SPME萃取头对茶油挥发物萃取效果的影响

固相微萃取目前被广泛地用来测定液态、气态,甚至固态物质的挥发组分,不同待测物的性质决定了萃取头的种类选择.采用4种常用的SPME涂层萃取头(100μmPDMS、85μmPA、65 μmaPDMS/DVB、50/30 μm DVB/CAR/PDMS)对荼油挥发物的提取性能进行了比较研究,结果表明:65 μmPDMS/DVB萃取头对较高沸点物质如苯甲醛、正辛醛、正辛醇、正壬醛、正壬醇的吸附比50/30 μmDVB/CAR/PDMS萃取头要灵敏,但50/30μmDVB/CAR/PDMS萃取头对较低沸点物质的吸咐要灵敏很多.DVB/CAR/PDMS涂层萃取头所得的总峰面积的平均值最大,其余依次是PDMS/DVB、PA、PDMS;DVB/CAR/PDMS、PDMS/DVB、PA、PDMS对挥发物吸咐总峰面积与挥发物总量之间存在有线性关系,其相关系数(R2)分别是0.9939、0.9888、0.9176、0.9917;因此,65 μmPDMS/DVB和50/30μm DVB/CAR/PDMS的萃取头较适用于茶油挥发物的提取.     

高温条件下多酚对茶油挥发性成分的影响

研究加热过程中多酚对茶油挥发性成分的影响,选取茶油和5组添加了0.02%多酚的茶油(没食子酸、儿茶素、槲皮素、没食子酸丙酯、3,4-二羟基苯乙酸)为材料,采用顶空固相萃取-气质联用法(HS-SPME-GC-MS)对6组样品在180℃下加热不同时间后挥发性风味成分进行分析。结果表明,在加热过程中添加多酚减缓了茶油挥发物数量的降低,但能抑制挥发物总量的生成;对挥发性物质种类的影响而言,添加多酚能有效减缓正构醛含量的减少,但对不饱和醛和其他不良挥发性成分如挥发性短链脂肪酸的生成具有抑制作用。因此,添加多酚能使高温下茶油的风味有所改善。     

大曲制曲过程中挥发性组分变化规律的研究

考察了不同萃取方式对顶空固相微萃取一气质联用（HS-SPME／GC-MS）技术萃取效果的影响,并剖析2种不同类型大曲挥发性组分的特点。结果表明,直接萃取的效果较好;高温大曲（叙府大曲）与2种中高温大曲（泸州老窖大曲、丰谷大曲）分别含26种、12种和21种挥发性组分,主要包括酯类、芳香族类、杂环及其他等4类。不同类型的大曲不仅所检出组分数量差异较大,且含量亦有区别。在不同种类大曲的制曲过程中,多数酯类的相对含量逐渐减少,芳香族亦呈类似的变化规律,多数的杂环化合物也仅是中间代谢物。丁子香烯则是大曲中后期合成的主要产物之一。     

茶油深层煎炸稳定性的研究

以棕榈油作对照,采用精炼茶油进行深层煎炸。测定煎炸用以及薯条中的油脂在煎炸过程中的主要化学指标,即酸值、过氧化值、羰基价、碘价、皂化值、K值及极性化合物含量等的变化;分析煎炸用茶油的挥发性成分的变化;评价薯条的感官品质。试验结果表明:连续煎炸30h(120批次),茶油及棕榈油的酸值、过氧化值、羰基价、极性化合物含量和K值均逐渐升高,碘价和皂化值则逐渐降低;总挥发物含量逐渐增加,而一些小分子质量挥发物呈先升后降的趋势;用新鲜油煎炸的薯条的总体得分较高;除过氧化值外,薯条中茶油的其它测定指标的变化滞后于煎炸用油的变化。对照国标GB7102,24h时除茶油中的羰基价超标外,其它指标至30h时仍处于规定限值范围。茶油的深层煎炸寿命为24h(96批次)。用茶油煎炸的薯条易被消费者接受。     

