2-羟丙基-β-环糊精/阿魏酸包合物对熏马肠中阴沟肠杆菌产酪胺的影响机制

制备2-羟丙基-β-环糊精（2-hydroxypropyl-β-cyclodextrin,HP-β-CD）/阿魏酸（ferulic acid,FA）包合物（HP-β-CD/FA）,探究其对阴沟肠杆菌（Enterobacter cloaca）L63的pH值、生长量、酪氨酸脱羧酶相关基因表达和酪胺积累的影响,以及对熏马肠中酪胺积累的影响。采用实时荧光定量聚合酶链式反应检测酪氨酸脱羧酶（tyrosine decarboxylase,tdcA）、酪氨酸/酪胺逆向转运体（tyrosine/tyramine antiporter,tyrP）、酪氨酸t-RNA合成酶和Na＋/H＋逆向转运体基因在酪胺产生途径中的表达水平。此外,采用高效液相色谱法检测酪胺在48 h内的累积水平。结果表明：FA和HP-β-CD/FA包合物在纯菌体系下均能够降低tdcA和tyrP基因的表达（P＜0.05）,对阴沟肠杆菌L63有较强的抑菌活性,在纯菌体系和熏马肠中均能够抑制pH值升高,同时有效减少酪胺积累,FA包埋后抑制酪胺积累效果更显著（P＜0.05）。     

阿魏酸对粪肠球菌和屎肠球菌产酪胺机制的影响

摘 要：研究阿魏酸对高产酪胺的粪肠球菌XL-M66和屎肠球菌XL-M76生长、基因表达以及产酪胺的影响。利用反转录实时荧光定量聚合酶链式反应技术分析2 株菌在阿魏酸作用下的酪氨酸脱羧途径相关基因表达情况,并使用高效液相色谱法检测2 株肠球菌培养48 h期间酪胺积累量。结果表明：未添加酪氨酸底物时,阿魏酸对酪氨酸脱羧酶（tyrosine decarboxylase,tyrDC）和酪氨酸/酪胺透性酶（tyrosine/tyramine permease,tyrP）基因的转录影响不大（P＞0.05）,但能促进酪氨酰-tRNA合成酶（tyrosyl-tRNA synthetase,tyrS）基因的转录（P＜0.05）。反之存在酪氨酸时,阿魏酸对tyrS基因表达的影响不大（P＞0.05）,却能显著抑制tyrDC和tyrP基因的表达（P＜0.05）。同时,阿魏酸能显著抑制粪肠球菌XL-M66和屎肠球菌XL-M76的生长（P＜0.05）,最终使得酪胺产量分别降低27.0%和19.9%。     

大蒜精油对熏马肠中德氏乳杆菌产腐胺的影响机制

研究不同质量浓度大蒜精油对熏马肠中德氏乳杆菌产腐胺的影响机制。利用反转录实时荧光定量聚合酶链式反应技术分析供试菌在不同大蒜精油质量浓度下的胍基丁胺脱亚胺酶相关基因表达情况,使用超高效液相色谱连续48 h监测纯菌体系中的腐胺产量;并将德氏乳杆菌接入到含不同质量浓度大蒜精油的熏马肠中发酵28 d,期间取样测其菌落总数、pH值及腐胺积累量。结果表明：无论是在纯菌培养还是在熏马肠发酵过程中,大蒜精油都能明显抑制细菌的增长,在纯菌体系中会明显抑制pH值的下降,但对熏马肠的最终pH值影响不明显;大蒜精油对调节基因aguR的转录影响不明显,但能极显著抑制操纵子aguBDAC的转录（P＜0.01）;增加纯菌体系以及熏马肠发酵过程中的大蒜精油质量浓度均能明显减少腐胺的生成。     

百里香精油微胶囊对摩根氏菌和变形杆菌产组胺机制的影响

本实验研究百里香精油微胶囊对产组胺的摩根氏菌ND和变形杆菌R3的生长、基因表达情况以及组胺积累量的影响。利用反转录实时荧光定量聚合酶链式反应分析供试菌在百里香精油微胶囊作用下的组氨酸脱羧途径相关基因的表达情况,采用高效液相色谱仪检测供试菌培养48 h期间的组胺积累量。结果表明,百里香精油微胶囊对两种供试菌有较强的抑菌活性,对摩根氏菌ND和变形杆菌R3的最低抑菌浓度(minimal inhibitory concentration,MIC)分别为1.56 mg/mL和0.78 mg/mL。百里香精油微胶囊可以通过抑制组氨酸脱羧酶(histidine decarboxylase,HDC)簇中HDC基因hdcA和组氨酸/组胺抗逆转录酶基因hdcP的表达从而明显减少组胺的积累。当百里香精油微胶囊的添加量为MIC时,可使摩根氏菌ND组胺积累量降低61.08%,变形杆菌R3组胺积累量降低55.89%。     

