基于LF-NMR及主成分回归分析的油脂煎炸品质预测

以大豆油和玉米油为研究对象,研究薯条煎炸过程(温度(180±5)℃,36 h)中低场核磁(LF-NMR)弛豫特性及理化指标(酸价、黏度、吸光值及总极性化合物含量)的变化规律。应用主成分回归分析建立通过LF-NMR弛豫特性预测理化指标的相关性模型。结果表明:随煎炸时间的延长,油样的LF-NMR弛豫特性中,峰起时间(T21、T22)及单组份弛豫时间(T2w)线性减小,T21特征峰的峰面积比例(S21)线性增大;油样的酸价、总极性化合物(TPC)均随煎炸时间的延长而线性增大,黏度、吸光值则呈二项式增大。与大豆油相比,玉米油的酸价、黏度、吸光值、S21等虽变化幅度较大,但TPC,T21,T22,T2w变化幅度较小。通过主成分回归分析可建立酸价、黏度及总极性化合物含量与LF-NMR弛豫特性间的相关性模型(R20.90),模型验证良好,说明可利用油脂煎炸过程中LF-NMR弛豫特性的变化,快速、有效地预测其理化指标的改变程度,从而有效监控煎炸油脂及食品的质量。     

低场核磁共振结合主成分分析法在食用油脂品质分析中的应用

应用主成分分析法(PCA)对多种不同品质油脂样品的LF-NMR弛豫特性数据(T21、T22、T23、S21、S22、S23)进行了分析。研究表明,应用PCA可明显区分正常大豆油和棉籽油,但棕榈油和猪油样品分布范围有一定的重合;无论是轻度煎炸还是深度煎炸,不同种类的煎炸油脂在PCA得分图中能够明显分区;随煎炸时间的延长,油样在PCA得分图上的分布逐渐向左上方移动,四种油脂能够明显分为两类:棕榈油和猪油,大豆油和棉籽油;食用猪油与掺伪猪油样品在PCA得分图上能够明显区分,掺伪比例愈高,二者的区分效果愈好,试验验证正确。说明基于油脂的LF-NMR弛豫特性,结合主成分分析可实现对食用油脂种类、煎炸油程度及掺伪猪油的品质区分。     

煎炸猪油掺杂比例对猪油低场核磁共振弛豫特性及脂肪酸组成的影响

研究不同比例煎炸猪油掺入食用猪油样品的低场核磁共振（low field-nuclear magnetic resonance,LF-NMR）弛豫特性及脂肪酸组成,并分析了二者间的相关性。结果表明：随着煎炸猪油掺杂比例的增加,猪油样品的T21峰起始时间显著减小（P＜0.05）、峰面积比例S21和S22/S23线性增加（R2＞0.968 1）,S22的增长规律符合二项式关系（R2=0.988 6）,峰面积比例S23、单组分弛豫时间T2W、不饱和脂肪酸C18∶1＋C18∶2的含量及不饱和脂肪酸含量/饱和脂肪酸含量（相对不饱和度）均线性降低（R2＞0.956 2）,而T22峰起始时间呈阶梯下降趋势,T23峰起始时间与掺杂比例间的规律性不明显。此外,样品的棕榈油酸C16∶1、棕榈酸C16∶0、亚油酸C18∶2、硬脂酸C18∶0、C18∶1+C18∶2含量及相对不饱和度与LF-NMR弛豫特性S21、T21、S22、T23、T2W存在良好的相关性（R2为0.942～0.995）。研究表明可通过样品的LF-NMR弛豫特性有效反映脂肪酸组成和含量的变化,并对煎炸猪油掺杂比例进行预测。     

