不同方法提取鮟鱇鱼皮胶原蛋白的比较和分析

为高效获得胶原蛋白,以鮟鱇鱼鱼皮为原料,以风味蛋白酶添加量、碱性蛋白酶添加量、超声时间、酶解时间、酶解温度和pH值为试验因素,采用超声-双酶法和双酶法提取胶原蛋白,利用正交试验确定胶原蛋白的最佳提取工艺并对结果进行比较分析,得出较好的提取方法。结果表明,超声-双酶法提取胶原蛋白最佳提取工艺为:风味蛋白酶添加量3 000 U/g,碱性蛋白酶添加量5 000 U/g,超声时间70 min,酶解时间5 h,酶解温度50℃,在此条件下得到胶原蛋白提取率为(8.86±0.64)%;双酶法提取胶原蛋白最佳提取条件为:风味蛋白酶添加量5 000 U/g,碱性蛋白酶添加量5 000 U/g,酶解温度55℃,p H8.0,在此条件下得到胶原蛋白提取率为(4.55±0.20)%,其中风味蛋白酶添加量比超声-双酶法多2 000 U/g,且胶原蛋白提取率比超声-双酶法低4.31%。综上可知,选取超声-双酶法提取鮟鱇鱼皮胶原蛋白。     

虾加工副产品中虾油提取工艺研究

通过比较碱性蛋白酶、中性蛋白酶、风味蛋白酶、复合蛋白酶和胰蛋白酶对虾加工副产品的酶解,确定风味蛋白酶作为最佳水解酶,并确定其起始pH值为6．5,考察了酶添加量、料液比、酶解时间和温度对虾油提取率的影响,确定最优工艺：酶添加量1．0g／100g,料液比1g：8mL,酶解时间2．5h,酶解温度50℃。     

超声波辅助酶解提取鮟鱅鱼皮胶原蛋白的工艺优化

以鮟鱇鱼皮为原料,以料液比、超声时间、加酶量、酶解时间、酶解温度、提取pH为实验因素,用超声-风味酶法和超声-碱性酶法分别提取,并利用正交试验确定鮟鱇鱼皮胶原蛋白最佳提取工艺。结果表明,超声-风味酶法提取鮟鱇鱼皮胶原蛋白的最佳提取工艺条件为:超声时间80 min,酶解时间5 h,风味蛋白酶5000 U/g,酶解温度40℃,在此条件下胶原蛋白提取率为3.54%±0.21%;超声-碱性酶法提取鮟鱇鱼皮胶原蛋白的最佳提取工艺条件为:超声时间80 min,酶解时间6 h,碱性蛋白酶4000 U/g,酶解温度45℃,在此条件下胶原蛋白提取率为3.25%±0.68%,其中酶解时间比超声-风味酶法多1 h,但胶原蛋白提取率却不及超声-风味酶法。综上,选取超声-风味酶法提取鮟鱇鱼皮胶原蛋白。     

响应面法优化面包果淀粉的酶法提取工艺

为确定酶法提取面包果淀粉的最佳工艺条件,采用中性蛋白酶法提取面包果淀粉,探讨了料液比、酶解温度、酶解时间、加酶量四个因素对面包果淀粉提取率的影响。在此基础上,利用响应面法优化了面包果淀粉的提取工艺。结果表明:面包果淀粉的最佳提取工艺参数为:料液比1:4 g/mL,酶解温度62 ℃,酶解时间6 h,加酶量0.13%。在最佳条件下,面包果淀粉的提取率理论值为69.66%,实际验证值为69.97%,拟合模型与实际验证吻合。中性蛋白酶法是一种高效提取面包果淀粉的方法,具有应用于面包果淀粉工业提取的潜力。     

