白酒风味物质研究进展及关键技术分析

白酒中存在的1%～2%微量成分对白酒风味起到决定性作用。白酒微量成分的提取、检测、分析对白酒的品质提高十分重要。该文总结了白酒风味成分研究现状与检测技术方法，对白酒风味检测技术和原理进行了分析，旨在为白酒风味研究和技术提升提供一定的参考。     

杏鲍菇分离蛋白和清蛋白的理化性质及功能分析

以杏鲍菇为原料,分别利用碱溶酸沉法提取杏鲍菇分离蛋白（Pleurotus eryngii protein isolate,PEPI）、Osborne法分离主要蛋白组分,并研究其理化性质和功能分析。结果表明,杏鲍菇的蛋白质量分数为17.57%（以干质量计）,以杏鲍菇清蛋白（Pleurotus eryngii albumin,PEA）为主,占总分离蛋白组分的81.12%。PEPI和PEA中均含18?种氨基酸,且必需氨基酸含量分别占总氨基酸含量的40.80%和40.51%。与PEPI相比,PEA的表面疏水性（265.25）显著高于PEPI（164.27）（P＜0.05）,而总巯基、二硫键含量较低,分别为61.53?μmol/g和10.39?μmol/g;热变性温度（100.98?℃）低于PEPI（108.27?℃）,且PEA持水性（1.64?mL/g）、持油性（5.59?mL/g）显著低于PEPI（3.58、8.36?mL/g）（P＜0.05）。PEPI和PEA的溶解性、起泡性、泡沫稳定性、乳化性及乳化稳定性随pH值的变化趋势均相似,在等电点时均为最低。傅里叶变换红外光谱显示PEPI和PEA的二级结构主要是β-折叠和β-转角,扫描电镜观察PEPI呈蜂巢结构。相比PEA,PEPI具有更好的理化性质和功能特性。     

应用生物技术 提高食品检测效率

正作为一种现代化的检测技术,生物检测技术将免疫学、分子生物学、微量化学、微量机械、微电子技术、探测系统、计算机技术等系统相结合,解决了传统食品检测成本高、效率低、效益差等问题。因此,近年来我国逐渐将生物技术作为食品检测技术的研发重点。目前生物检测技术常用的方法包括生物芯片、分子生物技术、生物传感器技术、免疫学方法等。一、FTA-PCR技术     

基于微量建库测序的毛皮鉴定技术研究

本研究目的是通过微量建库测序的方法,搭建动物物种DNA片段化数据库,建立毛皮动物物种鉴定检测技术体系。本研究选择11个无参考基因的物种,一共21份样品,提取样品的DNA,通过微量建库测序,成功建立了11个物种的DNA片段化数据库,建库成功率100%。测试:随机选择了5个物种共9个测试样品进行方法验证,测试样与所对应的物种聚类吻合率达100%。本研究建立的微量建库测序方法可以用于毛皮的物种鉴定。     

微型核反应堆超热中子活化分析食品中的微量砷

为提高食品中微量砷的检测能力 ,利用在微型核反应堆安装的超热辐射孔道对样品进行照射降低样品的本底值后测定食品中的微量砷。方法的检出限为 6 7× 10 -9g ,RSD =4 3% ,样品的回收率在 98%以上。微型核反应堆超热中子活化分析法可用于食品中微量砷的检测。     

老白干香型白酒酿造微生物菌群及其与微量成分的关系

利用高通量测序技术对老白干香型白酒酿造过程中的微生物进行测序,并对得到的有效数据进行α、β多样性分析,得到310个细菌属和59个真菌属,其中优势细菌属为Lactobacillus、Pediococcus和Weissella,优势真菌属为Saccharomycopsis、Issatchenkia、Rhizopus、Trichosporon、Candida和Aspergillus。采用顶空固相微萃取-气相色谱-质谱联用技术检测并定量酒醅中的微量成分,对检测到的微量成分进行热图绘制。结果表明:0~3 d是微量成分种类增加的一个小高峰;3~14 d微量成分种类变化较小,大部分微量成分含量增加;14~21 d大量酯类物质合成;21~30 d微量成分增速逐渐减小。通过计算微生物与微量成分之间和微生物与微生物之间的Spearman相关系数,分析得到对微量成分具有一定贡献老白干酒酿造核心微生物群为:Lactobacillus、Bacillus、Fusarium、Staphylococcus和Thelebolus。     

