scholarly journals Contribution of Lactococcus lactis Cell Envelope Proteinase Specificity to Peptide Accumulation and Bitterness in Reduced-Fat Cheddar Cheese

2002 ◽  
Vol 68 (4) ◽  
pp. 1778-1785 ◽  
Author(s):  
Jeffery R. Broadbent ◽  
Mary Barnes ◽  
Charlotte Brennand ◽  
Marie Strickland ◽  
Kristen Houck ◽  
...  
Keyword(s):  
Lactococcus Lactis ◽  
Cell Envelope ◽  
Cheddar Cheese ◽  
Gene Replacement ◽  
Reversed Phase ◽  
Reduced Fat ◽  
Key Factor ◽  
Industrial Strains ◽  
Group A ◽  
Or Gene

ABSTRACT Bitterness is a flavor defect in Cheddar cheese that limits consumer acceptance, and specificity of the Lactococcus lactis extracellular proteinase (lactocepin) is widely believed to be a key factor in the development of bitter cheese. To better define the contribution of this enzyme to bitterness, we investigated peptide accumulation and bitterness in 50% reduced-fat Cheddar cheese manufactured with single isogenic strains of Lactococcus lactis as the only starter. Four isogens were developed for the study; one was lactocepin negative, and the others produced a lactocepin with group a, e, or h specificity. Analysis of cheese aqueous extracts by reversed-phase high-pressure liquid chromatography confirmed that accumulation of αS1-casein (f 1-23)-derived peptides f 1-9, f 1-13, f 1-16, and f 1-17 in cheese was directly influenced by lactocepin specificity. Trained sensory panelists demonstrated that Cheddar cheese made with isogenic starters that produced group a, e, or h lactocepin was significantly more bitter than cheese made with a proteinase-negative isogen and that propensity for bitterness was highest in cells that produced group h lactocepin. These results confirm the role of starter proteinase in bitterness and suggest that the propensity of some industrial strains for production of the bitter flavor defect in cheese could be altered by proteinase gene exchange or gene replacement.

Water-soluble peptides in Cheddar cheese: isolation and identification of peptides in the diafiltration retentate of the water-soluble fraction

1995 ◽  
Vol 62 (4) ◽  
pp. 629-640 ◽  
Author(s):  
Tanoj K. Singh ◽  
Patrick F. Fox ◽  
Áine Healy
Keyword(s):  
Cell Envelope ◽  
Deae Cellulose ◽  
Cheddar Cheese ◽  
Reversed Phase ◽  
Amino Acid Sequences ◽  
Water Soluble ◽  
Isolation And Identification ◽  
Terminal Amino ◽  
Water Soluble Extract ◽  
Β Lactoglobulin

SUMMARYThe water-soluble extract of Cheddar cheese was fractionated by diafiltration using 10 kDa cut-off membranes. Peptides were isolated from the diafiltrate retentate by chromatography on DEAE-cellulose with a linear NaCl gradient in 50 mM-Tris-HCl, pH 8·6, and reversed-phase HPLC or electroblotting from urea-PAGE gels. Peptides were identified by determining N-terminal amino acid sequences and mass spectrometry. Most (45) of the total 51 peptides identified in the diafiltrate retentate originated from β-casein, especially from a short region in the N-terminal half of the molecule. Only six peptides originated from αs1-casein; β-lactoglobulin was also identified in the retentate. The origin of most of these peptides could be explained on the basis of known specificities of lactococcal cell envelope proteinases.

scholarly journals Altered Specificity of Lactococcal Proteinase PI(Lactocepin I) in Humectant Systems Reflecting the Water Activity and Salt Content of Cheddar Cheese

1998 ◽  
Vol 64 (2) ◽  
pp. 588-593 ◽  
Author(s):  
Julian R. Reid ◽  
Tim Coolbear
Keyword(s):  
Enzyme Activity ◽  
Polyethylene Glycol ◽  
Lactococcus Lactis ◽  
Water Activity ◽  
Cell Envelope ◽  
Salt Content ◽  
Cheddar Cheese ◽  
Major Product ◽  
Cheese Ripening ◽  
Hydrolysis Of

ABSTRACT By using various humectant systems, the specificity of hydrolysis of αs1-, β-, and κ-caseins by the cell envelope-associated proteinase (lactocepin; EC 3.4.21.96 ) with type P1 specificity (i.e., lactocepin I) from Lactococcus lactis subsp. lactis BN1 was investigated at water activities (aw) and salt concentrations reflecting those in cheddar type cheese. In the presence of polyethylene glycol 20000 (PEG 20000)-NaCl (aw = 0.95), hydrolysis of β-casein resulted in production of the peptides comprising residues 1 to 6 and 47 to 52, which are characteristic of type PIII enzyme activity (lactocepin III) in buffer. The fragment comprising residues 1 through 166, inclusive (fragment 1-166), which is typical of lactocepin I activity in buffer systems, was not produced. Similarly, peptide 152-160 from κ-casein, which is usually produced in aqueous buffers exclusively by lactocepin III, was a major product of lactocepin I. Most of the specificity differences obtained in the presence of PEG 20000-NaCl were also obtained in the presence of PEG 20000 alone (aw = 0.99). In addition, αs1-casein, which normally is resistant to lactocepin I activity, was rapidly hydrolyzed in the presence of PEG 20000 alone. Hydrolysis of casein in the presence of PEG 300-NaCl or glycerol-NaCl (both having an aw of 0.95) was generally as expected for lactocepin I activity except that β-casein peptide 47-52 and κ-casein fragment 1-160 were produced; both of these are normally formed by lactocepin III in buffer. The differences in lactocepin specificity obtained in the humectant systems can be attributed to a combination of aw and humectant hydrophobicity, both of which are parameters that are potentially relevant to the cheese-ripening environment.

