棉籽油与棕榈硬脂化学酯交换法制备零反式脂肪酸起酥油的研究

通过研究甲醇钠催化棕榈硬脂和棉籽油酯交换反应,以酯交换产物在20℃条件下固体脂肪含量(SFC)为指标,考察了反应温度、催化剂用量、反应时间对酯交换反应的影响。确定的最佳酯交换条件为:反应温度90℃,催化剂用量0.5%,反应时间60 min。通过酯交换产物SFC与市售焙烤型起酥油全统酥油SFC比较以及晶型分析,得出棕榈硬脂与棉籽油质量比为1∶1的酯交换产物,其SFC与市售焙烤起酥油全统酥油相似,结晶形态为β'型,且不含反式脂肪酸,符合零反式脂肪酸起酥油性质要求,适宜用作焙烤起酥油。     

猪油与棕榈硬脂酶法酯交换制备零反式脂肪酸起酥油的研究

研究了固定化脂肪酶Lipozyme RM IM催化猪油和棕榈硬脂酯交换制备起酥油的工艺,考察了反应温度、酶添加量、反应时间对酯交换反应的影响.并以反应后体系在20℃下的固体脂肪含量(SFC)为指标,确定了理想的工艺条件:反应温度60℃,酶添加量8％,反应时间1h.利用等温曲线和X-射线衍射技术研究了混合体系酯交换前后的相容性和晶体形态,结果表明:经酯交换后,混合体系的相容性得到显著改善,晶型由β型转变为β’型,适宜用作焙烤起酥油.     

富含中长链甘三酯起酥油基料油的理化性质研究

将棕榈硬脂(PS)和中长碳链甘三酯(MLCT)以6种不同体积比(2∶8、3∶7、4∶6、5∶5、6∶4、7∶3)混合来制备低热量、零反式脂肪酸的营养功能性起酥油基料油,并对6种起酥油基料油的理化性质进行研究。结果表明:6种起酥油基料油中不含反式脂肪酸,亚油酸含量在18%~36%;随着PS含量增加,起酥油基料油的固体脂肪含量增加,含有30%PS的起酥油基料油的固体脂肪含量符合理想蛋糕用起酥油要求;随着PS含量的增加,起酥油基料油的β'晶型含量增加;起酥油基料油吸热熔化的过程中存在β晶型向β'晶型转变的过程,其量热曲线与脂肪酸组成和甘三酯组成密切相关。     

核桃油与棕榈硬脂复配体系在涂抹脂基料油中的应用

对棕榈硬脂与核桃油复配体系的相容性及结晶性质变化进行探究,考察复配体系在涂抹脂基料油中的应用。结果表明,当核桃油含量达到20%以上时,复配体系的固体脂肪含量(Solid Fat Content,SFC)变化趋势符合涂抹脂的最佳SFC曲线特征,适合用作涂抹脂基料油;在温度高于33.3℃时,核桃油与棕榈硬脂在复配比例(1∶9、2∶8、3∶7、4∶6)下可以完全相容;在核桃油比例达到3∶7以上时,复配体系的屈服值符合涂抹脂的最佳屈服值范围;在温度低于30℃时,棕榈硬脂及复配体系具有较强的晶体网络结构,能在运输和贮藏过程中维持稳定的形态,在接近体温时也能快速熔化,产生涂抹脂类似的口感,复配体系中晶体以β′晶型为主。该结果为棕榈硬脂及核桃油复配体系在涂抹脂中的应用奠定基础。     

巴沙硬脂与6种油脂相容性的研究

利用固体脂肪含量等温曲线(SFC-T)和固体脂肪含量偏差曲线(ΔSFC-T),研究了几种常见的起酥油及人造奶油基料油——巴沙鱼油(BO)、棕榈仁油(PKO)、棕榈油中间分提物(PMF)、猪油(LO)、牛油及棕榈硬脂(PS)与巴沙硬脂之间的二元相容性。结果表明:熔点为53.1℃的棕榈硬脂及熔点为46.8℃的牛油与巴沙硬脂的相容性最好;其他油脂与巴沙硬脂混合时相容性较好的含量范围为棕榈仁油含量10%,棕榈油中间分提物含量10%~40%,猪油含量10%~20%及50%,巴沙鱼油含量10%~20%及50%。     