不同温度下葵花籽油低场核磁弛豫特性的变化及与理化指标的关系

借助于低场核磁共振(LF-NMR)技术快速监测葵花籽油理化品质的变化,有利于油脂品质及安全保障。对葵花籽油在105℃和180℃氧化过程中的LF-NMR弛豫特性变化规律进行了研究,并应用逐步回归分析了其与多个理化指标间的相关性。结果表明:在105℃氧化过程中,S21和T22变化规律较为明显,分别呈二项式上升和下降趋势,其他弛豫特性变化规律不明显;相关性分析表明,除酸值和碘值外,过氧化值、共轭二烯、共轭三烯和茴香胺值均与S21和T22呈显著相关(P≤0.05)或极显著相关(P≤0.01),极性化合物与T21、S21、S22和T23均呈显著或极显著相关,预测模型经验证后发现,仅过氧化值、共轭二烯和极性化合物含量模型可靠(R20.78);在180℃氧化过程中,S21和S22呈二项式上升,T21呈线性下降,T22和S23呈二项式下降趋势,且S21、T21、T22和S23均与除过氧化值外的其他理化指标呈显著相关或极显著相关,T23变化规律不明显,只有S22与过氧化值相关性显著;除过氧化值外,所有理化指标预测模型均建立准确(R20.89),验证可靠(R20.85)。     

不同温度下葵花籽油低场核磁弛豫特性的变化及与理化指标的关系北大核心CSCD

借助于低场核磁共振(LF-NMR)技术快速监测葵花籽油理化品质的变化,有利于油脂品质及安全保障。对葵花籽油在105℃和180℃氧化过程中的LF-NMR弛豫特性变化规律进行了研究,并应用逐步回归分析了其与多个理化指标间的相关性。结果表明:在105℃氧化过程中,S21和T22变化规律较为明显,分别呈二项式上升和下降趋势,其他弛豫特性变化规律不明显;相关性分析表明,除酸值和碘值外,过氧化值、共轭二烯、共轭三烯和茴香胺值均与S21和T22呈显著相关(P≤0.05)或极显著相关(P≤0.01),极性化合物与T21、S21、S22和T23均呈显著或极显著相关,预测模型经验证后发现,仅过氧化值、共轭二烯和极性化合物含量模型可靠(R2>0.78);在180℃氧化过程中,S21和S22呈二项式上升,T21呈线性下降,T22和S23呈二项式下降趋势,且S21、T21、T22和S23均与除过氧化值外的其他理化指标呈显著相关或极显著相关,T23变化规律不明显,只有S22与过氧化值相关性显著;除过氧化值外,所有理化指标预测模型均建立准确(R2>0.89),验证可靠(R2>0.85)。     

棕榈油在面制品煎炸过程中极性组分产生的集总动力学研究

旨在为植物油复杂反应体系的动力学研究提供新的思路,以棕榈油为研究对象,以面制品为煎炸物,在140、150、160、180℃下进行连续煎炸模拟试验,测定不同煎炸温度下不同煎炸时间煎炸油中极性组分含量,并通过集总的方法建立极性组分含量与煎炸温度和煎炸时间的动力学模型。结果表明：在140、150、160℃下煎炸36 h均没有达到煎炸油废弃点,而180℃下煎炸24 h即到达废弃点;棕榈油煎炸生成极性组分的过程为零级反应,反应活化能为35.98 kJ/mol,极性组分含量随煎炸时间延长线性增长;通过建立的模型预测不同温度下棕榈油煎炸的极限煎炸时间,预测结果与模拟试验结果相符。综上,通过集总的方法所建立的棕榈油煎炸生成极性组分的动力学模型可靠,所使用的集总动力学的研究方法可以引用至其他植物油的煎炸反应体系中。     

介电常数监测天然抗氧化剂抑制煎炸棕榈油劣变

采用介电常数法监测茶多酚(TP)、植酸(PA)、维生素E(VE)抑制煎炸棕榈油劣变效果。测定在3种天然抗氧化剂作用下,煎炸棕榈油过氧化值、酸价、羰基价、p-茴香胺值等化学参数与介电常数值的变化,分析了介电常数值与化学参数值之间的相关性,并进行天然抗氧化剂复合配方的优化。结果表明:介电常数与四种化学参数之间显著相关,可以取代4种化学品质参数衡量煎炸棕榈油品质的劣变,以介电常数为指标得到天然抗氧化剂复配最佳组合为:茶多酚0.04 g/100 g,植酸0.016 g/100 g,维生素E 0.8 g/100 g。     

