Evolution of free amino acids, biogenic amines and volatile compounds in fermented sausages inoculated with Lactiplantibacillus plantarum and Staphylococcus simulans

Lactic acid bacteria and coagulase-negative staphylococci play an important role in the production of fermented sausages,such as inhibiting the growth of undesirable bacteria and antioxidant.In this study,the effects of inoculation with different starter cultures(Lactiplantibacillus plantarum HN108 and Staphylococcus simulans NJ209)on the free amino acids(FAAs),biogenic amines(BAs)and volatile compounds of fermented sausages were investigated using an amino acid analyzer,ultra performance liquid chromatography and gas chromatography-ion mobility spectrometry,respectively.The pH and carbonyl content of the inoculated group was significantly lower than those in the control group(P<0.05).L.plantarum HN108 significantly reduced the content of FAAs and BAs in fermented sausage production(P<0.05),while S.simulans NJ209 promoted the formation of FAAs(especially bitter amino acids)and exhibited slight BAs-reducing activity.In addition,L.plantarum HN108 promoted the formation of volatile compounds such as ketones,alcohols and alkenes in sausages.In conclusion,L.plantarum HN108 could contribute to reducing the content of putrescine and tyramine and forming the desirable flavor compounds in fermented sausages.Thus,L.plantarum HN108 is expected to be a starter culture that can improve the safety and flavor of fermented sausages.

Simple Detection Method of Biogenic Amines in Decomposed Fish by Intramolecular Excimer Fluorescence

Biogenic amines are known to have various biological functions such as not only neurotransmitter and cell proliferation but also food poisoning. Bacterially-decomposed amines such as histamine, agmatine, putrescine, cadaverine, spermidine and spermine cause allergic symptoms. We developed simple method for measurement of polyamine as indicator of food decomposition with a fluorometer by using 4-(1-Pyrene)butyric acid N-hydroxysuccinimide ester (PSE). PSE reacts with primary and secondary amino moieties of polyamines and produces the intramolecular excimer fluorescence. Excimer fluorescence with broad peak at around 470 nm was clearly detected in linear type biogenic amines such as putrescine, cadaverine, spermidine and spermine at 10 mM. However neither histamine nor trimethylamine altered the fluorescence. Decomposed sardine and mackerel by improper storage showed stronger intensity than fresh ones. Comparing with OPA-method, PSE method was useful for screening biogenic amines present in food, esp. fish since the analysis was simple after one-step purification procedure. An inexpensive system which can rapidly detect biogenic amines from food is necessary in a medium and small-sized food business. The technique using excimer has potential to realize the high through-put screening system for evaluation of food freshness and is expected to bring the public interests such as food security and safety of consumer.

Antimicrobial effects of carnosic acid,kaempferol and luteolin on biogenic amine production by spoilage and food-borne pathogenic bacteria

Antimicrobial effects of carnosic acid,kaempferol and luteolin on biogenic amine(BA)production by five spoilage(Photobacterium damselae,Proteus mirabilis,Enterobacter cloacea,Pseudomonas luteola and Serratia liquefaciens)and five food-borne pathogenic bacteria(Staphylococcus aureus ATCC29213,Enterococcus faecalis ATCC29212,Escherichia coli ATCC25922,Salmonella Paratyphi A NCTC13 and Yersinia enterocolitica NCTC 11175)were investigated.The formation of ammonia(AMN),trimethylamine(TMA)and BAs by all bacterial strains were observed using ornithine decarboxylase broth.BAs,AMN,and TMA were determined by using high performance liquid chromatography(HPLC)method.The results showed that significant differences were observed(P≤0.05)in formation among spoilage and also food-borne bacteria.The impact of phenolic compounds on AMN,TMA and BAs production was dependent on bacterial strains.When total amount of cadaverine(CAD),putrescine(PUT),histamine(HIS)and tyramine(TYR)was considered,the phenolic compounds presented antimicrobial activity against fish spoliage bacteria and food-borne pathogens following the order;kaempferol>carnosic acid>luteolin.These phenolics have potential to be used as food preservatives.

