scholarly journals Compositional characteristics of commercial yoghurt based on quantitative determination of viable lactic acid bacteria

2009 ◽  
pp. 87-94
Author(s):  
Dragana Pesic-Mikulec ◽  
Gordana Niketic
Keyword(s):  
Lactic Acid ◽  
Lactic Acid Bacteria ◽  
Quantitative Determination ◽  
Dairy Products ◽  
Consumer Preferences ◽  
Streptococcus Thermophilus ◽  
Lactobacillus Delbrueckii ◽  
Manufacturing Methods ◽  
The Many

Yoghurt quality is particularly difficult to standardize because of the many forms, varieties, manufacturing methods, ingredients and consumer preferences that exist. Since these factors will always play an important role, it is unlikely that a uniform yoghurt quality concept will ever emerge, such as has been developed for other dairy products. There are a number of common denominators, however that have bearing on yoghurt quality. Since a number of producers are recognized within the broad category entitled yoghurt. This situation makes yoghurt an interesting, challenging, but also a confusing area to work in. The present investigation was undertaken to isolate from commercial yoghurt the strains involved in its manufacture and determine the characteristics of Streptococcus thermophilus and Lactobacillus delbrueckii subsp.bulgaricus. This study is concerned with the lactic acid bacteria (L.delbrueckii subsp. bulgaricus and S. thermophilus) growth in yoghurt from involving different procedures and with the determination of the number of lactic acid bacteria in dependence of the temperature and acidity in the period of storage. Predominant samples of yoghurt were with 11-107/ml lactic acid lactococci (44.28%).

scholarly journals RESEARCHES CONCERNING THE BIOSYNTHESIS OF EXOPOLYSACCHARIDES IN THE FERMENTED DAIRY PRODUCTS WITH THE YOGURT CULTURE YF-L 811

1970 ◽  
Vol 63 ◽  
Author(s):  
Ina Simiţaru ◽  
Rodica Segal
Keyword(s):  
Lactic Acid ◽  
Lactic Acid Bacteria ◽  
Rheological Properties ◽  
Dairy Products ◽  
Culture Media ◽  
Streptococcus Thermophilus ◽  
Lactobacillus Delbrueckii ◽  
Temperature Conditions ◽  
Fermented Dairy Products ◽  
Fermented Dairy

The exopolysaccharides produced by the lactic acid bacteria confer the possibility to obtain fermented dairy products of good quality, with desirable rheological properties, and diverse benefits for health. The capacity of lactic acid bacteria to produce exopolysaccharides is influenced by culture media and the conditions of growth. The purpose of this work was to study the thermophile yogurt culture YF-L 811, which contains Streptococcus thermophilus and Lactobacillus delbrueckii ssp. bulgaricus. The study was based on the capacity of the culture to produce exopolysaccharides in different temperature conditions and with different ingredients added in culture media. The amount of exopolysaccharides was correlated to viscosity of the yogurt.

Antibiotic susceptibility of different lactic acid bacteria strains

2011 ◽  
Vol 2 (4) ◽  
pp. 335-339 ◽  
Author(s):  
N. Karapetkov ◽  
R. Georgieva ◽  
N. Rumyan ◽  
E. Karaivanova
Keyword(s):  
Cell Wall ◽  
Lactic Acid ◽  
Lactic Acid Bacteria ◽  
Lactobacillus Acidophilus ◽  
Streptococcus Thermophilus ◽  
Lactobacillus Helveticus ◽  
Lactobacillus Delbrueckii ◽  
Cell Wall Synthesis ◽  
High Susceptibility ◽  
Lactobacillus Delbrueckii Subsp

Five lactic acid bacteria (LAB) strains belonging to species Lactobacillus acidophilus, Lactobacillus helveticus, Lactobacillus delbrueckii subsp. bulgaricus, Lactobacillus delbrueckii subsp. lactis and Streptococcus thermophilus were tested for their susceptibility to 27 antibiotics. The minimum inhibitory concentrations of each antimicrobial were determined using a microdilution test. Among the strains a high susceptibility was detected for most of the cell-wall synthesis inhibitors (penicillins, cefoxitin and vancomycin) and resistance toward inhibitors of DNA synthesis (trimethoprim/sulfonamides and fluoroquinolones). Generally, the Lactobacillus strains were inhibited by antibiotics such as chloramphenicol, erythromycin and tetracycline at breakpoint levels lower or equal to the levels defined by the European Food Safety Authority. Despite the very similar profile of S. thermophilus LC201 to lactobacilli, the detection of resistance toward erythromycin necessitates the performance of additional tests in order to prove the absence of transferable resistance genes.

