Growth of Staphylococcus aureus and Enterotoxin Production in Homemade Mayonnaise Prepared with Different pH Values

1987 ◽  
Vol 50 (10) ◽  
pp. 872-875 ◽  
Author(s):  
ESPERANZA GOMEZ-LUCIA ◽  
JOAQUIN GOYACHE ◽  
JOSE L. BLANCO ◽  
JOSE F. F. GARAYZABAL ◽  
JOSE A. ORDEN ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Ph Values ◽  
Enterotoxin Production ◽  
Initial Ph

The ability of Staphylococcus aureus to grow and produce enterotoxins in homemade mayonnaise prepared at different pH values was studied. Ten enterotoxigenic strains, producing one or two enterotoxin types (A, B, C, or D) were inoculated into mayonnaise samples with pH adjusted to values ranging between 4.0 and 5.8, and incubated at 37°C for 7 d. Counts were made on days 1, 3, 5, and 7 and extracts were prepared on day 7 to detect enterotoxin by ELISA. An important difference was seen between those samples prepared with pH below or equal to 4.9 and those over or equal to 5.0; in the range of pH between 4.0 and 4.9 the average of staphylococcal population was 100 CFU/g; at pH 5.0 it was 1.6 × 105, and at pH 5.15 and above it was at least 8 × 106 CFU/g. Enterotoxin was detected only at initial pH over 5.15 and when final pH was not less than 4.7. The highest amount of enterotoxin corresponded to 157.8 ng of SEB/100 g of mayonnaise.

Staphylococcus aureus Growth and Enterotoxin Production during the Manufacture of Uncooked, Semihard Cheese from Cows' Raw Milk

2006 ◽  
Vol 69 (9) ◽  
pp. 2161-2167 ◽  
Author(s):  
CELINE DELBES ◽  
JOMAA ALOMAR ◽  
NADIA CHOUGUI ◽  
JEAN-FRANÇOIS MARTIN ◽  
MARIE-CHRISTINE MONTEL
Keyword(s):  
Staphylococcus Aureus ◽  
Correlation Coefficient ◽  
Initial Level ◽  
Raw Milk ◽  
Ph Values ◽  
Enterotoxin Production ◽  
Raw Milk Cheese ◽  
Coagulase Positive Staphylococci

Staphylococcus aureus growth and enterotoxin production during the manufacture of model Saint-Nectaire, Registered Designation of Origin Saint-Nectaire, and Registered Designation of Origin Salers cheeses, three types of uncooked, semihard, raw milk cheese, were investigated. Coagulase-positive staphylococci (SC+) grew rapidly during the first 6 h. Between 6 and 24 h, counts increased by less than 0.5 log CFU/ml. Raw milk counts ranged from undetectable (<10 CFU/ml) to 3.03 log CFU/ml. Maximal levels reached in cheese on day 1 ranged from 2.82 to 6.84 log CFU/g. The level of SC+ after 24 h was mainly influenced by the milk baseline SC+ level (correlation coefficient, r > 0.80) but pH at 6 h influenced the SC+ growth observed between 6 and 24 h (r > 0.70). Thus, the initial level of SC+ in raw milk should be maintained below 100 CFU/ml and best below 40 CFU/ml. To limit growth, acidification should be managed to obtain pH values around or below 5.8 at 6 h in Saint-Nectaire cheeses and around or below 6.3 at 6 h in Salers cheeses. Enterotoxins were only detected in two Salers cheeses whose SC+ counts on day 1 were 5.55 log CFU/g and 5.06 log CFU/g, respectively, and whose pH values at 6 h were high (approximately 6.6 and 6.5, respectively).

Effect of tea tree oil on Staphylococcus aureus growth and enterotoxin production

Food Control ◽  
2016 ◽  
Vol 62 ◽  
pp. 257-263 ◽  
Author(s):  
Ce Shi ◽  
Xingchen Zhao ◽  
Haiyang Yan ◽  
Rizeng Meng ◽  
Yan Zhang ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Tea Tree Oil ◽  
Tea Tree ◽  
Enterotoxin Production

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.

Treatment of cooling tower blowdown water containing silica, calcium and magnesium by electrocoagulation

2009 ◽  
Vol 60 (9) ◽  
pp. 2345-2352 ◽  
Author(s):  
Z. Liao ◽  
Z. Gu ◽  
M. C. Schulz ◽  
J. R. Davis ◽  
J. C. Baygents ◽  
...  
Keyword(s):  
Cooling Tower ◽  
Target Species ◽  
Organic Additives ◽  
Dissolved Silica ◽  
Ion Removal ◽  
Ph Values ◽  
Silica Removal ◽  
Initial Ph ◽  
Aluminum Electrodes ◽  
Calcium And Magnesium