顶空固相微萃取-气相色谱法测定葡萄酒的风味组分

顶空固相微萃取技术是一种快速而简单的进样方法。顶空固相微萃取结合毛细管气相色谱技术无需复杂的样品制备过程就能有效测定葡萄酒中的风味化合物。本试验用标样定性了30个葡萄酒风味组分，并对与葡萄酒质量相关的风味化合物和影响定量结果的因素分别进行了讨论，大多数组分定量的相对标准偏差小于10％。     

HS-SPME-GC/MS法分析焙火对铁观音品质及挥发性香气组分的影响

以市售清香型铁观音为原料,通过控制高、中、低温组合方式及烘焙时间对其进行焙火工艺处理。处理后茶样经感官审评及SPME-GC/MS技术分析茶样品质及挥发性香气组分。结果表明:焙火铁观音茶样品质均高于对照茶样,其中c样品质最好。清香型铁观音主要挥发性香气成分:橙花叔醇、吲哚、α-法呢烯、脱氢芳樟醇、反-β-罗勒烯、苯乙酸香叶酯、茉莉内酯、苯乙腈、柠檬烯、苯乙醛等。焙火后带花香/果香类化合物相对含量降低,同时检出一些带烘焙香/火香类物质如:2-乙基-3,5-二甲基吡嗪、2-乙酰基吡咯、1-甲基-1-H-吡咯、2-正戊基呋喃等杂环类化合物。      

顶空-固相微萃取测定大曲香气组分的条件优化

采用顶空-固相微萃取方法测定大曲中的香气组分,以出峰数量和面积为指标比较,对影响萃取平衡的6个因素:萃取头、溶剂、大曲用量、萃取温度、萃取时间和盐离子浓度(NaCl)分别进行优化.结果表明,最佳的萃取方法为,以PA为萃取头,5 mL 12%vol乙醇为溶剂,0.2 g大曲取样量,不加入盐离子,经60℃超声平衡,在60℃...     

不同品种石榴果实挥发成分的SPME-GC-MS分析

采用固相微萃取和气相色谱-质谱联用技术,研究山东枣庄四种主产品种石榴果实的挥发成分,并对其萃取条件进行优化,以期为石榴果实特征香气研究及产品质量控制提供理论依据。通过对固相微萃取条件筛选,确定选用65 μm PDMS/DVB萃取头,在萃取温度60 ℃,萃取时间30 min,解析时间3 min的条件下进行提取分离。石榴果实中共分离鉴定出68种挥发成分,主要包括28种烯类、13种酯类、13种醇类,其中右旋柠檬烯、反式-α-香柑油烯、石竹烯、草酸环己基甲基十三酯、β-蒎烯和反-2-十四烯-1-醇为共有的关键香气成分。通过双向聚类分析将4种石榴品种在剩余信息为65%时分为3类,挥发性成分在剩余信息为10%时将挥发成分分为4类。结果表明,四个品种的石榴在挥发成分上即有共同特征又有各自的独特性和差异性。     

茶油挥发物质的固相微萃取条件的优化

以总峰面积、总峰面积与峰数比值、峰数及主要挥发物质峰面积为评价指标,研究了以DVB/CAR/PDMS为萃取头的固相微萃取条件对茶油挥发性成分萃取效果的影响.结果显示:当样品量为1.00 g(15 mL品瓶),搅拌速度为100 r/min,萃取温度为40℃,吸附时间为25 min,解析温度和时间为260℃和3 min时,提取到的挥发物数量较多,重现性好,主要挥发物质的萃取效果较好.     

