微波热烫和气调包装对中央厨房用胡萝卜理化特性及品质的影响

胡萝卜经去皮、切分等加工后容易受到氧气和微生物的作用而发生腐败变质,因此,需要合适的保鲜方法延缓其品质劣变。作者研究微波热烫和气调包装对鲜切胡萝卜贮藏品质的影响。对胡萝卜进行微波热烫和气调包装处理后,每隔5 d测定胡萝卜样品的硬度、β-胡萝卜素质量分数、水分质量分数、水分活度、水分状态、过氧化物酶活性、颜色和微生物数量等指标。微波热烫可以有效降低胡萝卜中的微生物数量,并降低其水分迁移率。相比之下,对照样品中自由水（T₂₄）的质量分数更为突出。360 W微波热烫300 s结合高氧气调包装（体积分数80% O₂、10% CO₂、10% N₂）降低了储藏期内胡萝卜中β-胡萝卜素的降解、硬度的损失和过氧化物酶的活性,且更好地控制了胡萝卜中水分活度和水分质量分数的增加。低功率微波热烫结合高氧气调包装是一种有效的保鲜方法,可用于改善胡萝卜的储藏品质。     

储藏条件对生鲜湿面条水分状态及相关品质的影响

探讨了生鲜湿面条在储藏条件为常温（25℃）覆膜保鲜、冷藏（4℃）覆膜保鲜、冷藏（4℃）不覆膜保鲜下品质随储藏时间的变化。结果表明：水分、横向弛豫时间T₂、酸度、质构、色泽等各指标之间具有显著相关性。面条水分随储藏时间的延长逐渐降低,冷藏储藏下降低的幅度较大;面条的弛豫时间T₂₁及T₂₂随储藏时间呈下降趋势;冷藏储藏面条酸度随储藏时间的延长而降低,其他两种储藏条件下,酸度则升高;色泽方面,面条白度均逐渐降低,其中冷藏储藏白度降低的幅度最小,常温储藏白度降低的幅度最大;质构方面,硬度随储藏时间延长而升高,弹性及内聚性随储藏时间延长而降低。      

冻藏时间对生、熟猪肉品质的影响

冷冻是猪肉常用贮藏手段，然而长期冻藏会对猪肉及其烹后品质产生较大影响。作者研究了-18 ℃不同冻藏时间（0、120、240、360 d）对猪肉加热前后营养品质、食用品质和贮藏特性的影响。结果表明：随着猪肉冻藏时间的延长，生、熟猪肉中水分质量分数、弹性和可溶性蛋白质质量分数显著降低（P<0.05），游离氨基酸质量分数、POV值、TBARS质量分数均显著上升（P<0.05），硬度、胶黏性、咀嚼性逐渐增加，电子鼻结果显示各组间风味具有显著差异（P<0.05）。表明猪肉品质随冻藏时间的延长而显著下降，且在冻藏120 d后，品质严重劣变，食用价值降低。     

玉米秸秆乙醇低聚糖纯化及热稳定性研究

本研究以从玉米秸秆乙醇法制浆废液中提取的乙醇低聚糖为原料,将其进行树脂纯化并分级得到分子质量在200~1000 D的低聚糖,通过测试不同升温速率下低聚糖的热稳定性能,并结合非线性拟合计算,得到低聚糖的热解活化能（E）和指前因子（lnA）。结果表明,在非等温程序下提纯分级所得低聚糖分解温度范围为160~300 ℃,灰分较多会降低低聚糖的热稳定性。分级处理所得未纯化低聚糖（O₀）、脱盐低聚糖（B₀）、脱色低聚糖（C₀）和脱盐+脱色低聚糖（D₀）对应的E分别为46.52、60.55、43.12和52.28 kJ/mol,lnA分别为4.03、7.70、2.98和5.47 min^-1。本研究及结果有助于选择合适的生产工艺参数,优化提取纯化工艺,为开发提取新方法提供借鉴。     

