菜籽蛋白水解物及其分离组分抗氧化性研究

本文采用超滤和凝胶过滤色谱技术分离菜籽蛋白的胃蛋白酶和胰蛋白酶混合水解物(PPH),并通过分析其Fe~(2+)螯合能力、Fe~(3+)还原力、DPPH自由基清除能力和氧自由基吸附能力(ORAC),评价了PPH及其分离组分的抗氧化性。结果表明:菜籽蛋白酶水解物中F3组分的Fe~(2+)螯合能力、Fe~(3+)还原力以及DPPH清除能力和ORAC值都最高,F3组分的ORAC值为(2 118.891±77.782)μmol TE/g,是GSH的1.6倍左右,说明F3组分的抗氧化性最强,其余组分也都表现出一定的抗氧化性,其抗氧化性强弱为:F3F4F2F1F5。研究认为,胃蛋白酶和胰蛋白酶组合可有效水解菜籽蛋白获得抗氧化肽,获得的分离组分(尤其是F3)可以作为抗氧剂开发相关功能性食品。     

菜籽蛋白水解物及其膜分离组分的降血压相关活性

应用商业化蛋白酶Alcalase水解菜籽分离蛋白(RPI),并通过膜分离技术将水解物分离成4种不同分子质量大小的多肽组分(<1kD、1～3kD、3～5kD和5～10kD);评价水解物(RPH)和多肽组分的血管紧张素转化酶-Ⅰ(ACE)、肾素抑制活性和氧自由基吸收能力(ORAC)。结果表明:分子质量大小与菜籽肽的氧自由基吸附能力成负相关;<1kD的组分具有最大的ACE抑制活性(抑制率为(83.42±0.35)%)和氧自由基吸附能力;与膜分离组分相比,Alcalase水解物具有最高的肾素抑制活性。研究认为,菜籽蛋白Alcalase水解物及其<1kD的膜分离组分可能作为功能性成分用于降血压相关的功能食品和保健品的开发。     

富锌小麦蛋白水解物制备技术及其理化性质研究

为研究锌-肽螯合物的制备方法,并对其理化性质进行初步探讨,以小麦蛋白（wheat protein,WP）和硫酸锌为原料,对富锌小麦蛋白水解物制备工艺进行优化,并采用光谱分析初步探明螯合位点,考察富锌小麦蛋白水解物的基本理化性质。结果表明,富锌小麦蛋白水解物的最佳螯合工艺条件为锌与蛋白质量比1.7∶1、螯合温度65℃、螯合时间60 min。在该螯合工艺条件下,螯合率可达66.88%;光谱分析初步探明Zn2+可能与肽链上的NH和CH2等基团发生配对反应;理化性质研究表明：与小麦蛋白水解物（wheat protein hydrolysate,WPH）相比,富锌小麦蛋白水解物（WPHZn）的起泡性、泡沫稳定性及溶解性相对较低;WPH-Zn的乳化能力较好。     

酪蛋白水解物中ACE抑制肽分离及氨基酸序列分析

以牛乳酪蛋白为底物,先经胃蛋白酶水解,再经胰蛋白酶水解,从水解物中分离获得血管紧张素转化酶（angiotensin converting enzyme,ACE）抑制肽并确定其氨基酸序列。酪蛋白的双酶水解物经超滤和葡聚糖凝胶色谱分离,分离得到3 个组分,收集高ACE活性抑制效果组分Ⅱ和Ⅲ。采用离子色谱法分析水解片段的氨基酸组成,液相色谱-质谱法分析水解片段的氨基酸序列,采用固相合成法制备获得的短肽片段,用分光光度法检测ACE活性抑制效果。结果表明,组分Ⅱ包含缬氨酸、丝氨酸、脯氨酸、亮氨酸、苯丙氨酸、谷氨酸、天冬氨酸、酪氨酸,共8 种氨基酸,组分Ⅲ包含痕量的丝氨酸和酪氨酸;将组分Ⅱ和Ⅲ经液相色谱-质谱分析,获得8 个片段,其中,αs2-f（56～57）∶YS、αs2-f（98～107）∶YQKFPQYLQY和κ-f（52～61）∶INNQFLPYPY具有ACE活性抑制作用,其IC50值分别为11.89、11.75 μg/mL和421 μg/mL。     

正交试验优化花生肽螯合锌的制备工艺

研究了花生蛋白水解物和锌离子制备肽锌螯合物的工艺条件,以螯合率为评价指标,考察肽与锌的质量比、反应pH、反应温度和反应时间对螯合反应的影响。在单因素试验基础上,采用4因素3水平正交法确定花生肽-锌螯合物的制备工艺。最佳工艺条件:花生肽-锌质量比4∶1、反应体系pH 6.0、反应温度50℃、反应时间40 min。在此条件下,锌的螯合率为57.04%。     

