双斑东方鲀在冷藏保鲜过程中的水分迁移与品质变化

为研究双斑东方鲀在冷藏过程中水分变化和品质劣变之间的相关性,本实验以新鲜双斑东方鲀为研究对象,将其分别置于4、0 ℃下贮藏11 d,隔天进行物理（剪切力、咀嚼性、色差值、持水性、低场核磁T₂弛豫时间）、化学（pH、挥发性盐基氮值、鲜度K值）和微生物指标（菌落总数）的测定,并运用低场核磁共振技术（LF-NMR）结合主成分分析评估其货架期。结果表明,随着冷藏时间的延长,4、0 ℃组鱼肉的剪切力、咀嚼性、L*值、持水性、T₂₁（结合水）和T₂₃（自由水）含量均呈下降趋势;pH、菌落总数（TVC）、挥发性盐基氮值（TVB-N）和鲜度（K值）则不断增加;相关性分析结果显示:T₂₁和T₂₃含量与pH、TVC、TVB-N和K值呈极显著负相关（P<0.01）,T₂₂与TVC和K值显著相关（P<0.05）;主成分分析（principal components analysis,PCA）分析结果显示,双斑东方鲀在0、4 ℃条件下分别于第5和第7 d开始发生腐败变质,与理化指标的分析结果一致。综上,通过LF-NMR结合PCA分析可以更直观的分析双斑东方鲀冷藏过程中的水分分布与其品质之间的相关性,可较好区分不同贮藏期间双斑东方鲀水分及品质变化情况,因此,可考虑运用LF-NMR结合PCA分析技术快速检测双斑东方鲀在冷藏期间品质及新鲜度变化。     

双斑东方鲀在冷藏保鲜过程中挥发性风味物质的变化

以双斑东方鲀鱼肉为研究对象,采用电子鼻及顶空固相微萃取-气相色谱-质谱（headspace solid phase microextraction-gas chromatography-mass spectrometry,HS-SPME-GC-MS）联用技术对冷藏（0 ℃和4 ℃）过程中双斑东方鲀鱼肉挥发性风味物质的种类和相对含量进行分析,探索鱼肉在冷藏过程中挥发性物质的变化规律。结果表明：双斑东方鲀在4 ℃和0 ℃条件冷藏1～3 d模糊数学感官评分较高,分别在7 d和9 d达到消费者可接受上限;电子鼻传感器响应值的主成分分析（principal component analysis,PCA）与线性判别分析能够对不同冷藏时期鱼肉中挥发性风味物质进行差异性分析,且分析结果与HS-SPME-GC-MS检测结果具有一致性。利用HS-SPME-GC-MS技术共检出48 种挥发性物质,包括烃类、醇类、醛类、酯类、芳香族化合物和含氮含硫杂环化合物,新鲜鱼肉具有鱼腥味、清新气味,冷藏11 d后,鱼肉的腥味增强,哈喇味、酸臭味加重,醛类和含氮含硫杂环化合物是导致其风味劣变的主要挥发性风味物质;结合气味活性值分析发现1-辛烯-3-醇、己醛、辛醛、壬醛和2,3-辛二酮是鱼肉在冷藏过程中的主要关键风味物质;使用PCA法构建挥发性风味物质综合评价模型为T=0.83T1＋0.15T2,评价结果与感官评价结果呈极显著负相关（P＜0.01）。由此可见电子鼻结合HS-SPME-GC-MS可用于双斑东方鲀在冷藏过程中的挥发性风味物质的区分与判别,可为研究不同冷藏时期的双斑东方鲀鱼肉风味变化提供理论参考。     

基于电子舌技术的鱼新鲜度定性、定量分析

为实现鱼新鲜度的快速定性、定量分析。采用电子舌技术对4℃下不同冷藏天数的鲳鱼进行检测。同时测量鲳鱼体内挥发性盐基氮(Total volatile basic nitrogen,TVB-N)含量及细菌总数(Total viable count,TVC)。对电子舌数据进行分析处理,构建了K最近邻(K-nearest neighbor,KNN)判别模型和BP人工神经网络(Back-propagation artificial neural network,BP-ANN)模型定性评价鲳鱼新鲜度。结果显示,KNN模型的训练集、测试集识别率分别为:99.11%和98.21%;BP-ANN模型的训练集、测试集识别率分别为:92.86%和91.07%。构建了电子舌数据和TVB-N及TVC之间的支持向量机回归模型对鲳鱼新鲜度进行定量评价,独立样本检验结果显示,对TVB-N及TVC的预测,支持向量机回归模型的预测值和实测值的相关系数分别为:0.9727和0.9457,预测均方根误差分别为2.8×10-4 mg/g和0.052 log(CFU/g)。可见三种模型均能达到较好的效果。研究表明:电子舌技术在鱼新鲜度的快速定性、定量评价中具有很大的潜力。     

