二种可食用精油的抗菌活性研究

对生姜和芫荽叶两种可食用精油的抗菌活性进行了研究.采用水蒸汽同步蒸馏法提取精油,以抗生素为参比,运用琼脂孔洞法测定生姜块茎和芫荽茎叶精油抗6种食源性致病菌和2种腐败真菌的抑菌圈直径.结果表明,生姜和芫荽精油均表现程度不等的广谱抗菌活性.生姜精油对肺炎克雷伯菌、志贺氏菌、金黄色葡萄球菌、黑曲霉和假丝酵母具有良好的抗菌作用...     

Polypropylene/Montmorillonite Nanocomposites Containing Nisin as Antimicrobial Food Packaging

Antimicrobial nanocomposites prepared with polypropylene, montmorillonite, and nisin were developed as food packaging material. Nisin was incorporated at 1, 2.5, and 5 % (w/w) and the characterization included antimicrobial, mechanical, thermal, barrier, and structural properties. Composite films inhibited the Gram-positive bacteria Listeria monocytogenes, Staphylococcus aureus, and Clostridium perfringens when tested on skimmed milk agar plates. Antimicrobial activity was released in food simulants after contact with the nanocomposites, increasing until 48 h in solutions containing the surfactant Tween 20 or acetic acid. The addition of nisin caused no significant modification in deformation at break values as compared with control films. However, results of tensile strength and Young modulus differed significantly among samples. The higher value for Young modulus was observed for films with 5 % nisin. Water vapor barrier properties were not significantly different among control and antimicrobial films, whereas oxygen permeability was higher for nanocomposites containing nisin. The nanocomposites tested had no significant differences in the melting temperature (165 to 167 °C), and the crystallization temperature ranged from 121 to 129 °C, with lower values for films containing 5 % nisin. Scanning electron microscopy showed that nanocomposites containing 1 and 2.5 % nisin present similar homogeneity to that of control films. Some film properties were affected after nisin incorporation in polypropylene/montmorillonite matrix but active antimicrobial films were obtained, showing suitable behavior as a food packaging material.     

含精油可食性抗菌膜研究进展

可食性抗菌膜是目前食品包装领域研究的重要方向,含精油可食性抗菌膜是其研究的热点之一。本文介绍含精油的可食性食品包装膜中精油的主要成分及其抗菌特性,概述此类膜的一般制备技术,对含精油膜抗菌的抗菌性能测试方法进行归纳,就精油对可食性膜抗氧化性、机械性能、渗透性及其他理化性能的影响作重点阐述,最后分析含精油可食性抗菌膜可能存在的问题,并预测其发展前景。     

Essential Oils as Natural Food Antimicrobial Agents: A Review

Food-borne illnesses pose a real scourge in the present scenario as the consumerism of packaged food has increased to a great extend. Pathogens entering the packaged foods may survive longer, which needs a check. Antimicrobial agents either alone or in combination are added to the food or packaging materials for this purpose. Exploiting the antimicrobial property, essential oils are considered as a “natural” remedy to this problem other than its flavoring property instead of using synthetic agents. The essential oils are well known for its antibacterial, antiviral, antimycotic, antiparasitic, and antioxidant properties due to the presence of phenolic functional group. Gram-positive organisms are found more susceptible to the action of the essential oils. Essential oils improve the shelf-life of packaged products, control the microbial growth, and unriddle the consumer concerns regarding the use of chemical preservatives. This review is intended to provide an overview of the essential oils and their role as natural antimicrobial agents in the food industry.     

植物精油抗菌包装膜研究进展

植物精油作为天然来源的抑菌物质,在食品保鲜领域的应用越来越广泛。该文介绍其作为抗菌剂添加至聚合物基质中制备包装抗菌膜的研究现状,总结精油在膜材料中的构建方式、对膜物理性能、机械性能、抗菌性能的影响以及在食品保藏中的应用。指出植物精油抗菌膜材料存在的问题以及未来的研究重点和发展趋势,为精油抗菌膜的进一步发展提供思路。     

海-岛型聚酯超细纤维的剥离开纤工艺研究

运用扫描电子显微镜（SEM）、差热分析仪（DSC）、纤维强力试验仪等先进测试仪器和分析手段,分析并比较不同处理条件下海-岛型聚酯复合超细纤维的碱处理效果,得出海-岛型聚酯复合超细纤维的最佳开纤工艺.     

