短梗五加果色素稳定性的研究

以短梗五加果为实验材料,结果表明:五加果色素属于花青素类,在525nm波长处有最大吸收峰.光照、高温、高pH可明显加速色素的降解,维生素C及Fe3+、Al3+、Cu2+、Mg2+金属离子对短梗五加色素稳定性的影响不明显.正交实验结果表明,pH对短梗五加色素稳定性的影响最大,其次为温度和维生素C,使短梗五加色素稳定的最佳条件为:pH4.0、0℃冷藏、添加维生素C 0.3mL,短期贮藏时添加维生素C对短梗五加果色素的稳定性有促进作用.     

壳聚糖在桑椹汁澄清中的应用

研究壳聚糖对桑椹汁的澄清作用,测定桑椹汁经壳聚糖澄清后其主要成分含量及色度的变化。结果表明:壳聚糖是一种优良的果汁澄清剂,经壳聚糖澄清的桑椹汁透光率可达85%以上,且果汁中主要营养成分即色素变化不大。同时,经澄清的果汁在低温条件下贮藏5～6个月能保持良好的稳定性。     

高澄清度桑椹果汁饮料加工工艺研究

详细介绍了高澄清度桑椹果汁饮料的加工工艺及关键技术,确定了产品的配方和最佳工艺参数.研究表明:采用-23℃低温速冻,40～50℃温水快速解冻,然后榨汁,再用果胶酶-明胶法澄清,可得高澄清度的桑椹果汁;产品的最佳配方为:桑椹原汁50%、糖酸比25:1、蔗糖用量9%.     

枸杞原汁常温保鲜技术的研究

目的 探讨枸杞原汁生产工艺与常温保鲜技术.方法 按照国标方法测定枸杞营养成分,研究了去籽、去皮、果汁分离、护色、杀菌等工艺条件对枸杞原汁质量的影响.结果 加入0.2%的维生素C和柠檬酸混合添加剂,在高温长时杀菌(80～85℃/20 min).结论 采用此保鲜方法使产品色泽正常,有天然的光泽,保质期长.     

基于降酸处理的高品质调配型猕猴桃果汁饮品工艺研究

本文探讨了碳酸钙(CaCO3)、碳酸钾(K2CO3)、酒石酸钾(K2C4H4O6)三种降酸剂对猕猴桃粗果汁的降酸效果,实验结果表明碳酸钙降酸效果最好,且可保留果汁的原味。调配型猕猴桃果汁饮品制备过程对降酸剂、原汁含量、甜味剂、香精四个重要工艺参数进行研究,正交实验结果表明最佳工艺参数为:降酸剂CaCO3的量为6g/L,原汁浓度为40%,蔗糖含量为6%,1%浓度的猕猴桃香精加入量为7.5mL,此工艺条件下所得调配型果汁饮品品质最优。     

蓝莓果汁饮品配方优化及品质分析

该文采用单因素试验和响应面优化法,研究蓝莓原汁添加量、白砂糖添加量、柠檬酸添加量以及复合稳定剂添加量对蓝莓果汁饮品感官品质的影响,并对最佳配方制备的蓝莓果汁饮品进行理化和微生物指标检测.蓝莓果汁饮品的最佳配方为蓝莓原汁添加量22.88％、白砂糖添加量10.80％、柠檬酸添加量0.15％、复合稳定剂(黄原胶和羧甲基纤维素...     

维生素对竹黄菌发酵产苝醌类色素的影响

采用单因素法研究了生物素、VB1、VB3、VB5、VB6,肌醇对氨基苯甲酸(PABA)和VC对竹黄菌Shiraia sp.SUPER-H168生长及其次级代谢产物苝醌类色素积累的影响。结果表明,添加VB5和VB1可显著促进竹黄菌的生长和色素的积累,菌体量和色素产量分别较对照提高了37.8%和31%,VB5和VB1的较适质量浓度为0.5 mg/L和1.0 mg/L。添加生物素和对氨基苯甲酸可显著提高菌体生长量,但低质量浓度的添加量对色素的积累起抑制作用。添加VB3、肌醇和VC可略微提高色素的产量,较适质量浓度为0.5、0.05、0.05 mg/L。添加VB6虽然可促进菌体的生长,但却抑制了色素的积累。将对色素积累有促进作用的VB3、VB5、肌醇、VB1、VC这5种维生素最优质量浓度下混合添加到5 L发酵罐培养基中,观察了菌体生长和发酵产色素的过程,最终的菌体量和色素产量较对照分别提高了33.7%和75%。     

对影响桑椹酒酿造工艺关键因素的优化

以桑椹鲜果为原料,利用现代发酵工艺与传统技术相结合可获得桑椹酒。通过对桑椹酒主发酵的正交试验分析和明胶澄清试验的选择,实现了对影响桑椹酒的酿造工艺关键因素的优化。结果表明:桑椹果汁中添加SO2含量为50 mg/L、初始含糖量为23%和酵母含量为0.02%可以得到最佳发酵结果。在桑椹酒的澄清工艺试验中,添加0.11%的明胶含量可以获得最佳澄清效果,当大于这个浓度时,原酒的色度将会持续降低,腥味将增大,从而影响桑椹果酒的品质。     

诺丽、葡萄、菠萝复合果汁的研制

以诺丽果(Noni)、葡萄、菠萝原汁进行复合,通过正交试验设计筛选出不添加糖、色素、香精的最佳体积配比为:诺丽汁:葡萄汁:菠萝汁为40:35:28,并在85℃下杀菌10 min.复合果汁营养丰富,风味特殊.     

刺葡萄花色苷色素稳定性研究

刺葡萄皮富含色素,具有良好的开发前景。研究了不同浓度的双氧水、抗坏血酸、亚硫酸钠、山梨酸钾和苯甲酸钠溶液对刺葡萄色素的影响,结果表明:双氧水能与刺葡萄色素发生强烈的氧化作用;抗坏血酸、亚硫酸钠对色素没有辅色作用,反而会加速色素液的褪色,且随浓度的增大,褪色速度加快;低浓度(≤0.05g/mL)的山梨酸钾和苯甲酸钠溶液对色素的影响较小。     

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.