酒酿凝乳剂研制干酪初探

研究了采用酒酿代替小牛凝乳酶制作干酪的方法。包括:不同的酒酿用量、凝乳温度、凝乳时间和加热排乳清温度对制作干酪的影响,其最佳工艺参数为:酒酿5%,凝乳温度25℃,凝乳时间15～17 h,加热排乳清温度45℃。     

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。     

山羊乳软质干酪加工技术研究

探讨了山羊乳软质干酪最佳工艺条件。采用正交试验的方法,研究发酵剂用量、凝乳酶用量、凝乳温度对山羊乳软质干酪凝乳时间和感官评鉴的影响,最终确定该产品最佳工艺条件:发酵剂用量2.5%(m/v)、凝乳酶用量0.2%(m/V)、凝乳温度28℃。     

响应面法优化Camembert干酪加工工艺

在氯化钙添加量、凝乳酶添加量、凝乳温度、排乳时间等单因素实验的基础上,根据Box-Behnken中心组合实验设计原理,采用4因素3水平响应曲面分析法,以凝乳效果为响应值建立二次多项回归模型,并验证模型的有效性。实验结果表明：Camembert干酪最佳制作工艺为氯化钙添加量为0．06％,凝乳酶添加量为0．02％,凝乳温度为32℃,排乳时间为30min。在此条件下,理论凝乳效果得分为89．63,验证值为89．50。     

嗜酸乳杆菌发酵生产低脂干酪凝乳工艺的优化

以脱脂乳为原料,采用嗜酸乳杆菌发酵进行预酸化,对其生产的低脂干酪凝乳工艺条件进行了研究。实验选取凝乳pH、氯化钙添加量、凝乳酶添加量、凝乳温度4个影响因素,以干酪产率、乳清中非脂乳固体物质残留量、嗜酸乳杆菌活菌数为指标,采用L₉（3⁴）正交实验进行优化。结果表明,凝乳的最佳工艺参数为凝乳pH6.0,氯化钙添加量0.02%（w/w）,凝乳酶添加量0.01%（w/w,酶活20000u/g）,凝乳温度35℃,以此条件生产的低脂干酪脂肪含量小于5%,干酪产率29.41%,乳清中非脂乳固体物质残留量5.66%,嗜酸乳杆菌活菌数在10⁹cfu/mL以上。     

甜干酪的加工工艺研究

研究凝乳酸度、凝乳温度、氯化钙添加量、凝块切割大小、排乳清温度和糖添加量对甜干酪的产率和凝乳特性的影响.结果表明,甜干酪的最佳加工工艺参数为:凝乳酸度26 °T,凝乳温度42℃,氯化钙添加量为0.018%,凝块切割大小4mm～6mm.排乳清温度44℃～48℃,糖添加量为2%～4%.     

Rhizopus sp.052凝乳酶的部分酶学性质

Rhizopus sp.052在pH1~7范围内,4℃条件下稳定。凝乳酶的最适作用温度为40℃,55℃保持20min完全失去活性,与小牛凝乳酶性质相似,而热失活的温度低于小牛凝乳酶。Rhizopussp.052凝乳酶对热不稳定的特性有利于干酪副产品乳清的加工处理。Rhizopussp.052凝乳酶对酪蛋白的水解能力比蛋白酶低,比小牛凝乳酶高,可以用于干酪的生产。对N-末段15个氨基酸序列GTGSVPVTDYQNDVE进行检索,结果表明,Rhizopus sp.052凝乳酶与其他菌株相比不完全相同,尚未见有研究者对其进行研究和报道。     

中式绿茶硬质干酪工艺的研究

研究了绿茶粉风昧干酪的制作工艺,结果表明,绿茶风昧干酪的最佳工艺条件为绿茶粉加入量1%,原料乳采用75℃,15s杀菌,冷却后加入2%的发酵剂,其中保菌和嗜菌比例为1:2,发酵温度为35℃。当发酵乳pH值至5.8时停止发酵,在发酵乳中加入0.02%的CaCl_2和1.5g/L的混合凝乳酶(动物凝乳酶和微生物凝乳酶比例为4:1),35℃条件下凝乳1h后经排乳清,加盐后熟化得到干酪产品,产品膻味大大降低,出品率为9.78%。     

凝乳酶及其在干酪生产中的应用

凝乳酶是制造干酪过程中起凝乳作用的关键性酶。本文介绍了凝乳酶的一般特性、小牛皱胃酶的代用品及其鉴别，以及凝乳酶在干酪生产中的应用。     

豆奶软质干酪的研制

通过不同豆奶比例、发酵剂添加量、氯化钙添加量对凝乳特性的影响进行研究，确定了豆奶软质干酪的制作工艺为：原料奶-杀菌-冷却（32℃）-混合（加入豆奶比例为20％）-加发酵剂（0．20％）-加氯化钙（0．06％）-加凝乳酶-切割-排乳清-压榨-盐渍-喷霉-熟化（后发酵）-包装，可得口感风味良好的白霉成熟干酪。     

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