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。     

Unravelling the relation between natural microbiota and biogenic amines in Brazilian dry-cured loin: a chemometric approach

Exploratory data analysis was used to evaluate the influence of NaCl concentration on the relation between endogenous microbiota (mesophilic aerobic bacteria, psychrotrophic bacteria, lactic acid bacteria, Enterobacteriaceae and Staphylococcus spp.) and biogenic amines (BAs) (histamine, tyramine, putrescine, cadaverine and spermidine) content in Brazilian dry-cured loin (BDL). Using hierarchical cluster analysis (HCA), initial data analysis led to samples separation into a higher and a lower NaCl cluster. The analysis of variance showed that the microbial counts did not differ between the clusters (p > 0.05). However, the higher NaCl cluster showed a lower level of BAs. Further, principal component analysis (PCA) demonstrated a negative correlation between the microbial counts and BAs content in the lower NaCl cluster, thus indicating the possibility of the higher BA’s content in the lower NaCl cluster being a result of a stress–response mechanism. On the other hand, in the higher NaCl cluster, the salt concentration had an inhibitory property in BA’s formation except for histamine. The collective results point to a NaCl threshold to minimise the production of BAs in BDL. The findings of the present exploratory study highlight the possibility of intervention for BA minimization without the need for designed starter cultures or preservation treatments.     

Interaction between lactic acid bacteria and food‐borne pathogens on putrescine production in ornithine‐enriched broth

Interactions of mixed cultures [lactic acid bacteria (LAB) and food‐borne pathogens (FBP)] on putrescine (PUT) as well as other biogenic amines (BAs) production were investigated in ornithine‐enriched broth. Significant differences in BAs production were found among the bacterial strains (P < 0.05). Conversion of ornithine into PUT by Salmonella Paratyphi A and Aeromonas hydrophila as well as Listeria monocytogenes and Staphylococcus aureus was high (>75 mg L^?1), whereas other bacterial strains yielded below 50 mg L^?1 of PUT. LAB strains resulted in significant reduction in PUT by Pseudomonas aeruginosa and Enterobacteriaceae, except for Escherichia coli, which was stimulated more than two‐fold PUT in the presence of Lactococcus lactis subsp. lactis. Lactobacillus plantarum had generally inhibition effect on histamine (HIS) and tyramine production by FBP, whereas Lc. lactic subsp. lactic slightly stimulated HIS by E. coli and A. hydrophila. Streptococcus thermophilus resulted in 1.5‐fold higher HIS formation by bacteria (10 mg L^?1). Consequently, the interaction between LAB and specific FBP might result in significant inhibition of amine accumulation, if the correct LAB strains are used.     

Chromohalobacter is a Causing Agent for the Production of Organic Acids and Putrescine during Fermentation of Ganjang,a Korean Traditional Soy Sauce

Ganjang, a Korean traditional fermented soy sauce, is prepared by soaking doenjang‐meju (fermented soybeans) in approximately 20% (w/v) solar salt solution. The metabolites and bacterial communities during ganjang fermentation were simultaneously investigated to gain a better understanding of the roles of the microbial population. The bacterial community analysis based on denaturing gradient gel electrophoresis of 16S rRNA gene sequences showed that initially, the genus Cobetia was predominant (0 to 10 d), followed by Bacillus (5 to 74 d), and eventually, Chromohalobacter became predominant until the end of the fermentation process (74 to 374 d). Metabolite analysis using ¹H‐NMR showed that carbon compounds, such as fructose, galactose, glucose, and glycerol, probably released from doenjang‐meju, increased rapidly during the early fermentation period (0 to 42 d). After removal of doenjang‐meju from the ganjang solution (42 d), the initial carbon compounds remained nearly constant without the increase of fermentation products. At this point, Bacillus species, which probably originated from doenjang‐meju, were predominant, suggesting that Bacillus is not mainly responsible for ganjang fermentation. Fermentation products including acetate, lactate, α‐aminobutyrate, γ‐aminobutyrate, and putrescine increased quickly with the rapid decrease of the initial carbon compounds, while Chromohalobacter, probably derived from the solar salts, was predominant. Multivariate redundancy analysis indicated that the Chromohalobacter population was closely correlated with the production of the organic acids and putrescine during the ganjang fermentation. These results may suggest that Chromohalobacter is a causing agent responsible for the production of organic acids and putrescine during ganjang fermentation and that the solar salts, not doenjang‐meju, is an important microbial source for ganjang fermentation.     

Evaluation of Putrescine, Cadaverine, and Indole as Chemical Indicators of Decomposition in Penaeid Shrimp

ABSTRACT: Putrescine, cadaverine, and indole were evaluated as chemical indicators of decomposition for wild and aquacultured Penaeid shrimp decomposed under controlled conditions at 0, 12, 24, and 36 °C and for commercial shrimp samples collected and evaluated by Food and Drug Administration experts. Putrescine, cadaverine, and indole levels increased with time as the temperatures of decomposition increased. Putrescine, at a reject level of 3 ppm, confirmed sensory evidence of decomposition more frequently than did cadaverine or indole at reject levels of 3 ppm or 25 μg/100 g, respectively. Based on this research, putrescine appears to be the most comprehensive chemical indicator for decomposition in fresh or frozen Penaeid shrimp studied to date.     

