Histamine and Tyramine Production by a Lactobacillus Strain Subjected to External pH Decrease

1994 ◽  
Vol 57 (3) ◽  
pp. 259-262 ◽  
Author(s):  
RIITTA MAIJALA
Keyword(s):  
Lactic Acid ◽  
Room Temperature ◽  
Lactobacillus Strain ◽  
Ph Values ◽  
Initial Ph ◽  
Ph Decrease ◽  
In The Beginning ◽  
Influence Of Ph ◽  
External Ph ◽  
Made In

The preservative effect of fermentation is based on the pH decrease during processing. However, most studies conceming the influence of pH on the formation of biogenic amines have been made in broths with different initial pH values. A histamine- and tyramine-positive Lactobacillus strain isolated from dry sausage was added at an initial level of 3.9- to 4.4-logl0 CFU/ml and incubated on a shaker at room temperature (20.0°C) for 6 days. The pH was decreased in histidine- or tyrosine-fortified MRS broth by adding glucono-delta-lactone (GDL) or lactic acid during the incubation. The external acidification decreased the growth and the production of histamine and tyramine by the strain. GDL was more effective as a preventative than lactic acid. According to these results, a rapid pH decrease resulting in decreased growth of amine-positive lactic acid bacteria in the beginning of fermentation may be a means of preventing the formation of high levels of amines in foods.

scholarly journals AVALIAÇÃO DA ATIVIDADE BACTERIOCINOGÊNICA DO Lactobacillus sakei NA FERMENTAÇÃO DA SARDINHA-VERDADEIRA ( Sardinella brasiliensis) UTILIZANDO GLICOSE COMO CARBOIDRATO FERMENTECÍVEL

2003 ◽  
Vol 21 (1) ◽  
Author(s):  
MILTON LUIZ PINHO ESPÍRITO SANTO ◽  
LUIZ HENRIQUE BEIRÃO ◽  
ERNANI SANT’ANNA ◽  
CESAR DAMIAN ◽  
BERNADETTE MELLO FRANCO
Keyword(s):  
Lactic Acid ◽  
Sodium Chloride ◽  
Lactic Acid Production ◽  
Starter Culture ◽  
Soluble Nitrogen ◽  
Lactobacillus Sakei ◽  
Protein Nitrogen ◽  
Ph Values ◽  
Bacteriocin Producer ◽  
Initial Ph

Lactobacillus sakei é comprovadamente uma cepa produtora de bacteriocinas e, neste estudo, procurou-se observar seus efeitos na fermentação de filés de sardinha ( Sardinella brasiliensis) em diferentes concentrações de NaCl e glicose. Verificou-se sua habilidade para produzir ácidos orgânicos e conseqüente redução do pH durante 21 dias de fermentação. Ao término desse período, a concentração de microrganismos deterioradores atingiu 9,7 log UFC g-1 correspondente a 6% de NaCl e 4% de glicose. Poucas diferenças foram observadas na produção de ácido lático quando se adicionou 2 e 4% de glicose, já que a acidez total foi 1,32 e 1,34%, respectivamente, para os experimentos com 6% de NaCl. O pH 6 inicial dos filés modificou-se ao término de 21 dias para 3,8, 3,9 e 4 nos experimentos com 2, 4 e 6% de NaCl. Tal comportamento pode ser atribuído ao poder inibidor do NaCl sobre a microbiota deterioradora. No término da fermentação, a concentração de bactérias ácido lácticas foi 14,5 log10 UFC g-1. A relação entre o nitrogênio protéico e o nitrogênio solúvel total mostrou-se típica de pescado salgado/curado em perfeitas condições de consumo. EVALUATION OF BACTERIOCINOGENIC ACTIVITY OF Lactobacillus sakei IN THE FERMENTETION OF TRUE SARDINE (Sardinella brasiliensis) BY UTILIZING GLUCOSE AS FERMENTABLE CARBOHYDRATE Abstract Lactobacillus sakei 2a is a bacteriocin producer strain and, in this study, it’s effects as a starter culture in the curing process of sardine ( Sardinella brasiliensis) fillets were observed at different concentrations of sodium chloride and glucose. It’s ability to produce organic acids and pH reduction during 21 days of fermentation was verified. After this period, the deteriorative microbiota concentration reached 9.7 log10 CFU. g-1 corresponding to 6% sodium chloride and 4% glucose. Little differences were observed in lactic acid production when 2 and 4% glucose were added, since total acidity was 1.32 and 1.34% respectively for the experiments with 6% NaCl. Initial pH of fillets was 6 and after 21 days pH values were 3.8, 3.9 and 4 for the experiments with 2, 4 and 6% NaCl. This may have been due to the inhibitory properties of NaCl over the deteriorative microbiota. At the end of the fermentation process lactic acid bacteria concentrations were 14.5 log10 CFU.g-1. The ratio protein nitrogen and total soluble nitrogen was typical of a cured fish under perfect eating conditions.

