奶酪中挥发性硫化物的风味贡献、检测方法及其生物合成调控的研究进展

奶酪中的硫化物主要包括甲硫醇、硫化氢、二甲基硫醚、二甲基二硫醚、甲硫基丙醛等,是奶酪关键气味物质之一,对于奶酪整体风味的形成有着重要贡献。本文在查阅相关文献的基础上,对常见奶酪中硫化物的组成、香气贡献进行了系统的综述,介绍了奶酪中测定硫化物的常用方法及其优缺点;总结了奶酪中硫化物的形成机理以及研究者们提出的生物合成调控策略,包括菌种筛选、微生物搭配组合、基因工程技术。最后对当前研究中存在的问题以及未来研究方向做了归纳与展望。为全面认知奶酪中硫化物风味及其形成和调控,开发更适合国人口味的奶酪产品和中国奶酪产业的转型升级提供理论参考。     

油桃采后衰老与病害发生中挥发性物质变化的主成分分析

采用固相微萃取与气相色谱-质谱联用技术,对油桃果实采后衰老与褐腐病害发生中近表皮和近果核的挥发性物质进行测定;用主成分分析(PCA)法研究不同样品挥发物谱的差异并对香气品质进行综合评价.结果表明,共检测到油桃果实挥发性物质14种,主要为C6化合物、酯类和内酯类物质.贮藏期间油桃果实挥发性物质逐渐由近果核处转向近表皮,褐腐病害发生后加速了这种转变.PCA结果表明,5-羟基-2,4-癸二烯酸-γ-内酯、γ-癸内酯、δ-辛内酯和乙醇可作为区分油桃果实贮藏4d时衰老与病害发生的标志性挥发物;C6醛类、乙醇和乙酸乙酯则可作为区分油桃果实贮藏0、2d与贮藏4、6d时的标志性挥发物.病害组贮藏2d后近表皮处香气品质最佳,贮藏4d后病害组香气品质远低于衰老组.     

板栗及其膨化制品的挥发性香气成分分析

采用顶空固相微萃取结合气相色谱-质谱联用技术对生板栗粉、煮板栗和3种膨化板栗制品的挥发性香气成分进行分离鉴定。共鉴定出68种挥发性物质,初步认定吡嗪类物质中的甲基吡嗪、2,3-二甲基吡嗪、2-乙基-6-甲基吡嗪、2,6-二甲基吡嗪;呋喃类物质中的2-戊基呋喃、γ-丁内酯、2-糠醇、2,5-二氢-3,5-二甲基-2-呋喃酮和γ-辛内酯及芳香族类物质中的苯甲醛是板栗的特征风味物质。煮制可提升板栗的香气。膨化板栗片的膨化加工方式对其香气成分影响显著,挤压膨化板栗片的香气物质组成和煮板栗比较相似,微波膨化板栗片中易产生具有枯焦气息的2,4-二叔丁基苯酚,油炸膨化板栗片的挥发性成分最复杂,醛类物质较多。     

不同凝乳方式加工的硬质奶酪特性分析

通过比较酶凝法、盐析法、酸凝法和内酯凝法的凝乳作用,分析不同凝固方式加工的硬质奶酪工艺特点和品质差异;通过不同凝乳方式加工的奶酪水分测定表明,酶凝法和内酯法得到的凝乳持水性较好,但内酯法凝乳过程中需再次对牛奶进行高温加热,不利于奶酪的正常色泽呈现;盐析法获得的奶酪质地紧实,含水率最低;通过黏度测试可知,酶凝法和酸凝法所得凝乳黏度较低,所需的凝乳时间相对较长;结合电子鼻技术对4种不同凝乳方式的奶酪进行分析,结果显示,不同凝乳方式加工的奶酪香气成分差异较大,香气成分的构成和比例均有较大不同。     

