顶空气相色谱法测定绿茶提取物中乙酸乙酯残留量

采用顶空气相色谱法对绿茶提取物中乙酸乙酯残留溶剂的分析方法进行了研究。试验采用大口径HP-快速GC残留溶剂柱为分离柱,对顶空平衡温度、平衡时间对残留有机溶剂乙酸乙酯测定的影响进行了分析研究。结果表明：乙酸乙酯在0.0765~0.612μg/ml内线性关系良好,相关系数为0.9993;方法精密度试验RSD(n=6)为3.60%;平均回收率范围95.42%~97.88%,RSD 1.95%~3.09%;检测限(S/N=3)为0.005μg/ml。本方法快速、灵敏、准确、无污染,适用于绿茶提取物中乙酸乙酯残留量的测定。     

3种不同萃取方法对黑胡椒香气物质的气质联用分析

为探究不同提取方法对黑胡椒挥发性成分的影响,本研究以黑胡椒为材料,利用顶空固相微萃取法（HS-SPME）、戊烷:乙醚（1:1）溶剂萃取法和甲基叔丁基醚（MTBE）溶剂萃取法对黑胡椒中的香气成分进行提取,结合气相色谱质谱联用法（gas chromatography-mass spectrometry）和主成分分析法（PCA）对提取的香气物质进行分析。3种提取方法共得到6类（烯类、醇类、酚类、烃类、崁类、烯类氧化物）33种物质。戊烷:乙醚（1:1）溶剂萃取法、MTBE溶剂萃取法及顶空固相微萃取法分别检测到25、23、27种挥发性化合物,其中,相对含量较高的化合物均为3-蒈烯、柠檬烯、β-石竹烯、β-蒎烯。2种溶剂萃取法中,戊烷:乙醚（1:1）溶剂萃取法检测到的特有化合物有α-松油烯、α-松油醇、β-金合欢烯;与2种溶剂萃取法相比,顶空固相微萃取法（HS-SPME）检测到的特有化合物有樟脑、4-萜烯醇、2-(4-甲基苯基)丙-2-醇、橙花醇、香树烯、β-甜没药烯和愈创兰油烃。结合主成分分析得出,β-蒎烯、3-蒈烯、柠檬烯、β-石竹烯对黑胡椒香气风味贡献率较大,其中顶空固相微萃取法（HS-SPME）与2种溶剂萃取法所得成分差异明显。在溶剂萃取法中,戊烷:乙醚（1:1）溶剂萃取法优于MTBE溶剂萃取法。溶剂萃取法与顶空固相微萃取法所得物质在种类与数量上均存在差异。在胡椒香气物质检测时,将2种方法相结合可以更大程度保证所得化合物种类的丰富性和全面性。     

顶空毛细管气相色谱法测定茶多酚中有机溶剂的残留量

建立了顶空毛细管气相色谱法测定茶多酚中正己烷、氯仿、乙酸乙酯和丙酮4种有机溶剂残留量的方法。并讨论了平衡温度、平衡时间、盐效应对测定的影响。分析结果表明，该方法对上述4种有机溶剂均达到了完全分离，相关系数为0.994-0．999，检出限范围为0.065～0、268μg／g，测定结果的相对标准偏差为0．39％～2、13％，样品的回收率为90．9％～105．3％。     

响应面优化传统发酵豆酱风味物质萃取条件的研究

本研究采用顶空固相微萃取方法(HS-SPME)优化黑龙江传统发酵豆酱风味物质萃取条件,结合响应面试验并考虑到实际操作条件,得出了最佳萃取条件为:萃取温度62℃,萃取时间41 min,解析时间2 min。风味物质检测鉴定采用顶空固相微萃取和气质联用法,对发酵一个月的传统豆酱样品进行鉴定,共鉴定出34种挥发性风味物质成分,主要包括烷烯烃类、酯类和芳香类,这些物质对黑龙江省传统发酵豆酱风味贡献最大,可能为黑龙江省传统发酵豆酱的特征风味物质。     