scholarly journals Dynamic Changes of Intracellular pH in Individual Lactic Acid Bacterium Cells in Response to a Rapid Drop in Extracellular pH

2000 ◽  
Vol 66 (6) ◽  
pp. 2330-2335 ◽  
Author(s):  
Henrik Siegumfeldt ◽  
K. Björn Rechinger ◽  
Mogens Jakobsen
Keyword(s):  
Lactic Acid ◽  
Lactic Acid Bacteria ◽  
Lactic Acid Bacterium ◽  
Intracellular Ph ◽  
Membrane Filter ◽  
Single Cells ◽  
Streptococcus Thermophilus ◽  
Extracellular Ph ◽  
Lactobacillus Delbrueckii ◽  
Rapid Drop

ABSTRACT We describe the dynamics of changes in the intracellular pH (pHi) values of a number of lactic acid bacteria in response to a rapid drop in the extracellular pH (pHex). Strains of Lactobacillus delbrueckii subsp.bulgaricus, Streptococcus thermophilus, andLactococcus lactis were investigated. Listeria innocua, a gram-positive, non-lactic acid bacterium, was included for comparison. The method which we used was based on fluorescence ratio imaging of single cells, and it was therefore possible to describe variations in pHi within a population. The bacteria were immobilized on a membrane filter, placed in a closed perfusion chamber, and analyzed during a rapid decrease in the pHex from 7.0 to 5.0. Under these conditions, the pHi of L. innocua remained neutral (between 7 and 8). In contrast, the pHi values of all of the strains of lactic acid bacteria investigated decreased to approximately 5.5 as the pHex was decreased. No pronounced differences were observed between cells of the same strain harvested from the exponential and stationary phases. Small differences between species were observed with regard to the initial pHi at pHex 7.0, while different kinetics of pHiregulation were observed in different species and also in different strains of S. thermophilus.

Characterization of the lactic acid bacteria in artisanal dairy products

1997 ◽  
Vol 64 (3) ◽  
pp. 409-421 ◽  
Author(s):  
TIMOTHY M. COGAN ◽  
MANUELA BARBOSA ◽  
ERIC BEUVIER ◽  
BRUNA BIANCHI-SALVADORI ◽  
PIER S. COCCONCELLI ◽  
...  
Keyword(s):  
Lactic Acid ◽  
Lactic Acid Bacteria ◽  
Broad Spectrum ◽  
Acid Production ◽  
Dairy Products ◽  
Streptococcus Thermophilus ◽  
Listeria Innocua

In all, 4379 isolates from 35 products, including 24 artisanal cheeses, were surveyed with a view to identifying strains that could be used as starters in commercial dairy fermentations. Of the isolates, 38% were classified as Lactococcus, 17% as Enterococcus, 14% as Streptococcus thermophilus, 12% as mesophilic Lactobacillus, 10% as Leuconostoc and 9% as thermophilic Lactobacillus. Acid production by the isolates varied considerably. Of the 1582 isolates of Lactococcus and 482 isolates of mesophilic Lactobacillus tested, only 8 and 2% respectively produced sufficient acid to lower the pH of milk to <5·3 in 6 h at 30°C. In contrast, 53, 32 and 13% of Str. thermophilus, thermophilic Lactobacillus and Enterococcus isolates respectively reduced the pH to 5·3. These isolates were found only in some French, Italian and Greek cheeses. Bacteriocins were produced by 11% of the 2257 isolates tested and 26 of them produced broad-spectrum bacteriocins which inhibited at least eight of the ten target strains used, which included lactic acid bacteria, clostridia and Listeria innocua. The most proteolytic of the 2469 isolates tested were Str. thermophilus from Fontina cheese followed by Enterococcus from Fiore Sardo and Toma cheese and thermophilic Lactobacillus from all sources. Exopolysaccharides were produced by 5·3% of the 2224 isolates tested.

scholarly journals Investigation of antimicrobial activity of polyphenol-enriched extracts against probiotic lactic acid bacteria

2019 ◽  
Vol 2 (1) ◽  
pp. 67
Author(s):  
Milena Dimitrova ◽  
Galin Ivanov ◽  
Kiril Mihalev ◽  
Alexander Slavchev ◽  
Ivelina Ivanova ◽  
...  
Keyword(s):  
Lactic Acid ◽  
Lactic Acid Bacteria ◽  
Food Industry ◽  
Lactobacillus Rhamnosus ◽  
Streptococcus Thermophilus ◽  
Starter Cultures ◽  
Lactobacillus Delbrueckii ◽  
Industrial Plant ◽  
Probiotic Lactic Acid Bacteria ◽  
By Products