花果山墨旱莲多糖的提取及体外抗氧化活性比较

在单因素试验的基础上,通过正交试验优化从连云港花果山墨旱莲中提取多糖的工艺条件,并且对墨旱莲多糖(polysaccharides of Eclipata Alba,PEA)与墨旱莲黄酮类化合物(flavonoids of Eclipata Alba,FEA)的抗氧化活性进行比较。结果表明：PEA的最适宜提取工艺条件为料液比1:15、提取温度90℃、提取时间1h、提取3次;用Sevag法去除PEA中蛋白质、核酸等杂质,并用紫外光谱、红外光谱对其进行表征;最后,利用Fenton反应和邻苯三酚自氧化反应比较PEA、FEA对羟自由基( ·OH)和超氧阴离子自由基(O2－ ·)的清除能力,结果表明PEA、FEA对两种自由基都具有良好的清除能力,而且对 ·OH的清除能力大于对O2－ ·的清除能力。当质量浓度大于0.085mg/mL时,FEA的抗氧化活性强于PEA。     

万山湖白酒微量香味成分用于其他浓香型白酒质量初步判断的研究

以浓香型白酒万山湖的微量香味成分作为检测数据模型,结合白酒色谱骨架成分,选取己酸乙酯、乳酸乙酯、乙酸、异戊醇、异戊醛为目标检测物,采用电子鼻检测验证浓香型白酒微量香味成分作为白酒质量判断基本依据的可行性,误差在5%以内.     

应用浸入式固相微萃取(DI-SPME)方法检测中国白酒的香味成分

研究了浸入式固相微萃取检测(DI-SPME)中国白酒风味成分的方法.对DI-SPME使用的条件进行了优化.其最佳检测条件是:将白酒酒精度调整到14%vol,采用PDME萃取头,在搅拌状态下,先将样品于30℃预热15min,再插入萃取头萃取30min.然后进行样品的GC-MS分析.对一种中国白酒样品进行了定量分析,发现DI-SPME的方法特别适合于中国白酒微量成分的检测.检测结果表明,浓香型酒中酯的含量约占整个微量香味成分含量的91%.一次检测出52个微量香味成分.     

高分子量聚己二酸乙二醇酯的合成及表征

用己二酸和乙二醇通过酯化和缩聚两步反应制得高分子质量聚己二酸乙二醇酯（PEA），通过研究缩聚反应的时间、温度和催化剂组成对高聚物的分子质量和机械学特性的影响，得到制备高分子量聚己二酸乙二醇酯的最佳路径。利用差示扫描量热仪（DSC）研究了PEA的结晶行为，观察到PEA在16℃附近具有最大的结晶速度。     

Anthocyanins in fruits of Prunus padus (bird cherry)

Bird cherry (Prunus padus) anthocyanins were extracted with acidified methanol, fractionated by column chromatography on Toyopearl HW40(S) and purified in a C‐18 Sep‐Pak cartridge. The pigment composition was very simple, as there were only two compounds. The anthocyanins cyanidin‐3‐rutinoside (60%) and cyanidin‐3‐glucoside (40%) were determined using chromatographic and spectroscopic methods. © 2002 Society of Chemical Industry     

Determination of dl-alpha-tocopherol acetate and dl-alpha-tocopherol in foods by HPLC using post-column photochemical reaction

A reliable analytical method for the simultaneous determination of dl-alpha-tocopherol acetate and dl-alpha-tocopherol in foods was established by HPLC using post-column photochemical reaction with UV and fluorescence detection. For low-fat food such as fruit juice and vegetable sauce, the tocopherols were extracted with methanol containing 0.1% ascorbic acid and the extract solution was injected into the HPLC. For fatty foods such as butter and margarine, the tocopherols were extracted with a mixed solvent of acetonitrile-2-propanol (9:1) containing ascorbic acid. The extract was cleaned up using a Sep Pak plus C18 cartridge and the eluent from the cartridge was injected into the HPLC. The peaks corresponding to tocopherols on the chromatogram were confirmed by comparing their UV spectra with those of the standard mixture at lamp-on and lamp-off of the photochemical reactor. The recoveries of tocopherols from low-fat foods (orange juice and barbecue sauce) fortified at levels of 10 and 100 microg/kg each were 88.3 to 105.8% (RSD 0.5 to 6.0%) and those from the fatty foods (peanut butter and margarine) fortified at 100 microg/kg each were 57.1 to 88.3% (RSD 3.0 to 6.4%). The determination limits corresponded to 10 microg/kg of the tocopherols in the low-fat foods and 20 microg/kg in the fatty foods.     

