Growth of, and aflatoxin production byAspergillus parasiticuswhen in the presence of eitherLactococcus lactisor lactic acid and at different initial pH values

1990 ◽  
Vol 69 (4) ◽  
pp. 512-519 ◽  
Author(s):  
Rosa H. Luchese ◽  
W.F. Harrigan
Keyword(s):  
Lactic Acid ◽  
Aflatoxin Production ◽  
Ph Values ◽  
Initial Ph

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.

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.

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.

Growth and Aflatoxin Production by Aspergillus parasiticus NRRL 2999 in the Presence of Potassium Benzoate or Potassium Sorbate and at Different Initial pH Values

1987 ◽  
Vol 50 (10) ◽  
pp. 820-825 ◽  
Author(s):  
GULAM RUSUL ◽  
ELMER H. MARTH
Keyword(s):  
High Performance ◽  
Aspergillus Parasiticus ◽  
Ph Value ◽  
Aflatoxin Production ◽  
Reversed Phase ◽  
Potassium Sorbate ◽  
Lag Phase ◽  
Ph Values ◽  
Initial Ph ◽  
Potassium Benzoate

Experiments were done to determine how different concentrations of potassium benzoate or potassium sorbate in a glucose-yeast extract-salts medium with an initial pH value of 3.5, 4.5 or 5.5 affected growth and aflatoxin production by Aspergillus parasiticus NRRL 2999. The pH of the medium, weight of mycelium and amount of aflatoxin produced were determined after 3 and 7 d of incubation. Aflatoxin was determined using reversed-phase high-performance liquid chromatography. Maximum concentrations of potassium sorbate and potassium benzoate that permitted growth were 0.2% and 0.4%, respectively, in a medium with an initial pH of 5.5. When the initial pH was 4.5, the maximum concentrations of potassium sorbate and potassium benzoate that permitted growth were 0.05% and 0.10%, respectively, but there was an extended lag phase. Increasing concentrations of potassium benzoate or potassium sorbate decreased amounts of aflatoxin B1 and G1 produced after 3 d in a medium with initial pH values of 5.5 or 4.5. Cultures growing in the medium containing 0.1, 0.15 or 0.20% potassium benzoate or potassium sorbate and with an initial pH of 5.5 were somewhat inhibited at 3 d of incubation, which was characterized by a slow decrease in pH, low mycelium dry weight and small amounts of accumulated aflatoxins. After 7 d these cultures overcame the initial inhibition and produced substantial amounts of aflatoxins and mycelium. This was also true for cultures growing in a medium with an initial pH of 4.5 and containing potassium benzoate or potassium sorbate. By decreasing the initial pH of the medium from 5.5 to 4.5, amounts of potassium benzoate or potassium sorbate required to achieve inhibition decreased by a factor of 10.

Effect of Phage on Survival of Salmonella Enteritidis during Manufacture and Storage of Cheddar Cheese Made from Raw and Pasteurized Milk

2001 ◽  
Vol 64 (7) ◽  
pp. 927-933 ◽  
Author(s):  
RAJESH MODI ◽  
Y. HIRVI ◽  
A. HILL ◽  
M. W. GRIFFITHS
Keyword(s):  
Lactic Acid ◽  
Salmonella Enteritidis ◽  
Cheddar Cheese ◽  
Raw Milk ◽  
Final Concentration ◽  
Pasteurized Milk ◽  
Ph Values ◽  
Standard Procedures ◽  
Raw Milk Cheese ◽  
And Storage