The antimicrobial activity of polyphenol-enriched extracts from industrial plant by-products (strawberry and bilberry press residues and distilled rose petals) against probiotic lactic acid bacteria (Lactobacillus delbrueckii subsp. bulgaricus – S10 and S19; Lactobacillus rhamnosus – YW and S25; Lactobacillus gasseri – S20; Streptococcus thermophilus – S13 and S32) was investigated. The minimum inhibitory concentration (MIC) in most strains tested was found to be relatively high (from 6.25 mg.mL-1 to 12.50 mg.mL-1). The maximum concentration of polyphenols without inhibitory effect (MCWI) ranges from 0.390mg.mL-1 to 0.781mg.mL-1. The results obtained in the present study showed that among the tested lactic acid bacteria Lactobacillus delbrueckii subsp. bulgaricus – S19, Lactobacillus rhamnosus – YW and Streptococcus thermophilus – S13 had the best growth characteristics in polyphenol-enriched culture medium. These strains had the highest MIC and MCWI values and could be used as starter cultures for polyphenol-fortified fermented milks. Practical applications: The use of polyphenol-enriched extracts from industrial plant by-products (waste) – distilled rose petals (by-products of rose oil production) and strawberry and bilberry press residues (by-products of fruit juice production) contribute for improving the economic effect and for solving environmental problems in food industry. Development of functional fermented milks with combination of probiotic starter cultures and polyphenol extracts is current and perspective direction of food industry.

scholarly journals Animal Rennets as Sources of Dairy Lactic Acid Bacteria

2014 ◽  
Vol 80 (7) ◽  
pp. 2050-2061 ◽  
Author(s):  
Margherita Cruciata ◽  
Ciro Sannino ◽  
Danilo Ercolini ◽  
Maria L. Scatassa ◽  
Francesca De Filippis ◽  
...  
Keyword(s):  
Lactic Acid ◽  
Lactic Acid Bacteria ◽  
16S Rrna ◽  
16S Rrna Gene ◽  
Streptococcus Thermophilus ◽  
Species Level ◽  
Lactobacillus Delbrueckii ◽  
Rrna Gene ◽  
Microbial Composition ◽  
Content Type

ABSTRACTThe microbial composition of artisan and industrial animal rennet pastes was studied by using both culture-dependent and -independent approaches. Pyrosequencing targeting the 16S rRNA gene allowed to identify 361 operational taxonomic units (OTUs) to the genus/species level. Among lactic acid bacteria (LAB),Streptococcus thermophilusand some lactobacilli, mainlyLactobacillus crispatusandLactobacillus reuteri, were the most abundant species, with differences among the samples. Twelve groups of microorganisms were targeted by viable plate counts revealing a dominance of mesophilic cocci. All rennets were able to acidify ultrahigh-temperature-processed (UHT) milk as shown by pH and total titratable acidity (TTA). Presumptive LAB isolated at the highest dilutions of acidified milks were phenotypically characterized, grouped, differentiated at the strain level by randomly amplified polymorphic DNA (RAPD)-PCR analysis, and subjected to 16S rRNA gene sequencing. Only 18 strains were clearly identified at the species level, asEnterococcus casseliflavus,Enterococcus faecium,Enterococcus faecalis,Enterococcus lactis,Lactobacillus delbrueckii, andStreptococcus thermophilus, while the other strains, all belonging to the genusEnterococcus, could not be allotted into any previously described species. The phylogenetic analysis showed that these strains might represent different unknown species. All strains were evaluated for their dairy technological performances. All isolates produced diacetyl, and 10 of them produced a rapid pH drop in milk, but only 3 isolates were also autolytic. This work showed that animal rennet pastes can be sources of LAB, mainly enterococci, that might contribute to the microbial diversity associated with dairy productions.

Production of natural folates by lactic acid bacteria starter cultures isolated from artisanal Argentinean yogurts

2012 ◽  
Vol 58 (5) ◽  
pp. 581-588 ◽  
Author(s):  
Jonathan Emiliano Laiño ◽  
Jean Guy LeBlanc ◽  
Graciela Savoy de Giori
Keyword(s):  
Lactic Acid ◽  
Folic Acid ◽  
Lactic Acid Bacteria ◽  
Culture Medium ◽  
Streptococcus Thermophilus ◽  
Starter Cultures ◽  
Lactobacillus Delbrueckii ◽  
Nonfat Milk ◽  
Native Strains ◽  
Lactobacillus Delbrueckii Subsp

