再制干酪的研究

以天然干酪为主要原料，通过对再制干酪加工条件以及乳化剂种类和添加量的优化研究，确定了制造块状再制干酪的工艺流程及主要参数。实验表明，块状再制干酪以车达和高达干酪为原材料，按照不同配比使平均成熟期为5～6个月；乳化剂确定使用焦磷酸钠及多聚磷酸钠的混合盐，添加量为2．5％；产品目标水分为46％，目标pH=5．8～6．0；融化条件为：85～87℃．6．5～7min。产品风味柔和、组织状态细腻，符合消费者的饮食习惯；平均理化指标均符合再制干酪质量标准。     

不同植物油脂对涂抹再制干酪品质的影响

研究以不同种类油脂作为原料油脂制得的涂抹再制干酪产品在品质上的变化。对添加不同原料油脂的涂抹再制干酪硬度、涂抹性、色度和感官方面进行考察并比较。研究发现,添加稻米油、山茶籽油的涂抹再制干酪硬度与对照组硬度接近,与全黄油对照组分别相差10.99%、7.44%。添加稻米油、花生油的涂抹再制干酪涂抹性接近对照组,分别与对照组20.59%、22.57%。其中添加花生油和葵花籽油的涂抹再制干酪ΔE*值与对照组分别相差0.30%、0.28%,在色泽上较接近对照组样品。添加稻米油样品感官总评分高达88.85。但添加花生油样品坚果味明显,添加菜籽油样品异味与苦味明显,添加起酥油产品可涂抹性差,三者接受度低。综合各项结果,稻米油是替代黄油作为涂抹再制干酪原料油脂较好的选择。     

添加大豆分离蛋白对羊乳干酪风味物质的影响

以新鲜羊乳为原料,直投式乳酸菌混合菌种为主发酵剂,费氏丙酸杆菌为次级发酵剂,添加不同比例(0、4%、10%m/m)大豆分离蛋白(soy protein isolate,SPI)制作混合型干酪。完全成熟之后利用固相微萃取(SPME)萃取富集干酪挥发性物质、气相色谱-质谱联用(GC/MS)检测干酪风味物质。以研究添加大豆分离蛋白对干酪风味物质的影响,确定适宜添加比例。实验结果表明:干酪中主要风味物质是酸类,其次是酮,醇,醛,酯类化合物;添加大豆分离蛋白使干酪中酸类、酮类化合物种类及含量明显减少;醇类化合物增加。大豆分离蛋白添加比为4%时,干酪有浓郁的奶香及黄油香气,羊乳膻味减少,并检出苯酚、吡咯等化合物,提高了干酪风味物质种类的丰富性。     

再制干酪加工技术的研究进展

介绍了再制干酪加工技术的研究进展,包括原料干酪的选择、乳化盐的种类及其添加量、加水量、pH等对再制干酪功能性质的影响和再制干酪加工设备及包装的最新进展情况.     

不同植物油脂在再制奶油干酪中的应用

为研究不同种类的植物油脂替代黄油在再制奶油干酪中的应用以及对品质的影响,测定了不同种类植物油脂制作的再制奶油干酪的质构特性、乳清析出率、油脂析出率以及感官评定,并进行比较分析。结果表明,添加玉米油和葵花籽油的奶油干酪硬度与对照组干酪相接近,分别减小了13.29%和增加了3.13%,但总体差异不显著(P0.05)。添加葵花籽油的奶油干酪涂抹性与对照组相比,增加了1.27%,数值上最为接近。在黏聚力和黏着性方面,添加稻米油和椰子油的奶油干酪与对照组相比,差异较为明显(P0.05)。添加玉米油的奶油干酪乳清析出率要优于对照组干酪,而添加其他植物油脂的奶油干酪乳清析出较为严重(P0.05)。添加葵花籽油的干酪的油脂析出率最大,为6.19%,显著高于对照组干酪(1.82%);添加玉米油的奶油干酪的油脂析出率稍大于对照组,但差异不显著(P0.05)。感官分析上,添加植物油脂制作的奶油干酪总得分都低于对照组干酪,由玉米油植物清香风味和黄油的乳香味结合带来的干酪的风味接受度要高于其他植物油脂制作的干酪。综合各项指标,玉米油是替代黄油作为再制奶油干酪原料油脂较好的植物油脂选择。     