Determination of 4-hexylresorcinol residues in prawns and crabs

A method for the determination of 4-hexylresorcinol residues in prawn and crab meat by HPLC was developed. 4-Hexylresorcinol in prawn and crab meats was extracted with methanol using a homogenizer. The extract was diluted 4 times with water, and the diluted solution was passed through a C18 cartridge. The cartridge was washed with water and methanol-water (4 : 6), and then 4-hexylresorcinol was eluted with acetonitrile-0.1% phosphoric acid (55 : 45). The eluate was separated on a Capcell Pak C18 MG column with a mobile phase of acetonitrile-0.1% phosphoric acid (6 : 4) and 4-hexylresorcinol was determined with a UV detector (210 nm). Recoveries of 4-hexylresorcinol from commercial prawn and crab meats spiked at 1.0 and 10 microg/g were 82.4-92.2 and 88.9-91.8%, respectively. The determination limit of 4-hexylresorcinol was 1.0 microg/g in the samples.     

Modification and Evaluation of a Reverse Phase High Performance Liquid Chromatographic Method for Amino Acid Analysis

A reverse phase high performance liquid chromatographic method was used to separate the o-phthaldialdehyde derivatives of of amino acids from food protein hydrolysates. Comparison of hydrolysis with hydrochloric, methanesulfonic and mercaptoethanesulfonic acids revealed that the latter could not be used because it interfered with derivatization. Methanesulfonic acid is preferable to hydrochloric acid since it protects the tryptophan in samples low in carbohydrates. Hydrolysates were prepurified with a Sep Pak C18 cartridge prior to derivatization. A linear gradient was used for combining the binary solvent system composed of acetonitrile and phosphate buffer. The derivatives were measured fluorometrically and histamine was used as an internal standard. Results obtained with this method were similar to those obtained with an ion exchange chromatography except that threonlne and glycine coeluted and cysteine, cystine and proline were not detected.     

Analysis of tetracyclines in honey and royal jelly by LC/MS/MS

A simple and accurate method using liquid chromatography coupled with tandem mass spectrometry (LC/MS/MS) was developed for the determination of tetracyclines (TCs), i.e., oxytetracycline (OTC), chlortetracycline (CTC) and tetracycline (TC), in honey and royal jelly. Mass spectral acquisition was performed in the positive mode. In LC separation, L-column ODS and 0.01% formic acid-acetonitrile were used as the column and mobile phase, respectively. TCs in a honey sample were diluted with water, while TCs in royal jelly were extracted with 2% metaphosphoric acid-methanol (6:4). They were cleaned up with Oasis HLB and Sep Pak C18 cartridges, respectively. The quantification limits of TC, OTC, and CTC were 5, 5, and 10 ng/g, respectively, while those in royal jelly were 25, 25, and 50 ng/g, respectively. The recoveries of TCs from both honey and royal jelly were 75-120%.     

Partial characterization of peptides from emmentaler cheese

A novel isolation procedure for the identification of casein breakdown products in Swiss‐type cheese is described. The cheese extracts were cleaned‐up and fractionated on Waters Sep‐Pak C₁₈ and ion‐exchange (CM‐ and QMA‐Plus) cartridges. The advantages of this preparation technique are discussed. Peptides of different physico‐chemical nature were analyzed by RP‐HPLC. The sequence assays of characteristic segments of the peptide spectrum were carried out by HPLC‐analysis of the phenylthiocarbamyl amino acid derivatives and by automated Edman‐degradation. This experimental approach holds promise for the characterization of the cheese ripening process. Relationships between casein peptides and flavor development are proposed. The results obtained suggest that changes in casein peptides do not parallel the development of cheese flavor. The sequences of six predominant basic peptides are presented. It is the first report on the sequence of protein degradation products in Swiss cheese.     