SPME-GC-MS和GC-O鉴定3种不同生产工艺马苏里拉奶酪的特征香气物质

利用固相微萃取-气相色谱-质谱联用法对3种不同工艺制备的马苏里拉奶酪中挥发性风味组分进行鉴定。利用气相色谱嗅觉测量技术进行嗅闻分析,共得到109种化合物进行半定量分析,并且结合香气活力值进行主成分分析,结果表明:新鲜水牛奶马苏里拉奶酪的主要挥发性风味物质为己醛、庚醛、己酸乙酯、(E)-2-壬烯醛、糠醛和丁酸乙酯;新鲜牛奶马苏里拉奶酪的主要挥发性风味物质为1-辛烯-3-醇、2-十一酮和δ-十二内酯;半硬质牛奶马苏里拉奶酪的主要挥发性风味物质为正癸酸、苯乙醛和乙酸乙酯。主成分分析检测结果能将这6种马苏里拉奶酪分为三大类,说明这些挥发性风味物质能很好地描述不同类别奶酪的风味差异。为马苏里拉奶酪的种类鉴别和水牛奶马苏里拉奶酪的掺假提供一定的理论指导。     

内源性脂肪酶对奶酪风味的作用及风味成分分析

研究了内源性脂肪酶对奶酪风味的影响,采用气相色谱-质谱法(GC-MS)对风味成分进行分析.利用电子鼻分析添加和未添加脂肪酶的奶酪的香气组成,利用主成分分析(PCA)和统计质量控制分析(SQC)多元统计方法对电子鼻传感器响应值进行数据分析.结果表明,添加内源性脂肪酶后,奶酪中酸、酯(十四酸乙酯除外)等挥发性成分物质增加,奶酪风味得到很好的改善.     

刺梨皮渣和籽仁中游离态和键合态香气物质的比较

采用顶空-固相微萃取法提取刺梨皮渣、籽仁中游离态香气物质和酶法释放刺梨皮渣、籽仁中键合态香气物质,结合气相色谱-质谱法分析技术对刺梨皮渣和籽仁中的游离态和键合态香气物质进行定性和定量研究。结果表明,检出的刺梨皮渣中游离态香气物质有21 种,萜烯类物质最丰富,其次是酯类物质和酮类物质;检出的键合态香气物质有23 种,其中酸类物质最为丰富,其次是酚类物质和醇类物质。皮渣中游离态和键合态香气物质有很大差异,只有辛酸1 种物质都以游离态和键合态的形式存在。刺梨籽仁中检出游离态香气物质有9 种,萜烯类物质最为丰富,其次是醇类物质和酚类物质;检出的键合态香气物质有18 种,包括酸类8 种、酚类3 种、醇类3 种、羟基醛类2 种,羟基酯类和羟基酮类各1 种。籽仁中被释放出来的香兰素（3-甲氧基-4-羟基苯甲醛）和异香草醛（3-羟基-4-甲氧基苯甲醛）2 种羟基醛是重要的键合态香气物质。     

内酯类化合物在食品中的风味贡献及形成机制

食品中的内酯类物质主要包括γ-内酯、δ-内酯、葫芦巴内酯、威士忌内酯,它们对食品整体风味的形成具有重要作用,能赋予食品奶香、水果香、坚果香、焦糖香等优良的风味特征,研究食品中内酯类化合物的风味贡献及形成机制具有重要意义。该研究综述了食品中常见的内酯类化合物,食品中内酯类化合物的组成及香气贡献,总结了对食品风味贡献较大的内酯类化合物的形成机制包括：δ-内酯和γ-内酯的羟基脂肪酸-内酯生成途径、一步分子内酯交换反应途径、葫芦巴内酯的羟醛缩合反应途径、果实中脂肪酸-酰基CoA-内酯形成途径、果实中不饱和脂肪酸-羟基脂肪酸-内酯形成途径等,并对当前研究中存在的问题和未来研究方向做了归纳与展望。为全面认知食品中内酯类风味化合物及其形成,改善食品风味并提高食品品质,实现食品产业转型和升级提供理论参考。     

