Behavior of Listeria monocytogenes in Pasteurized Milk during Fermentation with Lactic Acid Bacteria

2000 ◽  
Vol 63 (7) ◽  
pp. 916-920 ◽  
Author(s):  
WAYNE M. PITT ◽  
TERENCE J. HARDEN ◽  
RON R. HULL

The behavior of Listeria monocytogenes in pasteurized milk during fermentation with starter and nonstarter lactic acid bacteria was investigated. Pasteurized milk was co-inoculated with approximately 104 CFU/ml of L. monocytogenes and 106 CFU/ml of Lactococcus lactis, Lactococcus cremoris, Lactobacillus plantarum, Lactobacillus bulgaricus, or Streptococcus thermophilus. Inoculated milks were incubated at 30°C or 37°C for 24 to 72 h. Listeria monocytogenes survived and also grew to some extent during incubation in the presence of all starter cultures; however, inhibition ranged from 83 to 100% based on maximum cell populations. During incubation with L. bulgaricus and L. plantarum, L. monocytogenes was completely inactivated after 20 h and 64 h of incubation at 37°C and 30°C, respectively. The pH of the fermenting milks declined steadily throughout the fermentation periods and was approximately 4.2 at the conclusion of the experimental period regardless both of the starter culture and pathogen combination or the temperature of incubation.

2014 ◽  
Vol 32 (No. 2) ◽  
pp. 145-151 ◽  
Author(s):  
I. Složilová ◽  
S. Purkrtová ◽  
M. Kosová ◽  
M. Mihulová ◽  
E. Šviráková ◽  
...  

Eight individual bacteriocin-producing lactic acid bacteria (LAB) strains and three bacteriocin-non-producing cheese starter cultures were evaluated for their ability to inhibit the growth of six Listeria monocytogenes strains, originating from the guinea-pig lymph nodes, raw cow milk, and manufacturing dairy equipment. Results showed that either live cells or cell-free neutralised supernatant (CFNS) and/or heated CFNS of six individual LAB strains (Lcc. lactis subsp. lactis CCDM 416 and NIZO R5, Lbc. plantarum HV 11 and DC 1246, P. acidilactici HV 12, and Ent. mundtii CCM 1282) and one starter culture (DELVO-ADD<sup>&reg;</sup> 100-X DSF) were effective in the suppression of at least one listeria strain. Neither any individual LAB strain nor starter culture was antagonistic toward all studied L. monocytogenes strains, indicating diverse sensitivity/resistance among L. monocytogenes strains to antimicrobial compounds of LAB. The significant susceptibility of listerias isolated from raw milk and dairy equipment together with the strong antilisterial activity of DELVO-ADD<sup>&reg; </sup>100-X DSF could be applied in dairy technology, where commonly used starter cultures could play both the biopreservative and fermentation role. &nbsp;


2021 ◽  
Vol 13 (2) ◽  
pp. 117-124
Author(s):  
J. D. Zumunta ◽  
A. F. Umar ◽  
V. Agbo

This study was conducted to assess the microbial changes during the fermentation of Baobab (Adansoniadigitata)fruit pulp yoghurt. The Baobab fruit pulp yoghurt was prepared in the Laboratory using the conventional method. Lactobacillus bulgaricus and Streptococcus thermophilus were used as starter cultures while a control was produced without the starter cultures. de Man Rogosa Sharpe (MRS) agar was used to culture lactic acid bacteria. The microbialload, succession and percentage occurrences were determined using standard methods. The total aerobic bacterial count wasfound to be within the range of 1.9x103 - 1.4x105 cfu/ml. The Lactic acid bacteria and fungal count ranges were 4.5 x 103  - 7.5 x 103  cfu/ml and 8.0 x 101 – 2.8 x 104  cfu/ml respectively. At the end of fermentation time, there was significant difference between the test and control Baobab yoghurt at P<0.05.  Lactic acid bacteria recorded the highest count of 6.2 x 104  and 7.5 x 103 cfu/ml in the test and control respectively. Bacillus species , Staphylococcus aureus, Lactobacillus bulgaricus,Streptococcus thermophilus and Micrococcus species were the bacteria isolated while the fungal isolates were Saccharomyces cerevisiae and Hansenula species. Lacbacillusbulgaricus, Streptococcus thermophilus, Bacillus species and Saccharomyces cerevisiae were the only microorganisms found at the end of fermentation time. The study obtained low microbial count and isolated less number and type of microorganisms from Baobab fruit pulp yoghurt because of the antimicrobial effect of baobab pulp and pasteurization treatment.Based on the results of this study, Baobab fruit pulp yoghurt can be said to be of good microbiologicalquality for human consumption. The industrial use of Baobab fruit pulp in the production of yoghurt is recommended.