两种天然抗氧化剂对食用油脂抗氧化效果研究

研究天然抗氧化剂五倍子单宁和石榴皮多酚对常见食用油脂抗氧化稳定性的影响,采用Schaal烘箱法,测定食用油脂的过氧化值POV(peroxide value)、酸价AV(acid value)和碘价IV(iodine value),研究石榴皮多酚、五倍子单宁、茶多酚和特丁基对苯二酚(butylhydroquinone,TBHQ)对常用食用油如猪油、豆油、菜籽油、芝麻油的抗氧化特性。结果表明天然抗氧化剂五倍子单宁和石榴皮多酚对食用油脂具有很强的抗氧化性,五倍子单宁、石榴皮多酚可以作为油脂的天然抗氧化剂应加以开发利用。     

2种乳链菌肽天然变异体抑菌活性的研究

以利斯特氏菌和蜡状芽孢杆菌为材料 ,研究了 2种乳链菌肽天然变异体nisinA和nisinZ的抑菌活性。结果表明 ,nisinA和nisinZ对被试的 2株利斯特氏菌及蜡状芽孢杆菌1 189具有相同的抑菌效果。而对另一株蜡状芽孢杆菌 1 350 ,nisinZ比nisinA显示较强的抑菌活性。不同的培养基对这 2种乳链菌肽天然变异体的抑菌活性具有不同的影响     

丁香和肉桂挥发油的提取、主要成分测定及其抗菌活性研究

本文采用水蒸汽蒸馏法提取丁香和肉桂的挥发油,并对所得挥发油主要成分进行气相测定,通过体外抗菌试验,比较了这两种挥发油及其主要成分和目前常用化学防腐剂苯甲酸钠和山梨酸钾对金黄色葡萄球菌、大肠杆菌、枯草芽孢杆菌、沙门氏菌和志贺氏菌等5株食品中常见污染菌的抗菌作用。结果表明丁香油中丁香酚含量为78.1%,肉桂油中肉桂醛含量为86.8%;这两种挥发油及其主要成分丁香酚和肉桂醛的抗菌作用均强于两种化学防腐剂,其中肉桂油与其主要成分肉桂醛表现出的抗菌活性最强,最小抑菌浓度(MIC)为200～1600mg/L;仅为苯甲酸钠和山梨酸钾MIC(6400～25600mg/L)的1/64～1/16;丁香油及其主要成分丁香酚的抗菌活性次之,MIC为800～1600mg/L,相当于苯甲酸钠和山梨酸钾MIC的1/16～1/8。     

Comparisons of Chemical and Physical Properties of Catfish Oils Prepared from Different Extracting Processes

ABSTRACT:  Four different catfish oil extraction processes were used to extract oil from catfish viscera: process CF1 involved a mixture of ground catfish viscera and water, no heat treatment, and centrifugation; process CF2 involved ground catfish viscera (no added water), heat treatment, and centrifugation; process CF3 involved a mixture of ground catfish viscera and water, heat treatment, and centrifugation; process CF4 involved ground catfish viscera, enzymatic hydrolysis, and centrifugation. Chemical and physical properties of the resulting of catfish oils were evaluated. The CF4 process recovered significantly higher amounts of crude oil from catfish viscera than the other 3 extraction methods. The CF4 oil contained a higher percent of free fatty acid and peroxide values than CF1, CF2, and CF3 oils. Oleic acid in catfish oil was the predominant fatty acid accounting for about 50% of total fatty acids. Weight loss of oils increased with increasing temperatures between 250 and 500 °C. All the catfish oil samples melted around −32 °C regardless of the extraction methods. The flow behavior index of all the oil samples was less than 1, which indicated that the catfish oils exhibited non-Newtonian fluid behavior. The apparent viscosity at −5 and 0 °C was significantly higher ( P  < 0.05) than those at 5, 10, 15, 20, 25, and 30 °C. The average magnitude of activation energy for apparent viscosity of the oil was higher for CF2 than CF1, CF3, and CF4.     

