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The tables of data from the gassy cheese article.

 

Table 1. Major microbial groups that can produce gas in cheese

Microbial group

Substrate

Gaseous products

Clostridia
  Clostridium tyrobutyricum

Lactate

CO2, H2

Lactobacilli
  E.g. Lactobacillus brevis
  E.g. Lactobacillus casei

Lactose

Citrate

CO2

Streptococci
  Streptococcus thermophilus1

Urea

CO2

Coliforms

Lactose

CO2, H2

Yeasts

Lactose

CO2

Lactococci
 Lactococcus lactis ssp. lactis biovar. diacetylactis

Citrate

CO2

Bacillus species
  Bacillus subtilis

Lactose

CO2, H2

Leuconostocs
  E.g. Leuconostoc mesenteroides
  E.g. Leuconostoc dextranicum

Lactose/citrate

CO2

Propionibacteria
  Propionibacterium shermani

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

 

CFU/g

 

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

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:

(1) Defined multi-strain cultures that did not contain citrate utilising strains.
(2) Cheese analysed immediately after pressing for citrate (12 hours).
(3) Cheese was stored at 7C for 6 weeks before examination.
ND - not determined

 

TABLE 4.   Characteristics of Rogosa-agar isolates from a commercial mixed-strain   culture

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:

(1) Volumes at standard temperature and pressure (STP)
(2) No allowance made for adsorption/solution. Values are rounded
(3) Cheese mass 18 kg
(4) Assuming 3 moles of CO2 produced from 1 mole citrate
(5) Assuming 2 moles of CO2 produced from 1 mole lactose
NC. Not calculated. Citrate levels of >0.2% w/w are not normally found in Cheddar cheese.

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