茶多酚棕榈酸酯对棕榈油抗冻性和煎炸稳定性的影响

为了对棕榈煎炸油的开发提供参考，以不同茶多酚棕榈酸酯(抗氧化剂)添加量的分提18℃棕榈油为煎炸油，通过10℃和15℃冷冻试验中煎炸油(茶多酚棕榈酸酯含量分别为0、50、80、100、150、200、300 mg/kg)晶体微量析出时间和发朦时间的变化，以及180℃下薯条煎炸过程中煎炸油酸值、p-茴香胺值、总氧化值、色泽、脂肪酸组成、极性组分含量和3-氯丙醇酯含量的变化，分析了茶多酚棕榈酸酯对棕榈油抗冻性和煎炸稳定性的影响。结果表明：棕榈油的发朦时间与抗氧化剂的添加量整体呈阶梯增长的关系，尤其在15℃条件下，其抗冻性在茶多酚棕榈酸酯含量为50 mg/kg和150 mg/kg时明显增强；煎炸油的酸值、p-茴香胺值、总氧化值、脂肪酸组成、极性组分含量与茶多酚棕榈酸酯添加量无相关性；添加茶多酚棕榈酸酯的棕榈油在煎炸后的色泽均比空白组深；3-氯丙醇酯在煎炸初期降解剧烈，后期降解缓慢，最终趋于平缓，与抗氧化剂的添加量无相关性。总之，向棕榈油中添加茶多酚棕榈酸酯可以明显提高其抗冻性，茶多酚棕榈酸酯含量为50 mg/kg或150 mg/kg时，其抗冻性改进效果最为明显，但是并不能有效提升煎炸油的煎炸稳...     

大豆油和棕榈油煎炸薯条过程品质评价

为了对中包装的大豆油棕榈油煎炸专用调和油配方的开发和煎炸稳定性相关理化指标的选择提供参考,分别以一级大豆油、分提18℃棕榈油(一次精炼)及同批次的二次精炼18℃棕榈油为煎炸油,模拟薯条在180℃下高温煎炸32 h,对3种油品在煎炸过程中的酸值、过氧化值、p-茴香胺值、脂肪酸组成、极性组分含量、生育酚含量等理化指标进行了检测,并对18℃棕榈油中的风险因子,如PAH4、苯并(a)芘、3-氯丙醇酯(3-MCPDE)、反式脂肪酸含量进行了分析。结果表明：3种油品的酸值、过氧化值在煎炸过程中变化不明显,而p-茴香胺值、脂肪酸组成、极性组分含量在煎炸过程中变化比较明显;3种油品的生育酚氧化速度总体偏差不大;分提18℃棕榈油、二次精炼18℃棕榈油中的苯并(a)芘、反式脂肪酸含量均随煎炸时间延长呈缓慢升高的趋势;二次精炼18℃棕榈油的3-MCPDE在未煎炸时远高于分提18℃棕榈油的,3-MCPDE在煎炸初期降解剧烈,最终达到平衡;分提18℃棕榈油与二次精炼18℃棕榈油在煎炸稳定性方面没有明显区别,二次精炼不仅损失了部分有益的微量营养成分(如生育酚),还伴生出新的风险因子,如增加了3-MCPDE、反式脂...     

3种食用油在薯条煎炸过程中的品质变化

以大豆油、葵花籽油、棕榈油为研究对象,探讨在(180±5)℃条件下煎炸薯条,每天连续煎炸4h,共煎炸5d后各食用油理化指标的变化。结果表明:随着煎炸时间延长,3种食用油的色泽加深、黏度增加;酸价(AV)显著增加,但未超过国家标准;碘价(IV)则随着煎炸过程进行而逐步降低;过氧化值(POV)在煎炸过程中均先上升后下降,其中大豆油和葵花籽油的POV呈波动性;煎炸3d后,大豆油、葵花籽油的羰基值(CV)超过或非常接近国家标准50meq O2/kg,煎炸4d后,两种油的极性化合物(TPM)含量超过国家标准;整个煎炸过程中棕榈油的CV和TPM含量均低于大豆油和葵花籽油。     

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