2017 ◽  
pp. 39-52 ◽  
Author(s):  
Mirjana Bojanic-Rasovic

Traditional production of fermented dairy products involves lactic acid bacteria that are normally present in the milk and production environment. These lactic acid bacteria represent the niche microbiota of the geographical area and they are responsible for local types of fermented products. In order to standardize indigenous products, the basic requirement is the application of the determined indigenous lactic acid bacteria as starter cultures affecting their specific characteristics by performing fermentation and influencing the ripening process. In the process of cheese fermentation usually participate bacteria of the genus Lactococcus and homofermentative lactobacilli. However, the process ripening is influenced mainly by the so-called nonstarter lactic acid bacteria - lactobacilli and secondary microflora. Lactobacilli during ripening of cheese continue to breakdown the rest of lactose, but they are primarily important in the process of protein breakdown. During metabolism of sugars and amino acids, lactobacilli produce aromatic compounds which have a positive effect on the flavor of the product. Some species of lactobacilli are available as probiotics. Some lactobacilli produce bacteriocins, which prevent the growth of pathogens, as well as many spoilage microorganisms. Indigenous lactobacilli have application especially in the production of typical local dairy products that are well accepted by the local population. Besides that, the use of indigenous lactic acid bacteria as starter cultures allows the production of cheese with designated geographical origin that could be placed on the international market. Consequently, indigenous lactic acid bacteria are a challenge for further research and possible their practical application in the dairy industry.


2020 ◽  
pp. 32-44
Author(s):  
Hanaa M. A. Salih ◽  
Mohamed O. M. Abdalla

Aims: This study was conducted to determine the effect of starter culture addition on the physicochemical, microbiological and sensory characteristics of white cheese (Gibna Bayda) during the storage period (5°C/ 45 days). Methodology: Two treatments were prepared: Treatment 1 (T1): cheese manufactured with pasteurized milk with Lactobacillus bulgaricus and Streptococcus thermophilus (1:1) at the level of 2% (w/v); Treatment 2 (T2): the control; cheese manufactured with pasteurized milk without starter cultures. After cheese manufacture, physicochemical, microbiological and sensory characteristics were determined at 1, 15, 30 and 45-day intervals. Results: Results showed that the starter culture addition did not significantly (P>.05) affect all physiochemical characteristics of cheese, except for the ash content which was high in cheese manufactured with the addition of starter culture. The addition of the starter influenced the microbiological quality of the cheese, with total viable bacteria, Staphylococcus aureus and yeasts and moulds counts being significantly (P<.05) low. Furthermore, the cheese made with an added starter culture showed high scores of colour, taste and flavour. The storage period significantly affected all characteristics of the cheese, except for the fat content of the control, which remained unchanged during all storage periods. Conclusion: The results of this study show that starter culture (Lactobacillus bulgaricus and Streptococcus thermophilus) (1:1) is likely to be a suitable culture for Sudanese white cheese.


1988 ◽  
Vol 51 (8) ◽  
pp. 607-614 ◽  
Author(s):  
MICHELLE M. SCHAACK ◽  
ELMER H. MARTH

Behavior of Listeria monocytogenes in skim milk and in yogurt mix during fermentation with thermophilic lactic starters was determined. Sterile skim milk was inoculated with ca. 103 L. monocytogenes cells/ml and with 5.0, 1.0 or 0.1% of a milk culture of Streptococcus thermophilus, Lactobacillus bulgaricus or a mixture of the two species. The milk was incubated at 37 or 42°C for 15 h, followed by refrigeration at 4°C. Yogurt mix was inoculated with ca. 5 × 103 L. monocytogenes cells/ml of mix and then was incubated at 45°C for 5 h, followed by refrigeration at 4°C. L. monocytogenes survived the 15-h fermentation with S. thermophilus in all combinations of level of inoculum and temperature of incubation, but inhibition of growth ranged from 96 to 100%. When incubated with L. bulgaricus, L. monocytogenes survived only between 9 and 15 h of incubation; a decrease in pH to below 4.0 was accompanied by rapid death of the pathogen. The combination of the two species was more inhibitory to L. monocytogenes than was S. thermophilus alone but less inhibitory than was L. bulgaricus alone. In yogurt mix, L. monocytogenes grew during the fermentation and increased in number by about one order of magnitude.


2015 ◽  
Vol 6 (3) ◽  
pp. 337-343 ◽  
Author(s):  
M. Garriga ◽  
R. Rubio ◽  
T. Aymerich ◽  
P. Ruas-Madiedo

The capability of five lactic acid bacteria (LAB) to counteract the adhesion of Listeria monocytogenes to the epithelial intestinal cell line HT29 was studied. The highest adhesion ability to HT29 was achieved by the intestinal strain Lactobacillus rhamnosus CTC1679, followed by the meat-derived strains Lactobacillus sakei CTC494 and Enterococcus faecium CTC8005. Surprisingly, the meat strains showed significantly better adhesion to HT29 than two faecal isolates of Lactobacillus casei and even significantly higher than the reference strain L. rhamnosus GG. Additionally, the anti-listerial, bacteriocin-producer starter culture L. sakei CTC494 was able to significantly reduce the adhesion of L. monocytogenes to HT29 in experiments of exclusion, competition and inhibition. The performance was better than the faecal isolate L. rhamnosus CTC1679. Our results reinforce the fact that the ability of LAB to interact with a host epithelium model, as well as to antagonise with foodborne pathogens, is a strain-specific characteristic. Additionally, it is underlined that this trait is not dependent on the origin of the bacterium, since some food LAB behave better than intestinal ones. Therefore, the search for novel strains in food niches is a suitable approach to find those with potential health benefits. These strains are likely pre-adapted to the food environment, which would make their inclusion in the formulation of probiotic foods more feasible.