酶法用于茶油脱胶的研究

酶法脱胶是一种环保、经济的生化脱胶新技术。利用新型磷酯酶Lecitase Ultra对毛茶油（磷酯含量为304mg／kg）进行脱胶研究，确定最佳反应条件：pH值4．8，加酶量50mg／kg油，温度45℃，反应时间为5．0h，磷酯含量降到10．47mg／kg。研究结果表明：Lecitase Uhra脱胶达到了良好的脱胶效果。     

基于脂肪酸和甘三酯组成的茶油掺伪检测参数的确定

本实验研究了测定脂肪酸和甘三酯在检测茶油中掺伪4种其他植物油时的有效性。在本研究中,与脂肪酸和甘三酯指纹图谱向量夹角余弦相似度、亚麻酸相对含量、三亚油酸甘油酯(LLL)相对含量、碳当量数(ECN)42甘三酯的实际与理论含量绝对差(ΔECN42)值、(LLL/ECN42)×100值和ECN46/LLL值相比,(ECN44+ECN46)/LLL值是茶油中掺伪大豆油、葵花籽油和玉米油的最有效检测参数,分别可以检测茶油中掺伪3.35%的大豆油、1.73%的葵花籽油和3.01%的玉米油,亚麻酸相对含量是茶油中掺伪芥花籽油的最有效检测参数,可以检测茶油中掺伪7.55%的芥花籽油。     

微波预处理对毛茶油品质影响

采用微波技术对油茶籽进行预处理,探讨微波作用条件对茶油提取率和毛茶油品质影响。结果表明,微波预处理可增大提油率,缩短预处理时间,茶籽水分含量很快达到平衡;但毛茶油过氧化值、酸价均有一定程度上升,色泽也有所加深。     

油茶籽油提取技术研究进展

油茶籽油是世界上四大木本食用油之一,具有预防心血管疾病、抗肿瘤、抗菌、抗炎、保肝、抗氧化及增强人体免疫力等重要保健功效。随着中国油茶种植产业的迅速发展壮大,势必进一步推动更为绿色、高效的茶油加工新技术的发展。文章综述了压榨法、有机溶剂浸出法、临界流体萃取法、水代法及水酶法等茶油提取工艺的研究与应用现状,比较了各种提油技术的优、缺点,旨在为加快研究"安全、营养、经济"的茶油提取新技术提供参考。     

The determination of frying oil quality using a chemosensory system

Chemosensory systems are currently being introduced in the food industries for quality control and process monitoring. This study was conducted to determine the possibility of using a chemosensory system to differentiate among varying intensities of oil rancidity and investigate discrimination between good, marginal and unacceptable frying oils. Fresh, 1-day, 2-day used and discarded frying oils were obtained from a fast food restaurant in each frying cycle for 4 weeks. The oil samples were analysed using a quartz-microbalance-based chemosensory system. The discrimination between good, marginal and unacceptable frying oils with regard to rancidity was examined and the results were compared to their physico-chemical properties such as dielectric constant, peroxide value, and free fatty acid content. The different qualities of frying oils were successfully evaluated and discriminated using the chemosensory system. Good correlations (r from 0.87 to 0.96) were found between changes in physico-chemical properties of oil and the sensor signals.     

The determination of frying oil quality using Fourier transform infrared attenuated total reflectance

The possibility of using the whole spectra (wave numbers between 4000 and 850 cm⁻¹) from Fourier transform infrared attenuated total reflectance spectroscopy (FTIR-ATR) to differentiate between good, marginal and unacceptable oils with regard to various intensities of oil rancidity was investigated. Fresh, used, and discarded oils were collected from several fast food restaurants from each frying cycle for 4 weeks. Dielectric constant, peroxide value, free fatty acid content, and density of oil samples significantly (P<0.01) increased with frying time. The correlation (r) between FTIR absorbance at 3300 cm⁻¹ and free fatty acid content was from 0.84 to 0.94 for oils from the three restaurants. Similarly, the correlation between FTIR absorbance at 3471 cm⁻¹ and peroxide value was from 0.90 to 0.97. The results of principal component analysis using the whole spectra (4000-850 cm⁻¹) showed good discrimination and stability for identification between acceptable, marginal and unacceptable frying oils.     

