两步法催化高酸值油脂生产生物柴油的研究

以高酸值废油脂为原料,采用两步法即先用硫酸氢钠为催化剂催化废油脂中的游离脂肪酸和甲醇酯化反应降低原料的酸值,然后分离出硫酸氢钠,加入氢氧化钠催化中性油酯交换生产生物柴油。酯化反应的最佳条件为：温度65℃,催化剂硫酸氢钠用量4%,醇油摩尔比为12∶1,反应4h;酯交换反应条件是：在65℃下加入0.8%的氢氧化钠,醇油摩尔比为6∶1,反应时间为1h,最终生物柴油的得率为93.2%。该两步催化法具有不产生酸化废水,不需要耐强酸设备,同时硫酸氢钠可以回收重复利用等优点。     

固体酸连续催化桐油预酯化反应研究

利用固定床反应器,以固体酸为催化剂催化桐油预酯化反应。考察了醇油摩尔比、停留时间、床层温度等因素对预酯化效果的影响。优化反应最适宜的操作条件为:醇油摩尔比6∶1,反应时间88 min,床层温度65℃。在此条件下桐油的酸值可降至0.8 mgKOH/g,达到生物柴油后续酯交换反应酸值小于1.0 mgKOH/g的要求。     

废工业棕榈油制备生物柴油的研究

利用固体酸作催化剂对酸值较高的废棕榈油进行预酯化,采用正交试验优化预酯化的工艺条件,最佳工艺条件是:反应温度为70 ℃,反应时间为4.0 h,固体酸催化剂的用量为3.0%,预处理后废棕榈油的酸值为2.18 mg KOH/g.研究了预酯化后的废棕榈油与甲醇进行的酯交换反应,得到最优工艺条件是:反应温度为65 ℃,反应时间为1.0 h,催化剂KOH的用量为1.0%,酯交换反应的转化率为96.85%,生物柴油总得率为93.2%.以废棕榈油为原料制备的生物柴油,除倾点较高外,其主要性能均符合柴油标准.     

高酸值麻疯树油两步法制生物柴油的研究

以获得高酸值麻疯树油的生物柴油工业生产基础技术参数为目的,研究了高酸值麻疯树油的酸碱两步法催化制备生物柴油工艺。结果表明:在65℃、催化剂浓硫酸用量1%、反应120 min、醇油摩尔比9∶1的条件下,高酸值麻疯树油经预酯化处理其酸值从14.85 mg KOH·g-1降至0.41 mg KOH·g-1,满足碱催化的原油酸值要求;Na OH催化酯交换的优化工艺条件为:反应30 min、反应65℃、催化剂用量1%、醇油摩尔比6∶1,在此优化条件下,酯交换率达到90.55%。制备的生物柴油中脂肪酸甲酯含量占总组分的98.73%,主要理化性能符合生物柴油标准。     

两步法试制生物柴油的研究

采用硫酸作催化剂,利用高酸值油脂与甲醇进行预酯化反应;再用氢氧化钠作催化剂,进行酯交换反应.结果表明:预酯化的反应条件为:醇油摩尔比8∶1、催化剂用量0.25%、反应时间1h,游离脂肪酸的转化率达到97.2%;酯交换的反应条件为:醇油摩尔比6∶1、催化剂用量0.5%、反应时间0.5h,生物柴油的收率可达98%.     

固体碱催化地沟油制备生物柴油工艺研究

以地沟油为原料,硫酸铁作为催化剂,通过酯交换反应制备生物柴油。酯交换反应考察醇油摩尔比、反应时间、反应温度和催化剂氢氧化钾的用量对降酸后的地沟油酯化产率的影响。结果表明:醇油摩尔比为7∶1,反应时间为40min,催化剂氢氧化钾用量为油重的1.0%,反应温度为65℃时,生物柴油得出产率含量为96.53%。     

麻疯树籽油超声波辅助酯交换反应的研究

以野生植物麻疯树籽油为原料,经脱胶、脱酸及脱水处理后进行超声波辅助酯交换反应,在超声波频率25 kHz,反应温度65℃,催化剂用量为油重的1.0%,醇油摩尔比7∶1,反应时间60m in条件下,麻疯树籽油酯交换转化率达到93.79%。在相同反应时间内和相同醇油摩尔比条件下,超声波辅助酯交换反应比无超声波反应的酯交换转化率高,同时也降低了催化剂的用量。     

高酸值油脂制备生物柴油中循环酯化研究

在自制罐式反应器内,对高酸值油脂进行循环甲酯化反应研究,探索最佳酯化工艺条件;最佳工艺条件下,对3种不同高酸值油脂原料进行酯化效果验证。结果表明:罐式反应器可实现液相和气液循环交替反应,缩短反应时间,显著提高反应效率;罐式反应器中循环酯化的最佳工艺条件为浓硫酸为催化剂、催化剂用量为油脂质量的0.2%、醇油摩尔比8∶1、反应温度65℃、反应时间5 h、循环流量55 m L/min,在最佳工艺条件下酯化产物酸值(KOH)降至2.6 mg/g,满足油脂酯交换反应原料的酸值(KOH)小于4.0 mg/g要求,具有推广应用价值。     

餐饮业废油制备生物柴油的研究

研究以餐饮业废油为原料,采用循环气相酯化-酯交换-水蒸汽蒸馏制备生物柴油的工艺过程,着重考察如何快速降低餐饮业废油的酸值和酯交换反应的优化条件。实验结果表明,循环气相酯化可在很短的时间内将原料的酸值降到酯交换对原料酸值的要求,通过水蒸汽蒸馏可使生物柴油纯度达到99.5%以上。此工艺适合于用各种酸值的原料制备生物柴油。     

毛叶山桐子油制备生物柴油的研究

本文以毛叶山桐子油、甲醇为原料,研究了通过碱催化酯交换反应制备生物柴油并优化了制备工艺条件。试验依次考察了反应温度、NaOH浓度、醇油摩尔比及反应时间对毛叶山桐子油转化率的影响。结果表明,最佳酯交换反应条件：反应温度为60℃,NaOH用量为油重的1.0%,醇油摩尔比为6∶1,反应时间为60min,在此条件下毛叶山桐子油转化率最高,达到95.5%。检测结果显示,制备生物柴油性能达到美国生物柴油的标准。     

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.     

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.     

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.     

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.     

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.     

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.     

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