Low-Temperature Activity of Lactic Streptococci Isolated from Cultured Buttermilk

1982 ◽  
Vol 45 (13) ◽  
pp. 1208-1211 ◽  
Author(s):  
STEVEN L. HOGARTY ◽  
JOSEPH F. FRANK
Keyword(s):  
Low Temperature ◽  
Skim Milk ◽  
Potential Effect ◽  
Starter Cultures ◽  
Streptococcus Lactis ◽  
Streptococcus Cremoris ◽  
Generation Times ◽  
Significant Difference ◽  
Selection Of

Psychrotrophic and mesophilic lactic streptococci were isolated from commercial cultured buttermilk to determine their potential effect on the quality of this product. These isolates consisted primarily of Streptococcus lactis subsp. diacetylactis, with S. lactis, Streptococcus cremoris, and Leuconostoc spp. also being present. Psychrotrophic isolates of S. lactis subsp. diacetylactis were compared to mesophilic isolates in regard to their ability to grow and reduce diacetyl in acidified milk (pH 4.7) incubated at 7°C. There was no significant difference detected in the ability of the two groups to reduce diacetyl (P<.05). The mesophilic isolates grew more rapidly in acidified refrigerated milk than did the psychrotrophs, indicating that the psychrotrophic isolates were more acid sensitive. The psychrotrophic isolates exhibited generation times of 9 to 11 h when grown in skim milk (pH 6.7) at 7°C. Both psychrotrophic and mesophilic strains of S. lactis subsp. diacetylactis could rapidly reduce diacetyl in refrigerated acidified milk. The results of this study suggest that procedures for selection of starter cultures for buttermilk manufacture should be improved.

Behavior of Listeria monocytogenes in Skim Milk during Fermentation with Mesophilic Lactic Starter Cultures

1988 ◽  
Vol 51 (8) ◽  
pp. 600-606 ◽  
Author(s):  
MICHELLE M. SCHAACK ◽  
ELMER H. MARTH
Keyword(s):  
Lactic Acid ◽  
Listeria Monocytogenes ◽  
Lactic Acid Bacteria ◽  
Skim Milk ◽  
Starter Cultures ◽  
Plate Count ◽  
Inoculum Level ◽  
Plate Count Agar ◽  
Streptococcus Lactis ◽  
Streptococcus Cremoris

The ability of Listeria monocytogenes to grow and compete with mesophilic lactic acid bacteria was examined. Autoclaved skim milk was inoculated with 103 cells of L. monocytogenes (strain V7 or Ohio)/ml, and with 5.0, 1.0, 0.5 or 0.1% of a milk culture of either Streptococcus cremoris or Streptococcus lactis. Inoculated milks were fermented for 15 h at 21 or 30°C, followed by refrigeration at 4°C. Samples were plated on McBride Listeria Agar to enumerate L. monocytogenes and on either APT Agar or plate count agar to enumerate lactic acid bacteria. L. monocytogenes survived in all fermentations, and commonly also grew to some extent. Incubation at 30°C with 5% S. lactis as inoculum appeared to be the most inhibitory combination for strain V7, causing 100% inhibition in growth based on maximum population attained. S. cremoris at the 5.0% and 0.1% inoculum levels, was slightly less inhibitory to L. monocytogenes at 37°C, but it was slightly more inhibitory to L. monocytogenes at the 1.0% inoculum level than was S. lactis. In general, S. lactis reduced the pH of fermented milks more than did S. cremoris. The population of L. monocytogenes began to decrease before 15 h in only one test combination, which was use of a 5.0% inoculum of S. cremoris and 30°C incubation. In most instances, growth of the pathogen appeared to be completely inhibited when the pH dropped below 4.75.

Occurrence of lactose-negative mutants in chemostat cultures of lactic streptococci

1975 ◽  
Vol 21 (3) ◽  
pp. 245-251 ◽  
Author(s):  
I. J. McDonald
Keyword(s):  
Yeast Extract ◽  
Skim Milk ◽  
Starter Cultures ◽  
The Other ◽  
Batch Cultures ◽  
Streptococcus Lactis ◽  
Chemostat Cultures ◽  
Glucose Agar ◽  
Casamino Acids ◽  
Selection Of