三种微生物离体氨基酸脱羧酶催化活性的研究

氨基酸脱羧酶(AAD)是生物胺合成的关键酶。微生物AAD一般为胞内酶,但性质稳定,在脱离细胞体系中仍可保持催化活性。文章以具有产生物胺能力的3种微生物细胞超声破碎后的粗酶液为对象,探究了前体氨基酸浓度、pH和盐浓度对离体AAD催化活性的影响。结果显示,多数情况下前体氨基酸未充分转化为生物胺,但低浓度前体氨基酸显著降低了离体AAD的催化活性;Lactobacillusplantarum 1-8和Escherichia coli BA-1的AAD在pH为6时催化活性最强,Debaryomyces hansenii MB-1Y的AAD在pH为5时催化活性最强;盐浓度提升导致AAD的催化活性降低。该研究可为探讨食品发酵中AAD的催化特性及其控制提供参考。

乳酸菌接种发酵对耿马酸肉品质的影响

为提高耿马酸肉的品质和安全性,将植物乳植杆菌(Lactiplantibacillus plantarum)GMSR-4、戊糖乳杆菌(Lactiplantibacillus pentosus)GMSR-20和植物乳植杆菌GMSR-35按体积比1∶2∶2、接种量3%接种到耿马酸肉中,同时设置对照(control check,CK)组,在25℃发酵6 d,测定2组样品理化指标、微生物数量和感官品质的变化。结果表明,接种发酵(inoculated fermentation,IF)组的亚硝酸盐残留量、水分含量、pH值、生物胺总量、腐胺、尸胺、亚精胺、酪胺、苯乙胺和色胺含量显著低于CK组(P<0.05),菌落总数和乳酸菌数显著高于CK组(P<0.05),大肠菌群数显著低于CK组(P<0.05),IF组的各个感官指标评分均高于CK组。综上,人工接种发酵可提高耿马酸肉的食用品质和安全性。

响应型荧光探针检测神经递质的研究进展

神经递质是一类在神经系统中起重要作用的化学物质,其异常表达与多种神经系统疾病相关。荧光探针因高选择、高灵敏和可视化特性在众多神经递质检测方法中具有突出优势。该文主要综述了2019年以来响应型荧光探针在神经递质检测方面的新进展,介绍了6类神经递质,包括胆碱类、生物胺类、氨基酸类、神经肽类、嘌呤类以及气体信号分子。在分析各类神经递质结构和反应特点的基础上,介绍了相应探针的设计思路和反应机理。这些研究为神经递质的精确检测提供了重要的方法和理论支持,有望在神经系统疾病的早期诊断和治疗中发挥关键作用。最后展望了响应型荧光探针未来的发展趋势。

酱油中降生物胺乳酸菌的筛选、鉴定及其生长特性研究

为获得在酱油发酵中具有降解生物胺能力的乳酸菌,该研究从酱油和酱醪样品中筛选具有降生物胺功能的菌株,对目标菌株进行鉴定并研究其生长曲线、耐盐、耐酸等生长特性及降解特性。结果表明,采用稀释分离法、双层显色培养法、生物胺氧化酶定性检测和液相色谱-串联质谱法定量分析筛选得到5株高效降解生物胺的菌株,经形态学、生理生化和16S rDNA分子生物学鉴定,均为发酵乳杆菌;其中,菌株L2112、L31B2和L41B对酱油中主要生物胺——酪胺、组胺、亚精胺和苯乙胺的降解率分别达到63.76%、59.09%、43.38%和35.12%,菌株L2112和L41B耐酸耐盐能力均较好,在37℃、40 g/L NaCl和300 mg/L生物胺质量浓度时菌株L2112降生物胺能力最佳,在37℃、130 g/L NaCl和500 mg/L生物胺质量浓度时菌株L41B降生物胺能力最佳。该研究有望为酱油发酵体系中生物胺调控提供优良菌株。

耿马酸肉在发酵过程中生物胺和致病菌的变化

为探究耿马酸肉加工过程中生物胺和致病菌的变化,将传统耿马酸肉在25℃下发酵,取0,2,4,6 d样品检测生物胺、致病菌、主要理化指标和游离氨基酸,分析生物胺与各指标之间的相关性。结果表明,耿马酸肉中共检测出组胺、尸胺、腐胺、酪胺、苯乙胺、精胺、亚精胺和色胺8种生物胺,在发酵第6天时,生物胺总量为310.50 mg/kg,大约是限量值的1/3,酪胺含量最高,为118.14 mg/kg,已超过推荐的安全值(100 mg/kg),尸胺次之,为85.55 mg/kg。在整个发酵过程中均检测到大肠菌群,最高为5.28 lg CFU/g;金黄色葡萄球菌均小于10 CFU/g;沙门氏菌和单核细胞增生李斯特氏菌均未检出。大肠菌群、亚硝酸盐残留量、pH和NaCl含量与大多数生物胺具有显著相关性;腐胺、尸胺、酪胺、精胺、生物胺总量与多种游离氨基酸呈极显著正相关。生食耿马酸肉可能存在大肠菌群和酪胺中毒的风险。