scholarly journals Impact of Nisin and Nisin-Producing Lactococcus lactis ssp. lactis on Clostridium tyrobutyricum and Bacterial Ecosystem of Cheese Matrices

Foods ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 898
Author(s):  
Hebatoallah Hassan ◽  
Daniel St-Gelais ◽  
Ahmed Gomaa ◽  
Ismail Fliss
Keyword(s):  
Lactococcus Lactis ◽  
Cheddar Cheese ◽  
Economic Loss ◽  
Gas Production ◽  
Clostridium Tyrobutyricum ◽  
Nisin Production ◽  
Genus Clostridium ◽  
Milk Pasteurization ◽  
Cheese Slurry ◽  
Significant Economic Loss

Clostridium tyrobutyricum spores survive milk pasteurization and cause late blowing of cheeses and significant economic loss. The effectiveness of nisin-producing Lactococcus lactis ssp. lactis 32 as a protective strain for control the C. tyrobutyricum growth in Cheddar cheese slurry was compared to that of encapsulated nisin-A. The encapsulated nisin was more effective, with 1.0 log10 reductions of viable spores after one week at 30 °C and 4 °C. Spores were not detected for three weeks at 4 °C in cheese slurry made with 1.3% salt, or during week 2 with 2% salt. Gas production was observed after one week at 30 °C only in the control slurry made with 1.3% salt. In slurry made with the protective strain, the reduction in C. tyrobutyricum count was 0.6 log10 in the second week at 4 °C with both salt concentration. At 4 °C, nisin production started in week 2 and reached 97 µg/g after four weeks. Metabarcoding analysis targeting the sequencing of 16S rRNA revealed that the genus Lactococcus dominated for four weeks at 4 °C. In cheese slurry made with 2% salt, the relative abundance of the genus Clostridium decreased significantly in the presence of nisin or the protective strain. The results indicated that both strategies are able to control the growth of Clostridium development in Cheddar cheese slurries.

The influence of milk pasteurization temperature and pH at curd milling on the composition, texture and maturation of reduced fat cheddar cheese

1998 ◽  
Vol 51 (1) ◽  
pp. 1-10 ◽  
Author(s):  
T P GUINEE ◽  
M A FENELON ◽  
E O MULHOLLAND ◽  
B T O'KENNEDY ◽  
N O'BRIEN ◽  
...  
Keyword(s):  
Cheddar Cheese ◽  
Reduced Fat ◽  
Milk Pasteurization

Improvement of sensory quality of reduced fat Cheddar cheese by a Lactobacillus adjunct

1997 ◽  
Vol 30 (1) ◽  
pp. 35-40 ◽  
Author(s):  
M.A. Drake ◽  
T.D. Boylston ◽  
K.D. Spence ◽  
B.G. Swanson
Keyword(s):  
Sensory Quality ◽  
Cheddar Cheese ◽  
Reduced Fat

Varying influence of the autolysin, N-acetyl muramidase, and the cell envelope proteinase on the rate of autolysis of six commercial Lactococcus lactis cheese starter bacteria grown in milk

2000 ◽  
Vol 67 (4) ◽  
pp. 585-596 ◽  
Author(s):  
SELVARANI GOVINDASAMY-LUCEY ◽  
PRAMOD K. GOPAL ◽  
PATRICK A. SULLIVAN ◽  
CHRISTOPHER J. PILLIDGE
Keyword(s):  
Lactococcus Lactis ◽  
Cell Walls ◽  
Cell Envelope ◽  
Laboratory Strain ◽  
Proteolytic Cleavage ◽  
Zymogram Analysis ◽  
Sds Page ◽  
Derivatives Of ◽  
Free Strains

The autolysin, N-acetyl muramidase (AcmA), of six commercial Lactococcus lactis subsp. cremoris starter strains and eight Lc. lactis subsp. cremoris derivatives or plasmid-free strains was shown by renaturing SDS-PAGE (zymogram analysis) to be degraded by the cell envelope proteinase (lactocepin; EC 3.4.21.96) after growth of strains in milk at 30 °C for 72 h. Degradation of AcmA was less in starter strains and derivatives producing lactocepin I/III (intermediate specificity) than in strains producing lactocepin I. This supports previous observations on AcmA degradation in derivatives of the laboratory strain Lc. lactis subsp. cremoris MG1363 (Buist et al. Journal of Bacteriology180 5947–5953 1998). In contrast to the MG1363 derivatives, however, the extent of autolysis in milk of the commercial Lc. lactis subsp. cremoris starter strains in this study did not always correlate with lactocepin specificity and AcmA degradation. The distribution of autolysins within the cell envelope of Lc. lactis subsp. cremoris starter strains and derivatives harvested during growth in milk was compared by zymogram analysis. AcmA was found associated with cell membranes as well as cell walls and some cleavage of AcmA occurred independently of lactocepin activity. An AcmA product intermediate in size between precursor (46 kDa) and mature (41 kDa) forms of AcmA was clearly visible on zymograms, even in the absence of lactocepin I activity. These results show that autolysis of commercial Lc. lactis subsp. cremoris starter strains is not primarily determined by AcmA activity in relation to lactocepin specificity and that proteolytic cleavage of AcmA in vivo is not fully defined.

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