深海鲑鱼皮来源ACE抑制肽的分离及鉴定

为了考察海洋胶原低聚肽中ACE抑制肽的活性和结构,本文以深海鲑鱼皮为原料,采用两步酶解法制备出海洋胶原低聚肽,在对其分子量分布进行分析的基础上,测定了其血管紧张素转化酶(ACE)抑制活性。结果表明,海洋胶原低聚肽中分子量小于1000 u的组分高达90.79%,主要分布在132~576 u范围内,其ACE抑制活性的IC50为1.18±0.12 mg/m L。然后利用反相高效液相色谱(RP-HPLC)对海洋胶原低聚肽进行分离纯化,收集11个组分峰,对其ACE抑制活性进行了测定。结果表明,有7个组分的ACE抑制活性比海洋胶原低聚肽高。最后利用Q-TOF质谱仪对收集的11个组分进行了结构鉴定,并对鉴定出的15个肽段进行了ACE抑制活性测定。结果表明,15个肽段均有一定的ACE抑制活性,其中Ala-Pro(AP)、Val-Arg(VR)、Gly-Arg(GR)的ACE抑制率比海洋胶原低聚肽高,IC50值分别为0.07±0.01 mg/m L、0.35±0.03 mg/m L、0.92±0.85 mg/m L,活性大约是海洋胶原低聚肽的16.86、3.37、1.28倍,是具有较高ACE抑制活性的肽段。     

酪蛋白双酶水解物ACE抑制肽的分离纯化

采用胃蛋白酶和胰蛋白酶依次对酪蛋白进行双酶水解,制备ACE抑制肽。水解物经截留分子质量6ku的超滤膜初步分离,再通过Sephadex G-15进一步纯化,体外测定各分离产物ACE活性的半数抑制质量浓度(IC50值)。纯化得到的各组分经毛细管电泳分析肽谱、Q-TOF LC/MS检测分子质量范围。结果显示：双酶水解产物IC50值为560μg/mL,超滤流出物IC50值为250μg/mL;Sephadex G-15分离得到3个组分,组分Ⅰ的IC50值为123.41μg/mL,含有19个肽段;组分Ⅱ的IC50值为66.67μg/mL,含有14个肽段;组分Ⅲ的IC50值为64.29μg/mL,含有5个肽段。Q-TOF LC/MS测得纯化组分的分子质量范围为400～800u。     

三斑海马蛋白ACE抑制肽的制备及其二级结构的研究

以三斑海马为原料,经碱性蛋白酶酶解,获得富含血管紧张素转化酶(angiotensin I-converting enzyme,ACE)抑制肽的酶解液。酶解液经透析、Sephadex G-25凝胶过滤色谱和反相高效液相色谱得到进一步分离纯化。结果表明,透析产物的IC50值为(0.44±0.26)mg/mL,相比酶解液(0.81±0.12)mg/mL,其ACE抑制活性更强。透析产物经Sephadex G-25凝胶柱分离纯化后,得到3种组分,其中组分F2的ACE抑制活性最强,IC50值为(0.11±0.08)mg/mL。F2经反相高效液相色谱进一步分离后,得到6个具有ACE抑制活性的组分峰,其中组分F2-4的ACE抑制活性最强,IC50值为(0.005 7±0.000 9)mg/mL。经过3步分离纯化后,成功从三斑海马蛋白中分离得到一种活性较强ACE抑制肽:ProAla-Gly-Pro-Arg-Gly-Pro-Ala(PAGPRGPA),多肽分子量为721.39 Da。圆二色谱分析多肽二级结构表明其主要含无规则卷曲。因此,从三斑海马蛋白中分离得到的多肽可能成为营养保健品和抗高血压药品及相关疾病的一种有益成分,且对海马蛋白资源的开发利用具有重要意义。     

坛紫菜降血压活性肽的分离纯化及分子质量测定

用AS.1398 中性蛋白酶酶解制备坛紫菜(Porphyra haitanesis)ACE 抑制肽,并经超滤膜、Sephadex G-15 凝胶层析和反相高效液相色谱(RP-HPLC)分离纯化,纯化产物测定其氨基酸组成,并运用基质辅助激光解吸电离飞行时间质谱(MALDI-TOF-MS)测定分子质量。结果显示：坛紫菜酶解液经超滤分离获得分子质量小于2000D 的组分ACE 抑制活性最高,IC50 为0.73mg/mL;该组分进行Sephadex G-15 凝胶层析分离得6 个组分,组分E 的IC50 最小,为0.67mg/mL。组分E 经RP-HPLC 分离得峰6 对ACE 的抑制率最高,达到89.54%;峰6 再次过RP-HPLC,又洗出2 个蛋白峰,说明峰6 并不是单一物质,还需进行多次反复纯化。测定峰6 的氨基酸组成主要含有Tyr、Val 和Phe,同时采用MALDI-TOF-MS 分析发现有8 个主要的质子峰,信号最强的质子峰为m/z 861.17,有4 个峰聚集在m/z 860 左右,说明峰6 平均分子质量大约为860D,推算出紫菜降血压肽含有3 个Val、2 个Phe、1 个Tyr,N 端为Val,可能的排序顺序有18 种。     