保鲜奶在二次灭菌过程中瓶内压力实验研究

研究了HDPE瓶装保鲜奶在二次灭菌过程中瓶内压力的变化规律,通过模拟实验测定了HDPE瓶的变形量,建立了HDPE瓶变形量随温度及压力差变化的二元回归方程。在此基础上测试得到了HDPE瓶及其铝箔封口的临界压力差。     

High Pressure-Assisted and High Pressure-Induced Thawing: Two Different Processes

ABSTRACT: High pressure-assisted thawing (HPAT) and high pressure-induced thawing (HPIT) experiments were performed in agar gel samples at different pressures (50 to 210 MPa) and initial temperatures (−5°C to −20 °C). Lower pressures and temperatures yielded HPAT processes in which the sample temperature increased during pressurization because no melting took place. The complete phase transition occurred during the holding time. Higher temperatures and/or higher pressures yielded HPIT processes in which partial melting occurred during pressure loading, causing the sample temperature to decrease. In practice, whether HPAT or HPIT took place depended on the initial temperature of the sample for a given pressure value. Common situations were nonhomogeneous thawing processes.     

两种不同煮茧工艺路线的对比分析与探讨

我国制丝生产中主要有机内温差渗透煮茧工艺与机外真空渗透煮茧工艺两种不同的煮茧工艺。对不同原料茧分别用两种煮茧工艺进行对比试验显示,各原料茧的万米吊糙次数温差渗透工艺平均7.6次,真空渗透工艺平均3.4次,两者相差1.24倍;解舒光折真空渗透工艺比温差渗透工艺平均小6.6kg。在人工费、原料茧价格趋高的情况下,真空渗透煮茧工艺将为企业带来较大的经济利益。     

镍基催化剂在食用油脂氢化中性能研究

改进高压反应釜取样装置,用浸渍法制备负载在不同载体(硅藻土、活性炭、分子筛、凹凸棒土) 上镍基催化剂用于食用油脂加氢,并测得油脂在不同反应时间碘价、折光指数、熔点数据,分析比较其催 化活性,其中以凹凸棒土为载体镍基催化剂综合性能较好。     

适合不同纺织工艺的喷气交缠技术

大约25年前，长丝纱交缠技术还鲜为人知，但目前，几乎所有长丝纱在加工过程的某个工序都要经过交缠处理。无论是在纺丝阶段，还是在牵伸或变形阶段，交缠质量对后道加工起重要作用。不完全或不稳定的交缠会给后道加工带来问题。例如，织物上出现的条痕一般会被认为是染色不匀，但大多数情况下是由纱的交缠强度不同而造成的。这是一个非常严重的问题，因为纱的缺陷会直接影响织物的质量。这就是说，纱的薄弱点，也就是未交缠的部分是决定交缠纱最终质量的主要因素。喷气交缠能够防止出现纱疵。这是因为：喷气交缠能够增强单丝之间的紧密度或…     