Effect of frying time on acrylamide content and quality aspects of French fries

The effect of frying time on quality and acrylamide (AA) content of French fried potatoes, obtained simulating home-cooking practices, was studied in order to investigate the optimal conditions to minimize the amount of produced toxicant together with the maintenance of good culinary quality. French fries were obtained from fresh potatoes using a domestic fryer with static basket; a 4:1 oil:product ratio and a fixed initial oil temperature of 180 °C were used. Several batches were fried at different times (3, 4, 5, 6, 7, 8, 9 min). During frying tests the oil, the sticks surface and core temperatures were measured by thermocouples. Analysis of water removal, oil uptake, colour, texture and AA content were carried out on fried final products. AA content increased exponentially increasing the frying time. In our working conditions after around 4 min of frying, when the temperature of potato surface and the oil bath reached, respectively, 120 and 140 °C, the increase of time became a key factor in terms of the quantity of AA and its formation rate. On the basis of colour, oil content and AA level the best culinary product was obtained after 5 min of frying.     

立地对油茶籽出油率及油茶籽油品质的影响研究

为了探明立地对油茶籽出油率及油茶籽油品质的影响,以9个立地的低温压榨油茶籽油为样品,测定油茶籽出油率及油茶籽油的理化性质、感官品质、脂肪酸组成、功能性成分含量及氧化诱导时间,分析坡向、坡位因子对油茶籽出油率及油茶籽油品质的影响。结果表明:立地对油茶籽出油率及油茶籽油的过氧化值、碘值、皂化值、感官品质、功能性成分含量及氧化诱导时间均具有明显影响,对油茶籽油的酸价、脂肪酸组成无明显影响。说明立地是影响油茶籽出油率及油茶籽油品质的重要因素。     

Effect of repeated frying on the viscosity, density and dynamic interfacial tension of palm and olive oil

The effect of deep-fat frying on the viscosity, density and dynamic interfacial tension (against air and water) of palm oil and olive oil was investigated. Repeated frying (up to 40 batches) at two different potato-to-oil ratios (1/7, 1/35 kg_potatoes/L_oil) was examined. Results were compared to those from simple heating the oils at the same temperatures. Viscosity increased during repeated frying for both oils. However, only palm oil viscosity was sensitive to potato-to-oil ratio. Due to the novelty of dynamic interfacial characterization of such systems a discussion was made about the appropriate timescales and deformation types for interfacial measurements. Significant effects of repeated frying on the dynamic interfacial tension at the oil/water interface were observed. Contrarily, changes in density were not significant. Results were assessed with respect to the evolving chemical profile of the oils determined in previous works. Possible implications of the determined properties on the frying process were discussed.     

Effect of fish (Catla catla) frying on the quality characteristics of sunflower oil

The quality of sunflower oil, as affected by fish (Catla catla) frying at 180 °C for 14 h was investigated. The purpose of the study was to find out the quality deterioration of sunflower oil with respect to time as affected by fish frying and to generate equations that can be used for predicting the quality parameters. The physico-chemical characteristics of sunflower oil were evaluated by drawing out the oil samples (75 ml) from the fryer at an interval of 2 h. The parameters evaluated were refractive index, colour, total polar material, free fatty acids, iodine value and peroxide value. There was a gradual increase in refractive index and colour with time of frying which was found to be significant (P < 0.05) in the latter. Iodine value decreased significantly (P < 0.05) with time of frying. Peroxide value first increased up to 12 h of frying and then decreased. After 10 h of frying, the total polar materials were 26.9%, indicating the need for replenishment or refinement of sunflower oil. Total polar material correlated well (r > 0.97) with colour, free fatty acids, peroxide value and time of frying. Free fatty acids correlated well (r > 0.96) with colour, total polar material and duration of frying. Fit of the equations was determined for total polar material and free fatty acids as a function of the respective correlated parameters.