上海市市售婴幼儿配方乳粉中氯丙醇酯和缩水甘油酯的监测及膳食暴露评估

目的 了解上海市市售婴幼儿配方乳粉中氯丙醇酯（MCPDE）和缩水甘油酯（GE）的污染水平，评估婴幼儿膳食暴露风险。方法 利用2020年上海市市售90件婴幼儿配方乳粉中MCPDE和GE的风险监测数据，结合婴幼儿膳食消费量数据，采用点评估法对婴幼儿经婴幼儿配方乳粉的3-MCPDE、2-MCPDE和GE进行膳食暴露评估。结果 上海市市售婴幼儿配方乳粉中3-MCPDE、2-MCPDE和GE的检出率分别为100%、100%和12.2%，含量平均值分别为0.084、0.021和0.005 mg/kg，最大值分别为0.231、0.034和0.031 mg/kg。上海市0~6月龄婴儿每日经婴幼儿配方乳粉摄入3-MCPDE的平均暴露量和P₉₅暴露量分别为1.262和2.166 μg/kg·BW，分别占3-MCPDE每日耐受摄入量（TDI，2 μg/kg·BW）的63.1%和108.3%。6~12、12~36月龄婴幼儿每日经婴幼儿配方乳粉摄入3-MCPDE的平均暴露量和P₉₅暴露量均低于TDI值。不同月龄组婴幼儿每日经婴幼儿配方乳粉摄入2-MCPDE的平均暴露量为0.118~0.319 μg/kg·BW。不同月龄组婴幼儿每日经婴幼儿配方乳粉摄入GE的平均暴露边界比（MOE）和P₉₅ MOE均大于10 000。结论 上海市0~36月龄婴幼儿每日经婴幼儿配方乳粉摄入3-MCPDE和GE的健康风险总体上处于可接受水平。但对于高食物消费量的0～6月龄婴儿，其通过婴幼儿配方乳粉暴露3-MCPDE的健康风险需引起关注。     

顺序提取小米主要组分对挤压膨化产品特性的影响

对小米全粉依次进行去纤维、脱脂、去醇溶蛋白处理,连同小米全粉和淀粉共制得5种产品,通过挤压试验,研究不同产品的理化和质构特性。结果表明,纤维、脂肪和蛋白质的存在使产品的外层失去壁薄、圆润、完整的气孔特性,降低淀粉挤压样的比容;纤维、脂肪的存在限制产品膨胀,而蛋白质的存在有利于产品膨胀;纤维、脂肪、蛋白质的存在不利于淀粉糊化;纤维、蛋白质的存在使产品水溶性（WSI）降低,蛋白质对产品吸水性（WAI）没有显著影响;纤维和蛋白质的存在是小米粉挤压膨化产品色值较高的原因;纤维的存在使产品受压变形时的平均力(F_av)和平均力落差(F_d)降低,蛋白质的存在也会使F_av降低,但对F_d没有显著影响。     

高得率竹浆漂白中乙醇对H2O2分解规律的影响

本研究采用气量法研究了乙醇介质抑制H₂O₂无效分解的机理和提高高得率竹浆漂白的效果。主要探讨了乙醇质量分数、反应温度等参数对分解反应速率常数（k）和反应活化能（Ea）的影响规律,并对比了乙醇介质对漂白高得率竹浆的白度、返黄值和机械强度的影响。结果表明,乙醇介质通过降低k值和Ea值可以有效抑制H₂O₂的无效分解;乙醇质量分数升高,抑制H₂O₂分解能力增强,质量分数50%的乙醇抑制效果较好;与水介质相比,高得率竹浆在50%乙醇-水介质中进行H₂O₂漂白,漂后浆白度提高了117.4%,返黄值下降了72.2%,纸张抗张指数提升了60.9%。     

基于液相色谱-串联质谱技术的羊牛乳特征肽段鉴别及测定

目的 建立了一种基于液相色谱-串联质谱(LC-MS/MS)技术鉴别羊牛乳及定量检测羊乳中牛乳的检测方法。方法 样品经胰蛋白酶水解后,采用纳升液相色谱-串联飞行时间质谱仪(nanoLC-TOF-MS)检测,数据经ProteinPilot_^TM软件和UniProt蛋白数据库对比分析,并通过blast搜索,筛选出特征肽段。然后基于HPLC-MS/MS,应用牛乳、羊乳的特征肽段对样品进行鉴别和定量测定。结果 本方法测定羊乳中的牛乳含量,在5%-50%之间线性范围良好,相关性系数大于0.99,定量限为5.0%,在5%、20%和40%添加水平的回收率为85.2%~114%,相对标准偏差小于10%(n=6)。结论 该方法快速、准确, 适合应用于检测纯羊乳中是否掺入牛乳,也可应用于检测混合乳粉中羊乳和牛乳的占比。     