花生分离蛋白水解物中血管紧张素转化酶抑制肽的分离纯化与结构鉴定

利用碱性蛋白酶Alcalase对花生分离蛋白进行水解,制备花生分离蛋白水解物,并测定不同水解时间所得产物对血管紧张素转化酶(ACE)的抑制作用。未水解的花生分离蛋白没有ACE抑制活性,而利用碱性蛋白酶Alcalase水解所得的水解物具有很强的ACE抑制活性,水解30 min时水解物活性最高,其半抑制浓度为(IC50)0.56 mg/mL。通过超滤、Sephadex G-15凝胶过滤层析、反相高效液相色谱(RP-HPLC)、基质辅助激光解吸电离飞行时间串联质谱(MALDI-TOF-MS/MS)和氨基酸组成分析等分析手段从水解30 min所得的水解物中分离鉴定出两种新的ACE抑制肽,氨基酸序列为Gln-Gly-Gly-Ser-Gly-Met-Thr-Leu-Ala-Phe-Pro-Leu-Pro-Lys和Lys-Ile-Phe-Leu-Arg-Leu-Ser,其IC50值分别为10.6μmol/L和36.6μmol/L。     

红松仁清蛋白ACE抑制肽的分离纯化与结构鉴定

为研究酶解红松仁清蛋白中具有血管紧张素转换酶(angiotensin converting enzyme,ACE)抑制活性短肽的组分及其序列,采用超滤、Sephadex G-25、Sephadex G-15及反相高效液相色谱对松仁清蛋白酶解液进行分离纯化,对纯化后样品(组分D2)进行质谱结构鉴定。质谱结果进行从头测序,筛选得到ACE抑制肽Tyr-Leu-Leu-Lys(YLLK),分子质量为535.34 D。该肽经固相合成纯度为99.80%,其半数抑制浓度测定值为0.282 5 μmol/L。     

波纹巴非蛤ACE抑制肽的分离纯化

将波纹巴菲蛤酶解液经过凝胶层析柱(Sephadex G-15)分离收集到4个活性成分,活性最强的ACE抑制率达84.18%(0.5 mg/mL)。将组分4经过离子交换层析柱(SP Sephadex C-25)分离,并收集的高活性成分在可溶性蛋白为0.132 mg/mL ACE抑制率达到46.03%。最后将先后经过凝胶层析柱和离子交换层析柱收集到的ACE抑制率较高的组分通过反向高效液相色谱分析,出现2个洗脱峰,表明分离纯化效果良好。     

碱性蛋白酶酶解魔芋飞粉制备抗氧化多肽

为优化碱性蛋白酶酶解魔芋飞粉蛋白制备抗氧化多肽的条件,采用响应面分析法,以·OH清除率为响应值,研究酶解温度、酶用量、酶解p H值对制备抗氧化肽的影响。此外,还研究了不同分子质量魔芋多肽的抗氧化活性,结果表明:最佳酶解工艺参数:底物质量分数2.25%、温度55℃、酶用量3 228 U/g底物、p H 7.84、水解时间270 min。该条件下抗氧化多肽(18.35 mg/m L)的·OH清除率为73.41%,多肽得率为75.37%。通过Sephadex G-25和Sephadex G-15串联柱分离得到5个多肽组分,其中分子质量为1 500 u和1 000 u的组分抗氧化活性较高,其清除DPPH·的IC50分别为2.82 mg/m L和3.65 mg/m L;清除·OH的IC50分别为9.03mg/m L和14.16 mg/m L;抑制大鼠肝脏自发性脂质过氧化的IC50分别为0.21 mg/m L和0.66 mg/m L;抑制大鼠红细胞H2O2诱导氧化溶血的IC50分别为0.11 mg/m L和0.22 mg/m L。     