小米米糠蛋白水解物及其膜分离组分的降血压相关活性研究

植物源蛋白肽具有较好的抗氧化和降血压活性,研究采用蛋白酶Alcalase水解小米米糠分离蛋白(MBPI)获得小米米糠蛋白水解物(MBPH),经膜分离技术得到成4种不同分子质量大小的多肽组分。通过氧自由基吸附能力(ORAC)、血管紧张素转化酶(ACE)抑制活性、肾素(renin)抑制活性和体内降血压活性,评价了小米米糠蛋白水解物及其不同分子质量组分抗氧化及降血压活性,鉴定了1 ku组分多肽的氨基酸序列。结果显示,低分子质量小米米糠蛋白水解物具有更好的氧自由基吸附能力和降血压活性,1 ku组分的ORAC值为1 455.41μmol TE/mg,ACE抑制率分为73.667%,肾素抑制率为74%,且在灌胃6 h后降低SHRs的收缩压约37.8 mm Hg;1 ku组分中鉴定出7个小肽序列VALVR、VLER、VVRP、WVGK、FGPK、VLLF和LFGK。研究认为小米米糠蛋白水解物,尤其是1 ku肽组分可能作为功能性成分用于降血压相关的功能食品和保健品的开发。     

菜籽肽的ACE、肾素抑制活性及抗氧化性研究

本研究采用1、3、5、10 ku的超滤膜分离菜籽蛋白嗜热菌蛋白酶水解物(TPH),得到了4种不同分子质量的菜籽肽,研究了各菜籽肽的血管紧张素转化酶-Ⅰ(ACE)抑制活性、肾素抑制活性、氧自由基吸附能力(ORAC)和细胞抗氧化(CAA)活性。结果表明,菜籽肽的分子质量与其ACE抑制活性、肾素抑制活性以及ORAC值有明显的正相关性(P0.05);1 ku的菜籽肽的ORAC值远高于TPH的,其ORAC值(Trolox)高达(4 363.53±45.87)μmol TE/g,是谷胱甘肽(GSH)的2.4倍,其中2个菜籽肽的ORAC值与GSH相当(p0.05);细胞抗氧化试验表明TPH的CAA值最高,为(26.53±1.71)μmol QE/g,其次是1 ku组分,其CAA值是(23.91±0.69)μmol QE/g。研究认为,菜籽蛋白酶水解物及各菜籽肽不仅具有ACE和肾素双重抑制活性,还有一定的氧自由基吸收能力。因此,菜籽蛋白可用于开发降血压制剂或相关功能性产品。     

米发糕胃肠水解物抗氧化性及肽段差异性分析

以籼米粉为原料,三种发酵剂(酵母菌ZSM-001;酵母菌ZSM-001与米根霉ZSM-003;安琪酵母与酒曲发酵剂)制作米发糕,通过凝胶色谱测定其水提物和胃肠水解物分子质量分布,基于液相色谱-四级杆飞行时间质谱(TOF LC/MS/MS)研究肽的差异性,并进行胃肠水解物的抗氧化活性评价。结果表明,米发糕经胃肠水解后,其抗氧化活性提升,分子质量集中在3 ku以下,小分子组分(分子质量3 ku)的Fe~(2+)螯合能力和还原能力较其他组分高。发酵剂组合对米发糕胃肠水解物的肽段数量、疏水性和抗氧化性有显著影响,以安琪酵母与酒曲复合发酵制备米发糕的胃肠水解物中分子质量小于3 ku组分的肽段数最多,疏水性较强,且Fe~(2+)螯合能力最大,还原能力较好。     

反相高效液相色谱法分离菜籽蛋白水解物及其组分清除自由基能力的研究

采用反相高效液相色谱(RP-HPLC)技术分离菜籽蛋白的蛋白酶k水解物(PKH),并通过分析其DPPH·、O-2·、·OH的清除能力和氧自由基吸附能力(ORAC),评价了PKH及其分离组分清除自由基的能力。结果表明:菜籽肽清除DPPH·的能力与其疏水性之间具有显著的正相关性,疏水性最高的组分清除DPPH·的能力与谷胱甘肽(GSH)相当,IC50值为(0.183 8±0.002 1)mg/m L;分离后菜籽肽的O-2·和·OH清除能力虽然有所提高,但是仍然弱于GSH;4个分离组分的ORAC值高于PKH,其中2个组分的ORAC值与GSH的相当,1个组分(F7)的ORAC值是GSH的1.5倍,其ORAC值(Trolox)高达(2 413.41±162.98)μmol/mg。研究认为,基于疏水性的RP-HPLC分离显著提高了菜籽肽清除自由基的能力,获得的分离组分(尤其是F7)可以作为抗氧剂开发相关功能性食品。     

抗氧化性玉米肽的分离纯化及其性质

对玉米蛋白水解物中抗氧化组分进行分离提取以及结构鉴定,探讨水解物中抗氧化组分与其性质的相关性。采用超滤和反相高效液相色谱方法,对酶解4h的玉米蛋白水解物进行分离,并采用DPPH自由基清除法测定分离过程各个组分的抗氧化活性。结果表明：玉米蛋白水解物的抗氧化活性与其分子量以及疏水性具有相关性。分离纯化获得3个纯组分经Waters Platform ZMD 4000质谱仪分析和Biolynx软件处理,结合蛋白质SWISS-PROT数据库中玉米蛋白序列获得两个确定抗氧化性玉米肽结构,分别为Tyr-Ala和His—Cys-Met—Leu．     

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.