废纸脱墨浆H_2O_2漂白及后续漂白的优化实验

研究废纸脱墨浆的H2O2漂白工艺条件,探讨H2O2用量、NaOH用量、Na2SiO3用量、螯合剂用量、温度、时间对纸浆白度的影响,以及FAS(F)后续漂白效果。结果表明,废纸脱墨浆H2O2漂白的最佳工艺条件为:H2O2用量2.0%,NaOH用量0.5%,Na2SiO3用量1.2%,EDTA用量0.005%,温度85℃,时间90min,白度可达62.76%ISO,白度增值达12.74%ISO。之后进行后续FAS漂白,白度比单段H2O2漂白提高1.55%ISO,高达64.31%ISO。     

棉短绒浆粕短程序二氧化氯漂白

实验研究D1ED2漂白程序中ClO2用量、初始pH值和漂白温度对棉短绒浆粕漂白性能和浆粕聚合度的影响。实验所得较适宜的漂白工艺条件为:D1段ClO2用量1%,温度70℃,时间120 min,浆浓8%,初始pH值4;E段NaOH用量2%,温度70℃,时间90 min,浆浓8%;D2段ClO2用量1%,温度70℃,时间120 min,浆浓8%,初始pH值4。此漂白条件下棉浆粕白度可达82%ISO以上,聚合度略有降低。     

三倍体毛白杨KP纸浆TCF漂白的研究

实验室蒸煮得到三倍体毛白杨KP纸浆:白度35.0%ISO,卡伯值13.2,粘度939mg/l.对KP纸浆进行TCF-OQP漂白实验,得出OQP各段最适宜的工艺条件如下:O段,浆浓10%,用碱量3%,MgSO40.5%,氧压0.6MPa,温度95℃,时间60min;Q段,浆浓10%,EDTA用量0.3%,初始pH值3,温度70℃,时间60min;P段,浆浓10%,H2O2用量3%,MgSO40.1%,NaOH1.5%,温度90℃,时间210min.在优化的OQP条件下,KP纸浆的白度可达80.4%ISO,强度较好.     

稻草亚硫酸铵浆全无氯漂白

研究了稻草亚铵浆的氧碱漂白、酸预处理和过氧化氢补充漂的三段漂白。结果表明,稻草亚铵浆经一段氧碱漂白后(浆浓10%,用碱量3%,氧压0.6MPa,温度80℃,时间80min),白度为55.2%ISO,经硫酸第二段预处理后(用量1.5%,温度65℃,时间40min),进行过氧化氢第三段补充漂白(浆浓12%,过氧化氢用量4%,氢氧化钠用量2%,温度85℃,时间80min),浆料白度达到66.4%ISO。     

甲脒亚磺酸杨木APMP漂白效果的探讨

探讨了甲脒亚磺酸（FAS）用于杨木碱性过氧化氢化机浆（APMP）漂白时，FAS用量、NaOH和FAS用量比、浆浓、漂白温度和时间对漂后纸浆白度的影响，通过实验得出最佳工艺条件：FAS用量0.6%(对绝干浆的质量分数），漂白浓度10％,温度70℃，时间60min，FAS与NaOH用量比为2，得到漂白浆白度为62.3%SBD，白度提高了9.8%SBD。通过对Na2S2O4、H2O2单段票白的研究，从纸浆白度、强度、废水污染负荷和工艺条件等方面与FAS漂白效果进行了比较，得出FAS是一种较清洁和经济的新型漂白剂。     

三倍体毛白杨EMCC纸浆TCF漂白的研究

经过实验室模拟的延伸改良连续蒸煮(EMCC),得到EMCC纸浆:白度35.8%ISO,卡伯值12.3,粘度966 mg/L.对EMCC纸浆进行OQP全无氯漂白,通过对O段中NaOH用量和温度对氧脱木素效果的影响,确定O段最适宜的工艺条件为:浆浓10%,用碱量3%,MgSO40.5%,氧压0.6MPa,温度95℃,时间60min.通过对Q段中不同EDTA用量和初始pH值对后续H2O2漂白效果影响的研究,确定较适宜的工艺条件为:浆浓10%,EDTA用量0.3%,初始pH值3,温度70℃,时间60min.P段较适宜的工艺条件为:浆浓10%,H2O2用量3%,MgSO40.1%,NaOH 1.5%,温度90℃,时间180min.在优化的OQP条件下,EMCC纸浆的白度可达80%ISO以上,并保持较好的强度.     

