse osmosis (RO) was evaluated for concentrating key water soluble flavor compounds from lobster extracts. Major flavor-giving compounds in the extract were glutamic acid, glycine, arginine, uridine 5′-monophosphate (UMP), succninic acid and glucose. Factors affecting performance of the UF/RO systems, such as flow rate, feed solid level, temperature and pressure, on permeate flux and solids rejection were measured. The optimum UF conditions were 1.5% feed solid level, 15 L/min feed flow rate, 50°C feed temperature and 1 MPa log mean transmembrane pressure. The RO system retained all dissolved flavor components and its ideal operating conditions were 40°C, 2.8 MPa log mean transmembrane pressure and a flow rate of 15 L/min.     

Reactions of a sulfonamide antimicrobial with model humic constituents: assessing pathways and stability of covalent bonding

The mechanism of covalent bond formation of the model sulfonamide sulfathiazole (STZ) and the stronger nucleophile para-ethoxyaniline was studied in reactions with model humic acid constituents (quinones and other carbonyl compounds) in the absence and presence of laccase. As revealed by high resolution mass spectrometry, the initial bonding of STZ occurred by 1,2- and 1,4-nucleophilic additions of the aromatic amino group to quinones resulting in imine and anilinoquinone formation, respectively. Experiments using the radical scavenger tert-butyl-alcohol provided the same products and similar formation rates as those without scavenger indicating that probably not radical coupling reactions were responsible for the initial covalent bond formation. No addition with nonquinone carbonyl compounds occurred within 76 days except for a slow 1,4-addition to the β-unsaturated carbonyl 1-penten-3-one. The stability of covalent bonds against desorption and pressurized liquid extraction (PLE) was assessed. The recovery rates showed no systematic differences in STZ extractability between the two product types. This suggests that the strength of bonding is not controlled by the initial type of bond, but by the extent of subsequent incorporation of the reaction product into the formed polymer. This incorporation was monitored for (15)N aniline by (1)H-(15)N HMBC NMR spectroscopy. The initial 1,2- and 1,4-addition bonds were replaced by stronger heterocyclic forms with increasing incubation time. These processes could also hold true for soils, and a slow nonextractable residue formation with time could be related to a slow increase of the amount of covalently bound sulfonamide and the strength of bonding.     

Temperature-dependent uptake rates of nonpolar organic compounds by semipermeable membrane devices and low-density polyethylene membranes

The effect of temperature on sampling rates and sampler-water partition coefficients of semipermeable membrane devices (SPMDs) and low-density polyethylene (LDPE) strips was studied in an experimental setup under controlled flow conditions. Aqueous concentrations of chlorobenzenes, polychlorinated biphenyls (PCBs), and polyaromatic hydrocarbons (PAHs) were maintained by continuous circulation of the water over a generator column. Sampling rates for standard design SPMDs (460 cm2) were in the range of 20-200 L d(-1). No significant differences were observed between sampling rates of SPMDs and LDPE strips, but the latter samplers reached equilibrium faster because of their smaller sorption capacity. Sampling rates at 30 degrees C were higher than at 2 degrees C by a factor of about 3. Sampling rate modeling indicated boundary layer-controlled uptake for compounds with log octanol-water partition coefficients smaller than 4.4 and aqueous boundary-layer controlled uptake for more hydrophobic compounds. SPMD-water partition coefficients did not significantly change with temperature, but LDPE-water partition coefficients were larger at 2 degrees C than at 30 degrees C by a factor of 2. For field application of SPMDs, the results imply that temperature is not a key factor that controls uptake rates unless large geographical and temporal scales are involved. The results confirm that water flow velocity has a profound effect on sampling rates.     

栽培措施对白肋烟生长发育和产质量的影响

采用正交试验,对影响白肋烟产质量及烟碱含量的环剥与打顶、留叶、施氮量及采收方式4个栽培因素进行了研究,结果表明:采收方式是影响产量的主要因素,整株采收产量最低,全摘叶采收产量最高;氮肥用量12.5~15.5kg/667m2对产值影响最大;环剥是影响烟碱含量的主导因素,其中初花打顶后根基处环剥,能有效抑制烟株后期根系发育,烟碱含量降低。最佳栽培技术组合为留叶24片、初花打顶根基处环剥、施氮量12.5kg/667m2、全摘叶采收,其次是留叶22片、初花打顶根基处环剥、施氮量14kg/667m2、半整株采收。     

Reducing the sulfur-dioxide binding power of sweet white wines by solid-phase extraction

The high sulfur-dioxide binding power of sweet white wines may be reduced by extracting the naturally present carbonyl compounds from wine that are responsible for carbonyl bisulphites formation. The carbonyl compounds mainly responsible for trapping SO₂ are acetaldehyde, pyruvic acid, and 2-oxoglutaric acid. The method employed was selective solid phase extraction, using phenylsulfonylhydrazine as a scavenging agent. The scavenging function was grafted onto a support prepared from raw materials derived from lignin. This approach is more acceptable to winemakers than the polymer media previously reported, as it reduces the possible contamination of wine to molecules already present in the wine making process.