磺基水杨酸提取鱼粉中生物胺条件优化研究

本实验旨在对磺基水杨酸提取鱼粉中3种生物胺的条件进行优化。通过单因素实验和正交实验考察提取溶液种类、称量质量、提取溶液浓度、超声时间4种因素对生物胺提取效果的影响,并对优化后的条件,进行加标回收率实验及质控样品实验,验证结果的准确性。结果表明:正交实验优选生物胺提取的最佳条件为:称量质量0.5~1.0 g、磺基水杨酸浓度1.0%、超声时间30 min。加标回收率101%~105%,组胺质控样品实测值458 mg/kg,指定值(452.8±64.9)mg/kg,结果可靠。通过磺基水杨酸提取鱼粉中的生物胺、茚三酮作为衍生试剂,氨基酸分析仪检测,达到很好的检测效果,提供了一种简单、快捷的检测方法。

Risk assessment of chemical substances of safety concern generated in processed meats

This manuscript is reviewing the presence of substances of safety concern that may be generated in different types of meat products.Such substances include N-nitrosamines that can be generated under certain conditions when using nitrite as preservative,the polycyclic aromatic hydrocarbons generated as a consequence of particular smoking processes,heterocyclic aromatic amines generated under particular cooking conditions,compounds released from the oxidation of lipids and proteins,Maillard reaction products like acrylamide and carboxymethyl lysine,and amines that can be generated and accumulated in fermented meats.These hazardous compounds,their mechanisms of generation,risks for health and ways of preventing its presence in meat products are briefly described in this review.

Effect and mechanism of ferulic acid inclusion complexes on tyramine production by Enterobacter hormaechei MW386398 in smoked horsemeat sausages

Ferulic acid inclusion complexes(FA-HP-β-CD)effects on tyramine accumulation and gene expression of Enterobacter hormaechei MW386398 in traditional smoked horsemeat sausages were studied.Reverse transcription-quantitative polymerase chain reaction(RT-qPCR)was used to identify the expression of tyrosine decarboxylase(TDC)clusters in the tyramine producing pathway.In addition,relevant parameters such as microbial growth,moisture content,pH,and tyramine accumulation in pure cultures and during fermentation of smoked horsemeat sausages were evaluated.Ferulic acid(FA)and FA-HP-β-CD inclusion complexes both significantly decreased tyramine accumulation,as well as significantly inhibited tyrosine decarboxylase(tdcA)and tyrosine/tyramine antiporter(tyrP)genes expression(p<0.05).Furthermore,FA and FA-HP-β-CD inclusion complexes both reduced the number of Enterobacteriaceae in smoked horsemeat sausages,but did not alter the main microbiota.However,FA-HP-β-CD inclusion complexes exhibited stronger ability in hindering TDC related gene expression,reducing tyramine accumulation and antibacterial properties.These results indicate that FA-HP-β-CD inclusion complexes are able to reduce tyramine accumulation in smoked horsemeat sausages by inhibiting Enterobacteriaceae growth and gene expression.

低盐泡菜的贮藏后酸化及其对泡菜品质安全的影响

通过比较分析低盐泡菜熟后贮藏过程中的酸度和酸味喜好度,确定低盐泡菜后酸化指标参数。在此基础上,考察后酸化对低盐泡菜质构、色泽、氨基酸构成、生物胺和亚硝酸盐含量的影响。贮藏4 d时低盐泡菜的总酸和乳酸含量分别为0.6 g/100 g和3.71 g/kg,酸味喜好度得分为1.6,表明低盐泡菜已后酸化;贮藏10 d时泡菜的总酸和乳酸含量分别为0.8 g/100 g和6.56 g/kg,酸味喜好度得分低至1.0,表明泡菜达到重度后酸化。后酸化过程中,低盐泡菜的硬度和咀嚼性分别降低了54.1%和92.3%;L^(*)值减小且b^(*)值增大,泡菜的色泽发生褐变和黄变;苦味氨基酸含量从138.64 mg/kg逐渐升高至240.26 mg/kg;腐胺含量从18.71 mg/kg升高至35.47 mg/kg;但亚硝酸盐含量基本无变化。相关性分析结果显示后酸化会导致低盐泡菜的质构、色泽和风味发生劣变,乳酸菌数量降低(P<0.01)。