This research investigated the effectiveness of electrocoagulation using iron and aluminium electrodes for treating cooling tower blowdown (CTB) waters containing dissolved silica (Si(OH)4), Ca2 +  and Mg2 + . The removal of each target species was measured as a function of the coagulant dose in simulated CTB waters with initial pH values of 5, 7, and 9. Experiments were also performed to investigate the effect of antiscaling compounds and coagulation aids on hardness ion removal. Both iron and aluminum electrodes were effective at removing dissolved silica. For coagulant doses ≤3 mM, silica removal was a linear function of the coagulant dose, with 0.4 to 0.5 moles of silica removed per mole of iron or aluminium. Iron electrodes were only 30% as effective at removing Ca2 +  and Mg2 +  as compared to silica. There was no measurable removal of hardness ions by aluminium electrodes in the absence of organic additives. Phosphonate based antiscaling compounds were uniformly effective at increasing the removal of Ca2 +  and Mg2 +  by both iron and aluminium electrodes. Cationic and amphoteric polymers used as coagulation aids were also effective at increasing hardness ion removal.

scholarly journals Characterization of Melanoidins and Color Development in Dulce de Leche, a Confectionary Dairy Product With High Sucrose Content: Evaluation of pH Effect, an Essential Manufacturing Process Parameter

2021 ◽  
Vol 8 ◽  
Author(s):  
Analía Rodríguez ◽  
Patricia Lema ◽  
María Inés Bessio ◽  
Guillermo Moyna ◽  
Cristina Olivaro ◽  
...  
Keyword(s):  
Enzymatic Hydrolysis ◽  
Ph Effect ◽  
Dairy Product ◽  
Gel Filtration ◽  
Significant Degree ◽  
Product Analysis ◽  
Molecular Weights ◽  
Ph Values ◽  
Initial Ph

The effect on color of the initial pH employed in dulce de leche (DL) production was evaluated through physicochemical and spectroscopical characterization of the melanoidins formed in the process. Melanoidins originated at pH values of 6.5, 7.0, and 7.5, and they were released by the enzymatic hydrolysis of the protein backbone and purified by gel filtration. They showed a significant degree of polydispersity, in general, with molecular weights (MWs) below 1,800 Da. DL produced at a higher pH released melanoidins with higher average MW after the enzymatic hydrolysis. They also presented darker colors (dE*ab, C*), more closely resembling those typical of the commercial product. Analysis of the fractions isolated by gel filtration using HPLC-DAD and multinuclear NMR showed an heterogeneous and complex composition. Even though structurally related, the 1H NMR spectra of melanoidins showed a higher degree of aromaticity at higher pH values. In conclusion, the pH employed in DL production affects the amount and structure of the colored products originated by MR reactions, and thus the color of the final product.

Effects of Potassium Sorbate on Normal Flora and on Staphylococcus aureus Added to Minced Cod

1982 ◽  
Vol 45 (9) ◽  
pp. 824-828 ◽  
Author(s):  
DONALD J. LYNCH ◽  
NORMAN N. POTTER
Keyword(s):  
Staphylococcus Aureus ◽  
Storage Period ◽  
Inhibitory Effect ◽  
Potassium Sorbate ◽  
Normal Flora ◽  
Ph Changes ◽  
Normal Microflora ◽  
Enterotoxin Production ◽  
Plate Counts ◽  
Storage Temperatures

Minced cod and pasteurized minced cod, with and without 0.5% potassium sorbate, were subjected to abusive storage temperatures of 7 and 15°C. Staphylococcus aureus FRI 100 was inoculated into the cod before storage. Total aerobic plate counts (20 and 35°C), pH changes, S. aureus counts and the presence of thermonuclease were monitored throughout the studies. With the unpasteurized minced cod, potassium sorbate caused slightly lower aerobic plate counts (at 20 and 35°C) in the 7°C study over an 11-day storage period. Psychrotrophic organisms were inhibited to a slightly greater extent than were mesophilic organisms. Inoculated S. aureus was quickly outgrown by the normal microflora without or with sorbate. Similar results were obtained at the still more abusive temperature of 15°C over a storage period of 5 d, but the inhibitory effect of sorbate was less evident. Pasteurized minced cod, inoculated with S. aureus and stored at 15°C, showed a considerable difference in growth of S. aureus with and without sorbate. Potassium sorbate resulted in a markedly slower rate of growth of the pathogen and a substantial delay of several days in production of detectable levels of thermonuclease. This delay in nuclease production is indicative of a similar delay in enterotoxin production.

Impact of co-cultivation with Enterococcus faecalis over growth, enterotoxin production and gene expression of Staphylococcus aureus in broth and fresh cheeses

2019 ◽  
Vol 308 ◽  
pp. 108291 ◽  
Author(s):  
Gabriela Nogueira Viçosa ◽  
Clarisse Vieira Botelho ◽  
Cristian Botta ◽  
Marta Bertolino ◽  
Antônio Fernandes de Carvalho ◽  
...  
Keyword(s):  
Gene Expression ◽  
Staphylococcus Aureus ◽  
Enterococcus Faecalis ◽  
Enterotoxin Production

Enterotoxin production by Staphylococcus aureus: An outbreak at a Barcelona sports club in July 2011

Food Control ◽  
2013 ◽  
Vol 33 (1) ◽  
pp. 114-118 ◽  
Author(s):  
Rubén Solano ◽  
Sara Lafuente ◽  
Sara Sabate ◽  
Cecilia Tortajada ◽  
Patricia García de Olalla ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Enterotoxin Production ◽  
Sports Club
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