不同产地咖啡豆香气成分分析

分析了各地的16种烘焙咖啡豆的挥发性成分及其含量,研究了各地咖啡豆香气成分的差异性。采用同时蒸馏萃取法提取各样品的挥发性香气成分,采用了气相色谱-质谱联用仪对咖啡中的挥发性成分进行了分析检测,对数据进行了定性定量分析,应用SPSS19.0软件对数据进行聚类分析和主成分分析。从数据分析可以看出,不同产地的咖啡在中度烘焙的条件下,香气成分基本相似,含量较高的成分如:2-甲基吡嗪、糠醇、5-甲基呋喃醛、2-乙基-5-甲基吡嗪、2-乙基-3,5-二甲基吡嗪等,成分的含量有差别。经过聚类分析可以看出,用咖啡的挥发性香气成分进行聚类分析可以反映不同产地咖啡香气上的相似性。对咖啡的挥发性成分的主成分分析,提取的前5个主成分可以用来解释咖啡的香气品质。     

云南小粒咖啡的香气成分分析

采用同时蒸馏萃取法,提取了云南小粒咖啡中的香气成分,采用了气相色谱-质谱联用仪对云南小粒咖啡中的香气成分进行了分析检测,确定了其中的88种成分。其主要成分为:糠醇(32.799%)、糠醛(6.367%)、5-甲基呋喃醛(7.630%)、2-甲基吡嗪(4.673%)、2-乙基-5-甲基呋喃(3.641%)、2-乙基吡嗪(1.103%)、N-甲基-2-吡咯甲醛(1.269%)等。     

两种前处理方法在云南小粒咖啡香气成分分析中的对比

为了研究云南小粒咖啡的香气成分,采用正己烷、二氯甲烷、甲醇三种溶剂超声提取法和同时蒸馏萃取法对云南小粒咖啡中的香气成分进行了提取,采用了气相色谱-质谱联用仪对云南小粒咖啡中的香气成分进行了分析检测。采用不同溶剂超声提取法,共分离鉴定了53种成分,提取到的主要成分是酯类,并且随着溶剂极性的增加,提取的香气成分总类也在增加。采用同时蒸馏萃取法提取分离了88种香气成分,主要提取物是糠醇(32.80%)、糠醛(6.37%)、5-甲基呋喃醛(7.63%)、2-甲基吡嗪(4.67%)、2-乙基-5-甲基呋喃(3.64%)、2-乙基吡嗪(1.10%)、N-甲基-2-吡咯甲醛(1.27%)等。从分析结果看出不同提取方法提取的香气成分有显著差别,可以分别在不同的研究工作中应用。     

烘焙程度对云南小粒咖啡香气品质的影响

云南的小粒咖啡具有较高的品质。咖啡在烘焙过程中发生了美拉德反应和焦糖化反应,为了研究烘焙过程中咖啡香气的变化,对云南的小粒咖啡采用了浅、中、深3种方式烘焙,对烘焙好的咖啡豆采用同时蒸馏萃取法进行香气成分提取,并进行气相色谱-质谱联用分析,研究了不同烘焙程度条件下云南小粒咖啡香气成分定性定量结果。表明了不同烘焙程度对于咖啡的香气有影响。     