2020 ◽  
Vol 29 (12) ◽  
pp. 59-63
Author(s):  
O.I. Parakhina ◽  
◽  
M.N. Lokachuk ◽  
L.I. Kuznetsova ◽  
E.N. Pavlovskaya ◽  
...  

The research was carried out within the framework of the theme of state assignment № 0593–2019–0008 «To develop theoretical foundations for creating composite mixtures for bakery products using physical methods of exposure that ensure homogeneity, stability of mixtures and bioavailability of nutrients, to optimize diets population of Russia». The data on the species belonging of new strains of lactic acid bacteria and yeast isolated from samples of good quality gluten-free starter cultures are presented. A comparative assessment of the antagonistic and acid-forming activity of strains of lactic acid bacteria and the fermentative activity of yeast was carried out. The composition of microbial compositions from selected strains of LAB and yeast was developed. The influence of the starter culture on the new microbial composition on the physicochemical, organoleptic indicators of the bread quality and resistance to mold and ropy-disease was investigated.


1995 ◽  
Vol 58 (1) ◽  
pp. 62-69 ◽  
Author(s):  
K. ANJAN REDDY ◽  
ELMER H. MARTH

Three different split lots of Cheddar cheese curd were prepared with added sodium chloride (NaCl) potassium chloride (KCl) or mixtures of NaCl/KCl (2:1 1:1 1:2 and 3:4 all on wt/wt basis) to achieve a final salt concentration of 1.5 or 1.75%. At intervals during ripening at 3±1°C samples were plated with All-Purpose Tween (APT) and Lactobacillus Selection (LBS) agar. Isolates were obtained of bacteria that predominated on the agar media. In the first trial (Lactococcus lactis subsp. lactis plus L. lactis subsp. cremoris served as starter cultures) L. lactis subsp.lactis Lactobacillus casei and other lactobacilli were the predominant bacteria regardless of the salting treatment Received by the cheese. In the second trial (L. lactis subsp. lactis served as the starter culture) unclassified lactococci L. lactis subsp. lactis unclassified lactobacilli and L. casei predominated regardless of the salting treatment given the cheese. In the third trial (L. lactis subsp. cremoris served as the starter culture) unclassified lactococci unclassified lactobacilli L. casei and Pediococcus cerevisiae predominated regardless of the salting treatment applied to the cheese Thus use of KCl to replace some of the NaCl for salting cheese had no detectable effect on the kinds of lactic acid bacteria that developed in ripening Cheddar cheese.


2017 ◽  
Vol 17 (1) ◽  
pp. 5
Author(s):  
Agus Safari ◽  
Sarah Fahma Ghina ◽  
Sadiah Djajasoepena ◽  
O. Suprijana ' ◽  
Ida Indrawati ◽  
...  

Mixed lactic acid bacteria culture is commonly used in yogurt production. In the present study, two lactic acid bacteria (Lactobacillus bulgaricus and Streptococcus thermophillus) was used as starter culture. Calcium carbonate was added to the starter culture to increase the quality of mixed starter culture of L. bulgaricus and S. thermophillus with ratio of 4:1. The present study was directed to investigate the chemical composition of mixed starter culture with and without calcium carbonat addition. Furthermore, the effect of each starter culture on yogurt product chemical composition was also examined. The pH, lactose, soluble protein and acid content was determined as chemical composition parameters. For starter culture without calcium carbonate addition, the yogurt has pH, lactose, soluble protein and acid content of 4.18–4.39, 4.18–4.39% w/v, 2.88–4.36% w/v and 0.82–0.99% w/v, respectively. While for starter culture with calcium carbonate addition, the yogurt product has pH, lactose, soluble protein and acid content of 4.26–4.37, 1.47–1.75% b/v, 3.42–4.95% w/v and 0.86–1.11% w/v, respectively. Addition of 0.05% w/v calcium carbonate to mixed starter culture gave effect on lactose consumption, where it still can convert lactose to lactic acid up to 45 days of storage. Furthermore, the yogurt product made with starter culture with calcium carbonate addition has higher soluble protein content compared to yogurt made with starter culture without calcium carbonate addition


1988 ◽  
Vol 51 (8) ◽  
pp. 600-606 ◽  
Author(s):  
MICHELLE M. SCHAACK ◽  
ELMER H. MARTH

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.


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