Batch and chemostat cultures of Streptococcus cremoris HP and Streptococcus lactis 829 were examined for lactose-negative (lac−) mutants on indicator agar. In batch cultures, S. cremoris HP gave less than 1% of the total count as lac− colonies while S. lactis 829 consistently contained about 15% of the total as lac− colonies. In chemostat cultures of S. cremoris HP in 2% skim milk containing casamino acids and yeast extract (0.1% each), the percentage of lac− colonies increased markedly when the temperature of growth was 18 °C but not when the temperature of growth was 25 °C. The percentage of lac− colonies in chemostat cultures in the skim milk medium at 25 °C was about the same as that in batch cultures. On the other hand, when chemostat cultures of S. lactis 829 in the skim milk medium were grown at several temperatures between 18 and 33 °C, the percentage of lac− colonies was markedly lower than that found in batch cultures of this organism. Cultivation of S. cremoris HP in chemostats with yeast extract – lactose broth at low temperatures (14–18 °C resulted in cultures that gave plate counts on lactose agar, which were as much as 50% lower than counts on glucose agar but did not result in the selection of lac− mutants. Cultivation of S. lactis 829 in chemostats with yeast extract – glucose broth at low temperature (18 °C resulted in a selection of cells giving lac− colonies and atypical (small) lac+ colonies. The results show that cultivation of S. cremoris HP and S. lactis 829 in chemostats sometimes gave rise to altered populations. Conditions causing a change in one organism did not necessarily cause a similar change in the other. The results indicate that the successful propagation of lactic streptococci in chemostats for use as starter cultures in the dairy industry will require the careful establishment of optimum conditions for every strain so as to minimize the possible selection of undesirable populations.

Growth of Streptococcus cremoris and Streptococcus lactis in a chemostat. Production of cells and survival of bacteria during frozen storage

1973 ◽  
Vol 19 (10) ◽  
pp. 1285-1295 ◽  
Author(s):  
I. J. McDonald ◽  
B. Reiter ◽  
P. L. Rogers
Keyword(s):  
Yeast Extract ◽  
Frozen Storage ◽  
Skim Milk ◽  
Streptococcus Lactis ◽  
Streptococcus Cremoris ◽  
Constant Ph ◽  
Limiting Nutrient

Streptococcus cremoris HP and Streptococcus lactis 829 were grown in chemostats in tryptone yeast extract broth and in supplemented 2% skim milk medium. In both media, lactose was the limiting nutrient. Cultures were grown at various dilution rates in media poised at constant pH and temperature and also at constant dilution rates in media controlled at different pH levels and temperatures. The effects of the various conditions of growth on production of bacteria, viable counts, and acid-producing activities of cells and on the ability of bacteria to survive subsequent frozen storage were determined. None of the conditions of growth tested had very pronounced effects on the ability of cells to survive or on the inability of cells to retain acid-producing activity after being frozen at −70 °C and stored at −40 °C.

SUITABILITY OF LOW TEMPERATURE VACUUM PAN EVAPORATOR CONDENSATE FOR PLANT USES

1966 ◽  
Vol 29 (2) ◽  
pp. 40-44
Author(s):  
Daniel A. Stock
Keyword(s):  
Low Temperature ◽  
Skim Milk ◽  
Water Source ◽  
Additional Treatment ◽  
Pan Evaporation ◽  
Quality Of Water ◽  
Plant Uses ◽  
Preliminary Study ◽  
Exchange Medium

Summary A preliminary study to investigate the possibility of utilizing condensates and tailwater from the low temperature vacuum pan evaporation of skim milk for evaporating plant uses was made. The results indicated that the utilization of these condensates and tailwaters for various plant purposes is possible and should provide a readily available, safe and sanitary water source if adequate steps such as quality monitoring and treatment are taken to insure that the highest quality of water is retained and used. The use of tailwater as a heat exchange medium on a single pass basis should require only quality control monitoring. However, condensate or tailwater which is to be used for other purposes should be aerated and may need additional treatment to prevent the development of tastes, odors, growths, corrosion, and scale formation.

scholarly journals Selection of starter cultures for idli batter fermentation and their effect on quality of idlis

2010 ◽  
Vol 47 (5) ◽  
pp. 557-563 ◽  
Author(s):  
J. Sridevi ◽  
Prakash M. Halami ◽  
S. V. N. Vijayendra
Keyword(s):  
Starter Cultures ◽  
Idli Batter ◽  
Selection Of

Bacterial starter cultures induce suitable changes in milk fatty acid profiles at different fermentation conditions

2020 ◽  
pp. 1-5
Author(s):  
Gholamreza Bahrami ◽  
Ali Mostafaie ◽  
Amir Kiani ◽  
Maryam Chalabi
Keyword(s):  
Fatty Acid ◽  
Fatty Acid Profile ◽  
Starter Culture ◽  
Starter Cultures ◽  
Lactobacillus Bulgaricus ◽  
Fatty Acid Profiles ◽  
Animal Fat ◽  
Significant Difference ◽  
Sour Cream

