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1.
Lactic acid bacteria (LAB) are naturally found in fermented vegetable products. The ability of 230 kimchi bacterial isolates was investigated to produce tyramine by biochemical and genetic methods. The production of tyramine was determined by thin-layer chromatography (TLC) and high-performance liquid chromatography (HPLC). The presence of the gene encoding the corresponding tyrosine decarboxylase was also determined by PCR assay. After the production of tyramine was confirmed by chromatographic and molecular methods, the bacterial isolates producing the amine were identified by 16S rRNA gene sequence and species-specific PCR analyses. Only a small proportion of the bacterial isolates (14/230 isolates) decarboxylated tyrosine in vitro. All of the 14 bacterial isolates that produced tyramine were shown to possess the tdc gene, indicating that a positive correlation existed between the production of tyramine and the presence of the corresponding decarboxylase gene. The 14 isolates included three LAB species and one other species: Lactobacillus brevis (six), Lactobacillus curvatus (four), Leuconostoc mesenteroides (two), and Staphylococcus hominis (two). This study demonstrated that only a small proportion of LAB and other microbiota growing in kimchi had the ability to produce tyramine.  相似文献   

2.
3.
Bacteria with amine oxidase activity have become a particular interest to reduce biogenic amines concentration in food products such as meat and fish sausages. However, little information is available regarding the application of these bacteria in fish sauce. Hence, our study was aimed to investigate the effect of such starter cultures in reducing biogenic amines accumulation during fish sauce fermentation. Staphylococcus carnosus FS19 and Bacillus amyloliquefaciens FS05 isolated from fish sauce which possess amine oxidase activity were used as starter cultures in this study. Fermentation was held for 120 days at 35 °C. The pH value increased in all samples, while salt concentration remained constant throughout fermentation. Aerobic bacteria count was significantly lower (p < 0.05) in the control than in inoculated samples as a result of starter cultures addition. However, it decreased during fermentation due to the growth inhibition by high salt concentration. Proteolytic bacterial count decreased during fermentation with no significant difference (p > 0.05) among samples. These bacteria hydrolyzed protein in anchovy to produce free amino acid precursors for amines formation by decarboxylase bacteria. The presence of biogenic amines producing bacteria in this study was considered to be indigenous from raw material or contamination during fermentation, since our cultures were negative histamine producers. Amino acid histidine, arginine, lysine and tyrosine concentration decreased at different rates during fermentation as they were converted into their respective amines. In general, biogenic amines concentration namely histamine, putrescine, cadaverine and tyramine increased throughout fermentation. However, their concentrations were markedly higher (p < 0.05) in the control (without starter cultures) as compared to the samples treated with starter cultures. Histamine concentration was reduced by 27.7% and 15.4% by Staphylococcus carnosus FS19 and Bacillus amyloliquefaciens FS05, respectively. Both cultures could also reduce other amines during fermentation. After 120 days of fermentation, the overall biogenic amines concentration was 15.9% and 12.5% less in samples inoculated with Staphylococcus carnosus FS19 and Bacillus amyloliquefaciens FS05, respectively, as compared to control samples. These findings emphasized that application of starter cultures with amines oxidase activity in fish sauce fermentation was found to be effective in reducing biogenic amines accumulation.  相似文献   

4.
Saeu-jeot is made by the fermentation of highly salted [approximately 25% (w/v)] shrimp in Korea. Saeu-jeot samples were prepared in triplicate and their cell number, bacterial community, and metabolites were monitored periodically for 183 days. Quantitative PCR showed that bacterial populations were much more abundant than archaeal populations during the entire saeu-jeot fermentation period, which suggested that bacterial populations, not archaeal populations, might be primarily responsible for saeu-jeot fermentation. Pyrosequencing analysis revealed that Proteobacteria were dramatically replaced with halophilic Firmicutes as the fermentation progressed and members of Pseudoalteromonas, Staphylococcus, Salimicrobium, and Alkalibacillus were sequentially dominant and, eventually, Halanaerobium predominated after 66 days of fermentation. Halophilic archaeal genera, Halorubrum, Halolamina, Halobacterium, Haloarcula, and Haloplanus belonging to Euryarchaeota, were dominant, but their communities were relatively constant over the entire fermentation period. Metabolite analysis using a 1H NMR spectroscopy showed that the amount of metabolites including amino acids, glycerol, and nitrogen compounds rapidly increased during the early fermentation stage, but their levels were relatively constant or they decreased after approximately 49 days of fermentation. A statistical analysis based on bacterial communities and metabolites demonstrated that members of Halanaerobium might be responsible for the production of acetate, butyrate, and methylamines after 66 days of fermentation, which could be considered as a potential indicator to decide the appropriate seafood fermentation time. This study will provide insights into the microbial succession and metabolites of fermented seafood and allow for a greater understanding of the relationships between the microbial community and metabolites in seafood fermentation.  相似文献   