Folate is a B-group vitamin that cannot be synthesized by humans and must be obtained exogenously. Although some species of lactic acid bacteria (LAB) can produce folates, little is known about the production of this vitamin by yogurt starter cultures. Lactobacillus delbrueckii subsp. bulgaricus and Streptococcus thermophilus strains were isolated from artisanal Argentinean yogurts and were grown in folate-free culture medium (FACM) and nonfat milk after which intracellular and extracellular folate production were evaluated. From the initial 92 isolated LAB strains, 4 L. delbrueckii subsp. bulgaricus and 32 S. thermophilus were able to grow in the absence of folate. Lactobacillus delbrueckii subsp. bulgaricus CRL 863 and S. thermophilus CRL 415 and CRL 803 produced the highest extracellular folate levels (from 22.3 to 135 µg/L) in FACM. In nonfat milk, these strains were able to increase the initial folate concentrations by almost 190%. This is the first report where native strains of L. delbrueckii subsp. bulgaricus were shown to produce natural folate. The LAB strains identified in this study could be used in developing novel fermented products bio-enriched in natural folates that could in turn be used as an alternative to fortification with the controversial synthetic chemical folic acid.

scholarly journals Selection of Lactic Acid Bacteria for the Optimized Production of Sheep’s Milk Yogurt with a High Conjugated Linoleic Acid Content

2017 ◽  
Vol 6 (4) ◽  
pp. 44 ◽  
Author(s):  
Gabriela Christina Kuhl ◽  
Ana Paula Gusso ◽  
Brenda Lee Simas Porto ◽  
Carmen Maria Olivera Müller ◽  
Ricardo Ruiz Mazzon ◽  
...  
Keyword(s):  
Lactic Acid ◽  
Linoleic Acid ◽  
Lactic Acid Bacteria ◽  
Conjugated Linoleic Acid ◽  
Streptococcus Thermophilus ◽  
Linoleic Acid Content ◽  
Fractional Factorial ◽  
Lactobacillus Delbrueckii ◽  
Bacterial Strains ◽  
Sheep Milk

Thirty-five different lactic acid bacteria (LAB) strains were screened for their conjugated linoleic acid (CLA) isomers (C18:2 cis-9, trans-11 and C18:2 trans-10, cis-12) producing ability from linoleic acid (LA) in sheep’s milk. Preliminary experiments revealed that Lactobacillus delbrüeckii ssp. bulgaricus 2230 and Streptococcus thermophilus St 360 among the screened strains had the highest CLA-producing ability. This two strains were assayed in an 11-run fractional factorial design to investigate the effect of four variables included glucose, powdered sheep milk, LA and inoculum ratio on CLA production in a sheep’s milk yogurt. The optimum conditions for producing the highest levels of CLA (42.86%) were obtained by adding 10.00 mg/mL of glucose, 30.00 mg/mL of powdered sheep milk, 0.90 mg/mL of LA and a 1:2 (St:Lb) ratio of bacterial strains in the inoculum. This CLA-rich sheep’s milk yogurt could be an important supplementary food source for increasing the CLA in the human diet. 

Influence of ions on growth and production of exopolysaccharides by Lactobacillus delbrueckii subsp. bulgaricus NCFB 2772

2000 ◽  
Vol 67 (1) ◽  
pp. 131-135 ◽  
Author(s):  
GERT J. GROBBEN ◽  
INGEBORG C. BOELS ◽  
JAN SIKKEMA ◽  
MARK R. SMITH ◽  
JAN A. M. DE BONT
Keyword(s):  
Lactic Acid ◽  
Lactic Acid Bacteria ◽  
Streptococcus Thermophilus ◽  
Defined Medium ◽  
Lactobacillus Delbrueckii ◽  
Sugar Composition ◽  
Carbohydrate Source ◽  
Medium Components ◽  
Number Of Factors ◽  
Initial Ph

Several lactic acid bacteria produce exopolysaccharides (EPS), either attached to the cell wall or excreted into the environment as slime material. EPS produced by Lactobacillus delbrueckii subsp. bulgaricus (Lb. bulgaricus) and Streptococcus thermophilus play an important role in improving the texture and stability of yogurt and preventing syneresis (Cerning, 1990; Nakajima et al. 1990). The amount and composition of the EPS produced by lactic acid bacteria are dependent on a number of factors, such as temperature, initial pH, carbon source and the availability of minerals, vitamins and other medium components.In previous work it was shown that the production and sugar composition of the EPS from Lb. bulgaricus NCFB2772 are affected by the carbohydrate source (Grobben et al. 1995, 1996). In a simplified defined medium, from which several vitamins and trace elements were omitted, EPS production by Lb. bulgaricus significantly increased, although growth of the strain was reduced (Grobben et al. 1998).

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