SAS统计软件在茶叶中有机磷农药残留提取技术上的应用

选取提取时间、提取方式、提取溶剂以及提取溶剂用量这四个重要的提取参数,采用正交实验设计对茶叶中有机磷类农药残留的提取技术进行优化,减少了试验次数,提高了实验效率。应用SAS数据分析软件对实验数据进行分析,准确迅速得到了茶叶中有机磷类农药残留的提取最佳条件是用10ml乙酸乙酯作提取溶剂,震荡提取10min。     

普洱茶主要氧化产物提取条件的优化及其抗氧化活性分析

以普洱茶为原料,研究溶剂pH值、浸提温度、时间、料液比对茶褐素（TBS）提取率的影响。结果表明,溶剂pH值、浸提温度、时间、料液比等都显著影响TBS的浸提效果,其中料液比、浸提温度、浸提时问达到了极显著水平,各因素影响效果的重要眭依次为：料液比〉浸提温度〉浸提时间〉溶剂pH值。同时得到茶褐素浸提的优化条件为：温度100℃,溶剂pH=7,料液比1：30,时间20min。茶褐素抗氧化活性分析结果显示,其抗氧化活性优于普洱茶水提物。     

果蔬中甜蜜素残留快速检测试纸的研究

课题研究快速检测果蔬中是否残留甜蜜素的试纸。从试纸显色剂种类、显色剂浓度、试纸材料、浸泡时间、干燥温度、干燥时间、保存条件等方面进行研究。确定试纸材料为普通滤纸;显色剂为0.8%磺胺(10%盐酸稀释):0.4%N-1-萘乙二胺盐酸盐(1:1);浸泡时间10min;试纸的干燥温度为50℃;干燥时间为40～45min;甜蜜素标准品检出限为0.01mg/mL;保存条件为常温密封保存。检测的6种果蔬样品中有3种检出甜蜜素残留,3种未检出。该检测试纸具有制作简单、成本低、体积小、携带方便、操作简单、检测快等特点,能对果蔬中甜蜜素残留进行快速定性检测。     

冷冻丙酮法提纯α-亚麻酸的研究

利用冷冻溶剂法原理,分析了在提纯α-亚麻酸的过程中冷冻温度、冷冻时间、溶剂配比、溶剂酸碱度、溶剂纯度、冷冻次数等因素对产物中α-亚麻酸的纯度和收率的影响.使α-亚麻酸的浓度由46.0%提高到80.3%,收率达到56%.     

速溶鹧鸪茶的提取工艺优化及挥发性成分分析

采用响应面法优化鹧鸪茶提取工艺,研究超声时间、提取温度、料液比对水提液中多酚提取率(Y1)、游离氨基酸总量(Y2)和水浸出物含量(Y3)的影响。将提取液进一步干燥处理得到速溶粉,利用顶空固相微萃取(HSSPME)和气质联用(GC-MS)对茶粉及速溶粉挥发性成分定性分析。结果表明:优化得到速溶鹧鸪茶提取工艺参数为时间28 min、温度58℃、料液比1:21,在此工艺参数下制得的提取液的多酚提取率为14.53%,游离氨基酸总量为20.97 mg/g,水浸出物含量为33.45%。茶粉和速溶粉经GC-MS分析,共鉴定出挥发性成分72种,其中茶粉含44种,速溶粉含52种,二者相同挥发性成分为26种。本研究可为鹧鸪茶生产工艺条件提供理论支撑。      

朱砂根愈伤组织中岩白菜素提取工艺优化

在单因素试验（提取溶剂及提取溶剂浓度、提取时间、提取温度、提取功率、料液比和提取次数）的基础上选取提取温度、提取时间、料液比这3个因素进行二次回归正交组合设计试验（响应面分析法）,利用响应面法对朱砂根愈伤组织中岩白菜素提取工艺参数进行优化研究。结果表明：当提取时间为49.74 min,提取温度为80.08 ℃,料液比为1 ∶ 10.00时,岩白菜素的浓度达到最大为81.34 μg/mL。     

Analysis of Headspace Compounds of Distillers Grains using SPME in Conjunction with GC/MS and TGA

