不同茶类酸奶的研制

目的研制茶味酸奶,增加酸奶产品的多样性。方法采用6大茶类为原料,利用响应面优化方法确定茶叶酸奶的最佳配方。结果普洱茶、红茶、白茶、黄茶、绿茶、乌龙茶制作的茶叶酸奶最佳配方为:浸提茶汤茶水比为1:10,浸提温度为90℃,浸提时长为20min;牛奶中茶汤添加量5%,白砂糖添加量8%,菌种接种量2%,发酵时间6 h,发酵温度为42℃时制作的茶叶酸奶品质具佳。结论鲜牛奶中添加5%茶汤,在42℃下发酵6 h制作的茶叶酸奶奶香浓郁,与牛奶融合较好,具有独特口感与茶香,比普通酸奶滋味醇厚。     

乌龙茶酸奶的工艺研究

以乌龙茶和酸奶为主要原料,对乌龙茶汁的提取方法以及乌龙茶酸奶发酵工艺进行研究。对茶汁提取时间、提取温度、料液比和乌龙茶酸奶的菌种接种量、蔗糖添加量、稳定剂添加量、茶汁添加量酸奶的影响因素进行研究,利用单因素试验和正交试验,确定最佳的制作工艺配方。研究结果表明:乌龙茶汁提取条件是温度90℃、时间5min、茶和水的料液比为1:30,牛奶中添加乌龙茶汁量为5%,蔗糖6%,稳定剂添加量0.05%,菌种接种量2%,42℃发酵24h。制作出的乌龙茶带着乌龙茶特有的清香,口感顺滑。     

响应面法优化藜麦核桃酸奶发酵工艺研究

以藜麦、核桃、脱脂牛奶为主要原料,研究藜麦核桃酸奶的发酵工艺。利用单因素与响应面优化试验相结合,确定藜麦核桃酸奶的制备工艺。结果表明,藜麦核桃酸奶最佳生产工艺为：藜麦浆添加量为20.9%、蔗糖添加量为7.0%、发酵剂接种量为3.3%、发酵时间为6.1 h。以此条件进行藜麦核桃酸奶实际制作,感官评分为95.98分,与预测值96.583 5分较一致。     

无花果风味酸奶的研制

本文以牛乳为主要原料,无花果为辅料,制作无花果风味的凝固型酸奶。以感官评分为评价指标,通过无花果汁添加量、蔗糖添加量、发酵剂接种量和发酵时间4个单因素实验和响应面分析确定最佳工艺。结果表明,8%无花果汁添加量、5%蔗糖添加量、0.03%发酵接种量、4 h发酵时间条件下生产的无花果风味酸奶质地细腻,酸甜可口,具有清新甜香的无花果香味,感官评定评分最高,可达到89.8分。     

糯米酒制作凝固型酸奶的工艺研究

试验利用糯米酒制作凝固型酸奶,米酒发酵液的最适灭菌条件为95℃、5min,原料奶总固体物最佳含量16%.对蔗糖添加量、米酒发酵液添加量、发酵温度、发酵时间和发酵剂添加量做单因素试验,以米酒酸奶的感官评价为指标,通过正交试验,得出凝固型米酒酸奶最佳工艺组合蔗糖添加量7%、米酒发酵液添加量18%、发酵剂添加量1%、发酵温度42℃、发酵时间4h.其中米酒发酵液添加量对米酒酸奶品质影响显著.     

玫瑰酸奶的研制

以奶粉为主要原料,添加玫瑰花茶,在单因素基础上进行正交试验,通过感官评定确定玫瑰酸奶的最佳工艺配方。结果表明,影响玫瑰酸奶品质的因素依次为玫瑰花茶添加量、发酵时间、酸奶添加量和白糖添加量。最佳工艺配方:奶粉添加量为10%、白糖添加量为5%、酸奶添加量为5%、玫瑰花茶添加量为1.5%;在40℃条件下发酵4 h后于4℃冰箱冷藏24 h,此条件下制得的玫瑰酸奶品质良好。     

响应面法优化黄芪保健酸奶的工艺研究

通过单因素试验考察了黄芪多糖添加量、蔗糖添加量、菌种接种量、发酵时间对感官评分的影响,再采用响应面法优化黄芪保健酸奶的发酵工艺,最终确定黄芪保健酸奶的最佳发酵条件为:蔗糖添加量10%,黄芪多糖添加量5%,发酵时间为6 h,此工艺条件下制得的黄芪酸奶的感官评分为88分。     

木糖醇石榴汁酸奶发酵工艺研究

以木糖醇为甜味剂,将石榴汁与新鲜牛乳混合进行乳酸菌发酵制成木糖醇石榴汁酸奶。通过单因素试验选取石榴汁、木糖醇及发酵剂接种量3个因素,进行正交试验确定最佳工艺参数。试验结果表明,石榴汁的添加量12%,木糖醇的添加量6%,发酵剂的添加量5%,发酵时间6 h,发酵温度42℃,此工艺条件下制作的木糖醇石榴汁酸奶组织圆润,酸甜适度,口感细腻,并具有淡淡的石榴汁清香。     

紫薯酸奶的研制

以鲜牛奶,新鲜紫薯为主要原料,添加嗜热链球菌和保加利亚乳杆菌,研究搅拌型紫薯酸奶的加工工艺条件。通过单因素试验和正交试验确定制作紫薯酸奶的最佳工艺参数。结果表明,紫薯与鲜牛奶的比例为1∶4,接种量为4%,发酵温度37℃,发酵时间为12 h,白砂糖添加量为9%。此条件下制作的酸奶呈淡紫色,质地均匀一致,具有紫薯和浓郁的乳酸菌发酵酸奶的香味,酸甜可口,口感细腻,柔和。     

甘薯酸奶的工艺研究

以甘薯浆的添加量、复合稳定剂添加量、菌种添加量为参数,采用单因素试验和正交试验对甘薯酸奶的加工工艺进行了研究。最终确定了甘薯酸奶的最佳工艺条件:甘薯浆添加量40%,复合稳定剂添加量0.3%,菌种添加量4%,发酵温度42℃,发酵时间5 h。在此条件下得到的产品,其风味、色泽、组织状态较好。     

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.     

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.     

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.