饲喂不同配比油脂饲料对肉鸡肉品质及肌肉中脂肪酸组成的影响

研究日粮中添加不同配比油脂对肉鸡肉品质、肌肉胆固醇含量及脂肪酸组成的影响。选取648只1日龄AA肉鸡,随机分成6组,CON为对照组(饲喂基础日粮),SO为正对照组(日粮中添加豆油),LO为负对照组(日粮中添加猪油),COP、COC、COV组分别在日粮中添加以棕榈油为主的配比油脂、以椰子油为主的配比油脂、多种植物油组成的配比油脂,实验期为42d。结果表明：COP组胸肌24h的滴水损失显著升高(P＜0.05);COC组腿肌烹饪损失显著降低(P＜0.05)。LO组胸肌不饱和脂肪酸/饱和脂肪酸得到提高(P＜0.05);SO、LO、COP、COC组n-3多不饱和脂肪酸含量均得到提高(P＜0.05);SO、COC组n-6多不饱和脂肪酸含量高于CON组(P＜0.05);除COV组外,各组n-6/n-3低于CON组(P＜0.05)。SO组胸肌胆固醇含量低于除LO组外的各组(P＜0.05)。结论：配比油脂组提高了肉鸡肌肉中多不饱和脂肪酸(PUFA)含量,对肉鸡肉品质没有产生不良的影响,豆油组改善了胸肌中脂肪酸比例并降低胆固醇含量,以椰子油为主的配比油脂次之。     

不同溶剂同时蒸馏萃取艾叶挥发油的抑菌活性

采用二氯甲烷和正己烷2种溶剂,分别进行同时蒸馏萃取(SDE)工艺萃取艾叶挥发油,对得物进行气质联用(GC-MS)成分分析,测定其抑菌活性的差异,并通过扫描电镜(SEM)探究艾叶挥发油抑菌作用的机理。结果表明,SDE比水蒸气蒸馏萃取节省时间1 h,提取率达1.5%,是后者的3倍。SDE(正己烷)的得物抑菌活性更强,最低抑菌浓度集中在6.25μL/mL,GC-MS结果可知其成分的92.95%是水蒸气蒸馏得物和SDE(二氯甲烷)的公共主要成分,SEM结果显示艾叶挥发油可作用于微生物细胞壁结构,从而达到抑制效果。     

蒸馏法提取香根油成分的GC-MS分析

为研究蒸馏法香根油化学成分,以气相色谱-质谱联用仪检测水蒸馏法香根油,在香根油中鉴定发现异丁香酚等21种化学成分的化学结构,其中有5-甲基糠醛等12种化合物是香根油中首次发现的天然化合物,该发现对以香根油为原料的新食品添加剂研发及应用具有重要意义。     

Microstructural and Mechanical Characterizations of Natural Long Alfa Fibers Obtained with Different Extractions Processes

This study investigates the morphological changes and tensile properties of Alfa fibers extracted mechanically after two treatments namely water retting and alkali treatment. The Scanning Electron Microscopy technique is used in this experimental work. The main observation reveals the decrease of noncellulosic component in the fibers which is inversely proportional to the concentration of sodium hydroxide solution in the case of the alkali treatment. Tensile tests were carried out using tensile machine for determining the tensile properties mainly the tensile strength and the elastic modulus. The tensile strength and young’s modulus of retted fibers are assumed constant. The results relative to the alkalized fibers show an improvement of tensile strength and young’s modulus and are proportional to the sodium hydroxide concentration up to 14%.     

不同包装气氛条件和天然抗氧化剂对切块干腌火腿抗氧化效果的影响

采用真空气调包装和茶多酚、迷迭香等及其复合天然抗氧化剂对切块干腌火腿进行抗氧化处理,通过正交试验研究不同气氛条件、抗氧化剂及贮藏温度和时间对干腌火腿抗氧化的影响效果.结果表明:真空包装的过氧化值(POV)显著低于气调包装组(p<0.01);迷迭香+VE复合抗氧化效果最好(p<0.01),含茶多酚的复合抗氧化剂对维持火腿肌肉的红度值具有显著效果(p<0.05);酸价(AV)与贮藏温度呈正相关;AV、POV、TBARs值随着贮藏时间的延长显著上升(p<0.01),红度a*值显著下降(p<0.01),贮藏时间达到3个月,包装切块火腿POV超过国家限量指标(0.25g/100g);正交优化结果:采用0.05%迷迭香+0.05%VE喷淋切块火腿、真空包装、5℃贮藏2个月;实验结果与感官评定具有良好的一致性.