杨木化学浆甲脒亚磺酸-过氧化氢的漂白工艺

甲脒亚磺酸(FAS)是一种新型漂剂,在工业上也称二氧化硫脲。以杨木为原料,研究在CEHP漂白流程中的过氧化氢(P)漂段添加漂白助剂甲脒亚磺酸后的最佳漂白工艺及结果。结果表明,当FAS用量0.4%、H2O2用量1.8%、温度70℃、时间100min、NaOH用量1.7%时,纸浆漂白后得率97.61%,白度85.12%ISO,抗张指数17.65N.m.g-1。相比于CEH三段漂后78.45%ISO以及未添加FAS时CEHP漂后82.22%ISO的纸浆白度,白度增值分别为6.67%ISO、2.90%ISO。FAS-H2O2漂白工艺节省了漂白时间,节约了漂剂,同时提高了纸浆白度。     

四乙酰乙二胺(TAED)对稻草高得率浆双氧水漂白的影响

研究了四乙酰乙二胺(TAED)作为活化剂对稻草高得率浆双氧水漂白的活化效果,并在TAED的作用下以漂后白度为指标考察不同条件对活化效果的影响,以此确定最佳漂白条件。结果表明:最佳漂白工艺为浆浓10%,时间30min,温度70℃,TAED与H2O2摩尔比0.5,NaOH用量4%,H2O2用量6%,Na2SiO3用量3%,MgSO4用量0.05%;在该条件下,漂后浆的白度值为52.4%ISO,比原浆白度增加值可达38.6%ISO,比单纯的H2O2漂白提高了7.8%ISO。     

四羟甲基磷酸膦用于马尾松热磨机械浆漂白

采用四羟甲基磷酸膦(THPS)漂白马尾松热磨机械浆,探讨THPS用量、初始pH值、漂白时间和漂白温度对漂后纸浆白度的影响。研究结果表明,THPS漂白马尾松热磨机械浆的适宜条件是:浆浓10%,THPS用量2.0%,初始pH5.0,漂白时间2h,温度90℃时,漂后纸浆白度达到63.07%ISO,白度增值为7.07%ISO。通过比较连二亚硫酸盐(Y)漂白和THPS漂白的效果,当THPS用量为0.1%,Y用量为1.0%时,漂后纸浆的白度达到61.12%SO,比未漂浆的白度提高了5.12%ISO。     

混合废纸脱墨浆FAS漂白工艺

研究氧化还原两段漂白中还原漂剂FAS对混合废纸脱墨浆的漂白效果。在H2O2预漂白处理浆料的基础上,加入FAS进行还原漂白,探讨漂白温度、漂白时间以及FAS用量对浆料白度的影响。结果表明:在碱比0.4、FAS用量0.6%、浆浓8%、时间40min,温度75℃的条件下,漂白效果、生产成本达到最佳条件。     

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.     

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.     

Textural Properties of Cold-set Gels Induced from Heat-denatured Whey Protein Isolates

A 9% whey protein (WP) isolate solution at pH 7.0 was heat-denatured at 80°C for 30 min. Size-exclusion HPLC showed that native WP formed soluble aggregates after heat-treatment. Additions of CaCl2 (10–40 mM), NaCl (50–400 mM) or glucono-delta-lactone (GDL, 0.4–2.0%, w/v) or hydrolysis by a protease from Bacillus licheniformis caused gelation of the denatured solution at 45°C. Textural parameters, hardness, adhesiveness, and cohesiveness of the gels so formed changed markedly with concentration of added salts or pH by added GDL. Maximum gel hardness occurred at 200 mM NaCl or pH 4.7. Increasing CaCl2 concentration continuously increased gel hardness. Generally, GDL-induced gels were harder than salt-induced gels, and much harder than the protease-induced gel.     

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.     

Occurrence of bisphenol-F-diglycidyl ether (BFDGE) in fish canned in oil

The levels of bisphenol-F-diglycidyl ether (BFDGE) were quantified as part of a European survey on the migration of residues of epoxy resins into oil from canned fish. The contents of BFDGE in cans, lids and fish collected from all 15 Member States of the European Union and Switzerland were analysed in 382 samples. Cans and lids were separately extracted with acetonitrile. The extraction from fish was carried out with hexane followed by re-extraction with acetonitrile. The analysis was performed by reverse phase HPL C with fluorescence detection. BFDGE could be detected in 12% of the fish, 24% of the cans and 18% of the lids. Only 3% of the fish contained BFDGE in concentrations considerably above 1mg/kg. In addition to the presented data, a comparison was made with the levels of BADGE (bisphenol-A-diglycidyl ether)analysed in the same products in the context of a previous study.     

