柚皮中几种黄酮类物质的生物活性研究

研究柚皮中不同黄酮类活性成分对小鼠和人肝微粒体细胞色素P450的影响,并探讨与其抗氧化性的关系。结果表明:芦丁和槲皮素的DPPH清除率较高,柚皮苷和橙皮苷的DPPH清除率很低。小鼠肝微粒体经槲皮素、柠檬苦素处理,细胞色素b5和P450活性高于对照组,人肝微粒体试验中橙皮苷组P450的活性高于对照组。柚皮中活性物质对鼠和人肝细胞色素P450酶活性的影响与柚皮中活性物质的抗氧化活性不具备相关性。     

二次回归正交试验优化超声波辅助提取柚皮苷

以柚皮为原料,研究了超声波辅助提取柚皮中柚皮苷的工艺条件,在单因素实验基础上,通过二次回归正交试验优化了超声波辅助提取柚皮中柚皮苷的工艺条件。结果表明:柚皮中柚皮苷最佳提取工艺条件:料液比1∶26(g/mL),pH值11,乙醇浓度70%,超声波频率25kHz,提取温度60℃。在此条件下,柚皮苷提取率可达2.91%。     

柚皮黄酮化合物含量及抗氧活性的研究

采用60%乙醇溶液通过超声波处理提取柚皮中的黄酮化合物.通过定性、定量分析,结果显示：柚皮中含有黄酮、异黄酮和二氢黄酮醇等多种黄酮化合物,总黄酮含量3.148%.利用DPPH法评价柚皮的抗氧活性表明：柚皮中黄酮化合物抗自由基抑制率达79.60%,相当VC和食品抗氧化剂BHT抗自由基抑制率的81.02%和95.44%.     

柚提取物含量测定及其抗氧化、抑菌活性研究

采用水蒸气蒸馏法、超声波辅助溶剂萃取法以及酸提醇沉法分别提取柚叶、柚皮、柚肉、柚籽中精油、总黄酮和果胶,采用气相色谱-质谱(GC-MS)、Na NO2-Al(NO3)3法和咔唑-硫酸法分别对精油成分和总黄酮、果胶含量进行分析。通过精油、总黄酮和果胶的总还原力及清除1,1-二苯基-2-苦基肼(DPPH·)能力的测定实验评价其抗氧化活性,通过滤纸片扩散法评价其抑菌活性。结果表明:柚皮中精油和总黄酮含量最高;柚肉中果胶含量最高;柚皮精油共鉴定出25种化合物,其主要成分为D-柠檬烯(77.96%),β-月桂烯(12.40%)和β-蒎烯(2.14%);柚三种活性成分(精油,总黄酮和果胶)均具有较强的还原力,对DPPH·的IC50(清除率达到50%时的浓度)分别为1.53%、0.07%和0.21%,表现出较强的抗氧化活性;对3种受试菌(大肠杆菌、金黄色葡萄球菌和沙门氏菌)均有抑制活性,且随着物质浓度的增加,对受试菌的抑菌效果逐渐增强。该研究结果为柚资源的合理开发和回收再利用以及生物杀菌剂、天然食品抗氧化剂和防腐剂的开发提供了理论依据。     

柚皮提取物有效成分的研究概况

柚子(Citrus grandis)是芸香科柑橘属水果.柚皮占整个柚子的43%～48%,除含有水分、维生素、矿物质这些人体必需的营养素,还含有多种对人体健康有益的非营养性生理活性成分,如黄酮类化合物、类柠檬苦素、香精油、天然色素、膳食纤维等.本文对柚皮中黄酮类化合物、类柠檬苦素、天然色素、香精油、膳食纤维的化学组成与结构、生物活性、提取方法以及在食品、医药等方面的应用进行了综述.     

柚皮中有效成分综合利用的途径

柚皮含有丰富柚皮苷、类胡萝卜素、果胶和香精油等,具有较高的保健和药用价值,进行柚皮资源的综合利用具有良好的社会效益和经济效益。本文对柚皮中香精油、黄酮类化合物、色素和果胶的作用、应用和提取方法等方面进行了介绍。     

柚皮中有效成分综合利用的途径

柚皮含有丰富柚皮苷、类胡萝卜素、果胶和香精油等，具有较高的保健和药用价值，进行柚皮资源的综合利用具有良好的社会效益和经济效益。本文对柚皮中香精油、黄酮类化合物、色素和果胶的作用、应用和提取方法等方面进行了介绍。     

沙田柚皮中柚皮苷和果胶综合提取工艺研究

本研究利用柚皮苷、果胶性质的差异,探索了沙田柚皮中柚皮苷、果胶综合提取工艺。即先以沙田柚皮粉为原料,采用乙醇法提取沙田柚皮中柚皮苷,起到脱色、除杂的目的,且柚皮中原有的可溶性果胶损失少。再以脱柚皮苷后的沙田柚皮粉为原料,采用酒石酸法提取果胶。酒石酸可高效地催化沙田柚皮中的原果胶发生水解转化为可溶性果胶,此外酒石酸具有螯合钙、镁等金属离子作用,有利于果胶溶出,提高果胶的提取率。研究结果为,以沙田柚皮粉为原料,乙醇法提取柚皮苷的优化工艺为:固液比为1∶10,乙醇浓度为70%,提取温度为40℃,提取时间为60min。以脱柚皮苷的沙田柚皮粉为原料,酒石酸法提取果胶的优化工艺为:提取液pH为1.5,固液比为1∶20,提取温度为95℃,提取时间为2h。     

玉米皮活性成分提取工艺研究进展

玉米皮是玉米加工的主要副产品,含有多种活性成分。文章综述近10年来中国玉米皮中活性成分提取工艺研究进展,展望玉米皮活性成分研究方向,旨在为玉米皮的全面开发利用提供参考。     

柚皮的综合利用

柚子的内外皮中含有香精油、柚皮甙、黄色素和果胶等多种活性成分,具有较高的食用和药用价值。对柚皮资源进行深加工和综合利用,具有良好的社会效益和经济效益。对柚皮所含成分的作用、应用和提取方法等进行了分析及介绍。     

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.     

Focus on China's Paper Industry

In the English section of this issue, 〈China Paper Newsletters〉 will introduce ＂National Development and Reform Commission Issued Announcement for Selection of Major Preliminary Research Projects for the ＇13th Five-Year Plan＇＂, ＂2013 Annual Report of China＇s Paper Industry＂, and news of projects and other policies.     

Listen to downstream & search for innovation

正Nowadays,textile enterprises are all taking efforts in transformation and upgrading,like improving producing capacity and optimizing production structure to face market downturn.It claimed a higher request to the standard of textile equipments.In the upcoming of ITMA ASIA+CITME 2014exhibition,this magazine have interviewed several branch associations and a series of relative enterprises,to summarize industrial developing status