基于豆粕酶解液和脂肪控制氧化技术制备猪肉味香精的研究

以豆粕酶解液为原料,采用气质联用法(GC-MS)、电子鼻法和感官评价法,确定脂肪控制氧化技术制备肉味香精的工艺条件,并分析氧化脂肪对挥发性香气成分的影响。结果表明:肉味香精的最佳工艺条件:脂肪氧化温度130℃,氧化时间2 h,氧化脂肪的添加量5 g/100 mL酶解液;GC-MS和电子鼻分析结果可知,氧化脂肪能有效调控美拉德反应,生成较低量的含硫化合物、糠醛等美拉德反应的典型挥发性香气成分,同时生成大量的醇类、醛类等脂肪降解产物、美拉德反应产物和脂肪氧化降解的相互作用的产物。     

芝麻酶解液对浓香芝麻油美拉德反应风味的影响及工艺优化

利用美拉德生香源反应制备浓香芝麻油,并对浓香芝麻油制备工艺进行了优化。正交试验结果表明,浓香芝麻油的最佳制备工艺条件为反应料液比1∶5(g/m L)、料油比1∶10(g/m L),美拉德反应温度120℃、酶添加量2.5%、酶解时间3 h、美拉德反应时间30 min。验证试验表明,在此优化工艺条件下制备所得浓香芝麻油的感官结果综合得分可达到6.95分。探讨了不同原料酶解液对浓香芝麻油美拉德反应风味的影响,结果显示,芝麻粕酶解液是制备浓香芝麻油的最佳反应底物。     

天然牛肉调味品制备及其呈味氨基酸变化研究

以牛肉为原料,通过酶解及美拉德反应,制备天然牛肉调味品。以氨基态氮含量为指标,通过正交优化风味蛋白酶酶解工艺,确定适宜的酶解温度为52℃,初始p H5.5,料液比1:3.5,酶解时间5.5 h,加酶量为4000 U/g。正交优化后酶解液中氨基态氮含量为0.57 g/100mL,呈味氨基酸含量为3.91 g/100 m L,美拉德反应后呈味氨基酸含量变为1.88 g/100 mL,对美拉德反应贡献相对较大的氨基酸有Asp、Ser、Arg。调味物质中共检出香味物质32种,这些香味物质和呈味氨基酸协同,形成了特有的牛肉口感和香气。     

120 ℃条件下模型体系烤牛肉风味的形成

以牛肉酶解液为底物,通过添加糖、氨基酸和硫胺素进行美拉德反应,研究烤牛肉风味形成的最佳酶解条件和添加物配比。通过正交试验确定牛肉最优酶解条件为：酶解温度50 ℃、酶解pH 6.5、m（风味蛋白酶）∶m（复合蛋白酶）=1∶1、加酶量质量分数8%、酶解时间50 min;析因试验确定美拉德反应模型体系最优配比为牛肉酶解液20 g、葡萄糖1.0 g、甘氨酸0.8 g、硫胺素0.3 g,120 ℃、pH 7.5条件下反应90 min。气相色谱-质谱法分析结果表明,该模型体系烤牛肉特征风味物质（2-甲基-3-呋喃硫醇、2-甲基四氢噻吩-3-酮、双（2-甲基-3-呋喃基）二硫）相对含量较高。感官评定表明,该模型体系褐变程度高,吸光度最高为0.263,且肉香纯正,烤牛肉风味浓郁。     

枫槭叶酶解液美拉德反应及其挥发性成分分析

为了开发新型食用香精,以枫槭叶为原料对枫槭叶酶解后的酶解液在不同温度下进行美拉德反应,然后使用GC-MS分析美拉德反应样品的挥发性成分,采用主成分分析法对挥发性成分进行分析,探讨不同温度下美拉德反应样品的差异及特征成分。结果表明:枫槭叶酶解液与枫槭叶水提取物进行美拉德反应后相比,挥发性物质的种类数和含量都有所增加。GC-MS分析结果表明:美拉德反应90℃的样品挥发性香味成分的种类最多,为67种,并且挥发性物质总含量最多,为235.9 μg/g。通过主成分分析可知美拉德反应90、100、110℃的样品彼此距离较远,说明其主成分差异均较大,90℃美拉德反应挥发性物质分布最多,3,4-二甲基-3-环己烯-1-甲醛、金合欢基丙酮、萜品烯、棕榈酸、丁香酚、左旋-beta-蒎烯、桃金娘烯醇、十二烷酸、2,2'-亚甲基双-（4-甲基-6-叔丁基苯酚）、甲基庚烯酮为枫槭挥发性成分的主要特征化合物。结合上述结果,在美拉德反应温度为90℃时得到的样品具有最佳的风味和感官品质。     