超声预处理对金枪鱼皮胶原ACE抑制肽消化稳定性的影响及消化产物的分离纯化、鉴定

以金枪鱼皮为原料,超声预处理后酶解制得高血管紧张素转化酶(Angiotensin converting enzyme,ACE)抑制肽,研究ACE抑制肽的模拟胃肠道消化稳定性,并对消化产物进行分离纯化和鉴定。结果表明,超声处理后不同酶解时间酶解液的ACE抑制活性均有所提高;超声预处理20、40 min后,酶解5 min酶解液的消化产物的ACE抑制活性显著高于其他组(p<0.05)。采用葡聚糖凝胶G-15对E5U20和E5U40进行分离纯化,两组酶解液均可分离为3个组分,其中E5U20组组分2的IC₅₀值最小为0.393 mg/mL。采用半制备高效液相色谱对E5U20组分2进行分离纯化,得到8个组分,其中峰3的IC₅₀值最小为0.102 mg/mL。通过质谱法对峰3进行鉴定,测得峰3序列为GPSGPPGP,来源于α1肽链第842~849的位置,符合高ACE抑制活性的多肽构效特点,目前尚无该氨基酸序列的报道。     

金枪鱼皮胶原蛋白肽分离纯化工艺的研究

采用超滤法、凝胶层析柱法、离子交换法、高效液相分析法等研究金枪鱼皮胶原蛋白肽(TSCP)的分离纯化工艺。结果表明:通过超滤分离分子量越低TSCP组分DPPH·自由基、·OH自由基、超氧阴离子清除率越高,且分子量小于3kDa的TSCP-IV组分的清除率最高,IC50值分别为0.17,0.20,1.64mg/mL。对TSCP-IV进行Sephadex G-25凝胶柱过滤层析后得到4个峰,峰GP-I的得率较高,且峰GP-I对DPPH·自由基、·OH自由基、超氧阴离子的清除率较高,IC50值分别为50.01,86.56,623.75μg/mL。将凝胶过滤组分GP-I经离子交换柱用不同pH值溶液梯度洗脱后得到4个峰,pH 5.61时的洗脱峰IP-II的得率较高,且IP-II对DPPH·自由基、·OH自由基、超氧阴离子清除率较高,IC50值分别为21.59,20.28,121.23μg/mL。用高效液相色谱分析表明,IP-II为纯度较高的金枪鱼皮胶原抗氧化肽段。     

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.     

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.     

低温带皮菜籽粕微粉的不同粒级部分的功能特性

为研究低温带皮菜籽粕微粉的不同粒级部分的功能特性,以经低温脱脂的带皮菜籽粕为原料,经微粉碎后筛分成212~425μm、150~212μm和106~150μm的3个不同粒级的微粉样品,检测这些样品的吸水性、吸油性、乳化性和乳化稳定性、蛋白质体外消化率。结果表明:1 3个不同粒级的微粉样品之间的粗纤维含量存在显著差异,表明三者的结构组成成分有一定差异。23个微粉样品的乳化活性和乳化稳定性随粒度级别的减小而显著增加(P0.01)。33个微粉样品的蛋白质体外消化率随粒度级别的减小而显著增加(P0.01)。4不同粒级带皮菜籽粕微粉样品的吸水性与吸油性受其结构组成物质不同和粒度的双重影响,与粒度的相关性不明显。     

Microbiology of food taints

Fresh and processed foods are often spoilt by the presence of undesirable flavours and odours caused by microbial action. The aim of this paper is to review the current knowledge of microbiologically induced taints that occur in a wide range of foodstuffs, including meats, poultry, fish, crustaceans, milk, dairy products, fruits, vegetables, cereals and cereal products. Examples have been chosen where the compounds responsible for the taint have been identified and sufficient data obtained to demonstrate the involvement of microorganisms. However, in some cases the full identity of the causative organism may not have been elucidated. The types of microorganisms covered by this review include bacteria, fungi, yeasts, actinomycetes and cyanobacteria. Although cyanobacteria do not in general infect foods, their presence in aqueous systems and water supplies can lead to off-flavours in aquatic organisms and processed foodstuffs. Several examples of each of these processes are discussed. Wherever possible, the likely biosynthetic pathway used by the microorganism to produce the offending compound in a foodstuff is indicated.     