The ability of Salmonella Enteritidis to survive in the presence of phage, SJ2, during manufacture, ripening, and storage of Cheddar cheese produced from raw and pasteurized milk was investigated. Raw milk and pasteurized milk were inoculated to contain 104 CFU/ml of a luminescent strain of Salmonella Enteritidis (lux) and 108 PFU/ml SJ2 phage. The milks were processed into Cheddar cheese following standard procedures. Cheese samples were examined for Salmonella Enteritidis (lux), lactic acid bacteria, molds and yeasts, coliforms, and total counts, while moisture, fat, salt, and pH values were also measured. Salmonella Enteritidis (lux) was enumerated in duplicate samples by surface plating on MacConkey novobiocin agar. Bioluminescent colonies of Salmonella Enteritidis were identified in the NightOwl molecular imager. Samples were taken over a period of 99 days. Counts of Salmonella Enteritidis (lux) decreased by 1 to 2 log cycles in raw and pasteurized milk cheeses made from milk containing phage. In cheeses made from milks to which phage was not added, there was an increase in Salmonella counts of about 1 log cycle. Lower counts of Salmonella Enteritidis (lux) were observed after 24 h in pasteurized milk cheese containing phage compared to Salmonella counts in raw milk cheese with phage. Salmonella Enteritidis (lux) survived in raw milk and pasteurized milk cheese without phage, reaching a final concentration of 103 CFU/g after 99 days of storage at 8°C. Salmonella did not survive in pasteurized milk cheese after 89 days in the presence of phage. However, Salmonella counts of approximately 50 CFU/g were observed in raw milk cheese containing phage even after 99 days of storage. In conclusion, this study demonstrates that the addition of phage may be a useful adjunct to reduce the ability of Salmonella to survive in Cheddar cheese made from both raw and pasteurized milk.

Inhibition of Aflatoxin-Producing Fungi by Welsh Onion Extracts

1999 ◽  
Vol 62 (4) ◽  
pp. 414-417 ◽  
Author(s):  
J. J. FAN ◽  
J. H. CHEN
Keyword(s):  
Aspergillus Flavus ◽  
Mycelial Growth ◽  
Ethanol Extract ◽  
Aflatoxin Production ◽  
Inhibitory Effects ◽  
Welsh Onion ◽  
Extract Concentration ◽  
Ph Values ◽  
Ethanol Extracts ◽  
Yeast Extract Sucrose

Welsh onion ethanol extracts were tested for their inhibitory activity against the growth and aflatoxin production of Aspergillus flavus and A. parasiticus. The survival of spores of A. flavus and A. parasiticus depended on both the extract concentration and the exposure time of the spores to the Welsh onion extracts. The mycelial growth of two tested fungi cultured on yeast extract–sucrose broth was completely inhibited in the presence of the Welsh onion ethanol extract at a concentration of 10 mg/ml during 30 days of incubation at 25°C. The extracts added to the cultures also inhibited aflatoxin production at a concentration of 10 mg/ml or permitted only a small amount of aflatoxin production with extract concentration of 5 mg/ml after 2 weeks of incubation. Welsh onion ethanol extracts showed more pronounced inhibitory effects against the two tested aflatoxin-producing fungi than did the same added levels of the preservatives sorbate and propionate at pH values near 6.5.

Bacterial Spoilage of Citrus Products at pH Lower than 3.51

1976 ◽  
Vol 39 (12) ◽  
pp. 819-822 ◽  
Author(s):  
B. J. JUVEN
Keyword(s):  
Acetic Acid ◽  
Lactic Acid ◽  
Thermal Resistance ◽  
Tartaric Acid ◽  
Lactobacillus Brevis ◽  
Acid Inhibition ◽  
Temperature Range ◽  
Ph Values ◽  
Sugar Syrup ◽  
Z Value

A strain of Lactobacillus brevis, L-3, was isolated from a blown can of grapefruit segments in sugar syrup; it caused spoilage of citrus products having pH values lower than 3.5. When inoculated into orange (pH 3.38) and grapefruit (pH 2.99) juices, after 5 h at 30 C L-3 produced 15 and 22 μg diacetyl/ml, respectively, and off-flavor was detectable. L-3 grew in APT broth acidified to pH 3.0 with citric, hydrochloric, phosphoric, or tartaric acid. However, its growth was inhibited at pH 3.6 if the acidulant was lactic acid, while with acetic acid inhibition occurred at a pH between 3.7 and 4.0. The thermal resistance of L-3 in orange serum (pH 3.4) was studied in the temperature range of 52 to 60 C: a z value of 8.3 was obtained. A simple and reliable capillary technique for studying the thermal resistance of gas-producing organisms in liquid foods and media is presented.