5.
Beef steaks were inoculated with Clostridium estertheticum spores and Leuconostoc mesenteroides cells at all combinations of numbers of 0, 10, 100 or 1000/cm(2) for each organism. After vacuum packaging the steaks were stored at 4, 1, or -1.5°C. Pack volumes were determined by water displacement at suitable intervals. Irrespective of L. mesenteroides numbers, for packs containing meat inoculated with 0, 10, 100 or 1000 spores/cm(2), 60, 16, 3 and 1 of 60 packs did not swell. The times of onset of swelling were twice as long at -1.5 as at 4°C, but they were not affected by the inoculated numbers of L. mesenteroides. Rates of pack swelling increased with increasing storage temperature and number of spores, but decreased with increasing numbers of inoculated L. mesenteroides. Lactic acid bacteria can apparently prevent development of blown pack spoilage of vacuum packs containing meat contaminated with low numbers of C. estertheticum.  相似文献   

6.
Leuconostoc mesenteroides E131, isolated from Greek traditional fermented sausage, prepared without the addition of starters, produces a bacteriocin which is active against the pathogen Listeria monocytogenes. The bacteriocin was purified by 50% ammonium sulphate precipitation, cation exchange, and reverse-phase chromatography. Bacteriocin is active at pH values between 4.0 and 9.0 and retains activity after incubation for 1 h at 100 °C. Proteolytic enzymes inactivated the bacteriocin after 1 h of incubation, while renin resulted in full inactivation only after 24 h. Lipase resulted in full inactivation after 4 h. Applying molecular methods, it was determined that the bacteriocin produced, named as mesenterocin E131, was identical to mesenterocin Y105 and was expressed during the exponential growth phase.  相似文献   

7.
The microbial diversity of water kefir   总被引:1,自引:0,他引:1  
The microbial diversity of water kefir, made from a mixture of water, dried figs, a slice of lemon and sucrose was studied. The microbial consortia residing in the granules of three water kefirs of different origins were analyzed. A collection of 453 bacterial isolates was obtained on different selective/differential media. Bacterial isolates were grouped with randomly amplified polymorphic DNA (RAPD)-PCR analyses. One representative of each RAPD genotype was identified by comparative 16S rDNA gene sequencing. The predominant genus in water kefirs I and II was Lactobacillus, which accounted for 82.1% in water kefir I and 72.1% in water kefir II of the bacterial isolates. The most abundant species in water kefirs I and II were Lactobacillus hordei and Lb. nagelii followed by considerably lower numbers of Lb. casei. Other lactic acid bacteria (LAB) were identified as Leuconostoc mesenteroides and Lc. citreum in all three water kefirs. The most abundant species in water kefir III was Lc. mesenteroides (28%) and Lc. citreum (24.3%). A total of 57 LAB belonging to the species of Lb. casei, Lb. hordei, Lb. nagelii, Lb. hilgardii and Lc. mesenteroides were able to produce exopolysacchrides from sucrose. Non LABs were identified as Acetobacter fabarum and Ac. orientalis. The Acetobacter species were more prevalent in consortium III. Cluster analyses of RAPD-PCR patterns revealed an interspecies diversity among the Lactobacillus and Acetobacter strains. Aditionally, Saccharomyces cerevisiae, Lachancea fermentati, Hanseniaospora valbyensis and Zygotorulaspora florentina were isolated and identified by comparison of partial 26S rDNA sequences and FTIR spectroscopy.  相似文献   

