scholarly journals Conversion of Methionine to Thiols by Lactococci, Lactobacilli, and Brevibacteria

1998 ◽  
Vol 64 (9) ◽  
pp. 3320-3326 ◽  
Author(s):  
Benjamin Dias ◽  
Bart Weimer
Keyword(s):  
Lactic Acid ◽  
Lactic Acid Bacteria ◽  
Growth Medium ◽  
Cheddar Cheese ◽  
Sulfur Amino Acids ◽  
Aminotransferase Activity ◽  
Brevibacterium Linens ◽  
Whole Cells ◽  
Cell Extracts ◽  
The Matrix

ABSTRACT Methanethiol has been strongly associated with desirable Cheddar cheese flavor and can be formed from the degradation of methionine (Met) via a number of microbial enzymes. Methionine γ-lyase is thought to play a major role in the catabolism of Met and generation of methanethiol in several species of bacteria. Other enzymes that have been reported to be capable of producing methanethiol from Met in lactic acid bacteria include cystathionine β-lyase and cystathionine γ-lyase. The objective of this study was to determine the production, stability, and activities of the enzymes involved in methanethiol generation in bacteria associated with cheese making. Lactococci and lactobacilli were observed to contain high levels of enzymes that acted primarily on cystathionine. Enzyme activity was dependent on the concentration of sulfur amino acids in the growth medium. Met aminotransferase activity was detected in all of the lactic acid bacteria tested and α-ketoglutarate was used as the amino group acceptor. In Lactococcus lactis subsp. cremorisS2, Met aminotransferase was repressed with increasing concentrations of Met in the growth medium. While no Met aminotransferase activity was detected in Brevibacterium linens BL2, it possessed high levels of l-methionine γ-lyase that was induced by addition of Met to the growth medium. Met demethiolation activity at pH 5.2 with 4% NaCl was not detected in cell extracts but was detected in whole cells. These data suggest that Met degradation in Cheddar cheese will depend on the organism used in production, the amount of enzyme released during aging, and the amount of Met in the matrix.

Lactic Acid Bacteria in Cheddar Cheese Made with Sodium Chloride, Potassium Chloride or Mixtures of the Two Salts

1995 ◽  
Vol 58 (1) ◽  
pp. 62-69 ◽  
Author(s):  
K. ANJAN REDDY ◽  
ELMER H. MARTH
Keyword(s):  
Lactic Acid ◽  
Sodium Chloride ◽  
Lactic Acid Bacteria ◽  
Potassium Chloride ◽  
Starter Culture ◽  
Cheddar Cheese ◽  
Starter Cultures ◽  
Detectable Effect ◽  
Agar Media ◽  
Cheese Curd

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.

scholarly journals Encapsulation of a Lactic Acid Bacteria Cell-Free Extract in Liposomes and Use in Cheddar Cheese Ripening

Foods ◽  
2013 ◽  
Vol 2 (1) ◽  
pp. 100-119 ◽  
Author(s):  
Alice Nongonierma ◽  
Magdalena Abrlova ◽  
Kieran Kilcawley
Keyword(s):  
Lactic Acid ◽  
Lactic Acid Bacteria ◽  
Cheddar Cheese ◽  
Cell Free Extract ◽  
Cheese Ripening

scholarly journals Nonstarter Lactic Acid Bacteria Biofilms and Calcium Lactate Crystals in Cheddar Cheese

2006 ◽  
Vol 89 (5) ◽  
pp. 1452-1466 ◽  
Author(s):  
S. Agarwal ◽  
K. Sharma ◽  
B.G. Swanson ◽  
G.Ü. Yüksel ◽  
S. Clark
Keyword(s):  
Lactic Acid ◽  
Lactic Acid Bacteria ◽  
Cheddar Cheese ◽  
Calcium Lactate ◽  
Nonstarter Lactic Acid Bacteria

104. Studies in Cheddar Cheese. IV. Observations on the Lactic Acid Flora of Cheddar Cheese made from Clean Milk

1935 ◽  
Vol 6 (2) ◽  
pp. 175-190 ◽  
Author(s):  
John Gilbert Davis
Keyword(s):  
Lactic Acid ◽  
Lactic Acid Bacteria ◽  
Osmotic Pressure ◽  
Slow Growth ◽  
Carbon Sources ◽  
Lactate Concentration ◽  
Cheddar Cheese ◽  
Titratable Acidity ◽  
Distinct Species ◽  
Litmus Milk

1. The lactic acid flora of Cheddar cheese made from milk of certified quality form a well-defined, physiologically homogeneous group of bacteria, growing best over a temperature range of from 22 to 37° C. They may be classified into four well-defined types, Str. lactis, Str. cremoris, Sbm. plantarum and Sbm. casei, and have been studied over a period of five years. It appears from the evidence found that Str. lactis and Str. cremoris are distinct species, but that Sbm. casei and Sbm. plantarum represent different stages in the adaptation of a common progenitor to conditions in a ripening cheese. Both the streptococci and the streptobacteria appear to be unable to oxidise sugars and may thus be considered indifferent to molecular oxygen.2. A study of their frequency distribution from the curd at making to an 18 months old cheese has shown that Str. lactis and Str. cremoris are equally viable during the first month, after which the rod forms begin to predominate, Sbm. plantarum and, later, Sbm. casei being found. The former lactobacillus is only found when the cheese is from 1 to 5 months old, the flora consisting entirely of Sbm. casei after this time. The general vigour of all strains decreases with increasing age of the cheese. There is a marked correlation between the shape of the cell, the viability of the organism in cheese and its resistance to acids and lactates.3. The factors controlling the sequence of flora in Cheddar cheese are discussed. There is no evidence that titratable acidity, oxygen tension and differential carbon sources are responsible for the sequence. It is suggested that lactate concentration, the extent of protein degradation and osmotic pressure are factors responsible for the gradual replacement of the streptococci by the rod forms.4. The significance of sugar fermentations by the lactic 'acid bacteria studied is discussed. The slow production of lactase is shown to be the reason for the slow growth of weakened strains in litmus milk.5. Str. cremoris predominates over Str. lactis in the depth of the cheese in the early stages of ripening, whereas near the surface the reverse holds. Certain strains of Str. cremoris isolated from the depth of the cheese were particularly vigorous in growth in litmus milk, forming gas and beginning to peptonise the milk in about 3 days. Such strains consisted of very long chains of large cells of peculiar morphology. It is suggested that this finding is related to the known greater rate of ripening in the depth of the cheese.

Aminopeptidase Activities of Starter and Non-Starter Lactic Acid Bacteria under Simulated Cheddar Cheese Ripening Conditions

1998 ◽  
Vol 8 (4) ◽  
pp. 267-274 ◽  
Author(s):  
Harry Laan ◽  
Saw Eng Tan ◽  
Paul Bruinenberg ◽  
Gaëtan Limsowtin ◽  
Malcolm Broome
Keyword(s):  
Lactic Acid ◽  
Lactic Acid Bacteria ◽  
Cheddar Cheese ◽  
Cheese Ripening
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