Analysis for organic residues from aids to polymerization used to make plastics intended for food contact

Polymers intended for food contact use have been analysed for organic residues which could be attributed to a range of substances employed as polymerization aids (e.g. initiators and catalysts). A wide range of polymers was extracted with solvents and the extracts analysed by gas chromatography-mass spectrometry (GC-MS). The overwhelming majority of substances identified were not derived from aids to polymerization but were oligomers, additives and adventitious contaminants. However, a small number of substances were identified as initiator residues. These included tetramethylsuccinonitrile (TMSN) which was observed in two polymers and it derived from recombination of two azobisisobutyronitrile (AIBN) initiator radicals. Methyl benzoate, benzoic acid, biphenyl and phenyl benzoate were detected in one poly(methyl methacrylate) sample and in two polyvinylchlorides and they are thought to be derived from benzoyl peroxide initiator. TMSN was subsequently targeted for analysis of poly-(methyl methacrylate) plastics using proton nuclear magnetic resonance spectrometry (¹     

Tests of potential functional barriers for laminated multilayer food packages. Part II: Medium molecular weight permeants

Experiments were performed to characterize the kinetics of the permeation of different medium molecular weight model permeants: bisphenol A, warfarin and anthracene, from liquid paraffin, through a surrogate potential functional barrier (25 microns-thick orientated polypropylene--OPP) into the food simulants olive oil and 3% (w/v) acetic acid. The characterization of permeation kinetics generally observed the permeation models previously reported to explain the experimental permeation results obtained for a low molecular weight group of model permeants. In general, the model permeants exhibited behaviour consistent with their relative molecular weights with respect to (a) the time taken to attain steady-state permeation into the food simulant in which they were more soluble, (b) their subsequent steady-state permeation rates, and (c) their partition between liquid paraffin and the OPP membrane.     

The development of reference materials for paralytic shellfish poisoning toxins in lyophilized mussel. I: Interlaboratory studies of methods of analysis

This paper describes the first part of a project undertaken to develop mussel reference materials for Paralytic Shellfish Poisoning (PSP) toxins. Two interlaboratory studies were undertaken to investigate the performance of the analytical methodology for several PSP toxins, in particular saxitoxin (STX) and decarbamoyl-saxitoxin (dc-STX) in lyophilized mussels, and to set criteria for the acceptance of results to be applied during the second part of the project: the certification exercise. In the first study, 18 laboratories were asked to measure STX and dc-STX in rehydrated lyophilized mussel material and to identify as many other PSP toxins as possible with a method of their choice. In the second interlaboratory study, 15 laboratories were additionally asked to determine quantitatively STX and dc-STX in rehydrated lyophilized mussel and in a saxitoxin-enriched mussel material. The first study revealed that three out of four postcolumn derivatization methods and one pre-column derivatization method sufficed in principle to determine STX and dc-STX. Most participants (13 of 18) obtained acceptable calibration curves and recoveries. Saxitoxin was hardly detected in the rehydrated lyophilized mussels and results obtained for dc-STX yielded a CV of 58% at a mass fraction of 1.86 mg/kg. Most participants (14 out of 18) identified gonyautoxin-5 (GTX-5) in a hydrolysed extract provided. The first study led to provisional criteria for linearity, recovery and separation. The second study revealed that 6 out of 15 laboratories were able to meet these criteria. Results obtained for dc-STX yielded a CV of 19% at a mass fraction of 3.49mg/kg. Results obtained for STX in the saxitoxin-enriched material yielded a CV of 19% at a mass fraction of 0.34mg/kg. Saxitoxin could not be detected in the PSP-positive material. Hydrolysis was useful to confirm the identity of GTX5 and provided indicative information about C1 and C2 toxins in the PSP-positive material. The methods used in the second interlaboratory study showed sufficiently consistent analysis results to undertake a certification exercise to assign certified values for STX and dc-STX in lyophilized mussel.     

The Ministry of Environmental Protection Issued "Feasible Technology Guidelines for Pollution Prevention and Control in Wood Pulping Process of the Paper Industry (Trial)" and Two Other Guiding Technical Documents

On December 27t＂, 2013, the Ministry of Environmenta Protection announced that, in order to implement ＂The Environmental Protection Law of the People＇ s Republic of China＂, improve the working system in environmenta protection technologies, and promote technologica advancement in pollution prevention, the Ministry of Environmental Protection sponsored the formulation of three guiding technical documents including ＂Feasible Technology Guidelines for Pollution Prevention and Contro n Wood Pulping Process of the Paper Industry （Trial）＂     

1~(st) Intelli-Tissue~ EcoEc Tissue Machine Supplied by PMP Group Successfully Put into Operation in China

正On April 29th,2014,Intelli-Tissue EcoEc tissue machine supplied by PMP Group successfully put into operation at Hebei Xuesong Paper Co.,Ltd.,this is the first such kind of paper machine of PMP Group in China.