酪氨酸脱羧酶产生菌的筛选及脱羧条件研究

酪胺广泛应用于生化试剂、有机化工及医药中间体.从厂区周围土壤中筛选到一株能催化L-酪氨酸脱羧产酪胺的细菌ZQM4#,鉴定为普罗威登斯菌(Providencia Ewing).通过碳氮源、装液量、pH值、培养温度等条件的单因素试验和正交试验,得到该菌株的摇瓶脱羧培养条件为:牛肉浸膏5 g/L,酵母浸粉5 g/L,葡萄糖5 g/L,甘油5 g/L,磷酸氢二钾2 g/L,硫酸锰0.01 g/L,维生素VB6 0.003 g/L,温度37℃,pH 5.5.最后进行底物投料量的条件优化后,得到如下结果:10 g/L起始底物浓度下,3h能100％脱羧转化成酪胺,之后每3h补加10 g/L底物,可连续补充4次,底物仍能100％脱羧转化成酪胺.     

发酵剂对熏马肠成熟过程中生物胺含量变化的影响

利用从熏马肠中分离出的具有抑菌作用并可以产生物胺氧化酶的菌株,1株表皮葡萄球菌(Staphylococcus epidermidis),3株模仿葡萄球菌(Staphylococcus simulans)作为发酵剂加入到熏马肠,在熏马肠成熟过程中采用高效液相色谱检测不同发酵剂对生物胺含量变化的影响,进而阐明发酵剂对熏马肠中生物胺累积的控制作用。从研究结果可以看出,在马肠成熟过程中,B组对色胺、苯乙胺、腐胺、组胺、酪胺都有较显著的减少作用;C组对色胺、腐胺、尸胺、组胺、酪胺减少作用显著;D组对色胺、苯乙胺、腐胺、组胺、酪胺的减少作用显著;E组对组胺、苯乙胺、色胺的减少作用显著。添加发酵剂组对精胺、亚精胺的减少作用均不显著。结果表明,上述菌种对熏马肠成熟过程中生物胺产生有较好的抑制作用,具有肉品发酵剂的良好特性,为熏马肠以及其他发酵肉制品的工业化生产和安全性奠定了基础。     

大蒜精油对屎肠球菌和粪肠球菌产苯乙胺和酪胺的影响

本试验采用双倍试管稀释法,测定大蒜精油分别对高产苯乙胺和酪胺的E.faecium和E.faecalis的最低抑菌浓度(MIC)和最低杀菌浓度(MBC);并利用高效液相色谱法测定不同浓度的大蒜精油对两株高产苯乙胺和酪胺菌株的影响,从而明确大蒜精油对其产生物胺能力的抑制作用。结果表明:大蒜精油对供试菌株都具有较强的抑菌活性,大蒜精油对E.faecium的最大抑制率可达48.20%,对E.faecalis的最大抑制率为52.41%,且抑菌效果随大蒜精油浓度的增大而逐渐增强;在大蒜精油的添加量为1/2 MIC时,大蒜精油对E.faecium和E.faecalis的生长具有抑制作用;当大蒜精油浓度为0.025%时,能够显著(p0.05)降低供试菌株产苯乙胺和酪胺的含量,苯乙胺含量与空白组相比降低了26.61%,酪胺的降低了15.54%。说明大蒜精油对高产酪胺和苯乙胺的菌株具有显著(p0.05)抑制效果,从而减少了酪胺和苯乙胺的生成。     

新疆熏马肠中生物胺含量的调查

利用高效液相色谱丹磺酰氯柱前衍生法,检测了从新疆自治区4个县市采集的44个熏马肠中8种生物胺含量。结果显示:4.6%熏马肠样品的生物胺(BAs)总量超过FDA规定的1 000 mg/kg限量标准,色胺、酪胺和亚精胺含量在不同程度上超过生物胺安全用量标准,腐胺和尸胺含量与国外报道基本一致。     

