近红外光谱结合Lasso算法测定制浆材抽出物含量

为实现制浆材材性的快速测定,首先用常规方法测定了144个制浆材样品的冷水、热水、苯-醇和1% NaOH抽出物含量,并采集了样品的近红外光谱,然后对原始光谱进行预处理,并运用Lasso算法及交互验证建立最优校正模型。对模型进行独立验证,决定系数R2val分别为0.9186、0.9085、0.9241、0.9760,预测均方根误差分别为0.24%、0.30%、0.28%、0.38%,相对分析误差分别为3.50、3.31、3.63、6.45,绝对偏差分别为-0.42%～0.37%、-0.43%～0.41%、-0.47%～0.40%、-0.55%～0.57%。这些模型预测性能能够满足制浆造纸工业的要求,同时,也证实了Lasso算法用于制浆材抽出物测定的可行性。     

常见制浆用速生桉木的近红外材性分析

用常规方法测定了104个速生桉木样品的综纤维素、聚戊糖、酸不溶木素及苯醇抽出物含量并采集了样品的近红外光谱。对原始光谱进行多元散射校正后,运用偏最小二乘法和交互验证的方法,确定最佳主成分数并建立样品相关化学成分含量的校正模型。独立验证中综纤维素、聚戊糖、酸不溶木素和苯醇抽出物模型的决定系数Rval2分别为0.9067、0.9033、0.9504、0.9570;预测均方根误差(RMSEP)分别为0.33%、0.50%、0.31%、0.17%;相对分析误差(RPD)值分别为3.22、3.20、4.43、4.73;绝对偏差(AD)分别为-0.53~0.60%、-0.95~0.77%、-0.55~0.52%、-0.22~0.29%,四个校正模型较好地预测了验证集样品的化学成分含量,基本满足制浆造纸工业中快速测定速生桉木原料的需求。     

利用近红外光谱快速测定制浆材化学成分含量

为实现实际生产中制浆材综纤维素和木质素含量的快速测定和在线分析,按国家标准测定了5种制浆材共计87个样品的综纤维素和木质素含量,并利用国产便携式光谱仪采集了样品的近红外光谱。原始光谱经过MSC预处理之后,采用偏最小二乘法和留一法交叉验证方法分别建立相应的混合样品预测模型。预测结果表明:综纤维素和木质素模型的预测决定系数(RP2)分别为0.9658和0.9471,预测均方根误差(RMSEP)分别为1.1438%和1.1805%,相对分析误差(RPD)分别为5.41和4.35,这说明2个模型均具有较高的预测精度。因此利用便携式光谱仪对多种制浆材混合样品的综纤维素和木质素含量进行快速测定是可行的。     

近红外光谱技术快速测定木材抽出物含量的研究

探讨了近红外光谱法快速预测木材冷水、热水、1.0%NaOH和苯醇抽出物含量的可行性。四个模型的决定系数（R2）高,分别为0.9804、0.9800、0.9823和0.9648;交叉验证均方根偏差（RMSECV）低,分别为0.21%、0.29%、0.48%和0.24%;冷水、热水、1.0%NaOH抽出物模型的残留预测偏差（RPD）值分别为7.14、7.07和7.51,而苯醇抽出物模型的RPD值仅5.33。采用不同校正模型分别对样品进行预测,四个模型的预测偏差分别为-0.19%～0.20%、-0.29%～0.28%、-0.36%～0.42%和-0.25%～0.14%,基本符合标准方法的误差要求。结果说明可以利用近红外光谱分析技术对木材抽出物进行快速、准确地测定。     

近红外光谱法快速测定木材纤维素、戊聚糖和木质素含量的研究

探讨了近红外光谱法快速测定木材纤维素、戊聚糖和Klason木质素含量的可行性。用常规实验室方法测定106种木材样品的纤维素、戊聚糖和Klason木质素含量,用近红外光谱仪采集相应样品的光谱。利用偏最小二乘法（PLS）和完全交叉验证方式,对原始光谱进行一阶导数＋矢量归一化（SNV）和一阶导数＋多元散射校正（MSC）预处理后,选择7502-5446 cm^-1、4601-4247cm^-1和6102-4597 cm^-1区间建立样品纤维素、戊聚糖、Klason木质素含量和光谱数据之间的相关性模型。模型的决定系数（R2）高,分别为0.9705、0.9927和0.9827;交叉验证均方根偏差（RMSECV）低,分别为0.40%、0.38%和0.49%;残留预测偏差（RPD）分别为5.83、11.7和7.61。采用3个模型分别对样品进行预测,预测偏差分别为-0.36%-0.34%、-0.40%-0.32%和-0.36%-0.39%。结果表明,可以利用近红外光谱法快速测定木材纤维素、戊聚糖和Klason木质素含量。     

