芦苇硫酸盐浆OpP漂白的研究

研究了芦苇硫酸盐浆H2O2强化氧脱木素及H2O2补充漂白。芦苇KP浆未漂浆卡伯值27.5,白度29.9%ISO,黏度1036mL/g,H2O2强化氧脱木素条件为:用碱量5%、氧压0.6MPa、H2O2用量2%、温度80℃、漂白时间60min,反应后纸浆卡伯值为4.1、白度63.0%ISO、黏度为864mL/g。随后再用H2O2进行补充漂白,所得纸浆卡伯值为3.2,白度81.0%ISO,黏度822mL/g。     

金合欢浆Z(EOP)漂白工艺的研究

金合欢是一种优良的造纸速生材种。本试验研究了经氧脱木素后金合欢硫酸盐浆的Z(EOP)漂白工艺。重点分析了不同臭氧用量对金合欢硫酸盐漂白浆的卡伯值、黏度、白度和己烯糖醛酸含量的影响,并研究了臭氧用量与EOP处理前后纸浆卡伯值下降值、黏度下降值及白度升高值之间的相互关系。结果表明:在臭氧用量为4～6g.kg-1(对绝干浆)范围内,臭氧脱木素作用由相对剧烈逐渐趋于缓和;臭氧用量对EOP段处理前后浆料黏度下降值和白度升高值影响不大,但浆料初始卡伯值对其影响较大。     

AS-AQ稻草浆全无氯漂白

研究了AS-AQ稻草浆通过酸预处理后，借助H2O2强化的氧碱漂白及过氧化氢补充漂白。结果表明，稻草浆(未漂浆白度为42．8％ISO，卡伯值为8．2，粘度为913mL／g)经过一段强化氧漂(用碱量5％、氧压0．6MPa、H2O2用量0．5％、温度100℃、保温时间80min)之后，其白度达到67.0％ISO，粘度为841mL/g，卡伯值为3．1，适合进行下段漂白。过氧化氢补充漂白(NaOH用量0.3％、温度70℃、保温时间80min。H2O2用量3．0％、浆浓10％，DTPA用量0．05％，MgSO4用量0．05％)后，白度达到73．4％ISO，粘度为823mL／g，卡伯值为2．2，且白度稳定性较好。     

KP竹浆TCF漂白工艺条件探讨

对KP竹浆进行了单段氧脱木素、酸处理、螯合预处理及H2O2补充漂白研究.结果表明,未漂竹浆经过单段氧脱木素,其白度从37.0%SBD提高到51.3%SBD,卡伯值从19.0降低到10.1,粘度从1257mL/g降低到1026mL/g.另外进一步研究了在两段氧脱木素中,不同温度和用碱量对第2段氧脱木素的影响.在常规的H2O2补充漂白后,浆白度达到75.2%SBD,粘度为879 mL/g,卡伯值为5.7.同时还探讨了用氧加压的H2O2漂白工艺,结果浆的白度为83.6%SBD,粘度为890mL/g,卡伯值为4.2.     

加拿大一枝黄花制浆研究(系列报道之四)碱——蒽醌化学浆漂白性能的研究

对加拿大一枝黄花碱-蒽醌化学浆D/CEpD和D/CEpD1EpD2漂白条件、漂白浆特性和D/CEpD漂白浆的打浆性能进行了研究.确定了较佳的D/CEpD和D/CEpD1EpD2漂白工艺.D/CEpD漂白较佳工艺条件:总用氯量为10%(D/C、D段用氯量比6.5∶3.5),Ep段H202用量1.0%.漂白浆指标:AP+AQ浆得率89.61%,卡伯值1.9,白度79.6%ISO,返黄值5.6,粘度71 8mL/g;KP+AQ浆得率91.00%,卡伯值1.3,白度82.3%ISO,返黄值4.7,粘度711mL/g.D/CEpD1EpD2漂白较佳工艺条件:总用氯量10%(D/C、D1和D2段用氯量比为6∶3∶1),Ep段H2O2用量1.5%.漂白浆指标为:AP+AQ浆得率88.11%,卡伯值1.2,白度83.8%ISO,返黄值4.0,粘度710mL/g;KP+AQ浆得率88.96%,卡伯值1.1,白度84.7%ISO,返黄值3.9,粘度708mL/g.     

