微波灰化法测定焙烤食品中灰分的研究

建立用微波灰化仪测定焙烤食品中灰分的方法。运用程序升温微波灰化法对样品进行检测,寻找出测定焙烤食品灰分的最佳条件,检测结果和现行国家标准方法进行比对。数理统计结果表明,该方法与标准方法不但检测结果无显著性差异,且RSD值在0.52%~2.75%之间,结果重现性好,耗时少,能满足快速分析的要求,适用于焙烤食品灰分的批量检测。     

煤气明火加热炉与钢管马弗炉的应用对比

对煤气明火加热炉和钢管马弗炉的结构、控制系统、操作方式、工艺参数进行对比:煤气明火加热炉属于直接加热,比钢管马弗炉加热速度快,热效率高,节省燃料20%~30%;明火加热炉的炉内气氛可调,压力可控,后续生产的铅耗和酸耗比钢管马弗炉分别降低11.9%和4.7%;明火加热炉的烧嘴侧向安装,维护方便,而钢管马弗炉烧嘴顺向安装,易出现炉温波动,且钢管容易烧损,运行成本增加;明火加热炉的Dv值比钢管马弗炉的Dv值高4~5 mm.m/min。试验表明,钢管马弗炉与明火加热炉处理的钢丝力学性能差别不大。     

新型电脑自控燃煤马弗炉推广应用会在锡召开

新型电脑自控燃煤马弗炉推广应用会在锡召开我国煤炭资源丰富，在一定时期内，燃煤马弗炉仍将是我国金属制品行业钢丝热处理的主要生产设备之一。无锡市新科自动控制研究所开发的电脑自控燃煤马弗炉与普通燃煤马弗炉相比，煤耗降低４０％以上，热效率提高１倍，炉温稳定，...     

食品灰分两种测定方法适用性的研究

目的探讨《食品安全国家标准食品中灰分的测定》(GB 5009.4-2010)中灰分的两种测定方法的区别,以及如何针对不同的样品选择适宜的测定方法。方法按国家标准规定的两种方法对不同样品的灰分进行测定,同时测定其含磷量,通过两者的关系推断适用的方法。结果检测了10种样本的灰分和磷含量,含磷较低的样品灰分测定可采用直接灰化法,测定结果的相对相差小于5%。含磷量高于0.4%的样品的灰分测定应采用加入灰化助剂的方法测定,且样品的取样量应尽可能小。结论食品中灰分的测定,虽然操作简单,但需注意细节问题,保证数据结果的准确性。     

文献导读

正影响小麦粉灰分测定的因素综合性评价根据国标GB 5009.4—2016,研究评估标准应用于小麦粉灰分检测各影响因素对灰分含量变化的相对贡献,包括称样量、碳化时间、灰化时间、灰化温度。所有数据采用格鲁布斯检验法进行分析。分析结果表明,小麦粉灰分含量测定称样量推荐3 g范围内;控制碳化时间和过程非常重要,灰化温度和灰化时间分别为550℃和4 h;干基和湿基对灰分含量平均值影响不显著。提出一种基于国标的小麦粉灰分含量分析方法。(文/李振华等摘自《粮油食品科技》2020年第6期)     

影响小麦粉灰分测定的因素综合性评价

根据国标GB5009.4—2016，研究评估标准应用于小麦粉灰分检测各影响因素对灰分含量变化的相对贡献，包括称样量、碳化时间、灰化时间、灰化温度。所有数据采用格鲁布斯检验法进行分析。分析结果显示，小麦粉灰分含量测定称样量推荐3 g范围内；控制碳化时间和过程非常重要，灰化温度和灰化时间分别为550 ℃和4 h；干基和湿基对于灰分含量平均值影响不显著。提出一种基于国标的小麦粉灰分含量分析方法。     

石墨炉原子吸收光谱法直接进样测定红葡萄酒中铅

建立石墨炉原子吸收光谱法直接进样测定红葡萄酒中痕量铅的快速分析方法。通过对基体改进剂、灰化温度、原子化温度、背景扣除的研究,优化了测定红葡萄酒中重金属元素铅的条件。用浓度为0.15mol/L 的硝酸调节红葡萄酒,磷酸二氢铵作基体改进剂,灰化温度700℃,原子化温度1800℃,NH4H2PO4 扣除背景,氩气作保护气是进行红葡萄酒中铅测定的适宜条件。在优化条件下测定Pb 的加标回收率为98.00%,相对标准偏差为3.004%。石墨炉原子吸收直接进样法测定红葡萄酒中铅的含量,不需要进行样品的复杂处理,方法快速、准确。     

钯基体改进剂-石墨炉原子吸收光谱法测定茶叶中的铅和镉

目的建立石墨炉原子吸收光谱法测定茶叶中的痕量铅和镉。方法采用湿法消解对茶叶样品进行消解,加入氯化钯、硝酸镁、磷酸二氢铵作为基体改进剂扣除样品中背景干扰的影响,并优化仪器条件进行石墨炉原子光谱法测定。结果测定茶叶样品中铅的最佳基体改进剂为氯化钯-硝酸镁,测定镉的最佳基体改进剂为磷酸二氢铵+硝酸镁。铅优化后的条件为:灰化温度为900℃、原子化温度2000℃,镉优化后的条件为:灰化温度为700℃,原子化温度1100℃。结论本方法简便、快速、准确,可适用于茶叶样品中铅、镉的分析。     

钢丝电加热马弗炉的改造

<正> 本文对电加热马弗炉改造和收到的节能降耗、提高效率、延长使用寿命等效果进行叙述,并提出了存在的问题。我厂钢丝热处理所采用的电加热多孔马弗炉是生产的关键设备,因此,我厂决定对热处理炉进行改造,使其适应生产的需要,以提高效率,节约电能,延长使用寿命,方便维修。     

样品预处理结合红外光谱分析鉴定纸张中的硫酸钡

纸张中加入少量硫酸钡是为了起到防伪作用,但由于纸张本身所含有机基体、碳酸钙及高岭土所产生的干扰,对于纸张中的硫酸钡分析鉴定非常困难。本实验探讨了上述干扰因素对现行国家标准方法 (GB/T2679.12—1993)的影响,建立了一种样品预处理结合红外光谱分析鉴定纸张中少量硫酸钡的新方法。本方法基于国家标准方法进行样品灰化处理,然后采用1 mol/L的盐酸标准溶液对灰分残余物进行多次酸洗,依次排除有机物和碳酸钙的干扰。结果表明,该方法可以克服现行国家标准方法的缺陷,提高了红外光谱检测硫酸钡的灵敏性,适用于纸张中少量硫酸钡的定性分析。     

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