Growth and Aflatoxin Production by Aspergillus parasiticus NRRL 2999 in the Presence of Lactic Acid and at Different Initial pH values

1987 ◽  
Vol 50 (11) ◽  
pp. 940-944 ◽  
Author(s):  
FATHY E. EL-GAZZAR ◽  
GULAM RUSUL ◽  
ELMER H. MARTH
Keyword(s):  
Lactic Acid ◽  
Aflatoxin B1 ◽  
High Performance ◽  
Aspergillus Parasiticus ◽  
Ph Value ◽  
Aflatoxin Production ◽  
Reversed Phase ◽  
Ph Values ◽  
Initial Ph ◽  
Medium Weight

Twenty-five milliliters of glucose-yeast-salts medium containing 0, 0.5, 0.75, 1.0, 1.5 and 2.0% lactic acid with an initial pH of 3.5 or 4.5 were inoculated with 1 ml of a spore suspension containing 106 conidia of Aspergillus parasiticus NRRL 2999 and incubated at 28°C for 10 d. The pH of the medium, weight of mycelium and aflatoxin production were determined after 3, 7, and 10 d of incubation. Amounts of aflatoxin produced were determined using reversed-phase high-performance liquid chromatography. Cultures grown in the presence of 0.5 and 0.75% lactic acid at an initial pH of 4.5 produced more aflatoxin B1 than did the other cultures at the end of 3 d of incubation. This was not true for aflatoxin G1; with increasing concentrations of lactic acid, cultures produced decreasing amounts of aflatoxin G1. Also, cultures growing in the medium with an initial pH of 3.5 produced more aflatoxin B1 in the presence of lactic acid at the end of 3 d of incubation than did control cultures. Cultures growing in the presence of 0.5 and 0.75% lactic acid produced the most aflatoxin. Maximum amounts of aflatoxin G1 were produced after 7 d of incubation, with cultures growing in the presence of 0.5 and 0.75% lactic acid producing the most. Lactic acid did not inhibit growth (mycelium weight) of cultures in the medium with initial pH values of 3.5 or 4.5 except there was a slight decrease in mycelial weight when the medium contained 0.5% lactic acid and had an initial pH value of 3.5.

scholarly journals The Influence of The Degree of Grinding to Obtain of Some Fermented Mashes Based on Whole Wheat and Husked Millet

2011 ◽  
Vol 68 (2) ◽  
Author(s):  
Mariana PACALA ◽  
Lucica BRUDIU ◽  
Eniko GASPAR ◽  
Ecaterina LENGYEL ◽  
Letitia OPREAN
Keyword(s):  
Alcohol Concentration ◽  
Yeast Culture ◽  
Total Acidity ◽  
Ph Values ◽  
Whole Wheat ◽  
Character Type ◽  
Grain Milling ◽  
Initial Ph ◽  
Lactic Bacteria ◽  
Made In

The purpose of this article was to study the influence of degree of milling whole wheat (was ground in 4 variants of grain) and husked millet (was finely ground) to obtain fermented mashes type Braga. There have been 4 mashes of grist of whole wheat, grist husked millet, hop pellets and water and were boiled under continuous stirring and then cooled. Their content has diluted with water and then strainer by pressed through a sieve. Each mash-filtrate has divided in two and added white sugar 7%, resulting two series of sweet mashes. One has inoculated with a mixed culture of yeast and lactic bacteria and the other only with yeast culture. After fermentation were analyzed fermented mashes (pH, volatile and total acidity, total and soluble dry substances, dynamic viscosity, alcohol concentration, number of yeast and bacteria cells (UFC/mL). All determinations have made in triplicate. For both series of fermented mashes observed an increase in viscosity for increasing grain particles of grist. Increased viscosity was higher when using only inoculums of yeast culture. pH values for both series of mashes varied in opposite directions. Towards lower pH's initial pH was significant for the series of mashes fermented with mixed cultivation of microorganisms. Are balanced values of alcoholic strength of fermented mashes at 25°C for 40 h. Very small inoculums of yeast ensures appropriate alcohol concentration, but not a total acidity that provides drinking fermented sour-sweet character type specific Braga. According to the ingredients used and method of obtaining of fermented mashes recommended wheat grain milling at 0.3 and/or 0.4 mm for a positive sensory evaluation.

scholarly journals Effect of different levels of sodium chloride and glucose on fermentation of sardines (Sardinella brasiliensis) by Lactobacillus sakei 2a

