鲜食糯玉米采后与食用品质相关的糖代谢变化

研究了鲜食糯玉米采后与食用品质相关的糖代谢变化以及温度变化对糖代谢的影响。结果表明:鲜食糯玉米采后的蔗糖、还原糖、总糖含量都有较大下降,导致甜味品质下降;直链淀粉含量持续上升,而支链淀粉含量达到峰值后下降,导致黏滞性下降;木质素含量随贮藏时间延长而升高,导致柔嫩度下降。与20℃贮藏温度对比,贮藏温度为0℃时总糖含量下降较为缓慢;直链淀粉、木质素含量增速降低;支链淀粉含量峰值较低,下降幅度较小,表明低温贮藏有助于延缓食用品质的下降进程。     

调味饮料中维生素C在加工及贮藏过程中的变化

探讨了温度、pH、贮藏条件等因素对调味饮料中VC的影响。结果表明：温度单一因素对VC的影响并不明显,在不同的温度下加热0.5h,随着温度的升高,VC的含量轻微下降,最终保持在95%左右。温度与pH两因素结合对VC的破坏有着较大的影响,pH为12.0的饮料加热2.5h后,VC的含量仅存65%左右;在pH为6.0左右时,无论是在80℃还是100℃下加热,VC含量均较高也较稳定;相同的加热温度下,在pH 2～10的范围内,VC的最高含量可达90%。此外,贮藏条件对VC的破坏影响明显,研究表明：在不同贮藏条件下,饮料中的VC含量并不是在低温下才处于最佳保存状态,当样品在4℃下冷藏7d后,其VC含量下降趋势非常明显,冷藏到66d时,VC含量下降至22%左右;而在室温避光条件下贮藏却具有较好的稳定性,贮藏到66d时,VC含量达75%左右,表明室温避光条件下贮藏,有利于保持VC的稳定性。     

固相微萃取-气相色谱-质谱联用法分析荔枝汁贮藏过程中香气成分的变化

以荔枝果汁为研究对象,研究其在贮藏过程中香气成分的变化,旨在为荔枝汁生产和品质控制提供理论依据。采用SPME/GC-MS法分别对4℃和25℃贮藏的荔枝汁于贮藏4、5、6、7、8周后进行香气成分检测。结果表明：荔枝汁中香气成分总量在4℃和25℃贮藏4周后分别比贮藏前增长39.10%及31.99%。贮藏5周后呈显著下降趋势(P＜0.05),贮藏8周后香气保留率分别为96.17%及74.49%。其中醇类、酸类香气成分均在贮藏4周时含量最高,此后随着贮藏时间延长含量呈缓慢下降趋势;酯类物质在冷藏6周后达到最高,之后出现显著降低趋势(P＜0.05);烯类香气成分随着贮藏时间的延长逐渐减少,呈现显著下降趋势(P＜0.05);醛类香气成分含量在贮藏4周时变化不大,在4℃和25℃贮藏8周后保留率分别为59.86%和55.3%。荔枝汁中几种典型的香气成分如香叶醇、香茅醇、苯乙醇,β-月桂烯,D-柠檬烯,香叶醛的含量也是在贮藏4周达最大,此后逐渐降低。通过对4℃冷藏和25℃常温贮藏的荔枝汁主要香气类型及典型香气成分的比较分析表明,4℃冷藏后香气总量和绝大多数典型香气成分的含量显著高于同期常温贮藏(P＜0.05)。     

鲜切火龙果低温贮藏期间游离态和结合态香气物质的变化

以“密宝”火龙果为研究对象,研究其鲜切后4 ℃贮藏期间游离态和结合态香气物质的变化。采用酶解法释放结合态香气物质,结合气相色谱-质谱联用分析技术对鲜切火龙果中游离态和结合态香气物质分别进行定性定量分析。结果表明,火龙果中游离态和结合态香气成分在组成和含量上差异较大。火龙果进行切分后游离态香气物质含量显著上升,随着贮藏时间延长含量持续下降。结合态香气物质在贮藏第1天上升至最高值后第3天显著下降,贮藏后期含量保持稳定。     

不同贮藏方式对芦笋黄酮类物质含量的影响

采用普通冷藏、气调贮藏、化学试剂前处理后冷藏等几种方式保存绿芦笋,研究不同贮藏方式对芦笋中黄酮类物质含量的影响。结果表明,各贮藏方式黄酮含量整体均呈下降趋势,至28 d,各组黄酮含量保存率为35.4%～53.1%。100%O2气调包装和200μmol/L的CaCl2溶液浸泡2 h后冷藏可延缓整个贮藏过程中黄酮类物质含量的下降。     

