不同硬度棕榈油基人造奶油组成及结晶行为研究

对比分析了两个不同硬度棕榈油基人造奶油的甘三酯组成、结晶特性及微观结构,试验表明人造奶油B中饱和脂肪酸含量较高,SUS型甘三酯(POP,PLP)含量偏大,同时含有少量的中碳链甘三酯;X-衍射观察到两个样品中均含有β和β′晶型,但是样品B中β′晶型占主导;SEM图像显示硬度较小的样品显微结构更疏松多孔.     

流速对棕榈油基人造奶油物理特性的影响

研究了3种流速对棕榈油基人造奶油物理特性的影响,主要包括对产品熟化及其变温储藏过程中硬度、流变特性、晶体微观形态、晶体热稳定性和晶型的影响。结果表明:流速为30 L/h的样品熟化3 d后明显出现后硬现象,具有较大的黏弹特性,结晶网络遭受明显的破坏,在温度波动期间出现明显的起砂现象,储藏后期有较多β晶型的出现;流速50 L/h和70 L/h的样品具有合适的硬度和近似市售人造奶油的流变特性;流速50 L/h的样品抵抗温度波动能力强,能够较长时间维持β'晶型,流速70 L/h的样品在变温储藏后期有大量晶体转化为β晶型,差示扫描量热(DSC)曲线有少量波动,且存在起砂现象。因此,在实验条件下最佳流速为50 L/h。     

棕榈油中间分提物在零/低反式脂肪酸人造奶油中的应用

为扩大棕榈油中间分提物(PMF)在零/低反式脂肪酸人造奶油中的应用,对PMF、棕榈油硬脂(PSt)和大豆油的甘三酯组成、结晶及熔化特性进行分析。结果表明:PMF的甘三酯主要由二饱和型及单饱和型甘三酯POP、PLP、POO组成;PSt的甘三酯主要由三饱和型及二饱和型甘三酯PPP、POP组成;大豆油主要由三不饱和型及二不饱和型甘三酯LLL、OLL、PLL等组成。以PMF为主,复配PSt和大豆油作为人造奶油的基料油,可使人造奶油以二饱和型POP等形成β'结晶倾向,一定量的三饱和型甘三酯PPP等提供人造奶油的骨架结构,三不饱和型甘三酯LLL、OLL等填充高熔点甘三酯形成的网格,提高人造奶油的营养特性。PMF、PSt和大豆油三者的质量比为50∶30∶20时表现出良好的相容特性,按照这一质量比制备的人造奶油中的晶型为β'和β共存,且以β'为主,符合人造奶油的结晶及熔化性能要求。     

熟化温度对棕榈基人造奶油质构、流变和结晶特性的影响

研究了熟化温度对棕榈油基人造奶油质构、流变特性和结晶特性的影响,主要包括对产品储藏及其温度波动过程中硬度、流变特性、即时固体脂肪质量分数、微观形态、热稳定性和晶型的影响,结果表明:熟化温度为20℃的样品在储藏过程中出现后结晶现象,且其涂抹性最差;熟化温度为30℃的样品,虽然涂抹性较好,但其硬度较小,温度波动21 d后发生起砂,且大量转化为β晶型;熟化温度为25℃的样品具有合适的固体脂肪质量分数,完善的结晶网络,良好的硬度和涂抹性能,且其抵抗温度波动的能力较强,能够较长时间的维持β’晶型。研究也表明,稳定的熟化温度是很重要的,即便5℃的差异也会造成产品性能的显著差异。     

高熔点脂肪对凝胶油基人造奶油品质的影响

以全氢化棕榈油作为高熔点脂肪源,将0.5%～2.5%的全氢化棕榈油与葵花油混合作为基料油,制备凝胶油基人造奶油。探究高熔点脂肪对凝胶油基人造奶油的脂肪酸组成、稳定性、熔点、质构、流变性质、微观结构和晶型的影响。结果表明,当高熔点脂肪添加量低于1.5%时,人造奶油的熔点过低、可塑性较差;而添加量高于1.5%时,人造奶油的不稳定指数值大于1.5,体系劣变严重;添加量为1.5%时,硬度、可塑性和黏度均更接近于市售人造奶油,综合表现最佳。     

