红枣澄清汁加工工艺的研究

为了制备澄清透明且营养丰富的红枣汁,将干红枣经果胶酶解浸提,得到红枣汁。采用果胶酶和壳聚糖分别对红枣汁进行澄清处理,以透光率为指标,比较两种方法的澄清效果。对两种澄清方法进行正交试验的极差分析和方差分析,结果表明,壳聚糖的澄清效果更好。确定了壳聚糖澄清红枣汁的最佳工艺条件为:壳聚糖添加量为0.02%,50℃下澄清1h,所得澄清汁的透光率达到95.6%。清汁与原汁相比,汁液清澈透明、色泽自然。总糖含量提高,总酸含量无明显变化。     

红枣汁澄清工艺研究

以枣汁透光率、色差、贮藏稳定性变化为指标,在比较壳聚糖、硅藻土、膨润土等对红枣汁澄清效果的基础上,重点研究壳聚糖澄清红枣汁的工艺,并对澄清前后枣汁的主要化学成分和功能成分的变化进行测定.结果表明:壳聚糖的澄清效果优于硅藻土和膨润土,经壳聚糖处理的枣汁透光率可达91.5％以上、贮藏期间透光率变化很小、L值为58.38±0.40;壳聚糖澄清处理后总糖和可溶性固形物基本不变,黄酮、VC和环磷酸腺苷等功能成分的损失率小于10％,易使果汁产生浑浊的果胶和蛋白质的减少率分别为79.20％和49.32％.     

红枣汁澄清工艺研究

为制备稳定、澄清透明且营养丰富的红枣汁,将干枣经果胶酶浸提后得到红枣汁。用果胶酶、壳聚糖、硅藻土和膨润土澄清处理红枣汁,以透光率、色泽、贮藏稳定性为指标,比较其澄清效果,研究澄清工艺,并比较澄清前后枣汁的主要营养成分。结果表明:壳聚糖处理后的枣汁,其透光率可达98%以上,亮度最强,L值为51.15±0.16,贮藏一个月后浊度最低,为0.88±0.04;壳聚糖澄清处理后可溶性固形物、总糖和V_C含量保存率较高,均在90%以上。     

壳聚糖在红枣汁澄清中的应用

在采用壳聚糖澄清红枣汁中，研究了壳聚糖用量、温度、pH对澄清效果的影响。结果表明：壳聚糖澄清枣汁透光率可达98％以上，清汁与原汁相比，VC含量、可溶性固形物含量稍有下降。总糖含量变化不明显，其澄清优化工艺条件是壳聚糖用量3％(1％壳聚糖醋酸溶液)、温度45℃、pH3．5。     

不同的处理方法对红枣汁澄清效果影响的研究

探讨了采用果胶酶-滤纸结合法、果胶酶-单宁明胶结合法、果胶酶-皂土结合法3种澄清工艺技术制取红枣清汁的方法,通过对比确定了较好的澄清方法和最佳工艺条件。试验表明皂土的澄清效果最好。皂土澄清红枣汁的最佳工艺条件为：皂土添加量1.3g/L、澄清12h。所得的红枣清汁澄清透亮,枣香浓郁,呈现出自然的枣红色。     

鲜灵武长枣酒澄清工艺的研究

以宁夏灵武长枣为原料,对鲜灵武长枣鲜枣汁发酵酒发酵工艺和澄清工艺进行了研究。采用正交试验,优化发酵工艺过程中的关镑陛因素,得出生产红枣酒的最佳发酵工艺条件;对澄清剂进行了单因素及复配实验,选择出最佳的澄清方法。鲜枣汁经发酵、澄清后得到最终获得了一种色、香、味、外观俱佳的高品质鲜枣汁发酵酒。     

不同澄清剂对红枣汁的澄清效果的工艺研究

以新疆大红枣为原料,利用果胶酶酶解技术和壳聚糖的电解质作用对红枣汁的澄清效果进行研究,根据处理时间、处理温度、料液比及pH值的不同进行试验,利用单因素试验方法,分别研究果胶酶、壳聚糖对红枣汁澄清效果的影响,再进行果胶酶和壳聚糖的正交试验以确定最佳的工艺条件。试验结果表明:果胶酶添加量7 m L,温度50℃,时间2 h,固液比为1∶5(g/mL)澄清效果最佳。壳聚糖添加量0.02 g,温度50℃,时间30 min,pH值为3澄清效果最佳。     

红枣保健汁及壳聚糖保鲜技术的应用

应用果胶酶酶解技术,对红枣中营养及生理活性成分进行浸提,并利用壳聚糖保鲜技术对所得枣汁进行保鲜试验.通过澄清正交试验得到适宜的澄清剂用量为:果胶酶0.2%,明胶0.5%,单宁0.1%.壳聚糖用量1%时保鲜效果最佳.     

红枣葡萄果酒酿造工艺研究

以红枣和葡萄为主要原料,对红枣汁和葡萄汁混合酿酒的发酵工艺进行研究和对比澄清剂澄清效果。通过单因素、正交试验确定出红枣葡萄果酒的最佳酿造工艺条件为:葡萄汁、红枣汁的比例为3∶1(体积比),酵母添加量为3.0%,发酵温度为24℃,并用明胶和皂土混合澄清剂进行澄清效果最佳,透光率达到99.7%。在该工艺条件下酿造的红枣葡萄果酒浓馥幽雅,酒体丰满,风格独特,是集营养和保健功能于一体的天然饮品。试验研究结果可为实际生产优质红枣葡萄果酒提供理论依据。     

酶糖结合法制备红枣澄清汁

以红枣为原料,采用果浆酶和壳聚糖结合法制备红枣澄清汁,利用分光光度法进行检测以确定最佳实验条件。结果表明:果浆酶的最佳酶解条件为酶用量0.03%,温度30℃,酶解时间3 h;壳聚糖的最佳澄清条件为壳聚糖用量2.0%、温度为45℃、澄清时间为45 min,可制得73.54%透光率的红枣澄清汁。     

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.     

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.     

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.     

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.     

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.