温州蜜柑、椪柑采后酚类物质及抗氧化活性比较研究

通过研究温州蜜蜂柑、椪柑两个常见柑橘品种贮藏期间类黄酮、酚酸类物质及抗氧化活性的变化规律,评价其采后的营养品质。结果表明：贮藏60d后温州蜜柑较好地保持了抗坏血酸含量,而椪柑损失较大。类黄酮类物质较稳定,温州蜜柑中黄烷酮含量贮藏后有所增加,椪柑中则呈缓慢下降趋势,2种柑橘中酚酸类物质贮藏后都有所增加。总酚含量在贮藏前期呈下降趋势,贮藏后期温州蜜柑中总酚含量增加而在椪柑中进一步下降。抗氧化能力与抗坏血酸的变化趋势类似。与椪柑相比,贮藏期间温州蜜柑能更好地保持果实的营养品质及酚类物质,从而保持较高的抗氧化活性。     

不同贮藏温度对采后番荔枝品质的影响

以番荔枝(品种‘非洲骄傲’)为原材料,研究不同贮藏温度(4、25℃)对采后番荔枝呼吸速率、木质素与总酚含量等贮藏品质的影响,比较贮藏前后番荔枝果实细胞结构变化。结果表明:25℃贮藏条件下,番荔枝硬度迅速下降,失重率明显上升,可溶性固形物及可溶性蛋白含量显著下降;而4℃贮藏的番荔枝硬度缓慢下降,并且到贮藏第14 d,失重率仅为5.21%;可溶性固形物及可溶性蛋白含量呈先上升后下降的趋势。不同温度贮藏过程中,番荔枝果实细胞表面均出现很多孔隙,木质素颗粒沿细胞壁内侧沉积,形成完全木质化的细胞。木质素含量在不同贮藏温度期间均呈增加趋势,但在贮藏第5 d,25℃贮藏的番荔枝木质素含量增加了44.47%,而4℃贮藏的番荔枝木质素含量仅增加了30.48%;25℃贮藏条件下,总酚含量呈先上升后下降的趋势,而4℃贮藏条件下,总酚含量呈先上升后下降、最后上升的趋势;25℃贮藏的番荔枝在第2 d出现跃变高峰,呼吸速率达到600.23 mg/kg·h,而4℃贮藏条件番荔枝果实呼吸速率受到明显抑制。结论:低温贮藏显著抑制番荔枝的呼吸强度,有效延缓果实木质化进程,更利于番荔枝果实采后品质的保持。     

油炸专用改性淀粉的制备及理化特性分析

以淀粉为主要原料,乳清蛋白粉、棕榈油为辅料进行改性处理,获得三元复合物,并对复合物的理化特性进行分析。结果显示,与普通淀粉相比,复合物在12 h贮藏期间提高了水分含量并降低了油脂含量;溶解度在贮藏前4 h有明显上升,之后逐渐下降,膨胀度也得到了改善,0℃时贮藏12 h后析水率下降了43.90%;复合物的破损值、回生值均显著低于普通淀粉。10℃时回生值下降了55.29%,破损值下降了31.00%。复合物提高了油炸用淀粉的贮藏稳定性。     

贮藏温度对玛咖块根采后品质的影响

为确定玛咖块根采后适宜的贮藏温度,延长流通和供应期,研究4、10℃和20℃贮藏时玛咖块根生理及品质的变化规律。结果表明:与10℃和20℃贮藏相比,低温(4℃)贮藏能显著降低玛咖块根的质量损失率,延缓玛咖块根中可溶性蛋白质、可溶性固形物以及芥子油苷含量的下降,同时有效抑制玛咖块根褐变及黑芥子酶活性,但不同贮藏温度间总生物碱含量变化差异不显著(P>0.05)。玛咖块根在4℃贮藏14d,功效活性成分芥子油苷含量仅下降了3.8%,总生物碱含量下降14.6%,效果好于10℃和20℃。     

麻竹笋罐头贮藏过程中质构、果胶和色泽的变化

以麻竹笋为实验原料,研究麻竹笋罐头在常温（25 ℃）和低温（4 ℃）贮藏过程中质构、果胶和色泽的变化,并探讨麻竹笋罐头的硬度与果胶变化的相关性。结果表明：麻竹笋罐头在贮藏过程中硬度、原果胶和水溶性果胶含量逐渐下降,贮藏120 d后,常温贮藏和低温贮藏条件下麻竹笋的硬度分别下降39.5%和27.1%,原果胶含量分别下降66.4%和62.8%,水溶性果胶含量分别下降68.1%和75.7%。各果胶组分与硬度之间呈现较好的相关性,而原果胶与硬度之间的相关性高于水溶性果胶与硬度之间的相关性。麻竹笋罐头贮藏过程中亮度值L*和红绿值a*逐渐减小,黄蓝值b*逐渐增加;常温和低温分别贮藏30 d和70 d时,总色差ΔE＞2。     

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.     

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