8.
Leuconostoc citreum HO12 and Weissella koreensis HO20 isolated from kimchi were evaluated as starter cultures in the making of whole wheat sourdough bread. After 24 h of fermentation at 25 °C, both lactobacilli grew to the final cell numbers of ca. 109 cfu/g dough, and both doughs had similar pHs and total titratable acidities. In addition, the fermentation quotient of the dough with Lc. citreum HO12 was slightly lower than that of the dough with W. koreensis HO20 (1.6 versus 2.8). Sourdoughs and bread with 50% sourdough produced with the starter cultures exhibited consistent ability to retard the growth of bread spoilage fungi (Penicillium roqueforti and Aspergillus niger) and rope-forming bacterium (Bacillus subtilis). Sourdough breads underwent a significant reduction in bread firming during storage. It seems that both lactobacilli have the potential to improve the shelf-life of wheat bread. The results indicate that the selected lactobacilli have unique fermentation characteristics and produce sourdough breads with overall satisfactory quality.  相似文献   

9.
The potential impact of aromatic and pectinolytic yeasts on cocoa flavour was investigated using two defined mixed starter cultures encompassing strains of Pichia kluyveri and Kluyveromyces marxianus for inoculating cocoa beans in small scale tray fermentations. Samples for microbial and metabolite analysis were collected at 12–24 hour intervals during 120 h of fermentation. Yeast isolates were grouped by (GTG)5-based rep-PCR fingerprinting and identified by sequencing of the D1/D2 region of the 26S rRNA gene and the actin gene. Pulsed Field Gel Electrophoresis (PFGE) was conducted on isolates belonging to the species P. kluyveri and K. marxianus to verify strain level identity with the inoculated strains. Furthermore, Denaturing Gradient Gel Electrophoresis (DGGE) was performed to follow yeast and bacterial dynamics over time including the presence of the bacterial inoculum consisting of Lactobacillus fermentum and Acetobacter pasteurianus. Yeast cell counts peaked after 12 h of fermentation with the predominant species being identified as Hanseniaspora opuntiae and Hanseniaspora thailandica. P. kluyveri and K. marxianus were found to compose 9.3% and 13.5% of the yeast population, respectively, after 12 h of fermentation whilst PFGE showed that ~ 88% of all P. kluyveri isolates and 100% of all K. marxianus isolates were identical to the inoculated strains. Despite never being the dominant yeast species at any stage of fermentation, the un-conched chocolates produced from the two inoculated fermentations were judged by sensory analysis to differ in flavour profile compared to the spontaneously fermented control. This could indicate that yeasts have a greater impact on the sensory qualities of cocoa than previously assumed.  相似文献   

10.
In this study, two strains of Staphylococcus xylosus isolated from traditional fermented sausages of Vallo di Diano (Southern Italy) were used in combination with an acidifying strain of Lactobacillus curvatus as starter culture for the production of fermented sausages. Two starter formulation were developed combining the proteolytic but not lipolytic (prt(+), lip(-)) S. xylosus CVS11 with the L. curvatus AVL3 (starter S1) and the S. xylosus FVS21 (prt(-), lip(+)) with the same strain of L. curvatus (starter S2). Proteolysis and lipolysis were observed during ripening by the increase in total free amino acids (FAA) and free fatty acids (FFA), respectively. Such activities were observed in both started and non started sausages (control). Moreover, the proteolytic and lipolytic activities were detected in products started by both formulations irrespective of the presence of such activities in the strains used. Therefore, it was not possible to conclude whether the effect of proteolysis and lipolysis during ripening of the started fermented sausages was due to the activity of the starter cultures or to the action of meat endogenous enzymes.  相似文献   

