复合磷脂酶微乳体系非均相酶法制备甘油磷脂酰胆碱的研究

以磷脂酶A1和磷脂酶A2为复合酶,在非均相微乳体系下酶解制备甘油磷脂酰胆碱(GPC)。在单因素试验基础上,通过响应面优化试验确定最佳酶解条件为底物质量浓度92.10 mg/m L、酶解温度50.46℃、磷脂酶A1添加量12 U/m L、磷脂酶A2添加量12 U/m L、CaCl_2添加量4.50 mg/m L,在此条件下,GPC得率有最优值为95.34%。     

水相体系酶法制备溶血磷脂酰乙醇胺研究

探索了磷脂酶A1在水相体系中酶解制备溶血磷脂酰乙醇胺(LPE)的可行性,并进行了酶解条件对LPE相对含量的影响研究。得到最佳酶解条件为:磷脂酰乙醇胺(PE)的纯度为80%,液料比10∶1,酶解温度35℃,酶添加量0.04 m L/g,Ca Cl2添加量0.010 g/m L,酶解时间30 min。在最佳酶解条件下,得到酶解产物中的LPE相对含量为42.0%。     

酶法制备甘油磷酸胆碱的研究

研究了水相体系中磷脂酶A<,1>水解大豆粉末磷脂制备甘油磷酸胆碱(GPC)的可行性,探讨了反应条件对磷脂酰胆碱(PC)转化率和GPC得率的影响.确定磷脂酶A<,1>催化制备GPC的最佳反应条件为:在pH 7的150 mL磷酸盐缓冲溶液中,粉末磷脂添加量5 g、CaCl2添加量0.50 g、酶添加量0.50 mL,温度55 ℃,反应时间6 h;利用LC-MS分析最佳条件下的反应液,得到PC转化率为98%,GPC得率达到95%;同时验证了在磷脂酶A<,1>催化制备GPC的过程中生成的溶血磷脂(LPC)Sn-2位不饱和脂肪酸发生了酰基转移,转移到Sn-1位.     

响应面法优化酶辅助提取苹果梨渣中可溶性膳食纤维工艺及品质分析

建立纤维素酶辅助苹果梨渣可溶性膳食纤维的最佳提取工艺。以苹果梨渣为原料,首先研究了料液比、酶添加量、酶解时间、酶解温度对得率的影响。在此单因素实验基础上,优化出了纤维素酶辅助提取苹果梨渣可溶性膳食纤维的最佳工艺参数:料液比1∶17(g/m L),酶添加量60U/g,酶解时间7h和酶解温度49℃,此时可溶性膳食纤维的得率为15.31%。然后对所得可溶性膳食纤维持水力、持油力和膨胀力进行研究发现:所得苹果梨渣可溶性膳食纤维持水力4.72g/g、持油力2.39g/g及膨胀力4.46m L/g。     

磷脂酶A1水解卵磷脂的研究靠

研究磷脂酶A1水解卵磷脂的条件,确定最佳的酶解条件为酶解温度50℃,水∶磷脂(w/w)50,反应溶液pH 8.0,酶解时间9h,添加50μL 0.3mol/L Ca2 溶液及100μL磷脂酶A1溶液。     

双酶酶解制备黑小麦麸皮抗氧化肽

采用双酶法分步酶解黑小麦麸皮蛋白制备抗氧化肽,以水解度、肽得率及总抗氧化活性为指标,通过单因素试验及正交法优化其最佳工艺条件。第一步采用碱性蛋白酶酶解的最佳条件为pH 9,时间2 h,温度50℃,酶添加量18000 U/g;黑小麦麸皮蛋白水解度为11.46%,肽得率为38.33%,总抗氧化活性为6.65μmol/g。第二步采用风味酶酶解的最佳条件为pH 6,温度50℃,时间2 h,酶活添加量10000 U/g;此时水解度为22.74%,肽得率为52.36%,总抗氧化活性为8.47μmol/g。     