近红外光谱分析技术在泡芙水分测定中的研究

水分含量快速测定是保证泡芙制作品质的重要需求。利用IAS Online-S100型在线近红外光谱分析仪,采集了130个建模集样品和30个验证样品的近红外光谱,结合光谱预处理和偏最小二乘法建立泡芙水分定量分析模型。研究结果表明,采用移动窗口平滑（平滑点数为11）+SNV法进行光谱预处理,主因子数为9的条件下,模型的决定系数R2、校正集均方根误差（RMSEC）、交互验证均方根误差（RMSECV）和预测集均方根误差（RMSEP）分别为0.88、0.49%、0.55%、0.57%。模型的预测误差在±1.3以内,精度满足工厂的使用需求。     

利用近红外光谱技术快速测定木材水分和气干密度的研究

利用近红外光谱技术对木材水分和气干密度进行了快速测定。结果表明：两个水分模型的决定系数都接近1,RMSECV值小于0.2%,RPD值大于10,模型质量极好,对样品的预测偏差小于0.2%;气干密度模型的决定系数为0.976、RM-SECV值为0.0152g/cm^3、RPD值为6.47,模型质量好,对样品的预测偏差范围为-0.019～0.02g/cm^3。说明可以利用近红外光谱技术对我国造纸木材的水分和气干密度进行快速、准确的预测。     

蚁群和遗传算法优化花茶花青素近红外光谱预测模型的比较

以建立花茶花青素含量的最优近红外光谱模型为目标,对比研究了蚁群算法(Ant ColonyOptimization,ACO)和遗传算法(Genetic Algorithm,GA)优化近红外光谱谱区的效果。ACO-i PLS将全光谱划分为12个子区间时,优选出第1、9、10共3个子区间,所建的校正集和预测集相关系数分别为0.901 3和0.864 2;交互验证均方根误差(RMSECV)和预测均方根误差(RMSEP)分别为0.160 0 mg/g和0.202 0 mg/g;GA-i PLS将全光谱划分为15个子区间时,优选出第1、5共2个子区间,所建模型的校正集和预测集相关系数分别为0.906 3和0.879 3,交互验证均方根误差(RMSECV)和预测均方根误差(RMSEP)分别为0.156 0 mg/g和0.206 0 mg/g。研究结果表明:ACO-i PLS和GA-i PLS均可以有效选择近红外光谱特征波长,其中GA-i PLS模型的精度更高。     

近红外光谱结合偏最小二乘法用于纯茶油中掺杂菜籽油和大豆油的定量分析

采用偏最小二乘法(PLS)建立了油茶籽油中掺杂菜籽油和大豆油的近红外光谱定量检测模型。配制不同比例(0～100%)的油茶籽油和菜籽油、油茶籽油和大豆油混合样品共256个,采集样品在10000～4000cm-1范围内的近红外透反射光谱,模型采用交互验证和外部检验来考察所建立模型的可靠性,不需进行任何光谱预处理,所建立的PLS模型相关系数为0.9997,训练集的交叉验证均方根误差(RMSECV)为0.504,预测集的预测均方根误差(RMSEP)为0.66。应用建立的模型对未知样品进行预测,并对预测值和真实值进行比较,在掺杂油含量为2.5%～100%之间范围内准确可靠,研究结果表明,采用近红外光谱技术可以实现纯茶油中菜籽油和大豆油掺杂量检测。     

短波近红外光谱-偏最小二乘法测定白酒中乙醇含量

应用近红外光谱技术结合偏最小二乘法(NIRS-PLS)建立白酒中乙醇含量定量分析数学模型。所建校正模型相关系数(Corr.Coeff.)达到0.99986,校正集均方根误差(RMSEC)为0.00225,预测均方根误差(RMSEP)为0.00137,模型通过交互验证检验,得出PLS因子数为4时预测残差平方和(PRESS)和交互验证均方根误差(RMSECV)最小。用所建模型测定样品与气相色谱分析结果相对误差不大于0.81%。实验结果表明该方法准确性、稳定性好、精密度高。     

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