Effect of pH, Acidulant, Time, and Temperature on the Growth and Survival of Listeria monocytogenes

1989 ◽  
Vol 52 (8) ◽  
pp. 571-573 ◽  
Author(s):  
KENT M. SORRELLS ◽  
DAVIN C. ENIGL ◽  
JOHN R. HATFIELD
Keyword(s):  
Antimicrobial Activity ◽  
Acetic Acid ◽  
Lactic Acid ◽  
Listeria Monocytogenes ◽  
Citric Acid ◽  
Hydrochloric Acid ◽  
Malic Acid ◽  
Incubation Temperature ◽  
Growth And Survival ◽  
Ph Values

The effect of different acids, pH, incubation time, and incubation temperature on the growth and survival of four strains of Listeria monocytogenes in tryptic soy broth was compared. Hydrochloric acid (HCl), acetic acid (AA), lactic acid (LA), malic acid (MA), and citric acid (CA) were used to acidify tryptic soy broth to pH values 4.4, 4.6, 4.8, 5.0, and 5.2 pH. Incubation times were 1, 3, 7, 14, and 28 d at 10, 25, and 35°C. The inhibition of L. monocytogenes in the presence of high acidity appears to be a function of acid and incubation temperature. Based on equal pH values, the antimicrobial activity is AA > LA > CA ≥ MA > HCl at all incubation times and temperatures. When based on equal molar concentration, the activity appeared to be CA ≥ MA > LA ≥ AA > HCl at 35 and 25°C, and MA > CA > AA ≥ LA > HCl at 10°C. Greatest antimicrobial activity occurred at 35°C. Greatest survival occurred at 10°C and greatest growth occurred at 25°C. Final pH of the medium was as low as 3.8 in HCl at 28 d. All strains grew well at pH values lower than the minimum previously reported (5.5–5.6).

GROWTH OF STAPHYLOCOCCUS AUREUS IN ACIDIFIED PASTEURIZED MILK1

1970 ◽  
Vol 33 (11) ◽  
pp. 516-520 ◽  
Author(s):  
T. E. Minor ◽  
E. H. Marth
Keyword(s):  
Staphylococcus Aureus ◽  
Acetic Acid ◽  
Lactic Acid ◽  
Hydrochloric Acid ◽  
Ph Value ◽  
The Other ◽  
Antagonistic Effects ◽  
Pasteurized Milk ◽  
Ph Values ◽  
Effect On Growth

The effect of gradually reducing the pH of pasteurized milk with acetic, citric, hydrochloric, lactic, and phosphoric acids over periods of 4, 8, and 12 hr on growth of Staphylococcus aureus 100 in this substrate was determined. In addition, 1: 1 mixtures of lactic acid and each of the other acids, and of acetic and citric acids were evaluated for their effect on growth of this organism. To achieve a 90% reduction in growth over a 12 hr period, a final pH value of 5.2 was required for acetic, 4.9 for lactic, 4.7 for phosphoric and citric, and 4.6 for hydrochloric acid. A 99% reduction during a 12 hr period was obtained with a final pH value of 5.0 for acetic, 4.6 for lactic, 4.5 for citric, 4.1 for phosphoric, and 4.0 for hydrochloric acid. A pH value of 3.3 was required for a 99.9% reduction with hydrochloric acid, whereas the same effect was produced at a pH value of 4.9 with acetic acid. Correspondingly lower pH values were required to inhibit growth within 8 and 4 hr periods. Mixtures of acids adjusted to pH values at the borderline for growth (12 hr period) exhibited neither synergistic nor antagonistic effects between two acids.

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