基于粒子群优化算法优化反向传播神经网络构建冷藏草鱼新鲜度的近红外光谱预测模型

目的 构建基于各种机器学习算法结合近红外光谱的模型，从而确定出更准确预测冷藏草鱼新鲜度的方法。方法 采集连续冷藏6 d的草鱼片的新鲜度指标, 并进行方差分析。选择受冷藏天数影响最大的指标: 总挥发性盐基氮(Total volatile basic nitrogen, TVB-N)进行定量预测。运用x-y距离结合的样本划分(sample set partitioning based on joint x-y distance, SPXY)方法进行数据集的划分, 并采用正交信号校正法(orthogonal signal correction, OSC)、Savitzky-Golay (SG)、一阶导数及其组合算法进行光谱预处理。再运用竞争性自适应重加权采样(competitive adaptive reweighted sampling, CARS)、连续投影算法(successive projections algorithm, SPA)、主成分分析(principal component analysis, PCA)对光谱变量进行选择和降维。最后结合偏最小二乘回归(partial least squares regression, PLSR)、反向传播神经网络(back propagation neural network, BPNN)和粒子群优化算法(particle swarm optimization, PSO)优化BP神经网络(PSO-BP)建立草鱼(Ctenopharyngodon idella)片新鲜度定量预测模型。结果 各线性和非线性模型均得到了良好的预测效果, 预测集相关系数均超过了0.95。PLSR表现较为稳定, BP神经网络虽提高了校正集预测性能, 但是预测集性能不如PLSR。PSO-BP既保证了校正集预测性能, 也提高了预测集性能。基于OSC+D1预处理和CARS变量选择后的PSO-BP模型性能最优(R2P=0.987, 预测集的均方根误差为0.108, 相对分析误差为7.778)。结论 基于PSO-BP算法和近红外光谱结合的定量预测模型, 可以很好的预测冷藏鱼肉的新鲜度指标。     

四种河鲀鱼皮和鱼肉的营养成分分析与评价

对菊黄东方鲀Fugu. flavidus、双斑东方鲀Fugu. bimaculatus、红鳍东方鲀Fugu. rubripes和暗纹东方鲀Fugu. obscurus鱼皮和鱼肉的营养成分进行分析和评价。结果显示,4种河鲀具有较高的蛋白质含量、较低的脂肪含量,鱼肉的蛋白质质量较好,而鱼皮含有较高的微量元素,更具鲜甜风味。其中,鱼皮的粗蛋白质含量(20.17%～37.61%)高于鱼肉(18.13%～23.27%),菊黄东方鲀最高,但是鱼肉的∑EAA/∑TAA(39.01%～43.11%)、∑EAA/∑NEAA(65.26%～71.57%)和EAAI(0.75～1.00)高于鱼皮(16.61%～20.49%、19.78%～25.70%和0.25～0.51),且符合FAO/WHO标准,双斑东方鲀的含量最高;鱼皮(0.20%～0.40%)和鱼肉(0.21%～0.4%)的粗脂肪含量均较低,鱼肉的∑FA(0.28%～0.39%)、w-3 PUFA(0.05%～0.15%)和w-6 PUFA(0.01%～0.09%)含量高于鱼皮(0.15%～0.24%、0.02%～0.03%和0.01%～0.04%),其中红鳍东方鲀的w-3 PUFA含量最高;菊黄东方鲀鱼皮含有较高的Ca含量(1737.47 mg/100 g),双斑东方鲀鱼肉含有较高的K含量(439.00 mg/100 g),红鳍东方鲀含有最高的Zn含量(0.90 mg/100 g和8.93 mg/100 g)。研究表明,4种河鲀均是高蛋白低脂肪的经济鱼类,氨基酸、脂肪酸和矿物质元素丰富、比例均衡、营养价值较高。     

基于电子鼻和电子舌技术的鳕鱼鲜度评定

对不同储藏时间鳕鱼的气味和浸出液的滋味分别进行电子鼻和电子舌的分析,通过对数据进行PCA、DFA和负荷加载分析,并结合挥发性盐基氮(TVBN)和菌落总数(TVC)的分析,建立一种基于电子鼻、电子舌技术判别鳕鱼新鲜度的方法。结果表明:随着贮藏时间的延长,鳕鱼鱼肉的气味、滋味变化能被电子鼻、电子舌区分出来,且电子舌的DFA三维图谱的区分度更高。二者的分析结果与TVBN、TVC结果一致。因此,可以用电子鼻和电子舌来区分不同鲜度的鱼肉,电子舌的区分度要高于电子鼻。     