水相体系酶法制备甘油磷脂酰胆碱的研究

研究了脂肪酶(Thermo4S-3)在水相体系中制备甘油磷脂酰胆碱(GPC)的可行性,并探讨了脂肪酶水解条件对GPC得率的影响。实验结果表明脂肪酶(Thermo4S-3)可以实现豆粉末磷脂的水解反应,具有制备甘油磷酸胆碱(GPC)的工业应用前景。正交实验优化结果如下:反应温度40℃,底物浓度33.3g/L,酶添加量30U/mL,CaCl2添加量2g/L。利用HPLC-ELSD进行定量分析,GPC得率达到96.5%。LC-MS/MS定性分析,GPC的结构与标样分析的一致。     

响应面优化酶法制备磷脂-大豆分离蛋白复合乳化体系的研究

选择天然大豆分离蛋白(SPI)与磷脂构成的复合体系在磷脂酶A2(PLA2)酶解后经乳化,对其乳化活性进行研究。在单因素试验基础上,选定酶解温度、酶解时间和酶添加量对磷脂-大豆分离蛋白复合乳化体系进行响应面分析,建立复合乳化体系乳化活性数学模型。在分析各因素的显著性和交互作用后,确定提高磷脂-大豆分离蛋白复合乳化体系乳化活性的最佳酶解条件为酶添加量3 400U/100 g、酶解时间6 h、酶解温度47℃,该条件下的磷脂-大豆分离蛋白复合乳化体系乳化活性为35.72 m2/g,与未经酶解的磷脂-大豆分离蛋白复合乳化体系相比乳化活性提高了66.14%。     

复合酶法提取石榴皮多糖的工艺研究

对复合酶(纤维素酶、果胶酶和木瓜蛋白酶)提取石榴皮多糖的工艺条件进行研究。以陕西临潼石榴皮为材料,运用正交试验法确定了复合酶的最佳加入量配比。比较了酶解时间、温度、pH以及液料比对多糖得率的影响,通过正交试验确定了最佳酶法提取条件。结果表明复合酶的最佳加入量配比为:纤维素酶120 U/g,果胶酶150 U/g,木瓜蛋白酶90 U/g;提取因素对多糖得率的影响大小为:pH温度时间料液比;最佳酶解提取条件为:浸提时间为120 min、温度为53℃、浸提液pH为4.6、料液比为1:55 g/m L。此条件下石榴皮多糖得率为6.01%。此法可使石榴皮多糖得率比传统水提法提高2倍,是一种提取效率高、温和的多糖提取方法。     

响应面优化纤维素酶法提取桂花多糖工艺及其抗氧活性研究

目的:优化桂花多糖的提取工艺,并评价桂花多糖的抗氧化活性。方法:以桂花多糖得率为响应值,在单因素实验基础上,以液料比、酶解温度、酶解时间、酶添加量为实验因素,采用响应面法建立数学模型,筛选最佳提取工艺条件;采用自由基清除能力体系评价桂花多糖的抗氧化活性。结果:通过二次回归模型响应面分析,影响桂花多糖得率的因素按主次顺序排列为:纤维素酶添加量酶解时间液料比酶解温度;确定纤维素酶解桂花多糖最佳工艺条件为纤维素酶添加量6.0mg/m L、液料比8∶1m L/g、酶解温度55℃、酶解时间80min,在此条件下桂花多糖得率为18.43%,模型方程理论预测值为19.05%,两者相对误差小于5%。桂花多糖具有较强的抗氧化活性,对DPPH和O2-·自由基的半数抑制浓度分别为0.846mg/m L、1.256mg/m L,但与维生素C比较,抗氧化活性较弱。结论:采用响应面法优化得到了桂花多糖的最佳提取工艺,该工艺方便可行,得到的多糖具有较强的抗氧化活性。     

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.     

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.     

Announcing a new international peer-reviewed journal:Food Science and Human Wellness now accepting manuscript submission in English

<正>We are pleased to announce the launch of a new international peer-reviewed journal-Food Science and Human Wellness,ISSN 2213-4530,which is an open access journal,produced and hosted by Elsevier B.V.on behalf of Beijing Academy of Food Sciences.Food Science and Human Wellness is an international peer-reviewed English journal that provides a forum for the dissemination of the