2005 ◽  
Vol 48 (1) ◽  
pp. 42-52 ◽  
Author(s):  
Milton Luiz Pinho Espirito Santo ◽  
Cristiane Lisboa ◽  
Fernanda Gonçalves Alves ◽  
Daniela Martins ◽  
Luiz Henrique Beirão ◽  
...  
Keyword(s):  
Lactic Acid ◽  
Lactic Acid Production ◽  
Starter Culture ◽  
Lactobacillus Sakei ◽  
Producer Strain ◽  
Ph Values ◽  
Bacteriocin Producer ◽  
Initial Ph ◽  
Spoilage Microorganisms ◽  
Different Levels

Lactobacillus sakei 2a is a bacteriocin producer strain. In this study, it's effects as a starter culture in the curing process of sardine (Sardinella brasiliensis) fillets were studied at different concentrations of NaCl (2, 4, 6%) and glucose (2, 4%). After 21 days of fermentation, the spoilage microorganisms population reached 9.7 Log10 CFU g-1 corresponding to 6% NaCl and 4% glucose. With no addition of glucose and starter culture, sardine fillets began spoilage 72 hours after fermentation, even when 6% NaCl was used. Little differences were observed in lactic acid production when 2 and 4% glucose were added, since total acidity was 1.32 and 1.34% respectively, the experiments with 6% NaCl presented the best results. Initial pH of sardine fillets was 6.0 and after 21 days pH values were 3.8, 3.9 and 4.0 for the experiments with 2, 4 and 6% NaCl respectively. This could have been due to the inhibitory properties of NaCl over the spoilage microorganisms. After 21 days of the fermentation, the levels of lactic acid bacteria (LAB) were 14.5 Log10 CFU.g-1.

DNA Inspirited Rational Construction of Nonconventional Luminophores with Efficient and Color-Tunable Afterglow

2020 ◽  
Author(s):  
Yunzhong Wang ◽  
Saixing Tang ◽  
Yating Wen ◽  
Shuyuan Zheng ◽  
Bing Yang ◽  
...  
Keyword(s):  
Rational Design ◽  
Room Temperature ◽  
Double Helix ◽  
Mechanical Grinding ◽  
Room Temperature Phosphorescence ◽  
Color Tunable ◽  
Potential Applications ◽  
Rational Construction ◽  
Double Helix Structure ◽  
Made In

<div>Persistent room-temperature phosphorescence (p-RTP) from pure organics is attractive </div><div>due to its fundamental importance and potential applications in molecular imaging, </div><div>sensing, encryption, anticounterfeiting, etc.1-4 Recently, efforts have been also made in </div><div>obtaining color-tunable p-RTP in aromatic phosphors5 and nonconjugated polymers6,7. </div><div>The origin of color-tunable p-RTP and the rational design of such luminogens, </div><div>particularly those with explicit structure and molecular packing, remain challenging. </div><div>Noteworthily, nonconventional luminophores without significant conjugations generally </div><div>possess excitation-dependent photoluminescence (PL) because of the coexistence of </div><div>diverse clustered chromophores6,8, which strongly implicates the possibility to achieve </div><div>color-tunable p-RTP from their molecular crystals assisted by effective intermolecular </div><div>interactions. Here, inspirited by the highly stable double-helix structure and multiple </div><div>hydrogen bonds in DNA, we reported a series of nonconventional luminophores based on </div><div>hydantoin (HA), which demonstrate excitation-dependent PL and color-tunable p-RTP </div><div>from sky-blue to yellowish-green, accompanying unprecedentedly high PL and p-RTP </div><div>efficiencies of up to 87.5% and 21.8%, respectively. Meanwhile, the p-RTP emissions are </div><div>resistant to vigorous mechanical grinding, with lifetimes of up to 1.74 s. Such robust, </div><div>color-tunable and highly efficient p-RTP render the luminophores promising for varying </div><div>applications. These findings provide mechanism insights into the origin of color-tunable </div><div>p-RTP, and surely advance the exploitation of efficient nonconventional luminophores.</div>

scholarly journals Enhanced Oil Removal by a Non-Toxic Biosurfactant Formulation

Energies ◽  
2021 ◽  
Vol 14 (2) ◽  
pp. 467
Author(s):  
Emília Mendes da Silva Santos ◽  
Isabela Regina Alvares da Silva Lira ◽  
Hugo Moraes Meira ◽  
Jaciana dos Santos Aguiar ◽  
Raquel Diniz Rufino ◽  
...  
Keyword(s):  
Room Temperature ◽  
Low Cost ◽  
Aeration Rate ◽  
Oil Removal ◽  
Central Composite Rotatable Design ◽  
Chemical Methods ◽  
Ph Values ◽  
Spectroscopic Analyses ◽  
New Formulation ◽  
Central Composite