基于微生物菌群调控的枯草芽孢杆菌改善低盐发酵鱼露品质作用机制

以高产蛋白酶耐盐菌株Bacillus subtilis B-2作为鱼露发酵剂,研究加菌发酵对低盐鱼露发酵过程中微生物菌群、生物胺和氨基酸态氮(amino acid nitrogen,AAN)的影响。16S rRNA基因高通量测序结果显示,加菌发酵能够显著降低微生物群落的丰富度和均匀度,Bacillus始终占主导地位,腐败微生物丰度显著降低。加菌发酵能够显著抑制组胺、腐胺、尸胺和酪胺的生成,其含量在发酵末期较自然发酵鱼露分别下降了25.9%、35.6%、23.6%和9.3%。加菌发酵可显著增加低盐鱼露的AAN含量,发酵15 d可达1.23 g/100 mL,明显高于自然发酵鱼露(0.79 g/100 mL)。相关性网络图分析结果显示,Brevibacterium、Dietzia、Paracoccus、Aequorivita、Brachybacterium丰度的下降是低盐自然发酵鱼露发酵末期微生物菌群多样性下降的主要原因;在低盐自然发酵鱼露和低盐加菌发酵鱼露中,Stenotrophomonas均与多种生物胺呈显著正相关,表明其在低盐鱼露生物胺产生中发挥核心作用。对比两种鱼露发酵末期微生物菌群和品质指标,结果显示,B. subtilis B-2代谢是加菌发酵鱼露腐败微生物种类和丰度下降、AAN含量提高以及关键生物胺含量下降的主要原因。B. subtilis B-2有望开发为鱼露专用发酵剂,用以改善低盐快速发酵鱼露的品质和食用安全性。

发酵豆制品理化性质与微生物群落对生物胺形成的影响

以7种液态发酵豆制品和7种固态发酵豆制品为研究对象,对常见生物胺的含量、微生物群落多样性以及相关理化指标进行测定。结果表明,脱脂大豆酱油,蒸鱼豉油,牡蛎减盐酱油中的生物胺总量均高于8000 mg/L,并显著高于其他样品(P<0.05)。样品的pH值和凯氏氮含量与生物胺总量呈负相关,水分活度(因子载荷0.413)、总酸含量(因子载荷0.399)和盐度(因子载荷0.330)对生物胺生成的正面效应较大。假单胞菌属和芽孢杆菌属分别与生物胺含量呈正相关和负相关。本研究为相关标准制定提供一定理论基础。

不同产蛋白酶乳酸菌对风干牛肉品质影响及安全性评价

为提升风干牛肉的品质,筛选具有优良特性的乳酸菌发酵剂进行风干牛肉的制作。分别将3种产蛋白酶乳酸菌(乳酸乳球菌(S-1)、戊糖片球菌(S-2)、格氏乳球菌(S-3))接种于牛肉,研究牛肉腌制、发酵、风干、成熟等不同阶段的水分、pH、硫代巴比妥酸(TBARS)值、色泽、质构和微生物等品质指标变化。另外,采用高效液相色谱法分析样品中生物胺质量分数变化,并对添加的菌株安全性进行评价。结果表明,3种产蛋白酶乳酸菌均可以显著降低风干牛肉的pH和TBARS值(P<0.05),改善色泽和质构,但对水分质量分数变化没有显著影响(P>0.05);3种发酵剂均能有效抑制产品中大肠菌群的生长,其中S-2抑菌作用最强;3种发酵剂均可以有效抑制风干牛肉中生物胺(腐胺、尸胺、组胺、酪胺)的形成,其中S-2、S-3的抑制效果更好。因此,3株乳酸菌作为发酵剂应用于风干牛肉可以提升产品品质及安全性,可以为产蛋白酶乳酸菌在风干牛肉中的应用提供理论依据。