11.
The present study aimed to investigate the effects of 2 corn silage inoculation strategies (homofermentative vs. heterofermentative inoculation) under field conditions and to monitor responses in silage variables over the feeding season from January to August. Thirty-nine commercial dairy farms participated in the study. Farms were randomly assigned to 1 of 3 treatments: control (nonactive carrier; Chr. Hansen A/S, Hørsholm, Denmark), Lactisil (inoculation with 1 × 105Lactobacillus pentosus and 2.5 × 104Pediococcus pentosaceus per gram of fresh matter; Chr. Hansen A/S), and Lalsil Fresh (inoculation with 3 × 105Lactobacillus buchneri NCIMB 40788 per gram of fresh matter; Lallemand Animal Nutrition, Blagnac, France). Inoculation with Lactisil had no effects on fermentation variables and aerobic stability. On the contrary, inoculation with Lalsil Fresh doubled the aerobic stability: 37, 38, and 80 ± 8 h for control, Lactisil, and Lalsil Fresh, respectively. The effect of Lalsil Fresh on aerobic stability tended to differ between sampling times, indicating a reduced difference between treatments in samples collected in April. Lalsil Fresh inoculation increased silage pH and contents of acetic acid, propionic acid, propanol, propyl acetate, 2-butanol, propylene glycol, ammonia, and free AA. The contents and ratios of dl-lactic acid, l-lactic acid relative to dl-lactic acid, free glucose, and dl-lactic acid relative to acetic acid decreased with Lalsil Fresh inoculation. Lalsil Fresh inoculation increased the silage counts of total lactic acid bacteria and reduced yeast counts. The Fusarium toxins deoxynivalenol, nivalenol, and zearalenone were detected in all silages at all collections, but the contents were not affected by ensiling time or by inoculation treatment. The effect of inoculation treatments on milk production was assessed by collecting test-day results from the involved farms and comparing the actual milk production with predicted milk production within farm based on test-day results from 2007 and 2008. The average milk production of lactating cows at test days during the study (January to September 2009) was 30.7 ± 0.5 kg of energy-corrected milk/d. Milk production was 104.6 ± 0.7% of the predicted yield and did not differ among treatments. In conclusion, the present study showed that homofermentative inoculants might not compete efficiently or might not deviate sufficiently from the epiphytic flora on whole-crop corn to affect fermentation in standard qualities of corn silage. Heterofermentative inoculation increased aerobic stability and numerous fermentation variables. None of the treatments affected milk production, and more-stable corn silage seemed to have a similar production value as compared with less-stable homofermented silage. Heterofermented silage can be evaluated for its properties to limit aerobic silage deterioration in the feed chain.  相似文献   

12.
YS Park  JY Lee 《Meat science》2012,92(4):721-727
The effects of kimchi and freeze-dried kimchi-powder added to raw meat mixtures on the microbiological quality of fermented sausage were studied. The results clearly demonstrated that the lactic acid bacteria (LAB) integrated via the addition of kimchi as well as kimchi-powder were well adapted to the new habitat of fermenting sausage, reaching maximum numbers of 8.65-8.80log(10)cfu/g after 1-2days of fermentation. In all kimchi and kimchi-powder sausages, the growth of Enterobacteriaceae was completely inhibited throughout the processing period (<2log(10)cfu/g). The sausage batches containing more than 10% kimchi and 2% kimchi-powder showed no growth of S. aureus, whereas the control and another kimchi sausage batch reflected the growth of S. aureus (3.68-4.72log(10)cfu/g). As a result, the addition of kimchi (≥10%) and kimchi-powder to the sausage mixture prior to fermentation produced the microbiological stability required for fermented sausages.  相似文献   

13.
Quality of fermented sausages is affected by acidifying lactic acid bacteria (LAB) and colour- and flavour-promoting coagulase-negative staphylococci (CNS), whether or not used as starter culture. Artisan fermented sausages are often perceived as superior to industrial variants, partially because of the specific microbiota due to spontaneous acidification, which may be considered as an artisan characteristic. Therefore, two kinds of spontaneously acidified Belgian sausages were prepared (Belgian-type salami and Boulogne sausage), but with addition of a Staphylococcus carnosus culture. The Belgian-type salami was made from pork and beef, whereas the Boulogne sausage contained pork and horse meat. In all cases, Lactobacillus sakei was the dominant LAB species present on the raw materials and during fermentation, whereas enterococci remained present in the background. Enterobacteriaceae vanished after fermentation. The CNS species diversity on the raw materials was large and differed between the pork, beef, and horse meat. Nevertheless, this species diversity was annihilated during fermentation by the added S. carnosus culture. The volatiles fraction was mainly composed of aldehydes that originated from lipid oxidation and spices-derived compounds. Aromatic compounds that are typically associated to CNS activity, such as end-products from the metabolism of branched-chain amino acids, were not present in the Belgian-type salami and only marginally present in the Boulogne sausage. In conclusion, spontaneous acidification of Belgian-type fermented sausages leads to dominance of L. sakei and is no guarantee for bacterial contribution to the aroma profile when S. carnosus is added as a starter culture.  相似文献   