可见/近红外技术与感官评价信息融合预测冷藏条件下罗非鱼TVB-N的研究

应用可见/近红外光谱技术与感官评价信息融合实现冷藏条件下有鳞罗非鱼不同部位鱼肉挥发性盐基氮(TVB-N)的预测。通过便携式近红外光谱仪采集有鳞罗非鱼胸部、中部和尾部鱼肉在340~1063 nm的光谱数据,分别采用卷积平滑法、变量标准化、一阶(1st Der)和二阶(2nd Der)导数进行光谱预处理,利用连续投影算法(SPA)提取罗非鱼不同部位鱼肉的特征波长,建立鱼肉光谱与TVB-N偏最小二乘回归(PLSR)模型,结果表明尾部鱼肉的1st Der-SPA-PLSR模型预测均方根误差(RMSEP)=1.1295 mg/100 g,预测相关系数(Rp~2)=0.8998,预测结果高于其胸部和中部鱼肉模型,并稍高于尾部鱼肉全波段模型。因此,选择尾部鱼肉作为罗非鱼光谱采样区域。为进一步提高模型预测准确性,将尾部鱼肉特征光谱数据与感官评价进行信息融合。通过对比尾部鱼肉光谱、尾部鱼肉光谱与感官评价融合的SPA-PLSR、SPA-BP神经网络和SPA-偏最小二乘支持向量机(LS-SVM)模型,结果表明,尾部光谱和感官评价信息融合的SPA-LS-SVM模型预测结果为RMSEP=0.9701 mg/100 g,Rp~2=0.9255,能更准确预测罗非鱼冷藏条件下TVB-N变化。为冷藏过程中罗非鱼新鲜度预测方法提供了新的思路。     

近红外光谱技术快速检测紫薯半干面中菌落总数及新鲜度

利用近红外光谱分析技术和化学计量学分析方法,对紫薯半干面菌落总数(TVC)及其新鲜度鉴别进行研究。结合偏最小二乘法对比10种光谱预处理方法,建立紫薯半干面的TVC预测模型,最终选定SNV+2D为最优预处理方法。经优化TVC最优模型的校正集和预测集的决定系数R分别为0.99213和0.97537,交互验证均方根误差及预测集均方根误差分别为0.250和0.445。采用主成分分析结合马氏距离的定性判别分析法,定性鉴别紫薯半干面新鲜程度。当选用标准归一化为光谱预处理方法时,正确识别率达到100%。利用近红外光谱分析技术可以快速、无损地检测紫薯半干面中TVC及新鲜度。     

不同贮藏温度对暗纹东方鲀水分迁移、质构和色泽的影响及其货架期预测

以暗纹东方鲀为研究对象,实验研究了微冻(-3℃)、冰温(-1℃)、冷藏(4℃)、10℃和15℃条件下鱼肌肉中水分迁移、质构(texture profile analysis,TPA)和色泽的变化规律,以及水分迁移对鱼肉质构和色泽的影响,同时,构建了货架期预测模型。研究结果显示,不同贮藏温度下鱼肉的结合水、不易流动水和自由水的相对含量(p T_(21),p T_(22),p T_(23))随贮藏时间分别呈上升、上升后下降和下降后上升的变化趋势,鱼肌肉中结合水和自由水的弛豫时间(T_(21),T_(23))波动上升,T_(22)对应的不易流动水先上升后下降。总体上,不同温度贮藏组的不易流动水随着贮藏时间向自由水的迁移均较明显。不同温度组p T_(21)和T_(21)对应的结合水对鱼肉的弹性、硬度和白度有较大影响。相关性拟合结果显示菌落总数(total viable count,TVC)、挥发性盐基氮(total volatile base nitrogen,TVB-N)与感官评分的相关性最高(|r| 0. 95,R2 0. 90),并以此建立了货架期预测模型;验证结果表明,结合Arrhenius方程构建的TVC和TVB-N的时间-温度-品质的动力学模型能较准确地预测-3～15℃贮藏暗纹东方鲀的货架期。     

冷藏条件下鸡胸肉品质变化及新鲜度评价模型的构建

目的 对冷藏过程中鸡胸肉新鲜度评价指标进行分析并构建新鲜度评价模型。方法 以新鲜鸡胸肉为目标对象,通过对其在4℃冷藏过程中的pH值、挥发性基盐氮 (Total Volatile Base Nitrogen, TVB-N) 值、菌落总数 (Total Viable Count, TVC) 和感官评分等常用于肉类食品新鲜度和品质评价的指标进行测试,分析了鸡胸肉在4℃贮藏过程中的新鲜度变化特性。通过主成分分析法、层次聚类分析法和判别分析法等多元统计方法,对鸡胸肉多项新鲜度评价指标的信息进行分析,并搭建了新鲜度评价模型。结果 通过多元统计方法和新鲜度评价模型分析发现,鸡胸肉在4℃冷藏条件下贮藏过程中,0-2天为新鲜,3-5天为中度新鲜度,7-8天为腐败。结论 该结果可为鸡胸肉贮藏过程中新鲜度的相关研究提供理论依据,为其他肉类食品贮藏过程中新鲜度评价模型的构建提供借鉴意义,并有助于减少食品浪费和食源性疾病。     

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.