Determination of benzimidazole anthelmintics in livestock foods by HPLC

A simple and rapid liquid chromatographic method was developed for the simultaneous determination of twelve benzimidazole anthelmintics in livestock foods using reversed-phase high-performance liquid chromatography with photodiode array detection (PDA). A sample was homogenized with acetonitrile and n-hexane, and centrifuged. The acetonitrile phase was isolated and evaporated. The residue was dissolved in 0.1 mol/L carbonate buffer solution (pH = 9.1), sonicated, and then subjected to clean-up on a Bond Elut LRC-C18 cartridge. The benzimidazole compounds were separated isocratically on a Capcell Pak C18 UG 120 (5 microns, 150 x 4.6 mm i.d.) column and detected by PDA at 295 and 313 nm. Mixtures of acetonitrile and 0.05 mol/L ammonium acetate in mixing ratios of (20:80) and (40:60) were used as the mobile phase, and the flow-rate was 1.0 mL/min at 40 degrees C. The mean recoveries (n = 3) from 0.1-0.5 microgram/g added samples were 72.6-97.2% with coefficients of variation of 0.3-8.5%. The detection limits were 0.01-0.05 microgram/g.     

Phenolic composition and sensory characteristics of Cabernet Sauvignon wines: effect of water stress and harvest date

The effect of three water status level and two harvest date 55 and 64 days after veraison (DAV) on phenolic and sensory composition of Cabernet Sauvignon wines were investigated. The later harvest date led to wine with a higher alcohol content. Total phenols varied from 1439.66 to 1643.08 mg L^?1 with higher values at 64 DAV. No differences were observed between irrigation treatments. For total tannins and anthocyanins, no differences were found between harvest date. Separation of proanthocyanidins by Sep‐Pak Plus tC₁₈ cartridges showed only differences in concentration but not in the proportion of proanthocyanidin fractions. The wines from the most restricted treatment had a better colour and the same aroma of red fruits, persistence, astringency, fullness and bitterness, as the wine from the treatment with highest irrigation. Under the assay conditions, it was possible to obtain wines with a similar chemical and sensory composition earlier and using less irrigation water.     

维他奶举行七十周年庆典推出纪念版纸包装为健康与品质携手,利乐、维他奶庆祝合作三十五载

<正> 近日,维他奶国际集团有限公司在香港隆重举行了七十周年庆典。香港特区政府律政司司长黄仁龙、维他奶国际集团有限公司执行主席罗友礼、集团行政总裁黎信彦以及利乐集团总裁兼首席执行官杨德森等合作伙伴代表,共同出席了典礼。为此,维他奶携手利乐,专门推出了"Friend祝70周年"纪念版无菌纸包装。同时,作为利乐大中华区的首家合作伙伴,维他奶     

Determination of spiramycin and tilmicosin in meat and fish by LC/MS

A simple and reliable method using liquid chromatography-electrospray ionization-mass spectrometry (LC/ESI-MS) has been developed for the determination of the macrolide antibiotics spiramycin and tilmicosin in meat and fish. The drugs were extracted from meat and fish with 0.2% metaphosphoric acid-methanol (6:4), and the extracts were cleaned up on an Oasis HLB cartridge (60 mg). Positive ionization produced the molecular related ions, (M + 2H)2+, at m/z 350.2, 422.3 and 435.3 for neospiramycin I, spiramycin I and tilmicosin, respectively. The LC separation was performed on a Capcell Pak MG-C18 column (150 x 2 mm i.d.) with a gradient system of 0.02% formic acid-acetonitrile as the mobile phase at a flow rate of 0.2 mL/min. The molecular-related ions of the drugs were very clear under this condition. The calibration graph for each drug was rectilinear from 0.05 to 5 ng with selected ion monitoring (SIM). The recoveries of the drugs from meat and fish fortified at the level of 0.2 microgram/g was 73.2-89.2%, with high precision. The limits of detection of the drugs in meat and fish were 0.01 microgram/g.