14.
Water mobility and distribution in fermented sausages produced with differences in pH development as a result of the use of three different starter cultures (T-SPX, F-1, or F-SC-111) and two fermentation temperatures (24 °C, or 32 °C) were studied using low-field proton NMR relaxometry. Changes in the distribution and mobility of water in fermented sausages upon fermentation and drying were detectable by NMR T2 relaxation, and the progress in the drying process could be followed as a shift towards faster relaxation times. In addition, the distribution of water in the sausages was significantly affected by the pH decline. The sausages were spiked with Listeria monocytogenes, Salmonella, and Escherichia coli VTEC, and partial least squares regressions revealed that 90% of the variation in reduction of Salmonella and VTEC could be explained by the NMR T2 relaxation decay. Consequently, the study demonstrated that NMR relaxometry is a promising technique for elucidating process parameters and microbial safety in the production of fermented meat products.  相似文献   

15.
The development of Lactobacillus and Staphylococcus strains used as starter cultures throughout the ripening of Galician chorizo, a traditional dry fermented sausage from the north-west of Spain, was monitored combining different molecular-based techniques. The bacterial diversity occurring in the inoculated sausages at the beginning and the end of the ripening was also studied and compared to the indigenous population in an uninoculated control batch.  相似文献   

16.
The aim of this study was the evaluation of selected lactic acid bacteria (LAB) starter culture of dairy origin in the production of nitrite-free low-acid fermented venison (Dama dama) sausage (salame di daino) produced in a small-scale plant in Umbria (Italy), and their effect on microbiological, physico-chemical and sensorial properties of the products. Salame di daino was obtained with two different processes: with and without the addition of selected LAB starter cultures. Microbial counts of Enterobacteriaceae, coliform organisms and Pseudomonas spp. were lower in salami made with the addition of starter cultures. Staphylococcus aureus, Salmonella spp, and Listeria monocytogenes after the first week of ripening were only detected from control salami. Control salami were paler and harder, whereas those made with the addition of starter cultures were slightly saltier, juicier and in general more acceptable. Selected dairy-origin starter (SDS) cultures did prevent the growth of both indicators of food safety and of process hygiene and increased the acceptability of full-ripened salami.  相似文献   

17.
Recognized to confer health benefits to consumers, probiotics such as Lactobacillus acidophilus are commonly incorporated into fermented dairy products worldwide; among which yogurt is a popular delivery vehicle. To materialize most of the putative health benefits associated with probiotics, an adequate amount of viable cells must be delivered at the time of consumption. However, the loss in their viabilities during refrigerated storage has been demonstrated previously. This study focused on the effects of yogurt starter cultures on the survival of five strains of L. acidophilus, with emphases on low pH and acid production. Differential survival behavior between L. acidophilus strains was further analyzed. To this end, viable cell counts of L. acidophilus were determined weekly during 4 °C storage in various types of yogurts made with Streptococcus thermophilus alone, L. delbrueckii ssp. bulgaricus alone, both species of the starter cultures, or glucono-delta-lactone (GDL). All yogurt types, except for pasteurized yogurts, were co-fermented with L. acidophilus. Yogurt filtrate was analyzed for the presence of any inhibitory substance and for the amount of hydrogen peroxide. Multiplication of L. acidophilus was not affected by the starter cultures as all strains reached high level on day 0 of the storage period. Throughout the 28-day storage period, cell counts of L. acidophilus PIM703 and SBT2062 remained steady (~ 6 × 107 CFU/g) in yogurts made with both starter cultures, whereas those of ATCC 700396 and NCFM were reduced by a maximum of 3 and 4.6 logs, respectively. When starter cultures were replaced by GDL, all strains survived well, suggesting that a low pH was not a critical factor dictating their survival. In addition, the filtrate collected from yogurts made with starter cultures appeared to have higher inhibitory activities against L. acidophilus than that made with GDL. The presence of viable starter cultures was necessary to adversely affect the survival of some strains, as pasteurized yogurts had no effect on their survival. In particular, the inhibitory effect exerted by L. delbrueckii ssp. bulgaricus on L. acidophilus NCFM was highly pronounced than by S. thermophilus, nevertheless, the same effect was not observed on SBT2062. The inhibition against stationary-phase NCFM cells might be caused by the elevated level of hydrogen peroxide produced by L. delbrueckii ssp. bulgaricus. Delineating factors driving the differences in survival trait among probiotic strains will lead to a more efficacious delivery of health benefits in fermented dairy products through targeted technological interventions.  相似文献   