不同贮藏条件下芹菜可溶性糖质量分数及相关基因变化分析

芹菜（Apium graveolens L.）是伞形科二年生叶菜类蔬菜，可溶性糖是叶菜类蔬菜的重要营养成分之一。作者选取‘四季小香芹’和‘六合黄心芹’为试材，测定其在室温（25 ℃）、低温（4 ℃）和室温黑暗（25 ℃）条件下贮藏0、6、24、30、48、54 h的可溶性糖质量分数，利用实时荧光定量PCR技术检测可溶性糖代谢相关基因（AgIVR1、AgSPP、AgSPS、AgSS1 和AgUDPG ）的表达特性。结果显示：3种贮藏条件下芹菜可溶性糖质量分数存在品种和组织差异性，‘四季小香芹’可溶性糖质量分数高于‘六合黄心芹’；叶柄可溶性糖质量分数高于叶片；不同贮藏条件下可溶性糖质量分数无明显变化规律。低温贮藏至54 h时，2种芹菜AgSS1 基因的表达量均显著上升；不同贮藏条件下芹菜的AgSPS 基因表达量整体都呈下降趋势；不同基因之间可能通过互作共同调节芹菜贮藏过程中可溶性糖质量分数的变化，可溶性糖积累量与相关基因的变化有关。     

干燥方式对油茶粉品质及挥发性风味物质的影响

目的：探究适合油茶粉的干燥方式,以便油茶食用和贮藏。方法：采用喷雾干燥、真空冷冻干燥、真空干燥3种干燥方式对油茶汤进行干燥处理,并对干燥后油茶粉的品质（水分含量、感官评价、色泽）及挥发性物质进行评价。结果：真空冷冻干燥油茶粉感官得分最高（93）,含水量最低（3.78%）,色泽较优（ΔE值49.74）。利用SPME-GC-MS技术从3种方式干燥油茶粉中共鉴定出104种挥发性物质,其中,影响油茶粉风味的有14种。冷冻干燥的特征风味物质（壬醛、癸醛、（Z）-2-癸醛、（Z）-2-壬烯醛、（E）-3,7-二甲基-2,6-辛二烯醛）呈现青香、油脂香,喷雾干燥和真空干燥的特有香气均为（Z）-3,7-二甲基-2,6-辛二烯醛、（E）-3,7-二甲基-2,6-辛二烯醛、癸醛,呈现青香、果香、蜡香。结论：真空冷冻干燥风味品质最佳。     

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.     

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.     

Chlorohydrins of bisphenol A diglycidyl ether (BADGE) and of bisphenol F diglycidyl ether (BFDGE) in canned foods and ready-to-drink coffees from the Japanese market

BADGE.2HCl and BFDGE.2HCl were determined in 28 samples of ready-to-drink canned coffee and 18 samples of canned vegetables (10 corn, 5 tomatoes and 3 others), all from the Japanese market. HPLC was used as the principal analytical method and GCMS for confirmation of relevant LC fractions. BADGE.2HCl was found to be present in one canned coffee and five samples of corn, BFDGE.2HCl in four samples of canned tomatoes and in one canned corn. No sample was found which exceeded the 1mg/kg limit of the EU for the BADGE chlorohydrins. However the highest concentration was found for the sum of BFDGE.2HCl and BFDGE.HCl.H₂O at a level of 1.5mg/kg. A Beilstein test confirmed that all cans containing foods contaminated with BADGE.2HCl or BFDGE.2HCl had at lest one part coated with a PVC organosol.     

European priorities for research to support legislation in the area of food contact materials and articles

A strong science base is required to underpin the planning and decision-making process involved in determining future European community legislation on materials and articles in contact with food. Significant progress has been made in the past 5 years in European funded work in this area, with many developments contributing to a much better understanding of the migration process, and better and simpler approaches to food control. In this paper this progress is reviewed against previously identified work-areas (identified in 1994) and conclusions are reached about future requirements for R&D to support legislation on food contact materials and articles over the next 5 or so years.     

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.     

Detection of adulteration of locust bean gum with guar gum by capillary electrophoresis and polarized light microscopy

Capillary electrophoresis (CE) and polarized light microscopy (PLM) were utilized in the detection of the adulteration of locust bean gum with guar gum. For CE analyses, standards of locust bean and guar gums were extracted with 30% CH₃CN, removing the residual proteins from the gum matrix. A 8.75 mM NaH₂PO₄-20.6 mM Na₂B₄O₇ buffer, pH 9, was used to separate these proteins and to identify marker proteins that were present in the guar gum. These markers did not co-migrate with components in the extracts of mechanically processed locust bean gum, and are used as indicators of adulteration. Using PLM with toluidine blue and iodine staining techniques, unadulterated locust bean gum samples were distinguished from mixed samples through the differential staining of components in locust bean versus guar and tara gums. These experiments in the use of CE and PLM provide orthogonal and complementary methods for the verification of 'true' positives and the elimination of 'false' positives.