Chemical composition of headspace compounds of distillers grains was investigated using solid phase microextraction (SPME) along with GC/MS and TGA. Dryer feed (DF) and distillers dried grains (DDG) from a local distillery were utilised for this study. A SUPELCO 75 μm Carboxen/PDMS SPME fibre was found suitable for extraction of analytes from grains. Samples were placed in small vials (40 mL from SUPELCO) filled to one-third of their capacity. SPME was exposed to the headspace for 1 to 2 h. The fibre was then thermally desorbed in GC injection port for separation and identification. The gas chromatogram showed as many as 64 compounds eluting out of the column, the number being greater in DF as compared to DDG. Thermogravimetric analysis (TGA) was performed on the grains to study the oxidative stability of the compounds. SPME fiber was inserted directly into TGA purge gas outlet to study the compounds being evolved. Three weight loss transitions were observed in the TGA curve of DF and DDG. The components from the three transitions were captured by SPME and analysed by GC/MS for identification. TGA helped in determining the degradation stages of grains thereby indicating the temperature limits in drying grains. Difference between the heated and unheated DF and DDG have been discussed in detail.     

Polyhydric alcohol liquefaction of some lignocellulosic agricultural residues

Liquefaction of bagasse and cotton stalks was conducted by using polyhydric alcohols (polyethylene glycol PEG#400 and glycerin) in the presence of sulfuric acid (SA) as a catalyst. The effects of different liquefaction conditions, such as ratio raw material/liquefying solvent, effect of PEG#400/glycerin, acid concentration, liquefaction temperature and time on the liquefaction yield have been investigated. The hydroxyl and acid numbers for some liquefied samples were also determined. The results showed that the minimum residue content was obtained at 1/5 raw material to liquefying solvent. PEG#400 alone is not favoured as liquefying solvent as it gives ∼19% residual content for bagasse and ∼22% for cotton stalks at the optimum studied reaction conditions. Replacing 10% of PEG#400 with glycerin as well as increasing the SA concentration, liquefaction temperature or time, decreased the amount of residue for both bagasse and cotton stalks to less than 10%. The hydroxyl number of the produced polyols slowly decreased from 253 to 223 mg KOH/g on extending the reaction time till 120 min and the residual polyols prevented re-condensation of the liquefied components. It seems that this system can be applied on various types of lignocellulosic agricultural residues.     

海南省芒果主产区主栽品种果实挥发性成分的对比

采用顶空固相微萃取-气相色谱-质谱联用法（HS-SPME-GC-MS）测定芒果香气成分,分析HS-SPME的平衡时间、萃取温度、萃取时间及解吸时间对香气成分分析结果（包括总峰数目、总峰面积）的影响,得到最佳萃取条件,并通过谱库比对鉴定芒果香气成分的组成及相对含量。旨在明确HS-SPME-GC-MS测定芒果果实香气成分的最佳萃取条件及海南省芒果主产区主栽品种贵妃、台农果实的香气成分组成及差异,为芒果香气品质判断及种质资源评价提供依据。结果表明：（1）HS-SPME最佳萃取条件为平衡时间10 min,萃取温度45 ℃,萃取时间60 min,解吸时间5 min。（2）海南省芒果主产区主栽品种贵妃、台农共鉴定出102种匹配度大于70%的挥发性香气化合物,2个品种的香气成分主要由萜烯类构成,贵妃萜烯类占香气成分总含量的74.70%,台农萜烯类占香气成分总含量的86.79%,另外还有少量的醇、醛、酮、酯、羧酸类。（3）贵妃、台农共有的挥发性香气化合物有α-异松油烯、3-蒈烯、柠檬烯、3-己烯-1-醇、2-己烯醛、γ-己内酯、异佛尔酮、棕榈酸等15种。因此,α-异松油烯、3-蒈烯为海南省芒果主产区主栽品种贵妃、台农的主要特征香气成分,且台农的主要特征香气成分相对含量明显高于贵妃。     