乳化剂对富含甘油二酯的人造奶油乳化体系结晶行为的影响

以饱和单甘酯和棕榈油(24℃)为原料,采用脂肪酶Lipozyme TL IM催化酯交换反应制备含甘油二酯(31.2%)的人造奶油基料油。利用差示扫描量热仪(DSC)、核磁共振分析仪、偏光显微镜(PLM)和X-射线衍射仪(XRD)等研究不同乳化剂(单硬脂酸甘油酯、蔗糖酯、大豆卵磷脂)对甘油二酯基料油制备的人造奶油结晶行为的影响。结果表明:单硬脂酸甘油酯、大豆卵磷脂和蔗糖酯复配质量比为1∶1∶1(乳化剂含量为1%)时,制得的人造奶油熔点较低,固体脂肪含量满足食品工业人造奶油的要求,在45℃条件下可全部熔化,且晶体细腻均匀,能较好地包裹液油。     

低聚物对生物基聚对苯二甲酸丙二醇酯结晶性能的影响

逐步缩聚聚合物中通常含有一定比例的线性及环状低聚物,会影响纤维材料的成形加工、纤维性能、纺织品加工等。为探究低聚物对生物基对苯二甲酸丙二醇酯(PTT)结晶性能的影响,通过外部添加法制备得到具有不同低聚物质量分数(主要以环状二聚体为主)的生物基 PTT ,采用差示扫描量热仪分析方法对生物基PTT的结晶动力学进行研究。结果表明:低聚物的存在主要起成核剂的作用,其质量分数的增加可提高生物基 PTT的结晶速率、结晶温度及结晶度;添加低聚物质量分数为10%时,生物基 PTT的结晶速率常数由未添加的0.528提升至0.603,同时结晶温度由172.11 ℃提升至178.85 ℃。     

3种合成抗氧化剂在棕榈油煎炸过程中的损耗及其对煎炸油品质的影响

以棕榈油(熔点24℃)在180℃下间歇煎炸薯条60 h,研究合成抗氧化剂特丁基对苯二酚(TBHQ)、没食子酸丙酯(PG)和L-抗坏血酸棕榈酸酯(AP)的损耗情况及其对棕榈油中生育酚和生育三烯酚的保护效果;以酸价、极性组分含量、过氧化值、色泽和氧化诱导期评价这3种合成抗氧化剂对煎炸过程中棕榈油品质的影响。结果表明:3种合成抗氧化剂损耗速率的快慢顺序为TBHQPG AP,TBHQ和PG可以有效保护棕榈油中的生育酚和生育三烯酚,但是AP会促进生育酚和生育三烯酚损耗; PG和AP都可以显著抑制棕榈油酸价的升高,TBHQ无显著性影响; TBHQ和PG均可显著抑制煎炸过程中棕榈油极性组分含量的增加,AP无显著性影响;过氧化值与煎炸时间无线性关系; PG和AP可以抑制棕榈油煎炸过程中色泽的加深,TBHQ无显著性影响; TBHQ和PG可以延长棕榈油的氧化诱导期,而AP缩短了棕榈油的氧化诱导期。     

四种棕榈油结晶速度的研究

报道了棕榈油、棕榈软脂、棕榈硬脂及氢化棕榈油在0℃,10℃,20℃条件下的结晶速度,指出它们在结晶速度方面的差异,这些资料对人造奶油和起酥油生产具有实用意义。     

硬段结构对水性聚氨酯胶粘剂结晶性和微相分离的影响

聚氨酯胶粘剂的初粘力和终粘力与聚氨酯的结晶速率和结晶度密切相关。本文以异佛尔酮二异氰酸酯(IPDI)、六亚甲基二异氰酸酯(HDI)、聚己二酸丁二醇酯二醇(PBA)等为主要原料合成了结晶型水性聚氨酯胶粘剂,通过DSC、应力-应变、透光率、吸水率分析,研究了硬段结构对结晶型水性聚氨酯结晶性和微相分离的影响。研究表明,在相同硬段含量下,硬段结构的规整性对水性聚氨酯的结晶度和结晶速度及微相分离有重要影响。室温干燥成膜时,硬段含脂肪环或对称侧基的结晶型水性聚氨酯显示较高的结晶度和微相分离特性;而在高温干燥后的冷却结晶过程中,硬段结构规整的聚氨酯其软段结晶速度更快,结晶度和微相分离程度更高;随着结晶度和微相分离程度的提高,水性聚氨酯膜呈现出明显的屈服点,力学性能提高,吸水率和透光率降低。     

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