烘焙度对冷萃咖啡理化指标与风味成分的影响

以亚洲咖啡豆为研究对象,分别选取浅、中、深3 种烘焙度的中国云南和印度尼西亚苏门答腊产的卡蒂姆种咖啡豆,比较分析冷萃与热萃方式对萃取浓度、萃取率、可滴定酸、总酚、总糖、咖啡因、葫芦巴碱、绿原酸、抗氧化活性与挥发性成分的差异,并进行主成分分析,从而探究烘焙度对冷萃咖啡理化指标与风味成分的影响规律。结果表明,随着烘焙度增加,冷萃咖啡的萃取浓度、萃取率均显著上升,可滴定酸、总酚、葫芦巴碱、绿原酸、抗氧化活性均显著下降（P＜0.05）。冷萃咖啡较热萃咖啡拥有更高的萃取浓度、萃取率与总糖含量（P＜0.05）,而可滴定酸、总酚含量、抗氧化活性较热萃显著偏低（P＜0.05）。经顶空固相微萃取-气相色谱-质谱检测分析发现,浅烘咖啡豆萃取液中的挥发性成分含量显著低于烘焙度高的咖啡萃取液,深烘咖啡豆萃取液中挥发性成分种类与总含量最多。进一步通过主成分分析能较好区分冷萃和热萃咖啡,两者挥发性成分贡献率具有较大差异。2-丁酮、2-丁烯醛等花香类物质对浅烘冷萃咖啡贡献率更高,而2-甲基吡嗪、糠醇等呈现烘焙坚果类香气物质对浅烘热萃咖啡贡献率更高;2,6-二乙基吡嗪、川芎嗪等烘焙坚果类香气物质对中烘冷萃和热萃咖啡具有较高的贡献率;2-乙烯基呋喃、甲基糠硫醇、2,5-二乙基吡嗪、糠基甲基硫醚等物质对深烘冷萃咖啡有较高贡献率,二甲基二硫、对甲酚、1-甲基吡咯等物质对深烘热萃咖啡贡献率更高。相对于热萃咖啡,烘焙度对冷萃咖啡抗氧化能力与挥发性成分的影响更大。     

山核桃仁最佳烘烤条件的研究

利用顶空固相微萃取(HS-SPME)、气相色谱-质谱(GC-MS)方法对不同烘烤条件下山核桃仁挥发性成分的种类及含量的变化进行了测定,通过对各条件下各吡嗪类化合物等关键致香成分(2-甲基吡嗪、2-乙基-6甲基吡嗪、2-乙基-5甲基吡嗪、乙基吡嗪)含量的对比分析,并结合感官评价,探讨了烘焙工艺对烤山核桃仁挥发性风味的影响。实验结果表明,山核桃仁的最佳烘烤条件为:温度140℃,烘烤时间20min。     

烘烤葵花籽的香气成分分析及最佳烘烤条件研究

对烘烤葵花籽的香气成分进行分析,并以此为依据对最佳烘烤条件进行研究。采用同时蒸馏萃取装置萃取烘烤葵花籽中的挥发性成分,把挥发性成分分为酸、碱、中性三个部分,用气相色谱-质谱联用方法分析其中的香气成分。结果表明,碱性部分最具烘烤葵花籽的香气特征,其中关键致香成分是甲基吡嗪、2,5-二甲基吡嗪、3-乙基-2,5-二甲基吡嗪等化合物。通过对不同烘烤条件下葵花籽的香气特征、所含香气成分及含量进行对比分析,得出葵花籽仁的最佳烘烤条件为:温度160℃,烘烤时间35min。     

云南烤烟中半挥发性碱性成分的分析

本文采用水蒸汽蒸馏、溶剂萃取分离的前处理方法,以及配备氮－磷检测器的气相色谱和气相色谱－质谱联用分析鉴定技术,对云南中二烤烟中半挥发性碱性成分进行了分析研究,共鉴定出３６种半挥发性碱性成分。采用内标法定量测定了吡啶、２－甲基吡嗪、２,６－二甲基吡嗪、２,３－二甲基吡嗪、２,３,５－三甲基吡嗪、２－乙酰吡啶、３－乙酰吡啶、四甲基吡嗪、吲哚和２,３－二联吡啶等１０种碱性香味成分的含量。研究结果表明：该方法重复性好,回收率较高,操作简便,是分析烤烟中半挥发性碱性成分的一种可行方法。     