Effect of heat treatment on the flavor of oat flakes

In order to assess the effect of heat treatment procedure on the flavor and volatile compounds of oats, raw oats, kiln and dried oats, dehulled oats and oat flakes were analysed. A sensory profile method was used to monitor changes in flavor. It changed from hay-like for raw oats into nutty, bread-like for oat flakes. Headspace solid phase microextraction (SPME) and solvent assisted flavor evaporation (SAFE) techniques were applied for isolation of aroma compounds. The most abundant compound in headspace was hexanal – its concentration varied from 176 to 1671 μg/kg depending on the processing stage. The key aroma compounds of oat flakes identified using gas chromatography – olfactometry and aroma extract dilution analysis (AEDA) were 2-methyl-3-furanthiol with roast/cooked oatmeal flavor together with methional, dimethyl trisulfide, 1-octen-3-ol, 2-methyl-3,5-diethylpyrazine.     

顶空固相微萃取-气质联用分析香荚兰浸膏风味组分的条件优化

为选择适宜的香荚兰浸膏萃取条件,采用顶空固相微萃取-气相色谱-质谱联用技术,以固相微萃取样品处理量、萃取温度和萃取时间三个条件分析各萃取条件对香荚兰浸膏风味组分、面积及含量的影响。结果表明：在实验范围内香荚兰浸膏最佳萃取条件为萃取样品添加量2.0 g、萃取温度80 ℃、萃取时间25 min。最佳条件下香荚兰浸膏鉴定出匹配度90以上的化合物45种,此条件下总化合物面积（×10 ¹¹）及香兰素面积（×10 ¹⁰）最高分别为1.04±0.09、6.99±0.46,匹配度90以上化合物占总化合物相对百分含量的90.24%;香荚兰中主要化合物醛类百分含量占总化合物相对百分含量的72.03%。     

海南地区白胡椒粉风味成分的研究

采用固相微萃取法采集海南地区白胡椒粉的挥发性成分,用气相色谱-质谱法分析鉴定,并用总离子流色谱峰的峰面积对其风味成分进行归一化定量分析。结果表明：共鉴定出26种化合物,分别为3-蒈烯(20.37 %)、石竹烯(19.81 %)、柠檬烯(14.36 %)、β-蒎烯(9.10 %)、γ-萜品烯(8.18 %)、α-水芹烯(6.70 %)、α-蒎烯(3.60 %)、δ-榄香烯(3.22 %)、罗勒烯(1.97 %)、可巴烯(1.76 %)、异松油烯(1.63 %)、α-石竹烯(1.46 %)和δ-杜松萜烯(1.     

Dough and bread made from high- and low-protein flours by vacuum mixing: Part 2. Yeast activity,dough proofing and bread quality

The combined effects of reduced mixer headspace pressure and mixing duration on the yeast activity, proofing and quality of dough and bread made from both high-protein flour (HPF) and low-protein flour (LPF) were addressed in this study. Rheofermentometer analysis showed that a reduction in mixer headspace pressure up to 0.08 MPa did not affect the overall gassing power of yeast in either of the two dough matrices. An increase in mixing duration sped up the mass transfer rate of CO₂ at the initial stage of fermentation, leading to a faster expansion of dough volume at the beginning. Moreover, an increase in mixing time promoted dough development and gas inclusion, which resulted in a increased volume of dough and bread, as well as a softer texture of both baked bread and steamed bread. In general, reduced headspace pressure produced baked bread of smaller volume, denser structure and harder texture. On the other hand, vacuum mixing produced steamed bread with softer texture without significantly changing the bread’s volume and porosity.     

不同极性色谱柱在滇红香气成分分析中的对比研究

采用顶空固相微萃取(HS-SPME)对滇红的香气成分进行富集,分别使用两种不同极性的色谱柱进行色谱分离,气质联用(GC-MS)检测分析,比较了非极性色谱柱HP-5MS和极性色谱柱CP-Wax对红茶香气成分分离效果的差异。结果表明,两种不同极性色谱柱对红茶香气成分的分离效果均表现良好,但分析结果存在一定的差异。因此在对红茶中不同的香气成分进行研究分析时,应根据分析目标的不同选择合适的色谱柱。