In this study, a new formulation of low-cost, biodegradable, and non-toxic biosurfactant by Candida sphaerica UCP 0995 was investigated. The study was conducted in a bioreactor on an industrial waste-based medium, and a central composite rotatable design was used for optimization. The best results, namely a 25.22 mN/m reduction in surface tension, a biosurfactant yield of 10.0 g/L, and a critical micelle concentration of 0.2 g/L, were achieved in 132 h at an agitation speed of 175 rpm and an aeration rate of 1.5 vvm. Compositional and spectroscopic analyses of the purified biosurfactant by chemical methods, Fourier transform infrared spectroscopy, and nuclear magnetic resonance suggested that it is a glycolipid-type biosurfactant, and it showed no cytotoxicity in the MTT assay. The biosurfactant, submitted to different formulation methods as a commercial additive, remained stable for 120 days at room temperature. Tensioactive properties and stability were evaluated at different pH values, temperatures, and salt concentrations. The biosurfactant obtained with all formulation methods demonstrated good stability, with tolerance to wide ranges of pH, temperature and salinity, enabling application under extreme environmental conditions. Bioremediation tests were performed to check the efficacy of the isolated biosurfactant and the selected microbial species in removing oil from soil. The results demonstrated that the biosurfactant produced has promising properties as an agent for the bioremediation of contaminated soil.

scholarly journals Synthesis and Characterization of Polyphosphazenes Modified with Hydroxyethyl Methacrylate and Lactic Acid

2013 ◽  
Vol 2013 ◽  
pp. 1-7 ◽  
Author(s):  
Evelyn Carolina Martínez Ceballos ◽  
Ricardo Vera Graziano ◽  
Gonzalo Martínez Barrera ◽  
Oscar Olea Mejía
Keyword(s):  
Lactic Acid ◽  
Ring Opening ◽  
Room Temperature ◽  
Block Structure ◽  
Ring Opening Polymerization ◽  
Synthesis And Characterization ◽  
Poly Lactic Acid ◽  
Hydroxyethyl Methacrylate ◽  
H Nmr

Poly(dichlorophosphazene) was prepared by melt ring-opening polymerization of the hexachlorocyclotriphosphazene. Poly[bis(2-hydroxyethyl-methacrylate)-phosphazene] and poly[(2-hydroxyethyl-methacrylate)-graft-poly(lactic-acid)-phosphazene] were obtained by nucleophilic condensation reactions at different concentrations of the substituents. The properties of the synthesized copolymers were assessed by FTIR,1H-NMR and31P-NMR, thermal analysis (DSC-TGA), and electron microscopy (SEM). The copolymers have a block structure and show twoTg's below room temperature. They are stable up to a temperature of 100°C. The type of the substituents attached to the PZ backbone determines the morphology of the polymers.

Influence of pH values on electroless Ni-P-SiC plating on AZ91D magnesium alloy

2010 ◽  
Vol 20 ◽  
pp. s674-s678 ◽  
Author(s):  
Yin-ning GOU ◽  
Wei-jiu HUANG ◽  
Rong-chang ZENG ◽  
Yi ZHU
Keyword(s):  
Magnesium Alloy ◽  
Az91d Magnesium Alloy ◽  
Ph Values ◽  
Electroless Ni ◽  
Influence Of Ph

scholarly journals An investigation on the degradation behaviors of Mg wires/PLA composite for bone fixation implants: influence of wire content and load mode

2021 ◽  
Vol 28 (1) ◽  
pp. 39-47
Author(s):  
Xuan Li ◽  
Yu Cong ◽  
Jisheng Sui ◽  
Xiaolong Li
Keyword(s):  
Lactic Acid ◽  
Dynamic Load ◽  
Degradation Rate ◽  
Convective Transport ◽  
Poly Lactic Acid ◽  
Mechanical Loss ◽  
Bone Fixation ◽  
Load Mode ◽  
Degradation Behaviors ◽  
Ph Decrease

Abstract Poly-lactic acid based biocomposite strengthened with magnesium alloy wires (Mg wires/PLA composite) is prepared for bone fixation implantation. The influence of wire content and load mode on the degradation performances of the composite and its components is studied. The result suggests the degradation of Mg wires could slow down the pH decrease originated from the degradation of PLA, while a relatively high wire content contributes to descend the degradation rate of Mg wire in the composite. Dynamic load significantly promotes the mechanical loss of the specimens. After 30 days immersion, the Sb retention is about 65%, 52% and 55%, respectively for pure PLA, the composite at 10 vol% and 20 vol% under dynamic load, comparing to 75%, 70% and 72% under no load. Moreover, dynamic load could further mitigate the degradation of Mg wires by increasing convective transport of acidic products out of the composite.

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