The tables of data from the gassy cheese article.Table 1. Major microbial groups that can produce gas in cheese |
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Microbial group |
Substrate |
Gaseous products |
Clostridia |
Lactate |
CO2, H2 |
Lactobacilli |
Lactose Citrate |
CO2 |
Streptococci |
Urea |
CO2 |
Coliforms |
Lactose |
CO2, H2 |
Yeasts |
Lactose |
CO2 |
Lactococci |
Citrate |
CO2 |
Bacillus species |
Lactose |
CO2, H2 |
Leuconostocs |
Lactose/citrate |
CO2 |
Propionibacteria |
Lactate |
CO2 |
Notes:1 Streptococcus thermophilus can also produce gas from other substrates.
Table 2. Microbiological analysis of blown and normal cheese from factory X |
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CFU/g |
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Blown cheese-A |
Blown cheese-B |
Normal cheese |
|
'Total count' on milk agar |
1.3 x 10 8 |
6 x 107 |
2 x 107 |
Yeasts and moulds |
<10 |
<10 |
<10 |
Coliforms |
<10 |
<10 |
<10 |
Catalase-negative citrate utilisers(1) |
8 x 107 |
4 x 107 |
<1 x 106 |
Clostridia |
<1 x 10 2 |
<1 x 102 |
<1 x 102 |
Group D streptococci |
<1 x 102 |
1.3 x 103 |
2 x 102 |
Lactobacilli(2) |
4.1 x 104 |
4.1 x 105 |
1 x 103 |
Aerobic sporeformers |
1 x 102 |
1 x 102 |
1 x 102 |
Notes:
All cheeses were obtained from the same commercial plant and from the same production run.
Cheeses had been held at 7°C for 8 weeks after manufacture before sampling. Moisture, pH and salt
levels were within acceptable limits and similar in all samples.
(1)Determined using differential agar media13,14.
(2) Determined using Rogosa agar15
TABLE 3. Relationship between citrate level in cheese, ex-press, and gas production in Cheddar cheese |
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Days after manufacture |
Starter code |
Milk citrate level (% w/w) |
Cheese citrate level(2) (% w/w) |
Condition of barrier bag(3) |
1 |
1607 |
ND |
0.05 |
Blown |
3 |
1607 |
ND |
< 0.001 |
Slack |
15 |
1607 |
0.17 |
0.09 |
Blown |
29 (vat 1) |
1607 |
0.17 |
0.01 |
Blown |
29 (vat 3) |
SLA(1) |
0.17 |
0.21 |
Blown |
53 |
MS(1) |
0.17 |
0.19 |
Tight, no gas |
60 |
1607 |
0.18 |
0.14 |
Blown |
Notes: |
TABLE 4. Characteristics of Rogosa-agar isolates from a commercial mixed-strain culture |
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Isolate |
HM8/4 |
HM8/11 |
HM8/10 |
HM8/14 |
Morphology |
Cocco/ bacillus |
Cocco/ bacillus |
Cocco/ bacillus |
Cocco/ bacillus |
Gram reaction |
+ |
+ |
+ |
+ |
Catalase |
- |
- |
- |
- |
NH3 from arginine |
- |
- |
- |
- |
Nitrate reduction |
- |
- |
- |
- |
Lactic acid (isomer present) |
(D) |
(D) |
(D) |
(D) |
Acid produced in RSM(1) |
0.25% |
0.20% |
0.48% |
0.39% |
Gas from glucose |
+ |
+ |
+ |
+ |
Gas from gluconate |
+ |
+ |
+ |
+ |
Acid from arabinose |
- |
- |
- |
- |
Acid from xylose |
(+) |
- |
(-) |
+ |
Acid from maltose |
+ |
+ |
+ |
+ |
Growth at 40ºC |
- |
- |
- |
- |
Growth at 10ºC |
+ |
+ |
+ |
+ |
Growth at 6ºC |
- |
+ |
+ |
- |
Growth in 6% NaCl |
+ |
+ |
+ |
+ |
Growth in 6.5% NaCl |
- |
- |
- |
- |
Citrate utilisation |
+ |
+ |
+ |
+ |
TABLE 5. Maximum volumes 1,2 (L) of carbon dioxide available from citrate and lactose in cheese (3) |
% substrate (w/w) |
Volume of CO2(1) |
|
Citrate(4) |
Lactose(5) |
|
0.8 |
NC |
18.8 |
0.5 |
NC |
11.8 |
0.2 |
12.6 |
4.7 |
0.1 |
6.3 |
2.4 |
0.02 |
1.3 |
0.48 |
Notes: |