酶法提取茶叶籽中蛋白质工艺优化

研究酶制剂的种类、用量、酶反应温度、pH值、酶反应时间、料液比等因素对茶叶籽中蛋白质提取的影响,通过正交试验,获取最佳的提取工艺条件。结果表明,茶叶籽蛋白的等电点为pH3．6,碱性蛋白酶对茶叶籽粗蛋白的提取效果最好,各因素对提取率影响的次序为：酶反应时间〉pH〉酶反应温度〉碱性蛋白酶添加量;酶法提取茶叶籽蛋白最佳工艺条件为：料液比1：25、碱性蛋白酶用量200U／g、PH值为10．0、酶反应温度40℃、酶反应时间45min,在此条件下,茶叶籽蛋白提取率达到83．04％。     

水酶法同时提取核桃仁油脂及水解蛋白的工艺研究

本试验主要研究了水酶法提取核桃油的酶解工艺。试验首先对α-淀粉酶、中性蛋白酶、以及淀粉酶与中性蛋白酶组成的复合酶的酶解效果进行了比较,确定中性蛋白酶的酶解效果最佳。在确定中性蛋白酶的作用下,研究了酶解温度、pH、酶的添加量、固液比对油脂提取率的影响。最后通过正交试验得出水酶法提取核桃油脂的最佳工艺条件为:酶解温度60℃,蛋白酶添加量为1.5%(m/m),酶解pH为6.0,料液比1∶4,核桃的油脂提取率可达到34.0%,各因素对油脂提取率的影响主次顺序为:固液比酶解pH酶解温度酶的添加量。在油脂提取的最佳工艺条件下,核桃水解蛋白的提取率可达12.37%。     

碎米淀粉分步制取工艺优化

以稻谷加工副产物碎米为原料提取淀粉,通过单因素试验和正交试验,以碎米淀粉提取率和纯度为指标,用碱法浸提、超声波协同碱性蛋白酶法提取碎米淀粉,得出最佳工艺条件为:超声波处理25min,加酶量5mg/g,酶解时间2h,酶解温度45℃,固液比1:4(g/mL),该条件下淀粉提取率达98.56%,纯度达99.13%。     

苦荞麦蛋白质的酶提工艺研究

用酶法对苦荞麦蛋白质的提取进行研究,比较酸性、中性及碱性3种蛋白酶的提取试验,结果显示碱性酶的提取效果最好。采用单因素试验,测定了酶法提取的加酶量、提取时间、温度、料液比和pH值对苦荞麦蛋白质提取效果的影响,通过正交试验,确定碱性酶提取苦荞麦蛋白质的优化工艺为:加酶量0.3%,温度55℃,料液比1∶11(g/mL),pH=10,提取4h,蛋白质提取率为82.57%。     

牛蒡菊糖酶法提取

采用固定化酶法提取牛蒡菊糖。结果表明酶水解提取牛蒡菊糖的最佳工艺为：13.5g/100mL 中性蛋白酶、pH 7、固液比1:15、50℃、酶水解6h,菊糖提取率为14.57%;固定化酶制备最佳工艺为：以甲醛(40%):NaOH(2mol/L)=2:3 为凝结液、pH7.5、壳聚糖2.5g/100mL、60℃、加酶量7.5mg/mL,固定8h,酶活力回收率可达到39.13%;固定化酶提取牛蒡菊糖最适条件为：pH7、固液比1:15、60℃、固定化酶加入量13. 5 g/100mL、酶解5h,在此条件下菊糖提取率达到12.89%。固定化酶的稳定性与游离酶相比有显著的提高,连续反应10 次后,固定化酶仍然具有良好的使用性能,此时牛蒡菊糖的提取率为9.42%。     

碱性蛋白酶提取大米水解蛋白的研究

研究了用碱性蛋白酶提取大米水解蛋白的工艺,分析了温度、pH值、加酶量、液固比、提取时间对蛋白质提取率的影响,并用响应面分析法优化了碱性蛋白酶提取大米水解蛋白的工艺条件,确定了工艺参数。其最佳工艺条件为:温度58.9℃、pH值8.77、加酶量(E/S)0.89%、液固比8∶1、提取时间4 h。     

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.