油炸对黑虎虾关键性风味物质的影响

采用溶剂辅助风味蒸发法-气相色谱质谱联用仪(SAFE-GC-MS),通过双柱定性分别对鲜黑虎虾和炸黑虎虾的挥发性成分进行分析,从鲜虾中共检出81种化合物,炸虾中共检出93种化合物。通过气相色谱-嗅闻-质谱联用(GC-O-MS)和气味活性值(OAV)两种方法分别确定油炸前后黑虎虾的关键性风味成分,结果显示:鲜虾的关键性风味物质为:N,N-二甲基甲酰胺、2-糠酸甲酯、3-羟基-2丁酮、癸醛和庚醛。炸黑虎虾关键性风味物质为:2,3,5-三甲基吡嗪、2,3-二甲基-5-乙基吡嗪、2,5-二甲基-4-羟基-3(2H)-呋喃酮、2,5-二甲基吡嗪、2,5-二甲基-3-乙基吡嗪、2-乙酰基吡咯、吡嗪、5-甲基-2-乙基吡嗪、苯乙醛和反,反-2,4-癸二烯醛。经过油炸,构成黑虎虾的关键性风味物质发生了明显变化,其中,吡嗪类物质的含量显著增加。     

固相微萃取-气相色谱-质谱及气相色谱-嗅闻技术分析美味牛肝菌风味活性物质

采用顶空固相微萃取技术(HS-SPME)提取美味牛肝菌的挥发性成分,用气相色谱-质谱联用技术(GC-MS)结合气相色谱-嗅觉测量法(GC-O),鉴定美味牛肝菌的挥发性成分及主要风味物质.通过实验鉴定出53种挥发性成分,其中29种成分对美味牛肝菌的风味有贡献,还有3种呈味物质气相色谱检测不到.其中己醛、甲基吡嗪、3-甲硫基丙醛、2,6-二甲基吡嗪、1-辛烯-3-醇、2-戊基呋喃、2-乙基-6-甲基吡嗪、3-辛烯-2-酮、苯乙醛等化合物是美味牛肝菌主要的风味活性物质.     

Textural Properties of Cold-set Gels Induced from Heat-denatured Whey Protein Isolates

A 9% whey protein (WP) isolate solution at pH 7.0 was heat-denatured at 80°C for 30 min. Size-exclusion HPLC showed that native WP formed soluble aggregates after heat-treatment. Additions of CaCl2 (10–40 mM), NaCl (50–400 mM) or glucono-delta-lactone (GDL, 0.4–2.0%, w/v) or hydrolysis by a protease from Bacillus licheniformis caused gelation of the denatured solution at 45°C. Textural parameters, hardness, adhesiveness, and cohesiveness of the gels so formed changed markedly with concentration of added salts or pH by added GDL. Maximum gel hardness occurred at 200 mM NaCl or pH 4.7. Increasing CaCl2 concentration continuously increased gel hardness. Generally, GDL-induced gels were harder than salt-induced gels, and much harder than the protease-induced gel.     

Occurrence of bisphenol-F-diglycidyl ether (BFDGE) in fish canned in oil

The levels of bisphenol-F-diglycidyl ether (BFDGE) were quantified as part of a European survey on the migration of residues of epoxy resins into oil from canned fish. The contents of BFDGE in cans, lids and fish collected from all 15 Member States of the European Union and Switzerland were analysed in 382 samples. Cans and lids were separately extracted with acetonitrile. The extraction from fish was carried out with hexane followed by re-extraction with acetonitrile. The analysis was performed by reverse phase HPL C with fluorescence detection. BFDGE could be detected in 12% of the fish, 24% of the cans and 18% of the lids. Only 3% of the fish contained BFDGE in concentrations considerably above 1mg/kg. In addition to the presented data, a comparison was made with the levels of BADGE (bisphenol-A-diglycidyl ether)analysed in the same products in the context of a previous study.     

Review of techniques to manufacture micro-hydrogel particles for the food industry and their applications

Microgels are ‘soft’ microscopic cross-linked polymeric particles that are being increasingly exploited in a variety of industries for rheology control, encapsulation and targeted delivery. They are valued because of the ability to tune their functionality to address specific applications in oil recovery, coatings, drug delivery, cosmetics, personal care and foods. Food microgels are typically biopolymer hydrogels in the form of microspheres, nanospheres (also called nanogels), spheroids and fibres. The utilisation of engineered microgels in foods has so far been limited, despite their great potential to address several needs in the food industry, including: satiety control, encapsulation of phytonutrients and prebiotics, texture control for healthier food formulations (e.g. reduced fat products), and targeting delivery to specific areas in the digestive tract. We review the scientific and patent literature on the utilisation and manufacturing methods for producing microgels with an emphasis on micro-hydrogels for food applications.     