蔗渣氧碱浆的臭氧漂白研究

本研究对清洁的臭氧以及过氧化氢氧系漂白工艺的蔗渣氧碱浆漂白效果进行了探索与优化。结果表明,在浆浓40%、臭氧浓度为0.9 kg/(min·t)(以绝干浆计)、常温漂白10 min、复合酸用量1.5%、pH值2.5的条件下,可获得理想的臭氧漂白蔗渣氧碱浆。该浆在氧碱浆基础上,白度从58.6%提高到74.5%,增加15.9个百分点;黏度从827 mL/g下降到780 mL/g,降低5.7%。最佳臭氧漂白条件下得到的纸浆再进行过氧化氢漂白或氧强化过氧化氢漂白,在纸浆黏度基本保持不变的条件下,纸浆白度达80%以上。     

亚硫酸盐蔗渣浆氧脱木素后续漂白研究

研究了强化氧脱木素后的亚硫酸盐蔗渣浆过氧化氢漂白主要影响因素。结果表明:H2O2用量是最主要的影响因素,较适宜的漂白条件为:H2O2用量3.0%、漂白温度80℃、反应时间2h、碱量1.5%、浆浓10%。在此条件下,漂后浆卡伯值为8.9,纸浆黏度为753.2ml/g,白度为72.6%ISO。并提出进一步提高白度的方法。     

低浓纸浆臭氧漂白经验模型的建立

以臭氧(O_3)用量作为自变量,纸浆卡伯值(K)、黏度和白度为响应值,研究了臭氧用量对纸浆漂白性能的影响,结果表明,臭氧最佳用量为0. 77%,此时漂白后纸浆卡伯值、黏度、白度分别为8. 1、658. 4 mL/g、41. 9%。计算漂白过程中脱木素选择性、单位臭氧消耗内卡伯值的降低率和白度的增加率,通过线性回归建立合适的数学模型,求出各因素随臭氧用量(O_(3CON))或卡伯值的预估函数。研究表明,硫酸盐阔叶木浆低浓臭氧漂白时,臭氧用量对卡伯值的关系采用指数模型较为合适,其方程为K=7.359(O_(3CON))~(-0.2318), R~2=0.9987。结合黏度、白度随卡伯值变化的方程,臭氧用量取0. 77%、其他条件一定时,通过该模型预测得到纸浆卡伯值、黏度、白度分别为7. 8、624. 2mL/g、42. 9%,该经验模型可预测并优化低浓硫酸盐阔叶木浆的臭氧漂白反应。     

碱—蒽醌化学浆漂白性能的研究

对加拿大一枝黄花碱-蒽醌化学浆D／CEpD和D／CEpD1EpD2漂白条件、漂白浆特性和D／CEpD漂白浆的打浆性能进行了研究。确定了较佳的D／CEpD和D／OEpD1EpD2漂白工艺。D／CFpD漂白较佳工艺条件：总用氟量为10％（D／C、D段用氯量比6．5：3．5），Ep段H2O2用量1．0％。漂白浆指标：AP＋AQ浆得率89．61％，卡伯值1．9，白度79．6％ISO，返黄值5．6，粘度718mL／g；KP＋AQ浆得率91．00％，卡伯值1．3，白度82．3％ISO，返黄值4．7，粘度711mL／g。D／CEpD1EpD2漂白较佳工艺条件：总用氟量10％（D／C、D1和D2段用氯量比为6：3：1），EP段H2O2用量1．5％。漂白浆指标为：AP＋AQ浆得率88．11％，卡伯值1．2，白度83．8％ISO，返黄值4．0，粘度710mL／g；KP＋AQ浆得率88．96％，卡伯值1．1，白度84．7％ISO，返黄值3．9，粘度709mL／g。     

粗皮桉AS-AQ浆ECF漂白特性的研究

采用粗皮桉为原料,研究其AS-AQ浆的ECF漂白性能。实验的主要结果如下：采用D-Ep-D漂白,总用氯量为2．4％时,家系125纸浆的白度达到84．O％IS0,黏度868ml／g,卡伯值8．34;家系200纸浆的白度达到84．6％ISO,黏度958ml／g,卡伯值8．15。提高第一段CIO2漂白的温度,家系123纸浆漂白后白度达到85．0％ISO,黏度855ml／g,卡伯值8．10;家系200纸浆白度达到86．2％ISO,黏度892ml／g,卡伯值7．98。采用O-D-Ep-D漂序,用氯量为1．2％时,家系125纸浆的白度为85．9％ISO。采用O-D—E—D漂白时,总用氟量仅为0．8％时家系200纸浆就可以达到78．0％ISO;当总用氯量达到2．4％时,纸浆的白度可以到84．1％ISO。     

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.