发酵剂抑制发酵肉制品中酪胺形成机制及效果的研究进展

酪胺是以酪氨酸为前体物质，经脱羧后形成的一种生物胺。消费者从食品中摄入过量的酪胺会导致头痛、高血压等健康问题。发酵肉制品由于富含蛋白质，且经长期发酵产生了复杂的微生物菌群和大量的酪氨酸，因此易形成酪胺并在产品中大量积累。应用不产生酪胺或具有降解酪胺功能的发酵剂是降低发酵肉制品中酪胺含量的新方法。本文介绍了发酵肉制品中酪胺的形成及其影响因素，重点综述了发酵剂的种类、特性和发酵剂抑制酪胺形成的机制和效果，旨在为通过发酵剂法抑制发酵肉制品中的酪胺形成与积累、提高发酵食品安全提供理论支持。     

猪肉自然发酵香肠中细菌和乳酸菌对生物胺积累的作用

在猪肉香肠的自然发酵时，检测了选择的污染菌对形成的生物胺的性质和产量的作用。本文主要研究的是在肉腐败过程中胺的变化和微生物生长的变化，而且重点研究的是加入产酪胺的短乳杆菌（L．brevis）和产尸胺的阴沟肠杆菌（E．cloacae）的猪肉发酵香肠在发酵时生物胺的积累。在腐败和香肠发酵时相关微生物和胺的量较多。尸胺的高度积累和大量的不理想肠细菌有关，在香肠发酵时，酪胺的产生并不完全是乳酸菌的作用。另一方面，也涉及到必要的生产香肠的自然发酵菌，污染菌对于腐胺和其它生物胺的作用，现在还不清楚。     

大蒜精油和发酵剂对熏马肠中生物胺及微生物分布的影响

为研究大蒜精油和发酵剂对熏马肠中生物胺的影响,采用高效液相色谱法测定熏马肠中生物胺含量,利用 宏基因组学技术分析熏马肠中微生物多样性和生物胺含量的变化情况。结果表明：将大蒜精油和发酵剂联合使用能 够很好地减少熏马肠中尸胺、腐胺、组胺、酪胺和苯乙胺的产生,对控制生物胺在熏马肠中的含量起到非常显著的 作用;熏马肠中含有丰富的微生物物种,通过样品科分类水平物种分析,得出乳酸菌在熏马肠整个加工过程都是优 势菌种,而葡萄球菌在成熟后期数量较多。     

Application of Origanum majorana L. essential oil as an antimicrobial agent in sausage

This work reports on the antimicrobial activity in fresh sausage of marjoram (Origanum majorana L.) essential oil against several species of bacteria. The in vitro minimum inhibitory concentration (MIC) was determined for 10 selected aerobic heterotrophic bacterial species. The antimicrobial activity of distinct concentrations of the essential oil based on the highest MIC value was tested in a food system comprising fresh sausage. Batch food samples were also inoculated with a fixed concentration of Escherichia coli and the time course of the product was evaluated with respect to the action of the different concentrations of essential oil. Results showed that addition of marjoram essential oil to fresh sausage exerted a bacteriostatic effect at oil concentrations lower than the MIC, while a bactericidal effect was observed at higher oil concentrations which also caused alterations in the taste of the product.     

不同发酵方式对发酵马肉肠贮藏期品质劣变及食用安全性的影响

为有效确保发酵马肉肠贮藏期间的品质及安全性,研究添加汉逊德巴利酵母菌1808（Debaryomyces hansenii 1808）、木糖葡萄球菌21445（Staphylococcus xylose 21445）、植物乳杆菌E11（Lactobacillus plantarum E11）的复合发酵剂发酵组（FP）和单一乳酸菌发酵组（DZ）、自然发酵组（ZR）马肉肠贮藏过程中生物胺的变化,考察不同发酵方式对发酵马肉肠pH值、水分活度（aw）、色差、总挥发性盐基氮（total volatile basic nitrogen,TVB-N）含量、硫代巴比妥酸反应物（thiobarbituric acid reactive substances,TBARs）值及菌落总数的影响。结果表明：在贮藏期间,相比于自然发酵组和单一乳酸菌发酵组,添加复配发酵剂可有效减缓发酵马肉肠TVB-N含量、TBARs值、pH值的增幅,抑制贮藏后期有害杂菌的生长,防止产品过早发生腐败变质;此外,复配发酵剂可显著降低贮藏过程中马肉肠的水分损失（P＜0.05）,维持色泽的稳定,抑制生物胺（尸胺、腐胺、酪胺、组胺）的积累。综上,随着贮藏时间的延长,复配发酵剂可显著抑制发酵马肉肠品质的劣变及不良生物胺的过多积累。     

