Dairy Science and Food Technology

Scientific, information & consultancy services for the food industry

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DSFT has been providing science based consultancy services globally since 2002.
  
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The Dairy Science and Food Technology (DSFT) website provides scientific and technological information, Cloud-based tools and consultancy services for food scientists and technologists working in industry and in colleges and universities. A discussion forum and interactive content through "On Line" calculators are also provided. Writing/citation resources including a Harvard-type reference wizard and a range of citation-wizards can also be accessed.

There are sections on starter cultures, probiotics, cheese science and technology, bioactive peptides, ice cream, wine making, modelling in food technology, thermal processing and modified atmosphere packaging and labelling. Some general health information including reference to allergy and food intolerance is also presented.

PLGYG BROTH

PLGYG is based on the GT medium of Douglas et al (1974) and on MRS broth (de Man, Rogosa and Sharpe, 1960). The composition of PLGYG is given below:

Ingredient

g/Litre

Oxoid Bacteriological Peptone

10.0

Glucose*

10.0

Oxoid Lab Lemco

10.0

Oxoid Yeast Extract

5.0

b-disodium glycerophosphate (Sigma, Grade II)

7.2

pH (after autoclaving) 6.8

 
*Note for best results the glucose and glycerophosphate components should be sterilised separately and added to the sterile basal medium aseptically.


M17 BROTH

M17 broth was developed by Terzaghi and Sandine (1975). The composition of M17 broth is given below:

Ingredient

g/Litre

BBL Peptone

5.0

BBL Phytone Peptone

5.0

Oxoid Lab Lemco

5.0

Oxoid Yeast Extract

5.0

Lactose*

5.0

b-Disodium Glycerophosphate (Sigma, Grade II)

19.0

Ascorbic Acid

0.5

1 ml of 1M MgSO4

0.5

*Note for best results the lactose and glycerophosphate components should be sterilised separately and added to the sterile basal medium aseptically.

Both broth media should be sterilised at 121° C (15 pounds per square inch (psi) ) for 15 min in small portable autoclaves or at 10 psi (110° C) for 15 min in large autoclaves which longer `come up' and 'come down' times. The reduced time in the larger autoclave is necessary since media containing glycerophosphate are moderately heat sensitive.

Ideally the sugar and glycerophosphate component should be sterilised separately and added to the other sterile medium constituents aseptically.

LITERATURE CITED

de Man, J.C., Rogosa, M. and Sharpe, E. (1960). Medium for the cultivation of Lactobacilli. J. Appl. Bacteriol. 23, 103-135.

Douglas, J., Qanber-Agha, a. and Phillips, V. (1974). Medium for the propagation and assay of lactic and other phages. Lab. Practice 23, 3-5.

Mullan, W.M.A., Daly, C. and Fox, P.F. (1981). Effect of cheesemaking temperatures on the interactions of lactic streptococci and their phages. J. Dairy Res. 48, 465-471.

Terzaghi, B.E. and Sandine, W.E. (1975). Improved medium for lactic streptococci and their bacteriophages. Appl. Microbiol. 29, 807-813.

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