Abstract This study aimed to compare the effect of different ratios of Streptococcus thermophilus to Lactobacillus bulgaricus (3 : 1, 1 : 1, and 1 : 3) under the various stressful temperatures (37 and 45°C) on the fatty acid profiles quality of Kermanshahi roghan (yogurt by-product) and sour cream to obtain a formula for producing a kind of animal fat healthier than milk and cream. Stresses such as fermentation play an important role in bacterial behavior and consequently in food quality. Our findings presented a significant difference between roghan and sour cream fatty acid levels only at 37°C. Furthermore, starter culture 3 : 1 was the best starter for producing products with a higher quality of fatty acid profile at 37°C, and a 1 : 1 S. thermophilus to L. bulgaricus ratio was optimal at 45°C. It seems that bacteria adapt to harsh growth conditions by changing the fatty acid profiles, and these changes warrant consideration in the production of a kind of animal fat with the best fatty acid profiles. In conclusion, the roghan fatty acid profile is more suitable than sour cream only at 37°C.

CULTURAL STUDIES ON STREPTOCOCCUS DIACETILACTIS AND OTHER MEMBERS OF THE LACTIC STREPTOCOCCUS GROUP

1962 ◽  
Vol 8 (2) ◽  
pp. 161-174 ◽  
Author(s):  
W. E. Sandine ◽  
P. R. Elliker ◽  
Helen Hays
Keyword(s):  
Cultural Studies ◽  
Dairy Industry ◽  
Starter Cultures ◽  
Similar Data ◽  
Streptococcus Group ◽  
Cultural Information ◽  
Streptococcus Lactis ◽  
Streptococcus Cremoris ◽  
Manometric Method

Cultural information about Streptococcus diacetilactis strains is tabulated along with similar data on Streptococcus lactis, Streptococcus cremoris, and certain Leuconostoc species. These data facilitate comparisons of bacteria commonly found in mixed-strain lactic starter cultures. Characteristic reactions which indicate simple means of differentiating between these organisms may be observed. The data are used to justify the recognition of S. diacetilactis as a third species of the lactic streptococcus group. Leuconostoc organisms are separated into two groups on the basis of dextran production on a sucrose medium.Details of a manometric method for measuring CO2production by single and mixed-strain starter cultures are given. The Warburg Respirometer was employed for this purpose and possible application of the method in the design of mixed-strain starter cultures for use in the dairy industry is discussed.

scholarly journals Evaluating the Effect of Various Doses of Magnesium Sulfate on Quality of Cataract Intra Operative Sedation and Recovery

2017 ◽  
Vol 2 (2) ◽  
Keyword(s):  
Cataract Surgery ◽  
Magnesium Sulfate ◽  
Respiratory Effects ◽  
Patients Satisfaction ◽  
Significant Difference ◽  
The Common ◽  
Respiratory Variables ◽  
Selection Of ◽  
Narcotic Drugs

Background: The selection of sedative method for cataract surgery which is mostly done for adults is more favored. In this study, we compared various doses of magnesium sulfate for improving the quality of anesthesia and recovery during Cataract surgery. Materials and Methods: In this clinical trial, 150 patients candidate for Cataract surgery were studied in five groups of 30 individuals that 0(group 0), 10(group 10), 20(group 20), 30(group 30) and 40(group 40) mg/kg intravenous Magnesium Sulfate were added to the first to fifth groups at the onset of anesthesia in the common anesthetic method, respectively. The consumption doses of sedatives and narcotics (Midazolam, Fentanyl and Propofol), hemodynamic and respiratory variables during the surgery, and the incidence rate of pain, shivering, nausea and vomiting and the level of surgeon and patients’ satisfaction were studied in all groups. Results: 1) Demographic, hemodynamic and respiratory variables had no significant difference between the five groups. In the group 30 and 40, the consumption does of Midazolam, Propofol and Fentanyl was considerably less than that in other groups (P <0.001). 2) The highest and lowest levels of satisfaction in patients and physicians were recorded in the group 30 and respectively (P<0.001). 3) None of the patients suffered from postoperative shivering. 4) The incidence of other complications including nausea, vomiting and pain at time of discharging from the operating room had no significant difference between the 5 groups. Conclusions: Using Magnesium Sulfate, especially with the dose of 30 and 40mg/kg caused a significant reduction in need for sedative and narcotic drugs and increased satisfaction in patients and surgeons as well as minimal hemodynamic and respiratory effects during and after cataract surgery.

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