SPME Arrow-GC-MS鉴定3种不同杀菌乳中特征香气物质

利用新型箭型固相微萃取-气相色谱-质谱联用法（Solid-phase Microextraction Arrow-Gas chromatography-Mass spectrometry,SPME Arrow-GC-MS）对3类杀菌乳中挥发性风味组分进行研究,并结合香气活性值（odor activity values,OAV）与热图分析进一步探究3种杀菌方法对牛乳中特征香气物质的影响情况。3类杀菌乳中共检测到78种挥发性风味物质,其中脂肪酸类11种、酯类4种、内酯类7种、酮类12种、醛类18种、醇类14种、含硫化合物2种、芳香及杂环类化合物10种。对萃取到的风味组分进行热图分析,结果表明：不同杀菌乳中特征香气物质存在明显差异,其中巴氏杀菌乳中特征香气物质是辛醛和壬醛;UHT灭菌乳中特征香气物质是γ-十二内酯、顺式-4-羟基-6-十二烯酸内酯、2-壬酮、2-十一酮以及辛醛、壬醛;INF杀菌乳中则是1-辛烯-3-酮和壬醛。     

不同成熟时间切达奶酪中挥发性香气成分及其电子鼻判别分析

采用溶剂辅助风味蒸发法和固相微萃取法,结合气相色谱-质谱联用与电子鼻判别技术,对3种不同成熟时间的切达奶酪中挥发性风味成分进行鉴定及判别分析。结果表明:3种不同成熟时间的切达奶酪样品中共检测出78种化合物,脂肪酸类13种、酯类9种、内酯类8种、酮类9种、醇类5种、醛类12种、芳香及杂环类19种、含硫化合物3种。对3种奶酪风味组分主成分分析结果表明,淡味切达奶酪中主要挥发性化合物是脂肪酸类、甲基酮及杂环类;中味切达奶酪中主要挥发性物质有脂肪酸类、甲基酮及内酯类;浓味切达奶酪主要挥发性物质有脂肪酸类、酯类、甲基酮及内酯类;并且这3种不同成熟度的切达奶酪在电子鼻上也可以得到很好的区分。     

Reliable identification of grapevine rootstock varieties using RAPD PCR on woody samples

Since grapevine ( Vitis spp .) rootstock material is being traded increasingly as disbudded woody material a lack of distinctive morphological features on such material necessitates an alternative and reliable means of identification. Methods described here were developed for rapid and efficient extraction of DNA from woody samples rich in phenolic compounds and polysaccharides, and for subsequent identification of varieties by RAPD PCR. Using these methods, and with the application of only one selected RAPD primer, we were able to differentiate sixteen rootstock varieties, including the seven varieties most commonly used in Germany. Problems commonly encountered with reproducibility of RAPD patterns were avoided by choosing primers with a dinucleotide sequence and a high G/C content that allowed a rather high annealing temperature of 45°C. Methods described here should also be useful for other horticultural crops, especially those with woody tissues rich in phenolic compounds and polysaccharides.     

Aroma characterization of various apricot varieties using headspace–solid phase microextraction combined with gas chromatography–mass spectrometry and gas chromatography–olfactometry

The characterization of the aromatic profile of several apricot cultivars with molecular tracers in order to obtain objective data concerning the aromatic quality of this fruit was undertaken using headspace–solid phase microextraction (HS–SPME). Six apricot cultivars were selected according to their organoleptic characteristics: Iranien, Orangered, Goldrich, Hargrand, Rouge du Roussillon and A4025. The aromatic intensity of these varieties measured by HS–SPME–Olfactometry were defined and classified according to the presence and the intensity of grassy, fruity and apricot like notes. In the six varieties, 23 common volatile compounds were identified by HS–SPME–GC–MS. Finally, 10 compounds, ethyl acetate, hexyl acetate, limonene, β-cyclocitral, γ-decalactone, 6-methyl-5-hepten-2-one, linalool, β-ionone, menthone and (E)-hexen-2-al were recognized by HS–SPME–GC–O as responsible of the aromatic notes involved in apricot aroma and considered as molecular tracers of apricot aromatic quality which could be utilized to discriminate apricot varieties.     