18.
In this study, instrumental and sensory textural properties of chorizo with different levels of glucose (0.1%, 0.5% and 1.0%) and with different starter cultures (Lactobacillus sakei K29, Pediococcus sp. P22 and Pediococcus sp. P208) were studied as well as the relationship between them. The ripening process was followed by physico-chemical and microbiological analysis. Starter culture and concentration of glucose had a highly significant effect on pH, moreover an interactive effect of both factors was found; and also of day of ripening and both starter culture and concentration of glucose. In general terms, changes of pH over time are influenced by the presence of sugar and starter culture even if all chorizos showed at first a rapid decrease, a stay or slow decrease, and a final rise. Texture profile analysis (TPA) proved that hardness and chewiness differ significantly among chorizos with or without starter cultures, except in the batch with 0.1% sugar. Furthermore, the highest values in both textural parameters were found in batches with 0.5% and 1% sugar. The texture differences between chorizos just described were also noticeable in the sensorial evaluation. Likewise, instrumental textural attributes showed significant correlations with sensorial analysis.  相似文献   

19.
Malted barley is a major raw material of beer, as well as distilled spirits and several food products. In the malting process, dry barley kernels are steeped in water which initiates germination and invigorates microbial growth on the kernels. In the present study, field emission scanning electron microscopy (FESEM) was used to visualize the microbial community within the tissues of barley kernels before and after the steeping, with and without Lactobacillus plantarum E76 added as a starter culture. The results show that the community of 108 cfu g−1 on dry, stored barley kernels increased 5–10 fold during the steeping forming a dense biofilm of bacteria and fungi with slimy exopolymeric matrix. FESEM revealed that crevices between the outer epidermis and the testa of sound barley kernels were heavily colonized with microbes, whereas there were only few microbes on the outer surface of the husks, in the aleurone layer or in the endosperm underneath an intact testa layer. The microbes frequently possessed appendages forming bridging them to the kernel and the individual microbial cells to each other. The L. plantarum added to the steeping water reduced the amount of exopolymeric matrix in the biofilm and improved the wort filterability.  相似文献   

20.
Lee JY  Kim CJ  Kunz B 《Meat science》2006,72(3):437-445
The aim of the investigation was to identify strains of lactobacilli coming from kimchi with properties suitable for use as starter cultures in sausage fermentation. A total of 31 strains of lactobacilli were isolated from kimchi on the 4-6th day of fermentation at 20°C using MRS agar plates and identified on the basis of morphological, biochemical, and physiological characteristics. The isolates were identified as Leuconostoc mes.mes./dent (12.9%), Lactobacillus curvatus (9.7%), Lactobacillus brevis (35.5%), Lactobacillus sake (25.8%), and Lactobacillus plantarum (16.1%). Thus, 51.6% of the isolates were homo-fermentative or facultative hetero-fermentative bacteria and the rest (48.4%) were hetero-fermentative bacteria. Among them L. brevis, L. curvatus, L. plantarum, and L. sake were investigated for their growth profile and metabolism characteristics in the fluid (submerged) model-medium modified according to the special conditions of fermented sausages. Relatively good growth properties were found for L. brevis, L. plantarum, and L. sake with maximum numbers of 8.18, 8.51 and 8.17cfu/ml, respectively, whereas L. curvatus could not adapt to the special environmental conditions. Regarding souring properties, L. brevis showed little ability to decrease pH, whereas L. curvatus, L. plantarum, and L. sake showed relatively good acidifying properties. According to the results of glucose fermentation and its products, only L. plantarum exhibited homo-fermentative characteristics. As a result only L. plantarum among the isolates from kimchi had an ability to adapt to the complex environment of fermented sausage, which will thereby allow them to act as starter cultures and natural preservatives in sausage production.  相似文献   

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