钙盐对再制马苏里拉干酪质构的影响

以市售马苏里拉干酪为原料,以硬度、咀嚼性、弹性、胶着性、黏聚性5个性质为评价指标,研究了3种钙盐(乳酸钙、柠檬酸钙、氯化钙)对再制马苏里拉干酪质构的影响。结果表明:添加钙盐的不同种类和添加量对再制马苏里拉质构均有影响且影响不同;3种钙盐对再制马苏里拉干酪质构的影响顺序为柠檬酸钙氯化钙乳酸钙,其最适添加量为乳酸钙1.5%,柠檬酸钙1.0%,氯化钙2.0%。     

涂抹型再制干酪新品的研究

通过对涂抹型再制干酪的原料配合、融化条件、乳化剂、稳定剂种类和添加量的研究，确定其配方和加工工艺。结果表明：涂抹型再制干酪以车达、高达干酪为原材料，按照不同配比使平均成熟期为3个半月；辅料添加浓缩乳清蛋白4．5％～6．5％，黄油8％～10％；溶解盐选择Na4H2PO7为2．1％，Na2HPO4为0.3％；稳定荆选择黄原胶、刺槐豆胶、瓜尔豆胶，按照m黄原胶：m刺槐豆胶：m瓜尔豆胶=2：2：1的比例，添加0.3%;融化温度采用90～95℃；融化过程分2个阶段，第1阶段1500r／min搅拌10min；第2阶段60～80r／min搅拌2min。新品指标为：水分57％～59％、乳脂固形物45％～50％，pHOt05．8～6．0；组织细腻，口感柔软、奶香浓郁，具有良好的流动性和涂抹性。     

重制干酪及其生产工艺

重制干酪，又称融化干酪、加工干酪，系以一种或二种以上不同成熟度的天然干酪为主要原料，经粉碎，添加乳化剂、稳定剂，融化，必要时可加香辛料、调味料，最后冷却，包装而成。重制干酪在二十世纪初，于瑞士首先出现。目前，重制干酪的消费量约占全世界干酪总消费量的60～70％。重制干酪之所以如此普及，在于其风味较温和，并且可以随意调配以迎合不同口味的消费者的需要，又有较好的保存性，取用随意。我国大多数人不习惯食用天然干酪，特别是不喜欢带有强烈风味的某些品种。针对这种状况，上海乳品培训研究中心最新研制出一个新的干酪品…     

凝乳酶对低脂干酪微观结构和功能特性的影响

研究了低脂干酪成熟过程中蛋白质水解程度对干酪本身的微观结构和功能特性的影响.以低脂乳为原料,添加不同剂量的凝乳酶制备低脂干酪,测定干酪不同成熟期的熔度及质量分数为12%的TCA-SN并观察干酪的微观结构.结果表明,在低脂干酪中添加双倍的凝乳酶时可以减少干酪的硬度、增加熔度和改善其感官状态;当添加3倍凝乳酶时将会导致产品比添加正常凝乳酶量时更有胶弹性.因此,添加双倍凝乳酶时能有效改善低脂干酪的质构、功能特性及感官状态.     

蓝纹干酪加工工艺研究

以新鲜牛乳为原料，通过单因素实验和正交实验对蓝纹干酪的加工工艺进行了初步研究，确定了制备蓝纹干酪的工艺流程及参数。新鲜牛乳经添加发酵剂和凝乳酶，凝乳切割，加热，排乳清，入模，盐浴，打孔，经12～14d成熟即得到蓝白相闻的蓝纹干酪。pH值对凝乳质地和霉菌的生长具有显著的影响，添加凝乳酶的最佳pH值为6.1。凝块的加热温度为36℃，保证干酪的硬度，避免干酪打孔后孔隙复合及干酪坍塌。     

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.     

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.     

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.     

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.