乳酸菌浸米技术对黄酒酿造的影响

将乳酸菌浸米技术应用到黄酒生产新工艺中,通过检测米浆水的总酸含量、有机酸含量、生物胺含量以及发酵结束后黄酒的理化指标、感官评价、生物胺含量,分析其在浸米过程中的效果,以及对黄酒酿造过程和成品品质的影响。结果表明,乳酸菌浸米可以加快浸米进程,有效缩短浸米时间;能明显提高米浆水中乳酸菌含量,大幅降低米浆水和黄酒原酒中的生物胺含量,提高生物安全性。乳酸菌浸米技术应用于黄酒大生产中,发酵过程安全可控,工艺简单可行,黄酒各项理化指标都符合GB/T 13662《黄酒》中的要求,酒体协调柔和,具有黄酒的典型风格。

生物胺与食品安全

生物胺是一类含氮的脂肪族或杂环类低分子化合物 ,对动植物和微生物活性细胞有重要的生理作用。适量的生物胺有助于人体正常的生理功能 ,过量则会引起不良的生理反应。生物胺往往是在食品腐烂或发酵过程中产生。食品中毒的发作和某些毒理学特性与组胺和酪胺有密切联系。因此 ,对生物胺进行研究和认识可以提高和改善食品的质量及安全性。

黄酒中生物胺的形成及其影响因素

采用高效液相色谱技术,分析了黄酒酿造原料、发酵剂和不同年份酒中的生物胺含量,并对传统工艺和机械化生产过程中生物胺含量的变化进行了跟踪分析,剖析了影响生物胺含量的因素。结果表明,腐胺和酪胺是黄酒中的主要生物胺,糯米原料和曲中生物胺含量很低,检出的3种脂肪族生物胺(腐胺、尸胺和精胺)总量不超过6.01mg/kg;7种酒母中生物胺总含量差异极显著(P<0.01),总量变化范围为16.43～87.72 mg/L;酒母中生物胺总量与总酸呈正相关,与酒精度和感官品质呈显著性负相关;机械化工艺和传统工艺发酵过程中生物胺均呈先升后降的变化趋势,但传统工艺比机械化工艺生物胺含量高;发酵过程中氨基酸逐渐增多,与生物胺含量变化无相关性;发酵醪中细菌总数在前期急剧增加到最大值,之后逐渐降低,变化趋势与生物胺含量变化相同;陈酿时间对传统工艺生物胺含量影响明显,随着时间延长,生物胺含量降低,但陈酿时间对机械化工艺无明显影响。本实验检测的黄酒发酵醪及年份酒中生物胺总量范围为0.14～175.15 mg/L,不存在安全问题。

一株乳酸乳球菌产γ-氨基丁酸能力及其安全性评价

探讨了乳酸乳球菌乳亚种HUCM 201产γ-氨基丁酸的能力,并初步评价了其安全性。以γ-氨基丁酸含量为评价指标,通过正交试验优化了乳酸乳球菌乳亚种HUCM 201菌株产γ-氨基丁酸的发酵条件,即接种量为4%、初始pH值6.5,发酵温度31℃,发酵时间60 h,其发酵液中γ-氨基丁酸的质量浓度可达218.7μg/mL。通过硝基还原酶活性检测、生物胺产生能力分析、吲哚试验和溶血性试验,初步评价了菌株HUCM 201的安全性,发现其硝基还原酶阴性,吲哚试验阴性,无溶血,不能产生酪胺、组胺、尸胺和腐胺生物胺类物质,可初步认为是一株安全的益生菌。

食源性乳酸菌安全性的评价

从不同来源的样品中分离得到36株乳酸菌,对其进行常见抗生素如氯霉素、四环素、红霉素抗药性分析,结果表明,26株菌具有抗药性,其中4株携带抗生素抗性基因,并且菌株Enterococcus faecium KN9所携带的四环素抗性基因tet(M)和tet(L)能通过接合作用,转移到受体菌Lactococcus lactis MG1614中。对这些乳酸菌产生有害代谢产物分析结果表明,部分菌株可以产生生物胺,所有的菌株都不产生硝基还原酶和偶氮还原酶。所以,本实验分离到的大部分乳酸菌是安全的,只有携带有抗四环素基因的E.faecium KN9具有潜在的安全隐患。因此,需要在食用前对乳酸菌进行安全性评价,以减少可能的安全隐患。