Effects of the attachment of small molecules by carbodiimide-mediated condensation on the physicochemical and functional properties of bovine serum albumin

The effects of attaching three small molecules, namely N-butylamide, putrescine and lysine, via the carboxyl groups of bovine serum albumin on its physicochemical and functional properties ere studied. To levels of attachment ere achieved by choice of reaction time. All modified samples had high isoelectric points and ere highly positive hen separated electrophoretically. Partially and extensively modified samples behaved differently in their pH titration curves, their gelation properties and the hipping properties of their lysyl derivatives, in that partially modified samples had high values compared ith the control and extensively modified samples had loer values. This as explicable by to theories: either there is increased electrostatic attraction beteen molecules hose isoelectric points are closer to neutrality, or there is a midpoint here a partial degree of conformational disruption results in superior functional properties. The level of conformational disruption in the extensively modified samples as greater than the optimum, hich resulted in impaired functional properties. An EDC control sample produced ithout added nucleophile as extensively cross-linked intra- or intermolecularly and had impaired functional properties.     

Histamine, Putrescine and Cadaverine Formation in Spanish Semipreserved Anchovies as Affected by Time/Temperature

We studied the changes in counts of mesophilic, psychrotrophic, entera-bacteria, sulphite-reducing and Vibrio microorganisms in commercial samples of Spanish semipreserved anchovies. The influence of NaCl, oxygen concentration and pH on bacterial growth and histamine, putrescine and cadaverine formation were also studied. Notable histamine formation was detected in samples incubated at 20°C and preserved in olive oil (443.68 ppm-3012.13 ppm). This accumulation was probably caused by the conditions of the product, pH 5–6, relatively low NaCl (< 15%), and permissive temperature (product not refrigerated). Correlation between the microorganisms and histamine formation was not clear. Histamine was produced by too high storage temperatures but not by the ripening process.     

Histamine, Cadaverine and Putrescine Forming Bacteria from Ripened Spanish Semipreserved Anchovies

Histidine decarboxylase activity and production of putrescine and cadaverine were assessed in 200 bacterial isolates from ripened semipreserved Spanish anchovies. Highest levels of histidine decarboxylase activity were observed in Morganella morganii, with 2336.74 ± 356.32 ppm of histamine, produced in laboratory media, after 24 hr incubation at 37°C. Microorganisms producing histamine also produced detectable putrescine and cadaverine. The Niven medium was used to evaluate the 200 isolates for histidine decarboxylase activity, after incubation 24 hr at 37°C. An enzymic technique was used to distinguish false positives and to quantify bacterial histamine levels. The number of microorganisms was the most important factor in the accumulation of histamine.     

Methods for the Detection of Bacteria Producing Biogenic Amines on Foods: A Survey

The presence of biogenic amines in foods is of considerable public concern for the food industry and the regulatory agencies, since given the potential health hazard, there is a growing demand from consumers and control authorities to reduce the allowable limits of biogenic amines in foods and beverages. Rapid and simple methods are needed for the analysis of the ability to form biogenic amines by bacteria in order to evaluate the potential risk of bacterial occurring in some food products. Analytical chromatographic methods used for routine biogenic amine analysis of food substrates have been applied to bacterial cultures. Specific differential culture media for the presumptive identification of biogenic amine-producer bacteria have been developed. Recently, several PCR based methods targeting amino acid decarboxylases have been described. These latter molecular methods, in addition to its rapidity and specificity, offer the advantage of the identification of producer bacteria before the amine is synthesized.

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Zusammenfassung (Redaktion). Es wird darüber berichtet, unter welchen Umst?nden biogene Amine in Lebensmitteln vorkommen k?nnen und dass – aufgrund der damit verbundenen, m?glichen gesundheitlichen Gef?hrdung – von den Verbrauchern und der Lebensmittelaufsicht angemahnt wird, die festgesetzten Grenzwerte für biogene Amine in Lebensmitteln und Getr?nken abzusenken. Im Sinne der Vorsorge stellt sich aber die Frage nach schnellen und praktikablen Nachweismethoden, um Bakterien, die biogene Amine produzieren k?nnen, frühzeitig zu identifizieren. Analytische chromatographische Methoden, die für die Routine-Kontrolle von Lebensmitteln auf biogene Amine eingesetzt werden, sind für die Untersuchung von Bakterienkulturen modifiziert worden. Spezielle Kulturmedien sind für die Identifizierung von biogene Amine produzierenden Bakterien entwickelt worden. Au?erdem sind mehrere PCR-Methoden beschrieben worden, die nicht nur schnell und sehr spezifisch sind, sondern auch den Nachweis relevanter Bakterien erm?glichen, bevor diese mit der Synthese von biogenen Aminen begonnen haben.

     

Formation,Degradation, and Detoxification of Putrescine by Foodborne Bacteria: A Review

Biogenic amines (BAs) represent a considerable toxicological risk in some food products. Putrescine is one of the most common BAs in food. Its increased occurrence in food may lead to alimentary poisoning, due to enhancement of the toxic effects of other BAs, and also to lower quality of food, this amine is potentially carcinogenic. Increased occurrence of putrescine in food is mainly due to the bacterial metabolism of the Gram‐negative as well as Gram‐positive bacteria present. The bacterial metabolism of putrescine is very specific due to its complexity (in comparison with the metabolism of other BAs). There are 3 distinct known pathways leading toward the formation of putrescine, in some splices involving up to 6 different enzymes. The existence of more metabolic pathways and the possibility of their simultaneous use by different bacteria complicate the specification of the best conditions for food production and storage, which could lead to a lower content of putrescine. This review provides a summary of the existing knowledge about putrescine production and detection (mainly detection of specific genes for different enzymes using polymerase chain reaction) in both starter and contaminating microorganisms. Thus, this comprehensive review gives a useful overview for further research.