12—A CRITIQUE OF SOME HYPOTHESES RELATING TO THE HETEROGENEITY OF THE HIGH-SULPHUR PROTEINS OF WOOL

Joubert and Burns prepared a large number of fractions from the high-sulphur proteins of wool and estimated their molecular weights and amino-acid compositions. Their data have been re-examined in order to look for statistically significant interrelations between amino acids and between the proportion of various amino acids and molecular weight. Statistical analysis of the data is also used to examine the credibility of some hypotheses concerning the mechanism of keratin biosynthesis and to provide further evidence for the existence of families of proteins within the high-sulphur fractions of wool.     

Contribution of European research to risk analysis

The European Commission's, Quality of Life Research Programme, Key Action 1—Health, Food & Nutrition is mission-oriented and aims, amongst other things, at providing a healthy, safe and high-quality food supply leading to reinforced consumer confidence in the safety of European food. Its objectives also include the enhancing of the competitiveness of the European food supply. Key Action 1 is currently supporting a number of different types of European collaborative projects in the area of risk analysis. The objectives of these projects range from the development and validation of prevention strategies including the reduction of consumers risks; development and validation of new modelling approaches; harmonization of risk assessment principles, methodologies, and terminology; standardization of methods and systems used for the safety evaluation of transgenic food; providing of tools for the evaluation of human viral contamination of shellfish and quality control; new methodologies for assessing the potential of unintended effects of genetically modified (genetically modified) foods; development of a risk assessment model for Cryptosporidium parvum related to the food and water industries; to the development of a communication platform for genetically modified organism, producers, retailers, regulatory authorities and consumer groups to improve safety assessment procedures, risk management strategies and risk communication; development and validation of new methods for safety testing of transgenic food; evaluation of the safety and efficacy of iron supplementation in pregnant women; evaluation of the potential cancer-preventing activity of pro- and pre-biotic ('synbiotic') combinations in human volunteers. An overview of these projects is presented here.     

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 Latest Data about Development of Chinese Printing Industry in 2013

In the 2014 China（Shanghai）International Printing Week,Director Wang Yanbin released the latest data about development of Chinese printing industry in 2013.According to statistics,in 2013,the total output value of Chinese printing industry exceeded 1trillion Yuan for the first time,reaching 1.03985 trillion Yuan.There were 105,000 printing enterprises in China,employees were 3.415 million.The total asset was 1.06247 trillion Yuan;     

The State Council Issued "Directory of Government Approved Investment Projects(2013 Edition)"

正On December 2nd,2013,the State Council issued the notification of"Directory of Government Approved Investment Projects(2013 Edition)"(hereafter referred to as"notification").It is pointed out in the"notification"that in order to further deepen reforms in investment systems and administrative examination and approval systems,simplify administrative procedures and delegate powers to lower levels,earnestly     

China textile machinery: taking off in progress

正Among the 1600 exhibitors who take apart in the ITMA ASIA+CITME2014 2/3 are Chinese manufactures.If the numerous figures failed to attract your attention,the increase of quality should draw your focus.To adopt the demand of developing textile machine market,domestic textile machinery enterprises now follow the slogan of"technology drives development"to enhance product competitiveness.Our domestic sellers will showcase product ranging from spinning,weaving,dyeing and printing,     

Top Ten News of China's Paper Industry 2013

On December 24th, 2013, the meeting on the selection of top 10 news of China＇s paper industry 2013 sponsored by 〈China Paper Newsletters〉 was held in Beijing. The yearly selection of the top l0 news, which began in 2000, has become a brand activity widely recognized in the industry thanks to the support from the authorities at all levels and public participation.