黑曲霉固态发酵制备花生蛋白肽及抗氧化活性研究

研究黑曲霉固态发酵制备花生蛋白肽,为进一步研究发酵花生粕的深加工产品提供理论基础。运用单因素和正交试验方法对固态发酵制备花生蛋白肽工艺条件进行优化,其最佳制备工艺条件为:营养盐溶液添加量15 mL,黑曲霉液添加量1 mL,30℃下发酵36 h。此工艺下制备的花生蛋白肽的可溶性氮浓度达到38.74 mg/mL,发酵液对1,1-二苯基苦基苯肼(DPPH)自由基清除率为81.22%,羟自由基清除率为84.88%。分子量小于5 ku的花生蛋白肽具有较高的抗氧化活性。     

酵母固态发酵制备花生蛋白肽及抗氧化活性研究

研究啤酒酵母固态发酵制备花生蛋白肽,为进一步研究发酵花生粕产品提供理论基础。本研究运用单因素和正交试验方法对固态发酵制备花生蛋白肽工艺条件进行优化,其最佳制备工艺条件为:营养盐溶液添加量15 mL,啤酒酵母液添加量4 mL,30℃下发酵72 h。此工艺下制备的花生蛋白肽的可溶性氮浓度达到10.74 mg/mL,发酵液对1,1-二苯基苦基苯肼(DPPH)和羟自由基清除率分别为93.57%和98.40%。分子量小于5 kDa的花生蛋白肽具有较高的抗氧化活性。     

枯草芽孢杆菌发酵牦牛血制备抗氧化肽工艺优化

为优化枯草芽孢杆菌液态发酵制备牦牛血抗氧化肽工艺,以酵解液的羟基自由基(·OH)清除率为主要指标,研究发酵时间、接种量、底物浓度对酵解液抗氧化效果的影响,在该基础上进行响应面优化试验。确定最佳发酵条件为:底物浓度75g/L,接种量2.5%(V/V),发酵时间69.5h。在该条件下制备出·OH清除率为74.48%的牦牛血抗氧化肽,·OH清除率理论值为75.78%,最终发酵上清液多肽含量为2.31mg/mL。     

微生物发酵法制备乳清抗氧化肽的研究

通过筛选得到发酵法生产乳清抗氧化肽的最适乳酸菌菌株,同时以氧自由基清除率为指标研究了接种量、菌种比、发酵温度、初始pH值和时间对液态发酵法生产乳清多肽的影响,并采用正交试验确定了最佳发酵工艺条件.结果表明,接种量5%,菌种比1:1,发酵温度37℃,初始pH值6.4,时间16 h,此时测得乳清水解产物O2-清除率为39.45%,肽质量浓度为2.62 g/L.     

发酵法制备乳清抗氧化活性肽的研究

采用乳酸菌发酵法制备乳清抗氧化活性肽。从发酵菌株的筛选到发酵条件的优化以及多肽抗氧化活性比较方面做系统的研究。采用液态发酵法,以水解度和O2·-清除率为指标,筛选组建二元混菌体系;通过正交试验优化二元混菌体系的发酵工艺条件,以确定最佳发酵时间。试验结果表明,最佳发酵条件:初始pH6.4,发酵温度37℃,接种量5%,在此条件下测得乳清水解产物O2·-清除率为39.45%,最佳发酵时间14h。乳清多肽抗氧化活性的比较结果显示,随着活性肽浓度的升高,其总抗氧化能力、·OH清除率、O2·-清除率、总还原能力都有明显提高,表明乳清多肽具有抗氧化性。     

液态发酵法制备菜籽ACE抑制肽发酵条件优化

以菜籽粕为原料,通过枯草芽孢杆菌液态发酵生产菜籽ACE抑制肽。先以肽得率、ACE抑制率为指标通过单因素试验得到液态发酵的发酵条件,再以响应面法分析法,优化了枯草芽孢杆菌液态发酵的工艺条件,确定枯草芽孢杆菌液态发酵生产菜籽ACE抑制肽的最佳发酵工艺条件为发酵时间,发酵温度和接种量,最佳工艺条件分别为20 h、38℃和1×108个/mL。优化后的菜籽ACE抑制肽抑制率达到70.95%。     

乳酸菌发酵核桃粕制备多肽及其体外抗氧化活性

以核桃粕为原料,乳酸菌作为发酵菌种,通过发酵制备核桃粕多肽并对其抗氧化活性进行研究。首先对发酵时间、发酵温度、接种量3个因素进行单因素试验,在单因素试验的基础上进行响应面优化,得到最佳发酵工艺条件,通过体外抗氧化试验测定多肽的抗氧化能力。结果表明：影响试验的因素大小顺序为接种量>发酵温度>发酵时间。核桃粕多肽产量制备的最佳工艺条件：发酵时间12h,发酵温度37℃,接种量13%,在此条件下,多肽产量达到12.84mg/g,与预测值差异不大,证明该优化工艺可靠,按照优化工艺制备所得核桃粕多肽在质量浓度为10 mg/mL时,DPPH自由基清除率可达82%,具有较强的还原能力。     

羊胎盘多肽的制备及其清除自由基能力的研究

利用黑曲霉、米曲霉、枯草芽孢杆菌作为发酵羊胎盘菌种,筛选出黑曲霉作为发酵羊胎盘的菌株,制备羊胎盘活性肽.通过单因素试验研究了料液pH、碳源含量、发酵时间对制备羊胎盘抗氧化肽工艺的影响,在此基础上,以DPPH自由基的清除率为指标,通过响应面法优化得到了最佳发酵工艺条件为pH值4.61、葡萄糖添加量2.79％、发酵时间76.38h,此条件下的DPPH清除率为83.78％;对发酵液进行超滤处理得到6组分,其中60％的产物分子质量均＜10 000u,不同组分的抗氧化活性大小为分子质量为3 000～10 000u的产物高于分子质量＜3 000u的产物,并得出了发酵液中不同分子质量段的多肽含量分布曲线.     

纳豆菌液态发酵制备蚕蛹肽的工艺优化及其抗炎活性研究

为提高蚕蛹的资源利用率和产品附加值,本研究以蚕蛹蛋白为原料,通过纳豆菌液态发酵制备蚕蛹肽.通过单因素实验和响应面试验确定最佳发酵工艺条件;采用脂多糖诱导RAW264.7巨噬细胞建立细胞炎症模型,对最佳发酵工艺参数组合下获得的蚕蛹肽进行体外抗炎活性研究.结果表明:蚕蛹肽的最佳发酵工艺条件为接种量5.0 mL、蚕蛹蛋白添加...     

液态发酵法生产花生抗氧化肽和中性蛋白酶的工艺优化

以花生粕为原料,采用枯草芽孢杆菌AS1.398进行液态发酵生产抗氧化肽的过程中,可以积累大量的副产物——中性蛋白酶。单因素和中心组合实验结果表明,同时生产抗氧化肽和中性蛋白酶的最佳工艺条件为接种量1%(v/v),pH自然,发酵温度34℃,发酵时间71h,在此条件下,发酵液的理论DPPH自由基清除率为81.51%,中性蛋白酶活力为600U/mL。     

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.