Biogenic amine contents in selected Egyptian fermented foods as determined by ion-exchange chromatography

Biogenic amines in foods may pose a public health problem. Therefore, histamine, tyramine, putrescine, cadaverine, spermine, and spermidine concentrations were measured in selected food items commonly consumed in Egypt. Foods examined were dairy products (blue cheese and Mesh cheese), meats (fermented and smoked cooked sausage), and fish (smoked and salted fermented fish [Feseekh], salted sardines, and anchovies). Egyptian fermented sausage had the highest concentration of total biogenic amines (2,482 mg/kg), followed by Mesh cheese (2,118 mg/kg) and blue cheese (2,084 mg/kg). The lowest concentration was found in smoked cooked sausage (111 mg/kg). Histamine was found at a high level (521 mg/kg) in Feseekh, and tyramine was highest (2,010 mg/kg) in blue cheese. These results indicate that some traditional Egyptian foods may pose a health risk due to the concentration of biogenic amines, especially histamine.     

新疆哈萨克熏马肠煮制过程中汤汁中游离氨基酸和挥发性物质分析

熏马肠是我国哈萨克族居民加工的一种传统肉制品,煮制成熟的熏马肠和汤汁都深受人们的喜爱,为了量化熏马肠煮制过程中滋味和挥发性风味物质的释放,对不同煮制时间汤汁中的游离氨基酸、主体风味特征、味觉特性和挥发性风味物质组分进行分析。结果显示,汤汁中的游离氨基酸总量呈增加趋势,煮制105 min和120 min时游离氨基酸总量显著高于煮制初期(P<0.05),而不同煮制时间的呈鲜、呈甜和呈苦味氨基酸百分比差异不显著(P>0.05)。汤汁咸味值、鲜味值、丰富度、苦味值、苦味回味值均随时间的延长呈增加趋势,涩味值和涩味回味值的变化规律不明显。不同煮制时间汤汁的挥发性成分具有明显差异,挥发性物质总量呈先增加后降低的趋势。汤汁主体风味成分在PC1和PC2上的方差贡献率为97.06%,风味特征明显,且在LD1和LD2上的方差贡献率为85.27%,通过风味主体成分可以区分不同的样品。煮制105 min时游离氨基酸含量较高,主体风味得到一定保持,涩味值未显著升高,较适宜用作熏马肠的熟制。     

Reduction of biogenic amine formation using a negative amino acid-decarboxylase starter culture for fermentation of Fuet sausages

The ability of Lactobacillus sakei CTC494, a negative amino acid-decarboxylase starter culture, to reduce biogenic amine accumulation during sausage fermentation and storage at 4 and 19 degrees C was studied. The effect on the amine formation of the tyramine producer Lactobacillus curvatus CTC371, as a positive strain, was also examined in comparison to a spontaneous fermentation process without starter culture (control batch). The polyamines spermine, spermidine, and diaminopropane were not influenced by the ripening, and their levels slightly decreased in all the batches throughout the storage. Tyramine, cadaverine, and putrescine were the main amines formed during the ripening. The addition of starter culture resulted in a decrease on the biogenic amine formation, depending on the strain inoculated. A great reduction in tyramine content was achieved when L. sakei CTC494 was inoculated, whereas L. curvatus CTC371 only attenuated tyramine accumulation compared with the control batch. Both starters were able to significantly limit the production of putrescine and cadaverine, and they inhibited tryptamine and phenylethylamine formation by the wild microbial flora. Tyramine levels of the control sausages rose during the storage at both temperatures, whereas those of cadaverine only increased at 19 degrees C. On the contrary, sausages manufactured through the starter controlled fermentation did not show changes of amine contents during the storage. The addition of a proper selected starter culture is advisable to produce safer sausages with low contents of biogenic amines.