棕榈油硬脂和棕榈油中间分提物性能及相容性研究

为改善油脂可塑性和口溶性,及为开发以棕榈油产品为主要原料专用油脂产品提供理论依据,研究棕榈油硬脂(PSt)、棕榈油中间分提物(PMF)两者间相容性。测定二元混合体系固体脂肪含量(SFC)值,并通过计算其理论值与实测值之间差值△SFC,结合T–△SFC曲线、二元等温曲线等直观分析,结果表明:PSt与PMF混合物在25℃、PSt含量为30%～50%时,二者间偏晶现象严重;而在35℃～50℃时,二者间共晶现象较为严重;在0℃～10℃和30℃～35℃范围内,二者间具有较好相容性。     

棕榈油基基料油相容性及结晶形态的研究

利用ΔSFC和等固曲线研究了棕榈油硬脂分提物(POs)、棕榈油中熔点分提产物(PMF)及棕榈仁油(PKO)三元混合体系的相容性,并采用偏光显微观察对混合体系的晶体形态进行研究。结果表明:在考察的整个温度区间内所有配方中均出现共晶现象,多数配方在15～25℃区间共晶现象最为严重,但d配方(POs-PMF-PKO,质量比为0.45∶0.45∶0.1)的相容性最好,结合偏光显微观察发现甘油三酯的组成对混合体系的晶形影响显著。     

含山嵛酸低热量油脂的理化特性与功能性质表征

对含山嵛酸低热量油脂的脂肪酸组成、甘油三酯组成、固体脂肪含量(SFC)、熔点、结晶速率、晶型及晶体形态进行研究,结果表明含山嵛酸低热量油脂具有较好的功能特性,不含反式脂肪酸,可作为人造奶油/起酥油的基料油,也可作为烹调油、糖果脂及煎炸油等使用.     

酶促酯交换对棕榈硬脂基塑性脂肪甘三酯组成及物理性能的影响

利用脂肪酶Lipozyme TLIM催化棕榈硬脂(PS)与大豆油(SO)(PS∶SO分别为9∶1,8∶2,7∶3,6∶4,5∶5,wt%)酯交换反应,研究酯交换反应前后混合油脂体系中甘三酯组成的变化及其与油脂物理性能的关系。结果发现,酯交换后油脂中PPP、LLL、POP、PPL、PLL、PLO六种甘三酯含量发生明显变化,其中PPP、LLL含量下降,PPL、PLL、PLO含量增加,而POP除9∶1外,其含量均下降;SSS(S代表饱和脂肪酸)和UUU(U代表饱和脂肪酸)型甘三酯含量下降,而SUU和SUS含量增大,导致油脂熔点和固体脂肪含量(SFC)均不同程度下降,从而可制备不同SFC要求的塑性脂肪。PS∶SO为7∶3、6∶4、5∶5时,酯交换后油脂β'晶型增多,可为人造奶油、速冻专用油脂等塑性脂肪提供理想晶型。     

单棕榈酸山梨糖醇酯对塑型脂肪热性质及机械性能的影响

本研究以棕榈硬脂为基料油,添加1.0%、2.0%、4.0%(质量比)的单棕榈酸山梨糖醇酯(SMP),考察不同浓度SMP的加入对混合油脂固体脂肪含量和热力学性质的影响,并模拟起酥油工业制备过程,考察不同SMP添加量对模型起酥油的质构及流变特性的影响,为工业生产中提高产品品质提供指导。结果表明:SMP的加入起到了稳定混合油脂晶体结构的作用,随着温度升高及SMP浓度的增加,稳定晶体结构的作用越显著,当温度达到33.3℃时,加入4%SMP的混合油脂比棕榈硬脂的固体脂肪含量提高了1.65%。在降温过程中,SMP的加入缩短了混合油脂的结晶诱导时间,1%、2%、4%SMP的加入均可使棕榈硬脂的结晶起始温度提高约5℃。加入2%、4%SMP的模型起酥油样品的质构特性及流变特性变化基本一致,加入2%SMP的模型起酥油硬度和弹性模量比未加入SMP的模型起酥油分别提高了30%和15%。从产品品质及生产成本考虑,加入2%SMP即缩短结晶诱导时间,又有效提高了产品性能。     

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.     

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.