Tests of potential functional barriers for laminated multilayer food packages. Part I: Low molecular weight permeants

The advent of the functional barrier concept in food packaging has brought with it a requirement for fast tests of permeation through potential barrier materials. In such tests it would be convenient for both foodstuffs and materials below the functional barrier (sub-barrier materials) to be represented by standard simulants. By means of inverse gas chromatography, liquid paraffin spiked with appropriate permeants was considered as a potential simulant of sub-barrier materials based on polypropylene (PP) or similar polyolefins. Experiments were performed to characterize the kinetics of the permeation of low molecular weight model permeants (octene, toluene and isopropanol) from liquid paraffin, through a surrogate potential functional barrier (25 μm-thick oriented PP) into the food simulants olive oil and 3% (w/v) acetic acid. These permeation results were interpreted in terms of three permeation kinetic models regarding the solubility of a particular model permeant in the post-barrier medium (i.e. the food simulant). The results obtained justify the development and evaluation of liquid sub-barrier simulants that would allow flexible yet rigorous testing of new laminated multilayer packaging materials.     

Analysis of benzo[a]pyrene in spiked fatty foods by second derivative synchronous spectrofluorimetry after microwave-assisted treatment of samples

A simple, rapid and inexpensive method has been developed for the determination of benzo[a     

The development of reference materials for paralytic shellfish poisoning toxins in lyophilized mussel. II: Certification study

This paper describes the second part of a project undertaken to develop certified mussel reference materials for paralytic shellfish poisoning toxins. In the first part two interlaboratory studies were undertaken to investigate the performance of the analytical methodology for several PSP toxins, in particular saxitoxin and decarbamoyl-saxitoxin in lyophilized mussels, and to set criteria for the acceptance of results to be applied during the certification exercise. Fifteen laboratories participated in this certification study and were asked to measure saxitoxin and decarbamoyl-saxitoxin in rehydrated lyophilized mussel material and in a saxitoxin-enriched mussel material. The participants were allowed to use a method of their choice but with an extraction procedure to be strictly followed. The study included extra experiments to verify the detection limits for both saxitoxin and decarbamoyl-saxitoxin. Most participants (13 of 15) were able to meet all the criteria set for the certification study. Results for saxitoxin.2HCl yielded a certified mass fraction of <0.07 mg/kg in the rehydrated lyophilized mussels. Results obtained for decarbamoyl-saxitoxin.2HCl yielded a certified mass fraction of 1.59+/-0.20 mg/kg. The results for saxitoxin.2HCl in enriched blank mussel yielded a certified mass fraction of 0.48 +/- 0.06 mg/kg. These certified reference materials for paralytic shellfish poisoning toxins in lyophilized mussel material are the first available for laboratories to test their method for accuracy and performance.     

Announcing a new international peer-reviewed journal:Food Science and Human Wellness now accepting manuscript submission in English

<正>We are pleased to announce the launch of a new international peer-reviewed journal-Food Science and Human Wellness,ISSN 2213-4530,which is an open access journal,produced and hosted by Elsevier B.V.on behalf of Beijing Academy of Food Sciences.Food Science and Human Wellness is an international peer-reviewed English journal that provides a forum for the dissemination of the     

Chinese CTP Market

According to Printing and Printing Equipment Industries Association of China（PEIAC）＇s statistics to the plate manufucturer in China, in 2013, the actual offset plate production has reached 346 million square meters in China. Among them, the CTP production volume was 245 million square meters, up by 11% than that of last year; the total sales of the CTP plate was 239 million square meters, up by 13%.     

Preparatory Work of Print China 2015 is Going Smoothly

正Held at Guangdong Modern International Exhibition Center,Print China 2015 will cover 7exhibition halls,besides the original Hall No.3,4,5,6,7,the newly built F zone of Hall 3 will be used too.The total area will be140,000 square meters.Hall 3:Offset and large printing equipment,package printing equipment,post press     

INFOPRINT 2014 was Successfully Held in Dongguan

Sponsored by Printing and Printing Equipment Industries Association of China （PEIAC） and organized by Print China magazine, the Seventeenth Beijing International Printing Information Conference （INFOPRINT 2014） was successfully held on 11th Dec. 2014 at Dongguan Exhibition International Hotel.