Contribution of European research to risk analysis

The European Commission's, Quality of Life Research Programme, Key Action 1—Health, Food & Nutrition is mission-oriented and aims, amongst other things, at providing a healthy, safe and high-quality food supply leading to reinforced consumer confidence in the safety of European food. Its objectives also include the enhancing of the competitiveness of the European food supply. Key Action 1 is currently supporting a number of different types of European collaborative projects in the area of risk analysis. The objectives of these projects range from the development and validation of prevention strategies including the reduction of consumers risks; development and validation of new modelling approaches; harmonization of risk assessment principles, methodologies, and terminology; standardization of methods and systems used for the safety evaluation of transgenic food; providing of tools for the evaluation of human viral contamination of shellfish and quality control; new methodologies for assessing the potential of unintended effects of genetically modified (genetically modified) foods; development of a risk assessment model for Cryptosporidium parvum related to the food and water industries; to the development of a communication platform for genetically modified organism, producers, retailers, regulatory authorities and consumer groups to improve safety assessment procedures, risk management strategies and risk communication; development and validation of new methods for safety testing of transgenic food; evaluation of the safety and efficacy of iron supplementation in pregnant women; evaluation of the potential cancer-preventing activity of pro- and pre-biotic ('synbiotic') combinations in human volunteers. An overview of these projects is presented here.     

低温带皮菜籽粕微粉的不同粒级部分的功能特性

为研究低温带皮菜籽粕微粉的不同粒级部分的功能特性,以经低温脱脂的带皮菜籽粕为原料,经微粉碎后筛分成212~425μm、150~212μm和106~150μm的3个不同粒级的微粉样品,检测这些样品的吸水性、吸油性、乳化性和乳化稳定性、蛋白质体外消化率。结果表明:1 3个不同粒级的微粉样品之间的粗纤维含量存在显著差异,表明三者的结构组成成分有一定差异。23个微粉样品的乳化活性和乳化稳定性随粒度级别的减小而显著增加(P0.01)。33个微粉样品的蛋白质体外消化率随粒度级别的减小而显著增加(P0.01)。4不同粒级带皮菜籽粕微粉样品的吸水性与吸油性受其结构组成物质不同和粒度的双重影响,与粒度的相关性不明显。     

Microbiology of food taints

Fresh and processed foods are often spoilt by the presence of undesirable flavours and odours caused by microbial action. The aim of this paper is to review the current knowledge of microbiologically induced taints that occur in a wide range of foodstuffs, including meats, poultry, fish, crustaceans, milk, dairy products, fruits, vegetables, cereals and cereal products. Examples have been chosen where the compounds responsible for the taint have been identified and sufficient data obtained to demonstrate the involvement of microorganisms. However, in some cases the full identity of the causative organism may not have been elucidated. The types of microorganisms covered by this review include bacteria, fungi, yeasts, actinomycetes and cyanobacteria. Although cyanobacteria do not in general infect foods, their presence in aqueous systems and water supplies can lead to off-flavours in aquatic organisms and processed foodstuffs. Several examples of each of these processes are discussed. Wherever possible, the likely biosynthetic pathway used by the microorganism to produce the offending compound in a foodstuff is indicated.     

The development of reference materials for paralytic shellfish poisoning toxins in lyophilized mussel. I: Interlaboratory studies of methods of analysis

This paper describes the first part of a project undertaken to develop mussel reference materials for Paralytic Shellfish Poisoning (PSP) toxins. Two interlaboratory studies were undertaken to investigate the performance of the analytical methodology for several PSP toxins, in particular saxitoxin (STX) and decarbamoyl-saxitoxin (dc-STX) in lyophilized mussels, and to set criteria for the acceptance of results to be applied during the second part of the project: the certification exercise. In the first study, 18 laboratories were asked to measure STX and dc-STX in rehydrated lyophilized mussel material and to identify as many other PSP toxins as possible with a method of their choice. In the second interlaboratory study, 15 laboratories were additionally asked to determine quantitatively STX and dc-STX in rehydrated lyophilized mussel and in a saxitoxin-enriched mussel material. The first study revealed that three out of four postcolumn derivatization methods and one pre-column derivatization method sufficed in principle to determine STX and dc-STX. Most participants (13 of 18) obtained acceptable calibration curves and recoveries. Saxitoxin was hardly detected in the rehydrated lyophilized mussels and results obtained for dc-STX yielded a CV of 58% at a mass fraction of 1.86 mg/kg. Most participants (14 out of 18) identified gonyautoxin-5 (GTX-5) in a hydrolysed extract provided. The first study led to provisional criteria for linearity, recovery and separation. The second study revealed that 6 out of 15 laboratories were able to meet these criteria. Results obtained for dc-STX yielded a CV of 19% at a mass fraction of 3.49mg/kg. Results obtained for STX in the saxitoxin-enriched material yielded a CV of 19% at a mass fraction of 0.34mg/kg. Saxitoxin could not be detected in the PSP-positive material. Hydrolysis was useful to confirm the identity of GTX5 and provided indicative information about C1 and C2 toxins in the PSP-positive material. The methods used in the second interlaboratory study showed sufficiently consistent analysis results to undertake a certification exercise to assign certified values for STX and dc-STX in lyophilized mussel.