牛骨酶解制备牛肉香精及气质联用分析

以牛骨为原料,采用正交实验对复合蛋白酶和风味蛋白酶同步水解牛骨蛋白的工艺进行优化。再以水解动物蛋白(HAP)为基料,通过美拉德反应制备牛肉香精。结果表明,牛骨的最适酶解条件是用酶量5000U/g,料液比1:3,酶解温度50℃,酶解时间6h。美拉德反应的最佳时间为3h,在不添加香料的条件下最好。采用固相微萃取技术(SPME)并结合气质联用(GC-MS)检测技术对牛骨美拉德反应液进行分析,共鉴定出68种挥发性风味物质。     

狭鳕鱼排酶解物美拉德反应制备牛肉香型风味物

以狭鳕鱼排酶解液为原料,研究美拉德反应制备牛肉香型风味物的工艺,在单因素的基础上通过正交试验优化,得到工艺参数为：葡萄糖3．0g／100 mL,木糖1．0g／100 mL,VB11．25g／100 mL,L－半胱氨酸盐酸盐1?5g／100 mL,牛肉酶解液30mL／100 mL,pH值5．0,温度120℃,时间120min,在此条件下风味物具有纯正、浓郁的牛肉香气。美拉德反应后,游离氨基酸中损失率最大的为苏氨酸（高达63．02％）,表明此氨基酸是参与美拉德反应的主要氨基酸。此外,从美拉德反应产物中共检测到76种挥发性化合物,包括含硫类3种、醛类22种、酮类7种、酯类4种、醚类1种、烷烃类24种、羧酸类3种,其中甲硫醇、2－甲基－3－呋喃硫醇、3－甲硫基丙醛、正己醛、辛醛、苯乙醛、（E,E）－2,4－壬二烯醛和反式－2,4－癸二烯醛等被鉴定为重要的具有牛肉特征风味物质。     

基于大豆粕酶解物美拉德反应制备咸味香精的研究

实验以大豆粕为原料,通过酶解进而利用美拉德反应制备咸味香精。研究了碱性蛋白酶和复合植物水解酶Viscozyme L的添加顺序对酶解液性质的影响。利用HPLC和GC-MS对产物的氨基酸组分及香气成分进行分析。结果表明:先添加底物浓度10%的碱性蛋白酶,再添加底物浓度15%的复合植物水解酶Viscozyme L的酶解效果最佳,此时酶解液水解度是11.64%,还原糖含量为0.674mg/mL,氨基氮含量为1.553 mg/mL,游离氨基酸总量达到1433.14 mg/g。从美拉德反应液中检测出癸醛、2-癸酮、2-己基呋喃等挥发性化合物物质,它们对肉香味的生成具有重要的作用。     

羊肉酶解液美拉德反应工艺优化及其对挥发性风味物质的影响

文章以羊肉酶解液为原料,以A_420nm和感官评分为指标,优化美拉德反应羊肉香精的最佳条件,并采用气相色谱-离子迁移谱联用技术(gas chromatography-ion mobility spectrometry, GC-IMS)研究美拉德反应产物的挥发性风味物质变化。试验结果表明,美拉德反应的最佳添加参数：以羊肉酶解液为基准,反应温度115℃,反应时间120 min,初始pH值8,葡萄糖添加量1.4 g, L-半胱氨酸添加量0.8 g。所得反应产物呈红褐色,具有羊肉特有香气、海鲜风味及烧烤风味。从美拉德反应产物EMH-MRP-A和EMH-MRP-B中共检测出62余种挥发性风味物质,定性的有41余种挥发性风味物质,其中包括醛类17种、酮类10种、烯类4种、醇类3种、呋喃类3种、噻唑类2种、吡嗪类2种、吡啶类1种。2-呋喃甲硫醇、正壬醛、辛酸乙酯、3-甲基丁醛等化合物风味阈值较低,对整体香气具有重要的贡献作用。     

水解大豆制备食用香精的工艺优化

以大豆为原料,通过酸解法制备植物水解蛋白(HVP),以HVP 为原料通过美拉德反应制取肉味香精。通过正交试验获得酸解大豆蛋白的最佳反应条件为水解时间7h、浓硫酸体积分数25%、固液比1:7(g/mL),此时蛋白水解度(DH)达65.26%。在此基础上研究美拉德反应的最佳工艺条件,正交试验结果表明：pH7.0、D- 木糖添加量0.4g/mL、L- 半胱氨酸盐酸盐添加量为0.05g/mL 时,获得的产物香味持久、浓郁。     

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.     

An internet compendium of analytical methods and spectroscopic information for monomers and additives used in food packaging plastics

An internet website (http://cpf.jrc.it/smt/) has been produced as a means of dissemination of methods of analysis and supporting spectroscopic information on monomers and additives used for food contact materials (principally packaging). The site which is aimed primarily at assisting food control laboratories in the European Union contains analytical information on monomers, starting substances and additives used in the manufacture of plastics materials. A searchable index is provided giving PM and CAS numbers for each of 255 substances. For each substance a data sheet gives regulatory information, chemical structures, physico-chemical information and background information on the use of the substance in particular plastics, and the food packaging applications. For monomers and starting substances (155 compounds) the infra-red and mass spectra are provided, and for additives (100 compounds); additionally proton NMR are available for about 50% of the entries. Where analytical methods have been developed for determining these substances as residual amounts in plastics or as trace amounts in food simulants these methods are also on the website. All information is provided in portable document file (PDF) format which means that high quality copies can be readily printed, using freely available Adobe Acrobat Reader software. The website will in future be maintained and up-dated by the European Commission's Joint Research Centre (JRC) as new substances are authorized for use by the European Commission (DG-ENTR formerly DGIII). Where analytical laboratories (food control or other) require reference substances these can be obtained free-ofcharge from a reference collection housed at the JRC and maintained in conjunction with this website compendium.     

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.     

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.     

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.     

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.     

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.     

低温带皮菜籽粕微粉的不同粒级部分的功能特性

为研究低温带皮菜籽粕微粉的不同粒级部分的功能特性,以经低温脱脂的带皮菜籽粕为原料,经微粉碎后筛分成212~425μm、150~212μm和106~150μm的3个不同粒级的微粉样品,检测这些样品的吸水性、吸油性、乳化性和乳化稳定性、蛋白质体外消化率。结果表明:1 3个不同粒级的微粉样品之间的粗纤维含量存在显著差异,表明三者的结构组成成分有一定差异。23个微粉样品的乳化活性和乳化稳定性随粒度级别的减小而显著增加(P0.01)。33个微粉样品的蛋白质体外消化率随粒度级别的减小而显著增加(P0.01)。4不同粒级带皮菜籽粕微粉样品的吸水性与吸油性受其结构组成物质不同和粒度的双重影响,与粒度的相关性不明显。     

Microbiology of food taints

Fresh and processed foods are often spoilt by the presence of undesirable flavours and odours caused by microbial action. The aim of this paper is to review the current knowledge of microbiologically induced taints that occur in a wide range of foodstuffs, including meats, poultry, fish, crustaceans, milk, dairy products, fruits, vegetables, cereals and cereal products. Examples have been chosen where the compounds responsible for the taint have been identified and sufficient data obtained to demonstrate the involvement of microorganisms. However, in some cases the full identity of the causative organism may not have been elucidated. The types of microorganisms covered by this review include bacteria, fungi, yeasts, actinomycetes and cyanobacteria. Although cyanobacteria do not in general infect foods, their presence in aqueous systems and water supplies can lead to off-flavours in aquatic organisms and processed foodstuffs. Several examples of each of these processes are discussed. Wherever possible, the likely biosynthetic pathway used by the microorganism to produce the offending compound in a foodstuff is indicated.